Selection and maintenance of conveyorbelts for transportation of coal in mines

Item Type text; Thesis-Reproduction (electronic)

Authors Pundari, Nagubandi, 1933-

Publisher The University of Arizona.

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SELECTION AND MAINTENANCE OF CONVEYOR BELTS

FOR TRANSPORTATION OF COAL IN MINES

by

Nagubandi Pundarl

A T h esis Subm itted to th e F a c u lty o f th e

DEPARTMENT OF MINING ENGINEERING

In P a r t i a l F u lf i l lm e n t of th e R equirem ents

For th e D egree of

MASTER OF SCIENCE

In th e G raduate C ollege

THE UNIVERSITY OF ARIZONA

1962

STATEMENT BY THE AUTHOR

T his th e s i s has been subm itted in p a r t i a l f u l ­f i l lm e n t of req u irem e n ts f o r an advanced d eg ree a t th e U n iv e rs ity of A rizona and i s d ep o s ited in th e U n iv e rs ity L ib ra ry to be made a v a i la b le to borrow ers under r u le s of th e L ib ra ry .

B r ie f q u o ta tio n s from t h i s t h e s i s a re a llo w ab le w ith o u t s p e c ia l p e rm iss io n p rov ided th a t a c c u ra te acknow­ledgm ent of sou rce i s made. R equests f o r p e rm iss io n fo r ex tended q u o ta tio n from or re p ro d u c tio n of t h i s m anuscrip t in whole or in p a r t may be g ran te d by th e head of th e m ajor departm ent o r th e Dean o f th e G raduate C ollege when in t h e i r judgment th e proposed u se of th e m a te r ia l i s in th e i n t e r e s t s o f s c h o la r s h ip . In a l l o th e r in s ta n c e s , however, p e rm iss io n must be o b ta in ed from th e a u th o r .

SIGNED:

APPROVAL BY THESIS DIRECTOR

T his th e s i s has been approved on th e d a te shown below:

H. Ev. KRUMLAUF // P ro fe sso r of Mining E n g in eerin g

f Dat e

SELECTION AND1MAINTENANCE OF CONVEYOR BELTS

FOR TRANSPORTATION OF COAL IN MINES

r ' By • . ‘ r o . - ; :',c

' N. P undarl - f

v.: ;■ c ' :/ • 1 • .. : : " \o:', c. " J' ; .ABSTRACT

The f a c to r s t h a t a f f e c t th e s e le c t io n of p ro p er

b e l t in g f o r t r a n s p o r ta t io n of c o a l in mines a re d isc u sse d

in d e t a i l . The c o r r e c t d es ig n in g o f b e l t s to g e th e r w ith

c a r e fu l i n s t a l l a t i o n and m aintenance o f conveyors a re

s t r e s s e d . •' ' ■" - ■ : ; • . ■ .: ,

Model te ch n iq u e s of s e le c t in g p roper b e l t in g under

th e s p e c if ie d c o n d itio n s and of e s tim a tin g c o s ts of owning

and o p e ra tin g b e l t hau lage equipm ent a re developed and

i l l u s t r a t e d th ro u g h th e use of sample p rob lem s. A lso ,

ty p ic a l c o s t c h a r a c t e r i s t i c cu rves f o r c o n v e n tio n a l b e l t

hau lage system s a re c o n s tru c te d ; and methods f o r red u cin g

conveyor hau lage c o s ts a re enum erated. C onclusions r e ­

gard ing cho ice of i n s t a l l i n g b e l t conveyors and t h e i r

econom ical f e a tu r e s a re drawn. S uggestions f o r f u tu r e

s tudy of d i f f e r e n t k in d s of conveyor hau lage system s a re

l i s t e d .

i i

ACKNOWLEDGMENTS

The au th o r ta k e s t h i s o p p o rtu n ity to ex p ress h is

deep sense of g r a t i tu d e to th e fo llo w in g members of th e

f a c u l ty o f ; th e U n iv e rs ity o f A rizona, Tucson, A rizona, f o r

s t im u la tin g rs u g g e s t io n s and c o n s tru c tiv e c r i t i c i s m s du ring

th e cou rse of-, t h i s • s tudy and in th e p re p a ra t io n of t h i s

m an u scrip t:

H. E.i Krumlauf , P ro fe s s o r of M ining• E n g in ee rin g ;

and E. R. D revdahl and J . C. D otson, A sso c ia te P ro fe s s o rs

of Mining E n g in ee rin g .r;.7

The au th o r i s g r a te f u l to h is b r o th e r , Mr. N.

R anganayakulu, D ornakal, I n d ia , . f o r , f i n a n c i a l a s s is ta n c e

to u n d ertak e t h i s G raduate Study a t th e U n iv e rs ity of

A rizona., J

.... U .

i ' i i

TABLE OF CONTENTS

C hapter ! ; •- “ Page

I INTRODUCTION - - 1

I I REVIEW OF THE LITERATURE ' " v . . b_

E v o lu tio n o f conveyor b e l t hau lage systemin c o a l m ines 4

A dvantages of b e l t haulage system 10

F u tu re t r e n d s in b e l t hau lage system s * 13

I I I SELECTION OF BELT WIDTH AND SPEED ... . . . l8

IV DETERMINATION OF BELT HORSEPOWER REQUIREMENTS 24

Power to d r iv e th e empty b e l t . . . . 24k «•

Power to move m a te r ia l h o r iz o n ta l lyalong th e conveyor . . . . 28

Power to e le v a te or lower m a te r ia l or powerto be g en e ra ted in low ering i t 31

Power to d r iv e th e t r ip p e r . . . . 32

A c c e le ra tio n horsepow er . . . . 35

Summary o f b e l t horsepower c a lc u la t io n s 36

P e rm iss ib le an g le s of in c l in a t io n fo rh au lin g c o a l on b e l t s . . . . « 39

V SELECTION OF PROPER BELT . . . . 4 l

D ete rm in a tio n o f b e l t s t r e s s e s . . . . 42

D ete rm in a tio n of maximum number of p l i e s of b e l t s f o r p ro p er tro u g h in g and s t i f f n e s s . . . . 5l

i v

C h a p t e r

VI

VI I

V II I

D ete rm in a tio n o f s iz e of d r iv in g drums and p u lle y s ; , .

S e le c t io n o f p ro p er b e l t c o n s tru c tio n " : m a te r ia l • - . . .

S e le c t io n of p roper cover q u a l i ty and th ic k n e s s .

r -: . . .B e lt s e le c t io n problem s . . .

DISCUSSION ON BELT HAULAGE ECONOMICS AND - COST ESTIMATION . . . .

E s tim a tio n o f b e l t haulage c o s ts . . . .

Problem on c o s t e s tim a tio n o f b e l t • hau lage system . . . .

Cost c h a r a c t e r i s t i c s o f b e l t haulage system ' . •.

How to red u ce conveyor haulage c o s ts

INSTALLATION AND MAINTENANCE OF CONVEYOR BELTS FOR EFFICIENT OPERATION . . .

I n s t a l l a t i o n p rocedu re . . .

P ro te c t io n of b e l t s . . . .

B e lt m aintenance g u id es . . . .

CONCLUSIONS AND SUGGESTIONS'FOR FUTURE STUDY

BIBLIOGRAPHY AND SELECTED REFERENCES

• - _ j

53

5^

59

62

69

72

77

81

82

89

89

92

93

100

105

P a g e

v

LIST OF TABLES

T able Page

I Recommended b e l t speeds and a llo w ab le lu m p -s izes o f ru n -o f-m in e c o a l . . . . 23

I I V alues of com posite f r i c t i o n f a c t o r , C and c o n s ta n t , L0 . . . . 27

I I I V alues o f horsepower to d r iv e emptyconveyor . . . . 28

IV V alues o f h o r iz o n ta l horsepower to convey c o a l . . . . 30

V V alues of horsepower to e le v a te m a te r ia l 32

VI V alues of c o n s ta n t ,AI . . . . 3^

VI I Average t r ip p e r l i f t s . . . . 34

V III Maximum p e rm is s ib le an g le s of conveyor in c l in a t io n . . . . 40

DC V alues of c o e f f ic ie n t o f f r i c t i o n of b e l t s 45

X V alues of ,F* f a c to r . . . . 46

XI Maximum p e rm is s ib le te n s io n r a t in g s fo r d i f f e r e n t b e l t s . . . . 49

XI I Minimum p l i e s to su p p o rt lo ad and maximum p l i e s f o r p roper tro u g h in g . . . . 52

X II I Recommended conveyor top cover th ic k n e s s 62

LIST OF FIGURES

F ig u re Page

1 Ropenframe conveyor s t r u c tu r e . . . . 6

2 C a b le -b e lt conveyor d riv eh ead arrangem ent 9

3 C ro s s -s e c tio n of a loaded b e l t . . . . 22

4 B e lt te n s io n s in a runn ing b e l t . . . . 435 & 6 T y p ica l c o s t c h a r a c t e r i s t i c cu rves o f con­

v e n t io n a l b e l t hau lage sy s tem (rig id -fram e ty p e ) . . . . .

83 & 84

v i

................. CHAPTER I- . •» ' ■ ..

- , ,, INTRODUCTION

..In any b e l t hau lage system th e conveyor b e l t i s sub­

je c te d to th e g r e a t e s t s t r a i n , i s th e most e a s i ly damaged, i s

th e .m o st ex p en siv e , and has th e s h o r te s t l i f e o f any p a r t of

th e whole system . The b e l t i s th e on ly p a r t o f th e conveyor

which a c t u a l l y h and les th e m a te r ia l , and i s p r a c t i c a l l y th e

on ly item which has to be renew ed. The l i f e of th e b e l t , and

hence th e hau lage c o s t , depends on th e b e l t being c o r r e c t ly

s p e c if ie d f o r th e job and th e c a re and m aintenance th a t i t

r e c e iv e s . B e ltin g o f im proper d e s ig n to save f i r s t c o s t w i l l

have s h o r te r l i f e and g iv e s r i s e to h ig h e r hau lage c o s ts . I t

should be n o ted in t h i s co n n ec tio n th a t average conveyor

b e l t r e p r e s e n t s ap p ro x im ate ly h0% o f th e e n t i r e b e l t hau lage

i n s t a l l a t i o n .

The purpose o f t h i s s tu d y i s to d is c u s s a l l th e

f a c to r s t h a t a f f e c t th e s e le c t io n o f c o r r e c t b e l t in g f o r a

g iv en du ty and i t s good m ain tenance . P ro p e rly designed and

w e ll m ain ta ined b e l t s g iv e good perform ance a t low u n i t. • • - ••• ■ ■ ’ ‘ — *■' •"! V ’ * ’ l

c o s t s . The m ajor f a c t o r s e n te r in g in to p ro p er s e le c t io n of

conveyor b e l t s such as b e l t w id th , speed , c a p a c ity , c a rc a s s

q u a l i ty , te n s io n and horsepow er re q u ire m e n ts , cover q u a l i ty

and th ic k n e s s , economics and o th e r im p o rtan t f a c to r s a re

1

2

d isc u sse d In d e t a i l , i n t h i s t h e s i s . No a ttem p t has been .

made to compare th e u n i t c o s ts of c o a l t r a n s p o r ta t io n by

b e l t conveyors w ith t h a t o f . any o th e r system . I t i s con­

s id e re d in t h i s s tu d y th a t under c e r t a in c ircu m stan ces b e l t

conveyors a re e f f i c i e n t means of underground haulage when

p ro p e r ly d esig n ed and m a in ta in ed . . I t i s w ith t h i s assum ption

th a t a l l o th e r in v e s t ig a t io n s a re made.and im p o rtan t con­

c lu s io n s a re drawn.

O ther d e s ig n c o n s id e ra t io n s of b e l t hau lage system ,

such a s ty p e o f d r iv e s , takeup d e v ic e s , lo a d in g arran g em en ts,

ty p e of i d l e r s and t h e i r sp ac in g , and o th e r a u x i l ia r y equip­

ment re q u ire d have n o t been In v e s t ig a te d in t h i s s tu d y . A ll

of th e s e item s a re w e ll s ta n d a rd iz e d f o r any s p e c i f ic d u ty ,

and - i t i s on ly in th e s e le c t io n of c o s t ly b e l t s w here•m is­

ta k e s a re o f te n made. These m is tak es r e s u l t in i n e f f i c i e n t

b e l t o p e ra t io n and in c re a se d hau lage c o s ts . Hence th e im -

p o rtan c e of p ro p er b e l t s e le c t io n to g e th e r w ith p roper in ­

s t a l l a t i o n and good m aintenance a r e . s t r e s s e d in t h i s s tu d y ......... - r ' - - - - * ' - — 'v 1 ,■ r ■ , , .» v -■ . l v ,

More em phasis i s g iv en to s im p le , quick ' and c o r r e c t

methods of e s tim a tin g th e main s p e c i f ic a t io n s o f b e l t con­

v ey o rs f o r t r a n s p o r ta t io n o f ru n -o f-m in e c o a l in m ines. As

f a r as p o s s ib le th e u se of com plica ted c h a r ts and ta b le s

have been av o id ed . Most o f th e fo rm ulae used f o r d e te rm in in g

v a r io u s b e l t s p e c i f ic a t io n s a re n o t in ten d ed as a b a s is of

d e s ig n in g new i n s t a l l a t i o n s w ith o u t r e f e re n c e to th e

3

m a n u fa c tu re r , s su g g ested m ethod. The m anufac tu rer may p re ­

f e r to work ou t th e req u irem e n ts of th e system by an o th e r

method. The methods used in t h i s s tu d y fo r d e te rm in in g

c o r r e c t b e l t s p e c i f ic a t io n s a re v e ry h e lp fu l in o rd er to

d ec id e i f conveying i s p o s s ib le or s u i t a b le or econom ical

under c e r t a in s p e c if ie d c o n d it io n s . These methods a re a ls o

h e lp fu l to en ab le changes to be made econom ically in th e

e x is t in g conveyor hau lage system w ith o u t cau sin g undue b e l t

f a i l u r e s . The method of c a lc u la t io n s a re kep t as fundam ental

as p o s s ib le , and a l l s im p lify in g assum ptions and ap p ro x i­

m ations have been c l e a r ly s ta te d , so t h a t th e s e c a lc u la t io n s

can be m od ified to s u i t c o n d itio n s and ty p e s o f equipm ent

n o t s p e c if ie d in t h i s s tu d y .

I t i s hoped t h a t t h i s t h e s i s w i l l d em o stra te th e

ease w ith which r e l i a b l e methods of e s tim a tin g b e l t sp e c i­

f i c a t i o n s a re made a v a i la b le to th e r e a d e r . P r a c t i c a l

examples o f d e te rm in in g c o r r e c t b e l t s p e c i f ic a t io n s and c o s t

e s tim a tio n of a com plete b e l t haulage system a re g iv en to

a s s i s t in a b e t t e r u n d e rs tan d in g of th e p ro p er d e s ig n of

b e l t conveyors .

REVIEW OF THE LITERATURE

CHAPTER I I

EVOLUTION fig Tgg CONVEYOR BELT HAULAGE SYSTEM IN COAL

The t r a n s p o r ta t io n of m a te r ia l by b e l t conveyors was

f i r s t ex p lo red in th e m iddle of th e n in e te e n th c e n tu ry . By

1905 b e l t conveyors w ere being used underground in England

bu t were n o t in use in th e U nited S ta te s u n t i l abou t 1930.

They were o r ig in a l ly used in th e U nited S ta te s in p an e l

rooms to convey c o a l from th e fa c e to th e e n try and th e n to

c o l l e c t c o a l in e n t r i e s from ch a in to shaker co n v ey o rs .

D u rin g .t h i s p e r io d of e v o lu tio n many changes have

o ccu rred in th e g e n e ra l la y o u t o f th e conveyors. The f i r s t

conveyor hau lage c o n s is te d o f l e a th e r and canvas b e l t s

s l id in g on wooden tro u g h s . L a te r wooden r o l l e r s re p la c e d

th e tro u g h and th e y - in tu r n were re p la c e d by c a s t i r o n

r o l l e r s . T his l a t e r devlopm ent g r e a t ly encouraged th e use

o f conveyor hau lage o f c o a l and o th e r m in e ra ls . For many

y e a rs b e l t conveyors have proved to be an e f f i c i e n t , eco­

nom ical and s a fe method f o r underground t r a n s p o r ta t io n of

c o a l . S ig n i f ic a n t developm ents in th e d e s ig n and c o n s tru c ­

t io n o f conveyor hau lage system s have been and a re being made

to d e a l w ith v a r io u s f a c t o r s t h a t a f f e c t o u tp u t.

5.

S ince th e beg inn ing o f conveyor hau lage t r a n s p o r ta ­

t io n in m ines, v a r io u s ty p e s o f b e l t s have been m anufactu red ,

o f which th e fo llo w in g a re w orth n o tin g :

1 . C otton and s y n th e t ic f i b e r c a rc a s s b e l t s .

2 . U nip lane c o t to n cord b e l t s f o r h ig h te n s io n i n s t a l l a ­

t io n s where o u te r p ly s t r e s s e s may c o n tr ib u te to th e

u l t im a te d e t e r io r a t io n of th e c a rc a s s .1 ; _ ; . . . ■ i '

3 . U nusual b e l t w eaves, such as one w ith a th rea d ed h igh

modulus c o tto n f a b r ic runn ing le n g th -w is e in th e

c a rc a s s and w ith ny lon f i l l th re a d s to d ec re a se th e

crim ping in th e le n g th -w ise member. ^

4-. S te e l c a b le b e l t s u t i l i z i n g h igh te n s io n a i rp la n e ty p e

c a b le s a s , th e te n s io n c a rry in g members.

5. F i r e - r e s i s t a n t , b e l t s u s in g n eop rene , te ry le n e and po ly

v in y l c h lo r id e (p .V ic .) po ly e s t e r s y n th e tic f i b e r

m a te r ia l s . . '' ' ,. .-y ' .. .... v ■

6 . G lass c a rc a s s b e l t s f o r o p e ra tin g w ith m a te r ia ls a t

th e te m p e ra tu re s around 500 d eg rees F a h re n h e it . .

Many a tte m p ts have a ls o been made in th e d e s ig n of th e

su p p o rtin g s t r u c tu r e o f th e b e l t hau lage system . S ince 195$

th e ro p e-fram e conveyor s t r u c tu r e s have become alm ost

s ta n d a rd f o r some b e l t hau lage i n s t a l l a t i o n s in under­

ground m ines. (See f i g . l ) . Lower c a p i t a l c o s t p lu s th e

sav in g s in b o th tim e and money th a t can be r e a l iz e d from

f a s t e r i n s t a l l a t i o n , e x te n s io n , and r e lo c a t io n make ro p e

su p p o rted b e l t hau lage an a t t r a c t i v e o f fe r in g and have le d

' 6

ROPE

-:

7

to i t s r a p id accep tan ce by th e m ining in d u s t ry . However,

th e use of ro p e-fram e b e l t hau lage f o r perm anent, m ain- "

hau lage i n s t a l l a t i o n s i s uncommon and th e r ig id - f r a m e ,

co n v e n tio n a l b e l t hau lage i s s t i l l p rov ing e f f i c i e n t and

econom ical in t h i s f i e l d . - .. : v, :

The o th e r improvement in th e d e s ig n of b e l t hau lage

system i s th e developm ent of th e c a b le - b e l t conveyor.3 / 2 /

In t h i s d es ig n (see f i g . 2 ) , two e n d le s s .s te e l - w ir e rope

lo o p s , one on each s id e o f th e conveyor, a re a t ta c h e d to th e

runn ing b e l t by p re sse d s t e e l c l i p s . These ro p es ta k e th e

t e n s i l e s t r e s s in th e b e l t and in c re a s e th e l i f e of th e b e l t .

The rope loops a re c a r r ie d on to p and r e tu r n ro p e p u l le y s .

These ro p es a r e d isengaged from th e b e l t a t th e te rm in a ls of

th e conveyor by a p a i r of skewed or sp lay ed p u lle y s c a r r ie d

in a f a b r ic a te d s t e e l fram e. The ro p e s , which u n t i l th en

have been c a rry in g th e b e l t , p ass around th e v e r t i c a l p u lle y s

w h ile th e b e l t p a s se s around th e drum between th e p u l le y s .

The ro p es th e n p ass around th e skewed p u lle y s whose to p s a re

sp layed s u f f i c i e n t l y to enab le th e ro p es to p ass forw ard to

th e d r iv in g w hee ls . They th e n r e tu r n to p ic k up th e b e l t a s

i t le a v e s th e u n d e rs id e of th e b e l t drum. I t i s n o t

1 / T. D. E l l i o t , "Development o f th e c a b le - b e l t conveyor" I ro n and Coal T rades Review. Vol 176. No. 4689. A p ril h, 19% pp. 309 :137-*—

2 / "Three y e a rs of h o is t in g w ith th e P rin c e ss C able- B e l t" , Coal Age , Vol 6 3 , S ep t. 1958, pp . 106-08.

8

p r a c t ic a b le to ex tend th e c a b le - b e l t conveyor in s h o r t

le n g th s as f a s t as o th e r ty p e s . T his i s due to th e n e c e s s i ty

o f s p l ic in g a d d i to n a l ro p e . R egarding economics o f such a

type of b e l t hau lage system no d e ta i l e d s tudy has been made.

However, i t i s claim ed th a t under s im ila r working c o n d itio n s

a sm all amount of sav ing in horsepower i s n o ted in th e c a b le -

b e l t conveyors when compared to c o n v e n tio n a l ty p e b e l t con­

v e y o rs . The s ta n d a rd c a b le - b e l t conveyors, in b e l t w id th s

from 2 4 -in c h to 4 8 - in c h , u sin g d r iv in g ro p es from one in ch

to o n e -a n d -h a lf in ch es d iam eter w ith conveyor le n g th s up to

4000 f t . , have been i n s t a l l e d in a number of c o l l i e r i e s in

England du ring r e c e n t y e a r s .

? 13'

coavsio?-JG3BT2

10

ADVANTAGES OF BELT HAULAGE SYSTEM ' ;

In p lan n in g a hau lage system , I t should be determ ined

f i r s t w hether s u f f i c i e n t tonnage i s a v a i la b le f o r a number

o f y e a rs to j u s t i f y th e i n s t a l l a t i o n o f b e l t conveyors.

The a re a should be mapped and determ ined by crop l i n e s ,

p roperty" l i n e s , g rad es e t c . and th e n a d e c is io n w hether to

i n s t a l l com plete b e l t conveyor haulage or to use a com-

b in a t io n o f t r a c k h au lag e , s h u t t l e ,c a r s and b e l t s i s made.

The in t ro d u c t io n of b e l t hau lage system s in under­

ground c o a l m ining has made p o s s ib le b e t t e r methods of

m ining to s u i t l o c a l c o n d i t io n s , and in c re a se d fa c e

m ech an iza tio n . The su ccess o r f a i l u r e of a modern c o a l

mine depends, to a g r e a te r e x te n t , on th e e f f ic ie n c y .o f c o a l

t r a n s p o r ta t io n . The f a s t e r th e c o a l i s produced a t th e f a c e

by modern m ining m ethods, th e f a s t e r i t should be removed

from th e fa c e and t r a n s p o r te d to th e s u r fa c e a t minimum

c o s t . Today b e l t conveyors a re th e most advantageous and

econom ical means o f moving c o a l i n underground m ines, and

th ey form th e hub o f th e underground haulage system s th a t

handle a la rg e p e rce n tag e of U .S . m ining o u tp u t . The b e l t

conveyor hau lage system p o sse sse s many advan tages and

d e s i r a b le f e a tu r e s over t h a t o f o th e r ty p e s of t r a n s p o r ta t io n

system . The more im p o rtan t advan tages a re l i s t e d below:

1 . C ap ac ity : Because o f i t s con tinuous o p e ra t io n , no

o th e r method o f hau lage has such a wide range of c a p a c i t ie s

11

as th e b e l t conveyor system . W ith b e l t conveyors, th e amount

o f m a te r ia l c a r r ie d depends on th e b e l t w id th , speed and

w eight o f th e m a te r ia l conveyed. Owing to h ig h a b ra s iv e

r e s i s ta n c e o f ru b b er used in th e cover c o n s tru c tio n of b e l t s ,

ru n -o f-m in e (h e r e a f te r c a l le d r . o . m . ) c o a l o f a l l s iz e s can

be handled w ith o u t cau sin g s e r io u s damage or wear to th e

b e l t . : ■ ' ' .

2 . A d ap ta tio n to ground p r o f i l e : B e lt conveyors can fo llo w

le v e l or p itc h e d t e r r a i n w ith eq u a l ease up to 30$ g ra d e s .

Compare t h i s to th e norm al economic l im i ta t io n s o f 20$ g rad es

f o r t ru c k s and 3$ g rad es f o r r a i l r o a d t r a n s p o r t a t io n . In

some mines where, th e seams a re s te e p ly d ip p in g , t h i s f a c to r

a lo n e can make b u lk t r a n s p o r ta t io n econom ically f e a s ib le

only w ith -co n v ey o rs . ; .

3 . Simple e r e c t io n and minimum space: Underground b e l t con­

v eyo rs a llow th e use o f sim ple r ig h ts -o f -w a y , narrow e n t r i e s

and low .head room. No t r a c k s have to be l a id or t r o l l e y

w ire s s tru n g . L i t t l e g rad in g i s n e c e ssa ry and o f te n sim ple

ro o f su p p o rt can be u se d . The b e l t conveyors hold a un ique

p o s i t io n in th e reco v e ry of th in -seam c o a l where d r iv in g o f

la rg e e n t r i e s to accom odate o th e r means of hau lage would

make th e o p e ra tio n uneconom ical. ’ : \ ’

H-. F l e x i b i l i t y : The w e ig h t o f su p p o rtin g s t r u c tu r e s and

th e conveyor equipm ent i t s e l f i s sm all when compared w ith

th e volume of c o a l c a r r i e d . Hence i t i s e a s i ly extended or

r e t r a c t e d , d ism an tled , moved and reassem b led . However, ‘

12

g e n e ra lly b e l t conveyors a re sem i-fix ed and do n o t p rov ide ,

maximum f l e x i b i l i t y needed in some m ining o p e ra tio n s un-

l e s s th e y a re used in c o n ju n c tio n w ith some o ther, ty p e s of

t r a n s p o r ta t io n system , such as s h u t t l e c a r s , lo a d e rs and

movable b e l t h ead s. : :

5 . S a fe , smooth, s i l e n t , and sim ple o p e ra t io n : No method

of hau lage i s in h e re n t ly as s a fe as b e l t h a u l a g e T h e :

a c c id e n t r a t e w ith b e l t co n v ey o rv .h au lag e .is , ex trem ely low .

Freedom from v ib r a t io n s and q u ie t o p e ra t io n of b e l t hau lage

red u ces p e rs o n a l f a t ig u e and i r r i t a b i l i t y . D ust problem s

along th e p a th o f th e conveyor a re g r e a t ly red u ced , and,

where lump d e g ra d a tio n i s im p o r ta n t, th e smooth t r a n s f e r and

t r a n s p o r t o f b e l t hau lage low ers lump b reak ag e . P ro p e rly

designed , conveyor system s have push b u tto n c o n tro ls and can

be s e l f c o n t ro l l in g to a la rg e e x te n t by e l e c t r i c a l i n t e r ­

lo ck in g a rran g em en ts .

6 . E a rly w arning of impending danger: P robably no o th e r

haulage g iv e s such an e a r ly w arning of p o s s ib le f a i l u r e .

U n like th e a e r i a l tramways of which i t •i s s a id never have a

minor a c c id e n t , or th e r a i l r o a d where a washout o f i b a l l a s t

or a d e ra ilm en t may s t r i k e w ith o u t-warning', th e b e l t con­

v ey o r, i f m a in ta in ed p ro p e r ly , r a r e l y : s u f f e r s a sudden b reak­

down. The b e l t . i t s e l f s ig n a ls i t s need f o r rep lacem en t in

ample tim e to have a standby b e l t read y fo r i n s t a l l a t i o n .

7 . Minimum m aintenance and power re q u ire m e n ts : Two to

th r e e men per m ile p er s h i f t a re no rm ally s u f f i c i e n t f o r

d a i ly r o u t in e m ain tenance and o p e ra t io n . The r e tu r n ru n of

th e b e l t on a s lo p e b a lan ce s th e to p e ru n and, because of low

t a r e w eight o f th e moving p a r t s , conveyors can p ro v id e 1

t r a n s p o r ta t io n w ith th e lo w est p o s s ib le consum ption o f pow er.

B e lt hau lage needs on ly o n e -h a If th e power r e q u ire d by o th e r

m ethods. ..... ,

8 . Econom ics: I f th e problem i s to g e t h igh p ro d u c tio n a t

low er c o s ts , th e conveyor b e l t hau lage may be th e answ er.

The low u n i t c o s t per to n of m a te r ia l t r a n s p o r te d by b e l t

hau lage o f te n makes i t th e most econom ical means o f moving

c o a l . Long term sav in g s in la b o r c o s t and m aintenance a re

p o s s ib le w ith th e b e l t hau lage system . The o th e r im m ediate

sav in g s from b e l t hau lage a re r e d u c t io n in g rad in g a n d . -

b ru sh in g , th e e l im in a tio n o f s t r in g in g t r o l l e y w ire s , la y in g

o f t r a c k and of c u t t in g i n t r i c a t e hau lage ways. ': ■

•The s u b je c t o f b e l t hau lage economics i s d isc u sse d

in d e t a i l e lsew here in t h i s t h e s i s under a s e p a ra te head ing .

The main d isad v an tag e of b e l t conveyors i s h ig h "

i n i t i a l c a p i t a l ex p e n d itu re which means la r g e r tonnages must

be a v a i la b le f o r a lo n g e r p e r io d to i n s t a l l b e l t conveyors .

and to m inim ize hau lage c o s t s . A lso u n fo re see n random break­

down d u rin g o p e ra t io n may a f f e c t th e whole o u tp u t .

FUTURE TRENDS IN BELT HAULAGE SYSTEM............

13

The p o p u la r i ty o f b e l t conveyors f o r t r a n s p o r ta t io n

of c o a l in m ines has in c re a se d du ring th e :p a s t decade , and a

number o f s ig n i f i c a n t developm ents a re ta k in g p la c e in th e

underground b e l t h a u la g e .; The b e l t conveyors a re growing :-

s t e a d i ly in s i z e , th e horsepow er of th e motor i s in c re a s in g ,

lo a d in g m ethods, b e l t speeds and b e l t c o n s tru c tio n m a te r ia l

a re im proving and w i l l handle la r g e r o u tp u ts a t minimum c o s t .

The fo llo w in g a re th e g e n e ra l t r e n d s tow ard desig n in g ; f u tu r e

hau lage system s; : . v . ; , : : : : •

1 . S h i f t from r i g i d to rope supported b e l t equipm ent; The

concep t of mounting c a rry in g I d le r s on two s ta t io n a r y and

p a r a l l e l w ire -ro p e s in s te a d o f on a r i g i d framework i s .

f in d in g growing use in th e c o a l m in in g .in d u s try due to low er

c a p i t a l c o s t and sav in g s in i n s t a l l a t i o n c o s t . Conveyor b e l t

m an u fac tu re rs have e s tim a ted t h a t d u rin g 1961 rough ly of

new conveyor equipm ent so ld f o r p an e l and b u t t e n try hau lage

was of th e r o p e : suspended ty p e . -However, the- s h i f t from

r i g i d to ro p e -fram e id l e r s t r u c tu r e s f o r secondary and main­

l in e b e l t hau lage i s v e ry slow . . .

2 . Trends tow ard w ider b e l t s and h ig h e r sp eed s; The h ig h e r

w id th -sp eed com bination i s becoming in c re a s in g ly in d is p e n s ­

ab le in o rder, to p rov ide , th e surge, c a p a c ity needed .fo r h igh­

speed dumping, la r g e c a p a c ity s h u t t l e c a r s , and o th e r t r a n s ­

f e r r in g equipm ent. In some of th e German o p e n -p it c o a l mines

s t e e l c a b le r e in fo rc e d b e l t s up to 87- in ch wide c a rry 15,000

t o n s ;o f o v er-b u rd en m a te r ia l per hour a t . speeds ran g in g

15

from 900 to 1100 f t . p er m inute and u t i l i z i n g up to H000

h o rs e p o w e r .^

3 . Growing i n t e r e s t in 35 deg . and 4$ deg . c a rry in g i d l e r s :

These I d l e r s a re being used in th e above ground equipm ent.

In th e underground w orkings o f th e mine where th e o p e ra tin g

c o n d itio n s a re n o t as good a s on s u r fa c e , 45 deg . i d l e r s

p ro v id e g r e a te r c a p a c ity w ith o u t in c re a s in g b e l t w id th or

speed . They may a ls o h e lp to red u ce th e c o s t o f s p i l la g e

c le a n -u p , an expense w hich approaches $30,000 p er y ea r f o r

some m in es. The o th e r improvements in th e i d l e r d e s ig n a re

v a r io u s ty p e s of f l e x i b l e c a te n a ry i d l e r s f e a tu r in g moulded

ru b b er s p i r a l s in s te a d of a s e r i e s of ru b b er d i s c s . These

i d l e r s a re being used in c o n ju n c tio n w ith ro p e-fram e b e l t

hau lage s t r u c t u r e s .

4 . Development o f a r t i c u l a t e d and cascade conveyors:*^The

developm ent o f th e co n tin u o u s m iner and a ls o accompanying

em phasis on th e improvement o f conveying mediums has r e ­

s u lte d in th e d e s ig n o f a r t i c u l a t e d and cascade conveyors.

One v e r s io n of an a r t i c u l a t e d conveyor developed f o r th e

bo ring ty p e of co n tin u o u s m iner c o n s is ts of a s e r ie s o f

3 / E. R. T ra x le r , "Conveyor b e l t horsepower and o p e ra tin g d is ta n c e s co n tin u e to in c re a s e in f u tu r e " , E n g in ee rin g and Mining J o u r n a l . Vol 162, No. 8 , August 1961, pp . 86 f .

4 / Deep m ining Guidebook " P r a c t i c a l t r e n d s in t r a n s ­p o r ta t io n " , Coal Age, V o l. 6 3 , No. 7A, M id-July 1958, p . 77*

in te rc o n n e c te d b e l t conveyors on w hee ls-each w ith i t s own ,

d r iv in g a n d -p ro p e llin g m oto rs. _" - ■ . : •

The cascade system i s s u b s ta n t ia l ly s im i l a r . Here

th e conveyor need n o t be in te rc o n n e c te d , though h itc h e s a re

p rov ided to p erm it th e s e r ie s to be p u lle d behind th e boring

u n i t in th e rem ote m ining a r e a s . To avo id in s e r t in g and r e ­

moving conveyors one a t a tim e , th e l a t e s t id e a in rem ote

m ining a re a s i s to s to r e th e conveyors in a s t r u c tu r e w ith

c i r c u la r ram ps. As th e machine goes in to th e m ining a re a

i t p u l l s th e conveyor o f f , pushing them back onto th e ramps

on th e way o u t .

5. B ridge conveyors and p o r ta b le b e l t heads: The develop­

ment o f th e b r id g e conveyor u n i t was th e f i r s t s te p in

b r in g in g th e conveyor in to th e p ic tu r e as means of se rv in g

lo ad in g m achines and co n tin u o u s m in e rs . The n ex t s te p was

to d es ig n room conveyor so t h a t i t could be e a s i ly extended

to keep up w ith th e fa c e u n i t . The b r id g e conveyor i s th e

connecting l i n k betw een th e f a c e conveyor and con tinuous

m in e r. At th e t a i l s e c t io n of th e f a c e conveyor i t r id e s on

t r a c k s ; a t th e d isc h a rg e conveyor of th e lo a d in g u n i t or

con tinuous m iner i t i s su p p o rted by a b a l l and so ck e t f a s te n ­

in g . $ o th p o in ts o f c o n ta c t a llo w a 90 deg . movement to

e i th e r s id e . In any c a se , th e b rid g e I s always p o s it io n e d

to ac ce p t c o a l and d isc h a rg e i t onto th e fa c e co n v ey o rs .

16

A new developm ent w ith ro p e .su p p o rte d conveyors i s

17

th e p o r ta b le b e l t head . The d r iv e s e c t io n in c lu d in g m otor,

c o n t r o l l e r and power tra n s m is s io n f a c i l i t i e s i s made p o r t­

a b le by m ounting as a com plete u n i t on a r a i l t r u c k . The

p o r ta b le head on i t s t r u c k i s trammed to a sp o t in th e f i r s t

c ro s s - c u t inbye o f th e main l i n e . In t h i s p o s i t io n i t i s

60 to 100 f t . from th e b e l t d is c h a rg e . The t ru c k i s anchored

in p la c e w h ile rem ain ing : on th e r a i l s .

6 . Use of conveyors f o r t r a n s f e r o f men: Under p ro p er s a fe ­

g u a rd s , movement o f men on b e l t s i s p rov ing b o th s a fe and

e f f i c i e n t S p e c i a l lo w "speed (up to 200 f . p . m . ) and low

c o s t b e l t s a re now being employed in t r a n s f e r r in g men on

le v e l roadways and up s lo p e s . T his system should be so de­

signed th a t th e b e l t canno t be r e s t a r t e d w ith o u t a check fo r

p o s s ib le h a z a rd s . There should be emergency s to p cord or

s to p system a l l along th e b e l t so t h a t any man can s to p i t

a t any tim e: ample c le a ra n c e and smooth unencumbered fo o tin g

should be p ro v id ed a t a l l lo a d in g and un load ing p o in ts .

F in a l ly , in a d d i t io n to a l l th e above p re c a u tio n s , no move­

ment o f men by b e l t s should be p e rm itte d u n le s s a re s p o n s ib le

p e rso n i s p r e s e n t .

i / I b i d . . PP. 72-9) P assim .

CHAPTER I I I

SELECTION OF BELT WIDTH AND SPEED

When th e i n s t a l l a t i o n o f a b e l t hau lage system i s

decided upon, th e f i r s t s te p in i t s p roper d es ig n i s th e

s e le c t io n o f b e l t w id th and speed commensurate w ith f u tu r e

o u tp u t to be hand led , inasmuch as b e l t w id th and speed

govern th e h au lin g c a p a c ity of th e b e l t . From th e s tan d

p o in t o f econom ics, th e id e a l b e l t conveyor should o p e ra te

f u l l y loaded a t maximum p e rm is s ib le speed w ith i t s w id th as

narrow as p o s s ib le to h au l th e g iv en o u tp u t . The o p e ra tio n

of a b e l t below i t s c a p a c ity r e s u l t s in low er hau lage

e f f ic ie n c y and g r e a te r wear f o r a g iven tonnage conveyed.

For any p a r t i c u l a r problem concern ing th e under­

ground h au lin g o f c o a l by b e l t conveyors, i t i s p o s s ib le to

recommend more th a n one com bination of b e l t w id th and speed .

However, th e w id th and speed o f th e b e l t s e le c te d must be

s u f f i c i e n t to move th e c o a l as f a s t a s s h u t t l e c a rs or o th e r

t r a n s f e r conveyors t h a t may be used in c o n ju n c tio n w ith th e

b e l t can d isc h a rg e t h e i r lo a d s upon i t ; o th e rw ise d e lay s

w i l l o c c u r . To p rev en t th e s e d e la y s , s a fe ty d ev ices may be

used on th e b e l t s . These a re ( i ) t r a n s f e r conveyors ( e n try

b e l t s ) cap ab le o f ta k in g maximum s h u t t l e c a r d isc h a rg e a re

i n s t a l l e d to fe ed to th e main b e l t a t th e p roper r a t e s , or

18

( I I ) tw o-speed m otors a re I n s t a l l e d w ith an au tom atic tim in g

c o n tro l to speed up th e b e l t w h ile th e s h u t t l e c a rs a re d is ­

ch a rg in g ; t h i s tim in g c o n t ro l i s th e n c u t back a u to m a tic a lly .

Almost a l l b e l t conveyor c a lc u la t io n s s t a r t w ith a

c o n s id e ra t io n of th e c a p a c ity o f th e b e l t . The f a c to r s w hich

a f f e c t th e b e l t c a p a c ity a re b e l t w id th and speed , th e shape

of th e lo ad ed c ro ss s e c t io n , b u lk w eigh t o f th e m a te r ia l to

be conveyed, and tro u g h in g ang le of i d l e r s on which th e b e l t

ru n s . There a r e two methods of d e te rm in in g b e l t c a p a c ity : .

1 . The averag e b e l t c a p a c ity in to n s /h o u r I s computed by

d iv id in g t o t a l to n s moved p e r s h i f t by th e hours per : .

: s h i f t : "

2 . "Peak c a p a c ity " i s u s u a l ly ex p ressed in to n s /m in u te .

The peak c a p a c ity i s th e maximum amount o f m a te r ia l

t h a t w i l l be lo ad ed on to th e b e l t a t a l l o f th e lo ad in g

p o in ts in any one m in u te . The average or a c tu a l o u tp u t per

hour w i l l alw ays be l e s s th a n th e "peak c a p a c ity " . But th e

b e l t w id th and speed must be s e le c te d on th e b a s is of th e

peak c a p a c ity which i s th e o u tp u t f o r id e a l com binations of

lo a d in g . I f th e b e l t i s to be s e le c te d oh th e b a s is of th e

average c a p a c ity , i t i s n e c e ssa ry to c o n t ro l th e d r iv e of th e

e n try b e l t s as ex p la in ed a b o v e .- This p re v e n ts th e e n try

b e l t s from d isc h a rg in g on to th e main b e l t i f th e main b e l t

i s a lre a d y f u l l y lo a d e d . 1

1 . B e lt - W idth: - The fo rm ula f o r d e te rm in in g th e b e l t w id th ,

19

20

as g iven by N a tio n a l E l e c t r i c a l M anufactu rers A sso c ia tio n

(N.E.M.A.) , i s as fo l lo w s :

B e lt w id th ( i n in c h es) s 13 1 0 , 000? S x U / 5

i/h e re : P z peak lo ad in to n s per m inuteS = speed of th e b e l t in f t /m in u te U z w eight o f th e broken m a te r ia l

in Ib s /c u b ic f t .

2 . B e lt Speed: The maximum recommended b e l t speeds fo r

v a r io u s b e l t s iz e s a re g iv en in ta b le ( x ) . For c o a l mining

conveyors, speed i s u s u a l ly l im ite d to about 2^0 f t /m in . in

g a te ro ad s and ^75 f t /m in . on tru n k ro ad s in B r i t i s h c o a l

mines &

3 . L um p-size: For th e maximum a llo w ab le lu m p -size ru n -o f -

mine c o a l i t i s u s u a lly p r a c t i c a l to t o l e r a t e an o c c a s io n a l

lump o n e -h a lf th e b e l t w id th in i t s w id es t d im ensions. The

ta b le ( i ) shows th e recommended maximum a llo w ab le lu m p -s izes

f o r d i f f e r e n t b e l t w id th s . The maximum lu m p -size which can

be handled by a conveyor can a ls o be determ ined by th e

fo rm u la :2 /(W - 6)

A llow able lu m p -size ( in in c h e s ) s ----------- . .2 ________\2)

Where W z b e l t w id th in in c h e s .

4 . B e lt C a p a c ity : ( i ) The N.E.M.A. fo rm ula f o r de term in ing

6 / N a tio n a l Coal Board, "R e la tin g a roadway b e l t con­veyor to i t s d u ty " , In fo rm a tio n B u l le t in No. 58/197. N a tio n a l Coal Board, H obart House, Grosvenor P la c e , London, S .W .l.

2 / N. Brook, "E s tim a tio n of conveyor s p e c i f i c a t i o n s " , C o l l ie ry E n g in e e rin g T Vol 3 6 , No. 429, November 1959, p p . 4 b 6 -9 2 •

21

b e l t c a p a c ity f o r 20 deg . tro u g h in g i d l e r s i s a s fo llo w s :

T = 0.0032Ux(W -5)2 __________ (3)

Where: T ^ “ c a p a c ity in to n s (o f 2000 l b - t o n ) /hour a t 100 f t /m in . b e l t sp eed .

U * w eight in l b s . per c . f t . of th e ......... m a te r ia l to be conveyed.

W = b e l t w id th in in c h e s .

NOTE: ,The above c a p a c ity fo rm ula c o n s id e rs maximum

or peak c a p a c ity . The recommended c a p a c i t ie s under which

th e b e l t s a r e to be o p e ra ted must be abou t 10$ low er th a n

th e tonnage d e riv e d by t h i s fo rm u la .

For 35 deg . tro u g h in g i d l e r s and deg . uneq u a l-

r o l l tro u g h in g i d l e r s , th e c a p a c ity determ ined by th e above

fo rm ula must be in c re a se d by abou t 1$$ and 22$ r e s p e c t iv e ly .

( i i ) The re v is e d Goodyear f o rm u la ^ f o r b e l t capa­

c i t y f o r 20 d e g . s ta n d a rd e q u a l - r o l l tro u g h in g i d l e r s i s as

fo llo w s :

T = 5.,75(W - 3 .3 ) 1 *^6x S x U (4)200,000

Symbols a s g iv e n above.

8 / Handbook qf b e l t i n g . Akron, Ohio, The Goodyear T ire and Rubber Co . , IncV, 1953» P • 51•'

22

- : -

t .

BELT

PIG. 3 CROSS-SECTION OF LOADED BELT

( T i l ) A foTmula f o r d e te rm in in g 7 approxim ate b e l t

c a p a c ity as advocated by some m ining en g in ee rs can be de-

VP iV6Cl QS follows: ' ----- — ' . . . ■L et V a b e l t w id th in in ch es

a a th e edge d is ta n c e of b e l t n o t under lo ad . > (se e F ig . 3) ♦. , t :

U s w t. of th e m a te r ia l in I b s / c . f t .

S s b e l t speed in f t . / m i n .

The shape of th e r ib b o n o f m a te r ia l on th e belt" i s as shown

in F ig . 3* This a re a of r ib b o n i s app ro x im ate ly e q u iv a le n t

to a r e c ta n g le whose s id e s a r e (W-2a) by W/9 (see F ig . 3)•

23

T h e re fo re , th e c a p a c ity o f th e b e l t i s g iv en by;

T = (W -2a)x (W /9)x (S /lW x(U /2000)x60

For m in ing •conveyors th e edge d is ta n c e *a* i s about

3 in c h es (o r more a c c u ra te ly "a" = 0.055W - 0 .9 in c h ) .

S u b s t i tu t in g th e v a lu e o f 3 in ch es fo r "a" in th e above

eq u a tio n and rounding o f f th e c o n s ta n t g iv e th e c a p a c ity

fo rm u la ;m - (^-6)xWxSxU ; : . ^ (5)

TABLE I

MAXIMUM RECOMMENDED SPEEDS AND ALLOWABLE LUMP-SIZE OF R.O.M.

COAL FOR DIFFERENT SIZES OF PLY-TYPE BELTS

m m — - r - r t e .i j e m b m p j b — m — i i r h i i i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i" i i i I I ■ ■ T ' i ir~ ~ - - i — rrn m i Hill I ■

B e lt W idth Maximum b e l t speed ( f . p . m . ) la m p -s ize s ( in in c h e s ) in in ch es Goodyear U .S. Rubber Average I f un ifo rm I f mix-: , V.:: . V . - - .. ... . 1 ■' : - ' ; , ’ ' • . ed w ith

________________________ ______________________________________ f in e s

2b 500 400 450 5 8

30 600 450 525 ' 6 10

' 36 600 500 550 y 12

b2 650 . . 5oo , 575 8 ,48

6 5 9. 550 600 10 16

54 650 600 625 11 20

650 600 625 12 24

: • CHAPTER IV

' DETERMINATION OF BELT HORSEPOWER REQUIREMENTS

The, b e l t w id th and-speed f o r a g iven c a p a c ity i s

f i r s t dec ided a s d isc u sse d in th e l a s t c h a p te r ; and th en

th e t o t a l horsepow er re q u ire d to hau l th e m a te r ia l i s c a l­

c u la te d . This b e l t d r iv in g power i s u s u a lly d iv id ed in to

th e fo llo w in g com ponents:

1 . Power to d r iv e th e empty b e l t , he

2 . Power to convey th e m a te r ia l h o r iz o n ta l ly along th e

b e l t , h^

3 . Power to e le v a te th e m a te r ia l on s lo p e s or th e power

to be g en e ra ted in low ering th e m a te r ia l , hr

!+. A d d itio n a l power to d r iv e th e t r i p p e r , i f a t r ip p e r

i s used and i s to be d r iv e n by th e b e l t m otor. L et

t h i s t r ip p e r horsepower be eq u a l t o , h^

5. Power to a c c e le r a te th e lo ad ed b e l t a t s t a r t , ha

The c a lc u la t io n s f o r a l l th e above b e l t horsepower

components a re g iv en in d e t a i l below .

POWER TO DRIVE THE Em m

The power re q u ire d to d r iv e th e empty b e l t depends

2b

on th e f r i c t i o n a l lo a d s due to ( i ) th e w eigh t o f th e moving

p a r t s such as i d l e r s , p u l le y s , drag of th e s k i r t b o a rd s ,

drag caused by any m inute m isalignm ent o f p u lle y s or i d l e r s ,

(11) th e w eight o f th e m a te r ia l on b e l t , and ( i l l ) th e

i n t e r n a l f r i c t i o n of th e r ib b o n o f th e m a te r ia l as i t s h i f t s

and re sh a p e s i t s e l f in p a ss in g over th e i d l e r s . *

The c a lc u la t io n of a l l th e s e f r i c t i o n a l f o rc e s de­

pends on an assum ption of a “com posite f r i c t i o n f a c t o r " .

The accu racy of t h i s assum ption d e term in es th e accu racy of- ' . . • ' ‘ - • - . . . . . . . ... /v . . . . -

th e r e s u l t s o b ta in e d . . Most components o f f r i c t i o n a l f o rc e s

v a ry d i r e c t l y w ith th e len g th , o f th e conveyor. However,

th e r e a r e a few components which a re independen t o f b e l t

le n g th and, th e r e f o r e , may be added as com ponents.

The horsepow er to d r iv e th e empty b e l t , he

• t o t a l f r i c t i o n a l fo rc e ( lb s ) x b e l t _ ___________ speed ( f . p . m . )

r 3 3 ,0 0 0

= CxQx (L^Lq)xS : ‘______(6)■ 33,000

25

Where: C ■ com posite f r i c t i o n f a c to r as "explainedabove. U su a lly th e v a lu e of C mayr.be ta k en 0 .0 3 . However, f o r more a c c u ra te v a lu e s o f C, see p . 27.

. L - c e n te r - to - c e n te r d is ta n c e of b e l t * te rm in a l p u l le y s , in f t .

2 6

L0= A c o n s ta n t which r e p r e s e n ts f r i c t i o n a l lo s s e s th a t a re always to be in c lu d ed in th e com posite f r i c t i o n a l f o r c e s . These f r i c t i o n a l lo s s e s a re independen t o f b e l t le n g th and a re commonly known as " te rm in a l f r i c t i o n a l l o s s e s " .U su a lly LoSl5 0 f t . may be ta k e n . For more a c c u ra te v a lu e s see ta b le I I , p . 27-

Q = w eigh t o f th e moving p a r t s o f th e con­veyor system in I b s / l i n e a r f t . of th e b e l t , (see below ).

D ete rm in a tio n o f v a lu e Q:

The v a lu e o f Q i s v e ry d i f f i c u l t to o b ta in w ith

ac cu racy . The approxim ate v a lu e of Q may be ta k e n as

n u m e ric a lly eq u a l to th e w id th o f th e b e l t in in c h e s .

Hence f o r a 1+8- in ch b e l t th e v a lu e o f Q = 48 l b s . p e r

l in e a r f t . b e l t le n g th .

A more a c c u ra te v a lu e of Q can be determ ined by th e

fo llo w in g fo rm u la :2 /

Q = 2B / W ] /l i / W2/ I 2

Where: B = b e l t w eigh t in I b s / l i n e a r f t .

• - W]= w t. of th e re v o lv in g p a r t s of th ec a rry in g i d l e r s in l b s .

W£- w t. o f th e re v o lv in g p a r t s of th e r e tu r n i d l e r s in l b s .

2 / I b i d . , p a g e 6 9 .

27

l l = av e rag e spacing of th e lo ad c a rry in g i d l e r s , in f t .

Ip s av e rag e spacing of th e r e tu r n i d l e r s , i n f t .

TABLE I I

VALUES OF COMPOSITE FRICTION FACTOR, C, AND CONSTANT, LQ

C lass o f equipm ent V alue o f C V alue of L_ ( In f t . ) °

For conveyors w ith a n t i ­f r i c t i o n id l e r i n s t a l l a ­t io n s on tem porary , p o r- a b le or im p e rfe c tly a l ig n e d s t r u c t u r e s .

0 .030 150

For conveyors w ith h igh g rade a n t i - f r i c t i o n i d l e r s on perm anent or w e ll a l ig n e d s t r u c t u r e s .

0 .022 200

For conveyors as in (2) b u t w ith g rad es r e q u ir in g r e s t r a i n t of th e b e l t when lo a d ed .

0 .012 ^75

W ith th e above fo rm ula (6 ) , th e horsepower r e q u ire d

to d r iv e th e empty b e l t , he , can be c a lc u la te d . The ta b le

I I I g iv e s th e v a lu e s of hQ f o r d i f f e r e n t b e l t s iz e s a t 100

f .p .m . b e l t speed . The horsepow er a t o th e r b e l t speeds may

be c a lc u la te d by m u ltip ly in g th e v a lu e s in ta b le I I I by a

f a c to r o b ta in ed by d iv id in g th e new b e l t speed by 100.

28

TABLE I I I

APPROXIMATE VALUES OF HORSEPOWER TO DRIVE THE EMPTY BELT AT

" a SPEED OF 100 FEET PER MINUTEJjCV ,

B e lt w id th ( in in c h es)

• H o riz o n ta l c e n te r - to - c e n te r d is ta n c e of te rm in a l p u lle y s ( in f e e t ) _

b e l t

' ' w - ’.Jl ' ' 100 200 300 4oo 500 7 0 0 900 ; 1000 2000

24

30 > - , j • • ■- - \

0 .5 '

0 .7

0 .7 0 .9 l . o

1 .0 1 .3 1 .6

1 .2

1 .8

j ,1 .6

2 .4

2 .0

3 .0

2 .21 - ■ /

3 .2

4 .1

5-3

’ 36 ‘ 0 .9 1 .2 1 .6 1 .9

1 .5" 1 .9 . .... 2 .4

2 .2 2 .9 3 .6 4 .0 6 .4

42 1 .1 2 .8 3 .6 4 .9 5 .2 8 .1

48 1 .2 1 .7 2 .3 2 .8 3 .3 ^ .3 5 .4 5-7 1 1 .7

54 1 .6 - 2 .3 / 2 . 9" 3 .6 -, ■; ... ; . . - . 4 .2 5 .5 6 .7 7-4 1 2 .8

60 1 .9 2 .7 3-5 4 .3 5-0 6 .6 8 .1 8 .9 16 .6............ __ _ --

NOTE: This ta b le i s based o n .th e fo rm ula fo r c a l ­

c u la t in g empty b e l t horsepow er where 0=0 .03 and Lor l 50 f t .

POWER TO MOVE THE MATERIAL HORIZONTALLY ALONG THE CONVEYOR *

A fte r de te rm in in g th e empty b e l t d r iv e horsepow er, th e

n e x t s te p i s to d e te rm in e - th e horsepower to move th e lo ad of

m a te r ia l h o r iz o n ta l ly . As th e horsepow er to d r iv e th e empty

b e l t , he , i s g iv en by he = CxQx(L/Lp)xS (formu^a 6) th e33,000

v a lu e o f th e h o r iz o n ta l horsepow er, hm, can a ls o be c a lc u la te d

by th e same fo rm ula where th e symbols C, L, L0 and S have th e

same meaning as b e fo re , b u t th e v a lu e of Q changes due to a

lo ad of th e m a te r ia l p u t on th e b e l t . ' The v a lu e of Q I s =

c a lc u la te d in th e fo llo w in g way: -

L et T * o u tp u t in to n s /h o u r and S = b e l t speed in

T h en 'th e w eight of th e m a te r ia l on th e b e l t i s .......

eq u a l to -T to n s /h o u r or. 2000T p o u n d s/h o u r....As ..the. b e l t _____

speed in f e e t p e r m inute i s S, th e speed in f e e t per hour i s

eq u a l to 60S f t . T h e re fo re , th e w eight of m a te r ia l on the -.,

b e l t , Q ( in l b s ) , f o r each f t . o f b e l t le n g th = (2000T)/60S.

Hence th e h o r iz o n ta l horsepow er, hm, i s g iv e n 'b y " ’ 0 , ]

h CxQx (L^Lq) x S - 1 om : .. 33 ,000 : :. r -C. v : . , ;

' ■ ° J Cx ^ § § |2 (L /L 0 ) x S' - 33,000 j .

:* ■ ’ Cx(L/Ln )xS .v. : .

;

.(7)' ,.■v.'j 990 , •5,:.,

NOTE: Here th e v a lu e of C - 0 .0 4 i s recommended as

compared to 0 .0 3 f o r empty b e l t s s in c e th e .p re s e n c e of th e

lo a d w i l l modify: th e tro u g h in g c h a r a c t e r i s t i c s o f th e b e l t .

The ta b le IV g iv e s th e v a lu e s of h^ to h au l r .o .m .

c o a l a t d i f f e r e n t b e l t le n g th s and c a p a c i t i e s .

3 0

TABLE:H :: ; .Lx,::"-; }...l

HORSEPOWER VALUES TO CONVEY THE R.O.M. COAL ON A HORIZONTAL

BELT AT ANY SPEED V

T ons/, _______________T o ta l_ b e lt_ le n g th _ lin _ fe e t l_ _ _ _ -------- -hour 100

1 -> -x200I.--:-

4o6

§: 600 800*: • 1000 2000 2500

100 . 0 .8 : 1 .1 1 .7 : 2 .0 2 .3 : 2 .9 3 .5 - 6 .4 . 8 .1

200 1 .5 - 2 .1 3-3 3 .9 4 .5 u :• :5 .8 7 .0 . 12 .7 1 6 .1

400 3 .0 4 .2 ; 6 .7 7 .9 9 .1 . 11 .5 1 3 .9 26 .0 32 .2

500 3 .8 5-3 8^3 9 .8 1 1 .4 1 4 .4 1 7 .4 36.6 4 0 .3

600 > 5 6 :4 1 0 .0 1 1 .8 13 .6 17 .3 21 .0 3 9 .1 4 8 .3

800 ■ 6 .1 8 .5 • 13 .3 15 .8 1 8 .2 23 .0 28 .0 52.2 64 .2

1000 7 .6 10 .6 1 6 .7 19 .7 2 3 .O 29 .0 35 .0 62 .2 8 l.O

1500 11 .4 .1 5 .9 25.0 29 .0 34 .0 4 3 .0 52.0 97.6 112 .1

1800 13.6 1 9 .1 30 .0 3 5 .0 4 i . o 52.0 63 .0 117.5 145 .0

2000 15 .2 2 1 .0 33 .0 3 9 .0 4 5 .0 58.0 70 .0 131.0 161.0

NOTE: • T h is t a b le I s based on fo rm ula (7) where

C = 0 .03 and L0 = 150 f t . :V1

' ;■ uvl

POWER TO ELEVATE OR LOWER MATERIAL OR POWER TO BE GENERATED

IN LOWERING JX :v.

By th e d e f in i t i o n o f horsepow er, i t i s th e r a t e of

doing work (measured in f t - l b s p er m inute dr per second) in

r a i s in g or low ering a . lo a d . Let; th e m a te r ia l to be conveyed

i s eq u a l to T to n s per hour or 2000T/60S lb s p er m inu te .

Then th e r a t e -of doing th e work n e c e ssa ry to r a i s e or low er

2000T/60S lb s per m inute th ro u g h a d is ta n c e .H f t . i s __________ 20001 ■■■ - : - ■ ' :

- - ... ........ . h f t - l b s 3 e2 m inute ° —- * - ■ .. — ........... — — *

horsepower= 2000T x u Y 1*;■ 6 " & S ; 33 f OOO

" ' ' ' " '= hp " ' - - V ' V

T h e re fo re , th e power to r a i s e or low er th e m a te r ia l ,

hj,, i s g iven by • r : .-.J..,' •

• h y -r (TxH)/990 • (8)■ )

NOTE: The horsepower v a lu e , h r . , i s a lso c a lle d• * 4~\ ;■ \ \ • ’•>g ra v i ty horsepow er. In th e above form ula th e v a lu e of H i s

co n s id e red as th e d i f f e r e n c e in e le v a t io n between th e lo ad ­

ing s t a t i o n and th e d isc h a rg e p o in t . When th e b e l t p r o f i l e

i s u n d u la tin g , d iv id e th e p r o f i l e in to segm ents determ ined

by m ajor b reak s in th e g rad e . Then f in d th e l i f t f o r each

ad v erse grade segm ent. From th e sum o f th e s e in c liv id u a l

l i f t s , c a lc u la te t h e t o t a l l i f t , H, to de term ine th e v a lu e

of bp by th e above fo rm u la . The ta b le V g iv e s th e v a lu e s of

hp fo r d i f f e r e n t o u tp u ts and a t d i f f e r e n t s lo p e s .

: . • : TABLE V

HORSEPOWER VALUES TO ELEVATE MATERIAL OR POWER GENERATED IN

LOWERING THE MATERIAL

3 2

Tons/hour

L i f t or drop1 ( In f e e t )

10 25 50 100 150 200 250 300 400 500

100 1 .0 2 .5 5 .1 1 0 .1 1 5 .2 20 .0 25 .2 30 .4 4 0 .5 50.5

200 2 .0 5 .1 1 0 .1 2 0 .0 3 0 .0 4 0 .0 50 .0 60 .6 81 .0 101 .0

300 3-0 7 .6 1 5 .2 3 0 .0 4 5 .0 61 .0 75 .5 91 .0 123 .0 153 .0

1+00 ^ .0 1 0 .1 2 0 .0 b-0.0 '61.0 81.0 101.0 123.:0 :162.0 202.0

500 5 .1 1 2 .6 25 .0 51.0 76 .0 101.0 126 .0 154.0 202.0 252.0

700 7 .1 1 7 .7 35 .0 71 .0 106 .0 141.0 177.0 212.8 283.0 353.0

' 800 8 .1 20 .0 4 0 .0 81 .0 121 .0 162.0 202.0 243.0 324 .0 4 0 4 .0

900 9 .1 23 .0 ^ 5 .0 91 .0 136 .0 182.0 227.0 273.0 364 .0 4 5 5 .0

1000 1 0 .1 25 .0 51 .0 101.0 152 .0 202.0 252 .0 304.0 4 0 5 .0 505.0

2000 2 0 .0 51 .0 99 .0 202.0 302 .0 - 505.0 605.0 810.0 1010.0

NOTE: The above t a b le I s based on form ula ( 8 ) .

POWER TO DRIVE THE TRIPPER..t:

---- A t r i p p e r I s a m echan ical d ev ice f o r un load ing , a b e l t

conveyor a t p o in ts o th e r th a n over th e head p u l le y . I t l i f t s

3 3

a p o r t io n o f th e b e l t o f f th e r e g u l a r . conveyor ca rry in g ,

i d l e r s and bends i t around th e t r ip p e r p u l le y .1' 1 The m a te r ia l

i s d isc h a rg ed over th e t r ip p e r p u lle y (a s though i t were th e

head p u lle y ) and in to a chu te which i s a p a r t of th e t r i p p e r .

Depending upon th e d e s ig n of th e t r ip p e r c h u te , th e m a te r ia l; - "

may be d isch a rg ed to one s id e of th e b e l t conveyor, or

s e le c t iv e ly to e i th e r s id e , o r . t o bo th s id e s s im u lta n e o u s ly .

Many models of t r i p p e r s a re a v a i la b le , bu t a l l can be c l a s s i ­

f ie d in to th e fo llo w in g f iv e g e n e ra l ty p e s :

... ( i ) : motor p ro p e lle d t r i p p e r s " ^

( i i ) hand p ro p e lle d t r ip p e r s

. ( i i i ) s ta t io n a r y t r i p p e r s

( iv ) ro p e -h a u l t r ip p e r s

(v) b e l t p ro p e lle d t r ip p e r s

Of a l l th e s e ty p e s th e l a s t one, ( v ) , b e l t p ro p e lle d t r ip p e r s

a f f e c t th e t o t a l power req u irem en t o f th e conveyor system .

I f ..the b e l t p ro p e lle d t r ip p e r , i s . i n s t a l l e d , .the power, t o ..

d r iv e th e t r i p p e r i s o b ta in ed from th e b e l t by means of a

gear t r a i n which connects th e d r iv e w heels to th e t r ip p e r

p u lle y ( th e d i r e c t io n o f th e t r ip p e r t r a v e l can be re v e rse d

by s h i f t in g g e a r s ) . T his p o w e r is de term ined by th e

fo llo w in g fo rm u la :3=2/ .............. ...... ’ ' ' ............. ...‘a ': v ■■■.0B e lt p ro p e lle d t r i p p e r h p . , h t = -----

-990(9)

1 0 / H. E. P rim er, A ll about b e l t in g - Handbook M. 6314-B-17, 1957, R o c k fo ile r C en te r, New York 20, N .Y ., U nited S ta te s Rubber Company, P . , 22.

Where; A = a c o n s ta n t which v a r ie s w ith b e l t w id th . (See ta b le VI f o r v a lu e s of ,AI )

S = b e l t speed in f .p .m . r'■ • . /

T = o u tp u t in to n s per hour

H = t r ip p e r l i f t in f t . which v a r ie s w ith b e l t w id th . (See ta b le V II f o r v a lu e s

:: ........ . o f *H') . .

: - TABLE VI :

VALDES OF CONSTANT 'A ' ' ; : . ; r r.:

3 4

B e lt w id th ( in in c h e s) V alue of •A1

24 : .. ■: . 0 . 0030 :

30 0.0047

36 . • • v : 0.0058

42 0.0070

48 0.0082

* ; 0.0100

TABLE V II • - ;;

AVERAGE TRIPPER LIFTS (VALUES OF , H*)

B e lt w id th ( in in c h e s ) . T rip p er h e ig h t ( in f t )

24

30

36

4 8 .

’ 5if

4 .0

4 .5

5 .0

5 .5

6.0

7 .0

3 5

ACCELERATION. HORSEPOWER. : - c . ' cr-nr.:;:

The a d d i t io n a l horsepower r e q u ire d to a c c e le r a te th e

loaded b e l t , ha , i s de term ined by th e fo llo w in g f o r m u la :^ /

■ - ‘ - ( L ) x ( S(Q / M) x (100) (100) 2

6 3 . 8t___(10)

Where: Q = w t. of th e b e l t and moving p a r ts ( in lb s■:r: - p e r l i n e a r f t . of co n v ey o r). See page

26 f o r f u l l e x p la n a tio n o f th e v a lu e of-v.-- Q. v/..,-::. " '' L :

S z b e l t speed in f .p .m .

M r av e rag e lo a d in lb s per f t o f conveyor. : I t i s determ ined from th e fo llo w in g

fo rm u la :

u _ -------- where T i s th e averager ;; v " s o u tp u t in to n s /h o u r .

L. = t o t a l le n g th of th e conveying b e l t in f t ,

v i t = tim e in seconds to a c c e le r a te th e b e l tfrom r e s t to f u l l lo a d . (T h is tim e i s

:: :r . ' 1 u s u a lly l im i te d to 2 to 5 s e c o n d s ) .

This a c c e le r a t io n horsepow er, ha , i s r a r e ly added to

th e o th e r b e l t horsepow er req u irem e n ts to o b ta in th e t o t a l

b e l t horsepow er. Where th e a c c e le r a t io n r a t e i s u n u su a lly

h igh or o th e r in d ic a t io n s a r e t h a t th e horsepower re q u ire d

f o r a c c e le r a t io n may be uncommonly l a r g e , i t must th e n be

determ ined and in c lu d ed in th e t o t a l b e l t horsepow er. I f

th e a c c e le r a t io n horsepow er i s l e s s th a n 50%. of..th e sum of

11/ J H als ted S t r e e tCompany, 1961,

. W. Hardy, B e lt Conveyor C om putations., Chicago 9 , I l l i n o i s , Goodman M anufacturingP ♦» 5 •

he / hy, / h%., i t i s ig n o red s in c e m o to rs .a re norm ally cap ab le

of d e l iv e r in g power 50$ in excess of t h e i r con tinuous '

r a t i n g s .

3 6

A lso , a d d i t io n a l c o n s id e ra t io n must be g iv en to th e

e l e c t r i c a l equipm ent when a conveyor w i l l be s t a r t e d many

tim es d u rin g th e s h i f t . An abnorm al number o f sto p p in g and

s t a r t i n g tim es w i l l te n d to h ea t th e motor beyond i t s

norm al r a t in g and must be co n s id e red when s e le c t in g m otors

f o r th e conveyor system .

SUMMARY ££ BELT HORSEPOWER CALCULATION'S

The t o t a l b e l t horsepow er, h , i s th e sum o f th e in ­

d iv id u a l power item s he , hm, hr , h^, and ha ~. • U su a lly th e

v a lu e s of h t and ha a re n o t in c lu d ed in th e t o t a l b e l t h o rse -: : 3 ■ ■; • . : ■...............

power when th e t r i p p e r i s n o t p re s e n t or n o t o p e ra ted by th e

b e l t motor and when th e a c c e le r a t io n horsepower determ ined

by form ula (10) i s l e s s th a n 50$ o f th e sum of he , h^, and hr .

(A) Horsepower R equirem ents f o r H o riz o n ta l Conveyors:

For h o r iz o n ta l - b e l t conveyor i n s t a l l a t i o n s th e power

i s r e q u ire d on ly to overcome th e f r i c t i o n in runn ing th e

empty b e l t and to c a rry th e m a te r ia l along i t .

T h e re fo re , t o t a l motor horsepower fo r h o r iz o n ta l conveyors

v:; ;; - he ^ * V : ( 1 1 )m otor e f f ic ie n c y

37

(B) Horsepower R equirem ents f o r E le v a tin g Conveyors: -

The t o t a l m otor horsepower fo r e le v a t in g conveyors

he / bin / hp motor e f f ic ie n c y

(12)

(C) Horsepower R equirem ents f o r D escending (o r D ec lin in g )

Conveyors:

Two c o n d itio n s must be co n s id e red in co n n ec tio n w ith

a loaded d e c lin e d conveyor:

( l ) When th e g r a v i ty horsepow er, hp, i s LESS th a n

th e f r i c t i o n horsepower ( th a t i s , l e s s th a n sume of he and

hjjj), some power i s re q u ire d -fro m th e motor to ,d r iv e th e

loaded conveyor on d e c lin in g g ra d e s . This horsepower i s ^

i:(he V !%) - 4 - (hT ) .(13)

(2) When th e g r a v i ty horsepow er, bp, i s GREATER

th a n th e f r i c t i o n horsepower (he / h g ) , th e horsepower r e ­

qu ired , in th e b e l t to r e t a r d th e loaded conveyor a g a in s t• c - ", /'

g r a v i ty a c t in g on th e lo ad i s 1 3 /

(hr) - 4 - (ko / h j , ) ____________ (I'O

As (he / h m) approaches th e v a lu e o f hp, th e loaded

1 2 / U. S. R ubber, A ll abou t b e l t in g f o r Coal Mining Handbook M, 6314-B - l , 1957j R o c k fe lle r C e n te r , New York 20, N.Y. U nited S ta te s Rubber Company, p . 65*

1 3 / I b i d .

conveyor w i l l have a g r e a te r tendency to c o a s t when th e power

to th e motor i s sh u t o f f . When h r . i s g r e a te r th an (h e ,,/ hg.)

a b rake must be u sed .

. I t i s obvious t h a t in o rd e r to a r r iv e a t th e a c tu a l

motor horsepow er needed to d r iv e th e b e l t conveyor in a l l

th e above ca ses th e tr a n s m is s io n and o th e r lo s s e s between

th e motor and d r iv e p u l le y must a ls o be co n s id e re d . The

o v e r a l l e f f ic ie n c y o f th e motor may be ta k en a s eq u a l to 80$.

The s t a r t i n g to rq u e req u irem en t of a conveyor i s an

im p o rtan t f a c to r in s e le c t in g th e d r iv e m otor. The g e n e ra l

purpose s q u i r r e l cage motor w i l l f u l f i l l th e req u irem en ts of

most a l t e r n a t in g c u r r e n t i n s t a l l a t i o n s . However, some con­

veyors r e q u i r e an i n i t i a l s t a r t i n g to rq u e which exceeds th e

o u tp u t o f t h i s ty p e o f m otor. Such req u irem en ts n e c e s s i t a t e

th e use o f h ig h - to rq u e s q u i r r e l cage or w ound-ro tor in ­

d u c tio n m o to rs. These a l t e r n a t in g c u r re n t m otors o f f e r c e r ­

t a i n advan tages over d i r e c t c u r r e n t m otors on some a p p l i ­

c a t io n s . However, d i r e c t c u r r e n t m otors a re f r e q u e n t ly used

in c o a l mines where v a r ia b le speed req u irem e n ts a re

n e c e s s a ry . O pen-type m otors a re n o t p e rm is s ib le f o r use in

hazardous lo c a t io n s ; m otors t h a t a re i n s t a l l e d a t lo c a t io n s

where ex p lo s iv e q u a n t i t i e s of c o a l d u s t or methane gas may

be p re s e n t r e q u i r e s p e c ia l c o n s tru c tio n such as flam e­

p ro o f ing and “ i n t r i n s i c a l l y sa fe " f e a tu r e s .

3 8

PERMISSIBLE ANGLES OF INCLINATION FOR HAULING COAL ON BELTS

The an g le of in c l in a t io n depends on th e fo llo w in g f a c to r s :

(1) Shape and s iz e o f th e m a te r ia l to be conveyed -

I r r e g u la r ly shaped m a te r ia l has l e s s tendency to r o l l back

th a n sm o o th ;sy m m e tr ic a lly shaped m a te r ia l . However,

sy m m etrica lly shaped m a te r ia l can be conveyed up s te ep g rad es

w ith o u t f o i l - b a c k i f embedded iri a c o n s id e ra b le amount of

f i n e s .

(2) M oistu re - Wet m a te r ia ls ten d to s l id e back on

in c l in e d conveyors.

(3) Speed and lo ad in g - M oderate b e l t sp eed s , un ifo rm ly

c o n t ro l le d f e e d - lo a d in g , and lo a d in g on a h o r iz o n ta l s t r e t c h

o f th e b e l t ip rov ide th e g r e a te s t e f f ic ie n c y on s te e p ly in ­

c l in e d r u n s . .

In g e n e ra l , th e maximum ang le of in c l in a t io n a t

which th e m a te r ia l can be conveyed i s app rox im ate ly 10 to

15 deg rees l e s s th a n th e an g le of rep o se of th e m a te r ia l .

The fo llo w in g ta b le V II I l i s t s p e rm is s ib le an g le s over

which c o a l can be conveyed w ith o u t undue s p i l l a g e .

39

TABLE V I I I

MAXIMUM PERMISSIBLE ANGLES OF

CONVEYOR INCLINATION

M a te r ia l to be conveyed Maximum p e rm is s ib le an g le ( in d eg rees)

1 . A n th ra c i te Coal

(a) ru n -o f-m in e 16

(b) f in e s 20

(c) lumps only 16

2. B itum inous Coal

(a) ru n -o f-m in e 18

(b) f i n e s 20

(c) lumps on ly 16 r

CHAPTER V

SELECTION OF PROPER BELT

The proper s e le c t io n o f b e lt width and speed fo r

a g iven output and th e c a lc u la tio n of t o t a l b e lt horsepower

has been shown in the previous chapters. A fter determ ining

the t o t a l b e lt horsepower requirem ents, the f i r s t step in

s e le c t in g the correct b e lt i s to know the maximum s tr e s s e s

th a t w i l l be developed in the b e lt w h ile hauling the

m a ter ia l. A b e lt carcass of proper con stru ction i s then

s e le c te d to w ithstand th ese s t r e s s e s . F in a lly a b e lt

covering i s s e le c te d to p ro tect the b e lt carcass aga in st

ex tern a l wear, h eat, m oisture or other in ju rio u s pro­

p e r t ie s of the m a ter ia l to be conveyed. The s e le c t io n of the

proper b e lt fo r a g iven duty i s very important to minimize

tra n sp o rta tio n c o s t s . To determ ine the co rrect s p e c if ic a t io n s

of the b e lt in g , i t i s necessary to know the maximum operating

ten sio n under which the b e lt w i l l work. In the operation

of any b e lt conveyor there i s a d iffer en ce in b e lt ten sio n

between the p o in t where i t f i r s t con tacts the d rive p u lley

and the p oin t where i t le a v es the p u lle y . These ten sio n s

known as " tig h t side" te n s io n , T^, and "slack side" ten s io n

Tg, are in d ir e c t r e la t io n s h ip to one an oth er. The

d if fe re n c e .b e tw e e n th e t i g h t s id e te n s io n and s la c k s id e

te n s io n i s known as “ e f f e c t iv e " te n s io n , Te . These th r e e

b a s ic b e l t te n s io n s must be determ ined b e fo re choosing

c o r r e c t b e l t . However, th e r e a re o th e r minor b ielt .ten sions

th ro u g h o u t th e b e l t ru n t h a t may a f f e c t s u c c e s s fu l b e l t

o p e ra t io n under s p e c ia l c o n d i t io n s . These l a t e r b e l t te n s io n

com putations a re n o t d e a l t w ith in t h i s s tu d y and should be

r e f e r r e d to th e conveyor b e l t m anufactu rers* e n g in e e rs .

DETERMINATION OF BELT STRESSES

There a re many methods of c a lc u la t in g b e l t s t r e s s e s

or te n s io n s . Most o f th e la r g e r b e l t m an u fac tu re rs p u b lis h

a d es ig n m anual covering t h i s s u b je c t . But many of th e se

methods r e q u i r e th e use of c h a r t s , t a b le s , nomographs, e t c .

A lso , th e s e m anuals in c lu d e l i t t l e , i f any, in fo rm a tio n con­

ce rn in g th e b e l t te n s io n req u irem en ts f o r po ly v in y l c h lo r id e

covered b e l t i n g , s in c e t h i s ty p e of covering has been r e ­

c e n tly in tro d u ce d as f i r e r e s i s t a n t b e l t in g . In t h i s s e c t io n

a sim ple method of computing v a r io u s im p o rtan t b e l t te n s io n s

r e q u ir in g a minimum number of c h a r ts and ta b le s i s g iv en .

(1) E f f e c t iv e B e lt T ension:

The e f f e c t iv e te n s io n , TQ, i s th e p u l l on th e b e l t

to overcome th e f r i c t i o n a l lo s s e s caused by th e movement of.........

th e b e l t and i t s lo a d in p a ss in g over i d l e r s and any l i f t o f

th e lo ad on a g rad e . The e f f e c t iv e te n s io n , Te , i s th e

d i f fe re n c e between t i g h t s id e te n s io n and s la c k s id e te n s io n

43

of th e b e l t . That i s , » -

: ; . T o = CT1 - T 2 ) . ---------------------------------- ( 1 5 )

: A lso , T. = — ?. 33.?QQ2.S --------------------- (16 )

Where: h - t o t a l b e l t h o r s e p o w e r - ,

8 « b e l t speed in f .p .m .

(2) Maximum o p e ra tin g te n s io n :

T igh t s id e te n s io n , T^, i s th e te n s io n in th e b e l t

a s i t f i r s t c o n ta c ts th e p u l le y . The maximum b e l t , te n s io n

i s th e h ig h e s t te n s io n in th e whole b e l t loop and t h i s

te n s io n d e te rm in es th e re q u ire d t e n s i l e s t r e n g th of th e b e l t

to w ith s ta n d th e w orking s t r e s s . In h o r iz o n ta l or n e a r ly

h o r iz o n ta l b e l t s th e maximum o p e ra tin g te n s io n may be tak en

as eq u a l to T^. In o rd er to de te rm ine th e maximum o p e ra tin g

te n s io n (h e n c e fo r th d e s ig n a te d w ith symbol T ^), th e v a lu e of

e f f e c t iv e te n s io n Te , must be m u lt ip l ie d by a f a c to r , F

(which w i l l be ex p la in ed l a t e r ) . 'T hat i s ,

.•Maximum o p e ra tin g te n s io n T^ = Te x F (17)

F ig . 4 B e lt T ensions In a Running B e lt

R e fe rr in g to F ig . 4 , i s t i g h t s id e te n s io n and Tg

th e s la c k s id e te n s io n . When th e b e l t i s abou t to s l i p on

th e d r iv in g d ru a , th e r a t i o to and Tg w i l l re a c h i t s

maximum v a lu e and i s g iv en by th e fo rm ula:

T 1

T 24 T _ (18 )

Where: © = an g le o f wrap in ra d ia n s

/ I * c o e f f ic ie n t o f f r i c t i o n between b e l t and d r iv in g p u lle y

e ■ base of th e N aperian lo g a rith m

S ince • Vs (T^ - T2 ) (from form ula 15)

and H3 11 Te x F ; (from form ula 17)

T h e re fo re ,..... i II •* - ^ - ■■ * * - ^ »*. t

Or F = h / ( * i - 5 2 ) .

r ri / (n - 1) 3&/

Where n =

.(19)

T h is ,v a lu e o f F and th e im p lied v a lu e of Tg i s th e

minimum v a lu e to p rec lu d e s l i p on th e d r iv in g drum. In

p r a c t ic e s l i p i s p rev en ted by u sin g in th e d es ig n a sm a lle r

l V S ince = 'e 6 (from form ula 18 ) th e r e fo r e ,T2

T1 = T2 x ^ ° * "

Then T1 = x ^ = "2 r . & = n(Tr i 2 ) T ig x / « » ) - i 2 t 2 % ^ - a (n- 1)

Where n - ^

value fo r the c o e f f ic ie n t o f f r ic t io n between b e lt and drum

than Is a c tu a lly obtained in s e r v ic e .

The'approximate v a lu es of the c o e f f ic ie n t of f r ic t io n

fo r variou s b e lt s i s g iven in th e fo llo w in g Table IX:

- - , • - ■ ' .. . . ■ - - . • - - - ■ *•

VALUES OF COEFFICIENT OF FRICTION

4 5

B elt Cover P la in drum Lagged drum

Rubber covered b e lt in g 0 .25 0 .3 5

Poly v in y l ch lor id e ( p . v . c . )

covered b e lt in g : 0.20 0 .28

.... In th e eq u a tio n (19) th e v a lu e s o f 0 can v ary from

180 deg. to 270 d eg . f o r a s in g le d r iv e depending on th e

snub p u lle y arran g em en ts; and f o r m ulti-d rum d r iv e s an an g le

of wrap of 220 deg . per d r iv in g drum i s th e u s u a l v a lu e .

The ta b le X g iv es th e v a lu e s of F based on form ula

(19) and on ta b le IX fo r c o e f f ic ie n t o f f r i c t i o n v a lu e s .

1

TABLE X •

VALUES OF "F" FACTOR

4 6

Angle of -wrap Rubber covered b e l t in g p .v .c . covered b e l t in g

( in d eg rees)P la indrums

Laggeddrums

P la indrums

Lagged - drums

220 , . , 1 .6 2 1-35 1 .8 6 1 .52

270 , 1 .4 4 1 .2 3 1 .63 1-36

^ o 1 .1 7 , 1 .0 7 i #27 ; ; 1-13

• . 660 ; 1 .0 6 1 .0 2 1 .1 1 1 . * *

We have a lre a d y e s ta b l is h e d th e fo rm u la : -~F x Te

where T_ - 4 x 33>000 ( s e e fo rm u la 1 6 ) . I t i s ap p a ren t from• '• - ' 6 S

t h i s fo rm ula t h a t th e h ig h e r th e b e l t speed , th e sm a lle r w i l l

be th e maximum te n s io n f o r th e same to n n ag e . P r a c t i c a l ly

t h i s means t h a t f o r a g iven tp h ( to n s p er h o u r) , th e lo ad

bed on th e f a s t moving b e l t i s th in n e r and th e re w i l l be

l e s s w eight on th e t o t a l le n g th a t one tim e . Hence th e p u l l

to move th e b e l t w i l l a ls o be l e s s ; f o r exam ple, a b e l t

t r a n s p o r t in g 300 to n s p er hour a t 300 f .p .m . r e q u ir e s a

t e n s i l e s t r e n g th on ly o n e -h a lf t h a t of a b e l t t r a n s p o r t in g

th e same tp h b u t a t l$ d f,.’p.m .

A fte r d ec id in g th e d e s ire d b e l t w id th and th e max­

imum b e l t te n s io n , th e n e c e ssa ry p ly w eigh t and number of

^7

p i l e s can be d e te rm in ed . The t e n s i l e s t r e n g th of th e b e l t

i s co n s id e red to be in th e b e l t c a rc a s s . .The ru b b er covers

and skim c o a tin g in th e c a rc a s s a re m erely to b ind th e

f a b r ic p l i e s to g e th e r and to p r o te c t th e c a rc a s s from im­

p a c t , a b ra s io n , m o is tu re and d i r t . The. conveyor b e l t i s

commonly made up of s e v e r a l p l i e s o f c o t to n , ray o n , n y lo n or

com bination of th e s e woven in to a f a b r ic and sometimes r e ­

in fo rc e d by c o t to n co rd s or s t e e l c a b le s as in "Campass

cord" b e l t s . The p ly s t r e n g th i s s p e c if ie d in pounds p er ,

in c h -w id th and i s d e s ig n a te d as th e p e rm is s ib le working

s t r e s s . ( p .w . s . ) . I f p .w .s . i s exceeded in th e norm al b e l t

ru n th e f i b e r w i l l te n d to s e p a ra te from i t s b in d in g in th e

c a rc a s s . The p e rm is s ib le w orking s t r e s s i s determ ined as

fo llo w s :

p .w .s .* ____ ___________ ( 20)— ■ - W ' , ' :.....:

where T^ i s th e maximum"operating te n s io n in pounds, and W

i s th e b e l t w id th in in c h e s .

. Tx " -A lso , — - 77— = fx p in lb s p e r in c h of w id th

_____________________ ( 21)

Where: f = maximum w orking s t r e s s /p ly / in c h - w id th

p * number o f p l i e s in th e b e l t

The v a lu e o f - th e maximum w orking s t r e s s in th e b e l t depends

upon th e fo llo w in g f a c t o r s :

(a ) th e q u a l i ty o f m a te r ia l used in th e b e l t c a rc a s s .

(b) th e ty p e of j o i n t used f o r end to end b e l tjo in in g

"Hook J o in ts " w ith m e ta l l ic f a s te n e r s have a s t r e n g th of

about 50$ o f th e o r ig in a l b e l t in g and "S p lic ed J o in ts " can

have a s t r e n g th up to 75$ o f th e o r ig in a l b e l t s t r e n g th , de­

pending on th e number o f p l i e s in th e b e l t .

(c ) th e method of b e l t te n s io n in g arrangem ent.

( i ) In screw ty p e te n s io n in g , th e b e l t i s s t r e s s e d by a screw

arrangem ent u n t i l s u f f i c i e n t te n s io n i s developed in th e

b e l t in g . The a c tu a l te n s io n in th e b e l t canno t be gauged by

th e te n s io n d ev ice o p e ra to r , and so th e u su a l p r a c t ic e i s to

co n tin u e te n s io n in g th e b e l t u n t i l s l i p does n o t occur a t

th e d r iv in g drum. I t should be n o ted th a t th e b e l t i s e a s i ly

o v e r - s tr e s s e d by t h i s m ethod.

( i i ) The g r a v i ty ty p e te n s io n in g i s designed to app ly only

th e s la c k s id e te n s io n Tg on th e s la c k s id e o f th e b e l t :

The v a lu e o f T2 i s much low er th a n th e maximum fo rc e in th e

b e l t and can be a p p lie d d i r e c t l y by w eighted r o l l e r s or in ­

d i r e c t ly by th e lo ad ed w ire r o p e s . This method of te n s io n ­

ing cannot over s t r e s s th e b e l t and so i t a llow s a h ig h e r

v a lu e of p e rm is s ib le w orking s t r e s s to be u sed .

(d) th e cy c le tim e o f th e b e l t .

As th e cy c le tim e in c re a s e s th e b e l t te n s io n r a t in g must be

in c re a s e d . •

The ta b le XI g iv e s th e v a lu e s of maximum working

s t r e s s r a t in g s f o r ty p i c a l conveyor b e l t s .

MAX

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3» Slope B e lt T ension : '

. W ith a l l In c l in e d conveyors th e w e ig h t-o f th e b e l t

on th e s lo p e cau ses te n s io n a t th e to p of th e s lo p e . The

slope b e l t te n s io n , Ts , depends on th e w eight o f th e b e l t

and th e f r i c t i o n of th e r e tu r n i d l e r s . W ith a f r i c t i o n co­

e f f i c i e n t of 0 .03 f o r th e r e tu r n id le r s ^ th e s lo p e b e l t

te n s io n can be determ ined by th e fo llo w in g fo rm ula

Ts = C x L x (0 -1 /1 5 ) . ___________ (22)

Where: G = g ra d ie n t o f th e s lo p e ex p ressed as af r a c t i o n ^

L = b e l t le n g th in f e e t

C r b e l t w eight i n pounds p er l i n e a r f t .( s e e below f o r th e d e te rm in a tio n of

; b e l t w e ig h t)

Should th e v a lu e of s lo p e te n s io n , Ts , as c a lc u la te d

by th e above fo rm u la exceed th e v a lu e of s la c k s id e te n s io n ,

Tg, th e n th e maximum b e l t t e n s io n , T^, w i l l be eq u a l to

(Te / Ts ) and th e b e l t shou ld be designed a c c o rd in g ly . The

v a lu e of Ts r a r e ly exceeds Tg even fo r conveyors on s te e p

s lo p e s u n le s s a th ree -d ru m d r iv e i s u sed .

D ete rm in a tio n o f B e lt W eight: -

The v a lu e o f b e l t w e ig h t, C, v a r ie s w ith th e ty p e

of b e l t c o n s tru c t io n and m an u fac tu re r* s s p e c i f i c a t i o n s .

1 5 / N. Brook, o p. c l t . « p . 1*90

I f no In fo rm a tio n a s to th e w eight o f b e l t I s a v a i la b le an

approxim ate v a lu e may be determ ined by th e fo llo w in g

fo rm ula: 3 ^ /

C r W f l U L l / q) I b s / l l n e a r f t . _______________ (23)1200

"Where: ¥ * b e l t w id th in in ch es

w = duck w eight in ounces (u s u a lly su p p lie d )

p = number of p l i e s in th e b e l t

q * w eigh t o f th e to p and bottom cover of th e b e l t ( in lb s ) per f t . long and p e r in c h wide of b e l t . U su a lly th e v a lu e of q = 0.030 l b s . when to p and bottom cover th ic k n e s s = 1 /32 In ch .

NOTE: The above fo rm u la must be used only to determ ine th e

w eight o f p ly type b e l t s . For s t e e l ca b le r e in fo rc e d b e l t s ,

th e e x tra w eight of th e s t e e l members must be co n s id e red .

DETERMINATION OF MAXIMUM AND MINIMUM NUMBER OF PLIES OF

BELTS FOR PROPER TROUGHINO AND STIFFNESS

The ch o ice o f number o f p l i e s in a norm al m u lti­

p ly b e l t I s governed n o t on ly by th e s t r e s s bu t a ls o by th e

tro u g h in g and s t i f f n e s s c h a r a c t e r i s t i c s o f th e b e l t . In

o th e r w ords, a b e l t may p ro v id e s u f f i c i e n t s t r e n g th In

te n s io n bu t owing to s iz e and w eight of m a te r ia l i t may be

too f l im s y . C on v erse ly , a b e l t may be so heavy or th ic k

th a t i t w i l l n o t be tro u g h a b le in th e r e q u ire d w id th . In

16/ i& ia

TABLE X II

- 'MINIMUM PLIES TO SUPPORT LOAD OF R.O.M. COAL UP TO 2 0 -INCH MAXIMUM .LUMP-SIZE AND MAXIMUM PLIES FOR PROPER TROUGHING

Duck w eight and p ly qual . i t y

B e lt w id th

( in in ch es)Minimum p l ie s to su p p o rt load Maximum p l i e s f o r p ro p er tro u g h in g

28 o z ._ c o tto n -

32 02. c o tto n -

36 02. c o tto n -

42 02. U stex­

Heavy 28 o z . c o tto n -

32 oz . c o t to n -

36 02. c o t to n -

42 02. U stex -

Heavy

nylon nylon nylon nylon rayon nylon n y lo n n y lo n n y lo n< . . '' ' . ;

ray o n

2k 4 4 4 4 5 6 5 ■ 4 6

30 5 5 4 4 6 7 ; V : 6 ■ 5 5 7

36 6 5 5 4 6 9 6 5 8

42 6 6 5 5 6 10 8 8 ;■ 7 9 .

48 7 6 6 6 7 12 12 U 8 10

54 7 7 6 6 7 _ , 12 : 12 8 11

60 7 7 7 6 8 13 13 9 12 .

NOTE: 1 . Campass cord and s t e e l ca b le b e l t s by t h e i r n a tu re , more tro u g b a b le th a n p ly - ty p e b e l t s and each w id th

of th e s e I s d es ig n ed w ith s u f f i c i e n t body to p ro v id e l a t e r a l s t a b i l i t y

2 . The v a lu e s above a re based on 20 deg . e q u a l - r o l l t coughing i d l e r i n s t a l l a t i o n . A c u ta lly th e d e s ig n o f a

c a rc a s s f o r s u f f i c i e n t s t r e n g th to su p p o rt th e lo ad p rov ided th e prop er tro u g h in g . c h a r a c t e r i s t i c s . .■ Hence i t may n o t be

n e c e ssa ry to check th e b e l t f o r minimum or maximum p ly re q u ire m e n ts .

t h is case an a lte r n a t iv e i s to use a Campass cord or s t e e l

cab le b e lt w h ich 'w ill trough in the d esired w idth, or e ls e a

wider b e lt w ith fewer p l ie s may be used i f i t i s w ith in th e

minimum and maximum p ly l im it a t io n s . • '

53

The ta b le X II g iv e s the minimum and maximum p ly

l im ita t io n s of ty p ic a l rubber covered b e lt s to carry ru n -o f-

mine c o a l. For p . v . c . covered b e lt s th ese v a lu es may be■ 1 ' , . ' ' • . . • • • 1 ' r'

found from the fo llo w in g form ulae:1 2 /

Maximum number of p l ie s

Minimum number o f p l ie s

7-5Ww •

3-5Ww

__(2W

— (25)

Where: W = b e lt w idth in inches

w r duck weight in ounces

DETERMINATION OF SIZE OF DRIVING DRUMS AND PULLEYS,

The s iz e o f drums and p u lley s required depends on

th e number of p l ie s and duck w eight used in th e b e lt con­

s tr u c t io n . These s iz e s must be such th a t i t should not cause

the outer p ly o f the b e lt to exceed i t s e l a s t i c l im it during

the bend and su ffe r p ly sep a ra tio n . Hence th ick ca rca sses

( i . e . larger number of p l ie s ) req u ire la rg e diameter p u lley s

and th inner ca rca sses ( i . e . fewer p l ie s ) need sm aller and

l e s s expensive p u lle y s . . The thinner carcass of rayon w i l l

1 2 / Ik M -

$ 4

have the same maximum p erm iss ib le ten s io n per inch per p ly

as the th ick er carcass of co tto n . Sometimes i t i s d e s ir ­

ab le to use th in carcass b e lt s fo r u t i l i z in g older p u lley s

of sm aller s i z e , i f a v a ila b le a t no extra c o s t . Otherwise

th e th inner carcass o f rayon or nylon having the same

stren gth as a th ick carcass of co tto n would in v o lv e the

purchase of a more expensive b e l t . The fo llo w in g formulae

serve th e gen era l gu ides fo r determ ining the s iz e of drums

and p u l l e y s : ^ /

, •

f' ::v

Diameter o f d riv in g ,drums

( in in ch es) = y . — . . R' 6

(2 6 )

.(27)

( 28)

( i i ) Diameter of driven drums

( in in ch es) r v x ? _ _______- -■ - . . : 8

( i l l ) Diameter o f snub p u lley s

( in in ch es) = ________\ ■ ' . . . - ■ 1° ' ■

. Where: w = duck, weight in ounces

. u ; p = number o f p l ie s in a b e lt

SELECTION g F PROPER BELT CONSTRUCTION MATERIAL

Of the many t ie lt s a v a ila b le , se v e r a l of th ese may

s u it the predetermined ten s io n requirem ents. The conveyor

b e lt s are made o f co tton fa b r ic , rayon, nylon and other

1 8 / I b i d . , pp. 486-92 , p assim .

s y n th e t ic f i b e r m a te r ia l s , s t e e l cab le r e in fo rc e d members,

f i r e - r e s i s t a n t b e l t s u s in g p . v . c . , te ry le n e and neop rene , -

e t c . In th e s e le c t io n of b e l t , "proper te n s io n i s n o t only

th e f a c to r to be co n s id e red and i t does n o t n e c e s s a r i ly con­

f irm th e u l t im a te s t r e n g h t o f b e l t . In o rd er t h a t some

knowledge may be had o f some o f 1th e o th e r f a c to r s in vo lved

in th e s e le c t io n of a s u i t a b le b e l t , th e fo llo w in g c o n d itio n s

t h a t a f fe c t 'w o rk in g te n s io n s a re b r i e f l y d is c u sse d :

1 . F a tig u e o f B e it Duck: In any b e l t I n s t a l l a t i o n th e

te n s io n member.of th e b e l t p asse s from h ig h er to a low er

or low er to a h ig h er te n s io n r e g io n somewhere in i t s hau l

d is ta n c e . Thus th e re w i l l be c y c l ic te n s io n changes de­

pending upon th e b e l t speed and le n g th . When th e f a b r ic

i s s t r e s s e d to more th an 50^ o f i t s u l t im a te s t r e n g th

f a i l u r e from f a t ig u e occu rs r a p id ly .

2 . S tr e tc h : The more h ig h ly th e b e l t i s s t r e s s e d th e more

i t w i l l s t r e t c h . The e x tra s t r e s s causes more f re q u e n t ta k e -: ■ • ' • . ' : VV ' . . . . . . . ... . ; ,. - t , . ;up ad ju s tm en ts by th e screw ty p e takeup or more t r a v e l f o r

au to m atic ta k e u p .

3* S p lic e L im ita t io n s : Conveyor b e l t s may be s p lic e d

11 e n d le s s u by means of m e ta l f a s te n e r s ' or by v u lc a n iz in g .

The p la te ty p e m e ta l f a s te n e r s has p u l l - o u t s t r e n g th t h a t i s

l e s s th a n th e s t r e n g th o f th e duck i t s e l f . T his f a c to r i s

ta k en in to c o n s id e ra t io n by th e te n s io n r a t in g s g iv en in

Table X I.

5 5

The b e l t s o f campass cord or s t e e l cab le r e in fo rc e d

c o n s t ru c t io n .a r e made " e n d le s s " by v u lc a n iz e d s p l ic in g ONLY.

The s t r e n g th i n th e s p l i c e cannot be as g r e a t as th e sum of

th e s t r e n g th s o f th e in d iv id u a l co rds or c a b le s . The f a b r i c

p ly b e l t s may a ls o be v u lc a n iz e d "e n d le ss" w ith a diamond or

b ia s ty p e s p l i c e . W hile t h i s method does n o t p ro v id e a

s p l i c e as s tro n g as an u n d is tu rb e d b e l t s e c t io n s , however, i t

i s very s tro n g and f r e e from th e l o c a l s t r e s s e s found in a

m e ta l fa s te n e d j o i n t . The use of v u lc an iz ed j o i n t in c re a s e s

p e rm is s ib le te n s io n r a t in g as compared to a m e ta l fa s te n e d

j o i n t . The t a b l e XI g iv e s th e te n s io n r a t in g s f o r th e v u l­

can ized s p l i c e b e l t s .

P u lle y Bending F o rc e s : The fo rm ulae 26 th ro u g h 28 on

page 54 a re e s ta b l i s h e d in o rd e r to o b ta in th e same degree

of bending s t r e s s r e g a rd le s s o f th e b e l t th ic k n e s s . No

m a tte r what th e p u lle y d iam ete r may b e , th e o u te r p l i e s ofv - '

th e b e l t must e lo n g a te as th e b e l t i s b en t around th e

p u lle y . The e x t ra s t r e s s in th e o u te r p l i e s induced by

bending i s dependent on th e d iam eter o f th e p u l le y , th e

th ic k n e s s of th e b e l t , and th e e l a s t i c c o n s ta n t o f th e b e l t

te rm in a l . Hence th e p e rm is s ib le working s t r e s s must be l e s s

th a n th e u l t im a te s t r e n g th o f th e duck to a llow fo r th e se

bending s t r e s s e s . The campass cord and s t e e l cab le b e l t s

a re so c o n s tru c te d th a t th e p u lle y bending s t r e s s e s a re

r e l a t i v e l y i n s i g n i f i c a n t .

5 6

57

5. A c c id e n ta l Damage to B e l t : In underground c o a l h au lag e ,

b e l t s a re su b je c te d to many h aza rd s . B r i e f l y . th e fo llo w in g

f a c t s a re d isc u sse d a s an a d d i t io n a l a id to b e t t e r s e le c t io n

of b e l t s to guard a g a in s t p o s s ib le dam ages. .

(a ) P ieces o f tram p i ro n and o th e r hard m a te r ia ls

may p ie rc e th e b e l t , b reak th e c a rc a s s , c u t th e to p cover

or cause o th e r o p e ra tin g damages and red u ce th e working

th ic k n e s s of th e b e l t . U su ally i t i s n o t co n v en ien t to

s to p and r e p a i r a b e l t th e i n s t a n t i t i s damaged. Hence a

b e l t i s expected to ru n u n t i l a conven ien t s to p p in g tim e can

be a rra n g e d . T h e re fo re , th e c a rc a s s must have a s u i t a b le

f a c to r o f s a f e ty in c lu d ed in th e a llo w ab le s t r e s s of th e .

f a b r i c , co rd or s t e e l c a b le s to p ro v id e a r e s e rv e f o r ..tempo­

r a r y o p e ra t io n under such c o n d i t io n s .

(b) D e te r io ra t io n o f b e l t c a rc a ss ta k e s p la c e due

to fu n g a l grow th on '.b e lts w orking ’ in m o is t and humid con-

d i t io n s in m ines. . I t i s a breakdown of th e c e l lu lo s e of th e

c o tto n or ray o n f i b e r to p ro v id e nourishm ent f o r th e fu n g a l

grow th. Hence th e u s e ;o f som e:m a te r ia l in th e b e l t con­

s t r u c t io n which w i l l a l l e v i a t e t h e ; g ro w th .o f fungus i s h e lp ­

f u l to guard a g a in s t such d e t e r io r a t io n . W ith th e advent o f

th e u se of rayon in th e b e l t c a rc a s s , th e d i r e c t e f f e c t of

th e p resen ce of m o is tu re had to be ta k e n in to acco u n t. The

c o tto n f a b r ic in th e p resen ce of m o is tu re does n o t lo s e i t s

s t r e n g th bu t a c tu a l ly i s somewhat s tro n g e r assum ing no

b a c t e r i a l d e t e r io r a t i o n . C onversely , depending upon th e

5 8

p e rce n tag e o f m o is tu re p re s e n t In th e m in e ,: rayon may lo s e

a n .a p p re c ia b le p e rce n tag e of i t s dry s t r e n g th . Adhesion

between th e p l i e s and f l e x l i f e a ls o a re a f f e c te d by ex­

trem e ly wet c o n d i t io n s . Hence rayon b e l t s shou ld n o t be used

under such, c o n d i t io n s .

In s t e e l c a b le r e in fo rc e d b e l t s , a d i f f e r e n t ty p e of

d e t e r io r a t io n may o c c u r , namely c o r ro s io n . M echanical

damage o f th e ru b b er cover by gouging or open s p l i c in g , i f

n e g le c te d , can become a s e r io u s f a c to r because of th e r e ­

s u l t in g c o r ro s io n of c a b le s encased in th e b e l t .

(c ) F i r e H azards: Many f i r e s have o ccu rred in c o a l

mines and some of th e s e have b een ,cau sed by b e l t , conveyors.

As a m a tte r o f f a c t conveyor f i r e s a re exceeded in number

on ly by spon taneous com bustion o f c o a l or carbonaceous ma-

t e r i a l . Hence a l l underground b e l t s shou ld be f i r e - r e s i s t a n t .

The U. S. Bureau of Mines has recommended th e u se o f .n e o ­

p rene and po ly v in y l .c h lo r id e ( p .v .c . ) in th e c o n s tru c tio n

of f i r e - r e s i s t a n t b e l t s . N o tw ith stand ing a l l th e s e con­

s id e r a t io n s f o r s a fe ty re q u ire m e n ts , th e b e l t s s e le c te d must

f u l f i l l th e d u ty f o r which i t i s to be u sed . . *

A new hazard has been p re d ic te d d u rin g r e c e n t y e a rs .

One of th e p r o p e r t ie s of p .v .c . used in f i r e - r e s i s t a n t b e l t s

i s i t s h ig h e l e c t r i c a l in s u la t io n q u a l i t i e s or i t s h ig h r e ­

s i s t i v i t y . On some conveyors, m ostly o p e ra tin g in d ry

c o n d it io n s , an e l e c t r o s t a t i c charge i s found to be g e n e ra te d .

59

This charge w i l l g iv e r i s e to u n d e s ira b le and sometimes

dangerous sp a rk in g s which may cause conveyor f i r e s . Hence

th e concept o f develop ing a n t i - e l e c t r o s t a t i c m a te r ia l f o r

b e l t c o n s tru c tio n i s being r e a l iz e d to guard a g a in s t s t a t i c

e l e c t r i c i t y t h a t cau ses conveyor f i r e s . A lso , w ith th e

h igher b e l t speeds th e chance of dangerous sp a rk in g s i s more

l i k e l y to o cc u r. The b e l t s must be ru n w ith in th e maximum

recommended speeds commensurate w ith o th e r e f f ic ie n c y

f a c t o r s . I t i s found t h a t e l e c t r o s t a t i c sp a rk s w i l l no t be

produced when th e b e l t s a re ru n below 475 f t . p er m in u te .

SELECTION OF PROPER QUALITY AND THICKNESS OF BELT COVER

The l i f e of th e b e l t depends, to a g r e a te r e x te n t ,

upon th e s e le c t io n o f c o r r e c t to p and bottom cover q u a l i ty

and th ic k n e s s . The to p cover must be of s u i t a b le com position

and s u f f i c i e n t th ic k n e s s . I d e a l ly , i t i s d e s i r a b le to f u r ­

n is h a cover q u a l i ty and th ic k n e s s such th a t i t s s e rv ic e

l i f e w i l l m atch th e s e rv ic e l i f e of th e c a r c a s s . The cover

th ic k n e s s i s im p o rta n t, n o t on ly from th e s ta n d p o in t of

w ear, bu t a ls o as a cush ion to absorb th e lo a d in g im pact

of m a te r ia l to be conveyed. A la y e r o f f a b r i c having a

s p e c ia l weave c a l le d “b reak e r p ly “ i s o f te n imbedded in th e

co v e r. The b reak e r p ly ab so rb s im pact and p r o te c ts th e

c a rc a s s and cover a g a in s t gouging . The s e le c t io n of p ro p er

cover q u a l i ty and th ic k n e s s i s sometimes d i f f i c u l t because

of many v a r ia t io n s of working c o n d it io n s . E xperience w ith

p rev io u s b e l t s w i l l h e lp i n th e s e le c t io n o f th e p ro p er b e l t

co v e r. T h is e x p e r ie n c e ' shou ld in d ic a te many, c lu e s f o r f u tu r e

s e le c t io n . Loss o f cover by a b ra s io n w h ile th e c a rc a s s i s

r e l a t i v e l y i n t a c t would in d ic a te t h a t succeed ing b e l t s could

p r o f i t a b ly c a r ry a h e a v ie r or a b e t t e r q u a l i ty c o v e r . Severe

c u t t in g o f th e cover w ith o u t s e r io u s a b ra s io n lo s s would in ­

d ic a te e i th e r a lo ad in g problem or a need f o r more cover

th ic k n e s s . I t would, o r d in a r i ly , be more econom ical to im­

prove lo a d in g c o n d i t io n s . F a i lu r e due to o th e r causes of a

cover t h a t i s r e l a t i v e l y i n t a c t would show e i th e r an im proper

cover or th e need to red u ce th e c o n d itio n s producing th e

f a i l u r e .

6 0

.. The bottom cover th ic k n e s s of a b e l t depends m ainly

on th e l ik e l ih o o d of damage caused by th e m a te r ia l con­

veyed g e t t in g betw een th e b e l t and i d l e r s and p u l le y s .

A b rasiv e m a te r ia ls r e q u ir e a h ea v ie r cover th a n n o n -a b ra s iv e

m a te r ia l s . The g e n e ra l c le a n l in e s s of th e i n s t a l l a t i o n

should a ls o be c o n s id e re d . Where th e b e l t i s kep t c le a n and

s p i l l a g e or p i le -u p s a re u n l ik e ly , i t i s l e s s im p o rtan t to

have a th ic k bottom c o v e r . In g e n e ra l , a 1/16 in c h th ic k

bottom cover i s q u i te s a t i s f a c to r y f o r h and ling r .o .m . c o a l

w ith b e l t o p e ra t io n under good c o n d it io n s . However, b e l t s

w ith a h ig h ly s t r e s s e d c a rc a s s such as ray o n , campass cord

or s t e e l c a b le shou ld have th e e x tra p r o te c t io n of 1 /16

in c h a d d i t io n a l th ic k n e s s of bottom co v e r.

61

To a s s i s t i n th e s e le c t io n o f p ro p er th ic k n e s s of

to p cover f o r b e l t s c a rry in g c o a l , t a b le X II I has been p re­

p ared based on b e l t s p e c i f ic a t io n s o f Goodyear T ire and

Conveyor B e lt M anufacturing Company.

v: In conclud ing t h i s c h a p te r , i t should ag a in be no ted

th a t b e s id e s d e te rm in in g p roper b e l t w id th , speed , motor • "

s i z e s , and. maximum o p e ra tin g te n s io n o f th e b e l t , o th e r r e ­

qu irem en ts such as b e l t t r o u g h a b l l i ty and s t i f f n e s s , s iz e of

d r iv in g drums and p u l le y s , q u a l i ty o f b e l t c o n s tru c tio n .

m a te r ia l , b e l t cover th ic k n e s s , and p h y s ic a l working con-

d i t io n s in th e mine must a ls o be co n s id e red s im u ltan eo u sly

th ro u g h o u t b e l t s e le c t io n p ro ced u re . A ll of th e s e f a c to r s

a re i n t e r r e l a t e d an d . in te rd e p e n d e n t .

6 2

TABLE X III

RECOMMENDED CONVEYOR TOP COVER THICKNESS FOR CARRYING COAL

2LCycle tim e (= ~ ) Lumpsize ( in in ch es)

f o r com plete re v o -

lu t i o n of b e l t . • * ,

L - b e l t le n g th in f t .

B itum inous Coal A n th ra c i te Coal

S = b e l t speed in f .p .r a .

D ust i " t o 2 " to 6" & to-i" l i-M 5" over

Dustt o i "

g-"to 2 " tol i " 5”

6" & over

0 .2 3 /32 3/16 5/16 3 /8 3/16 3 /8 1 /2 . -

0 .4 1 /16 3 /32 3 /16 1 /4 3 /32 3/16 3 /8 -

0 .6 1/16 3 /32 1 /8 3/16 3 /32 1 /8 1 /4 . . 3 /8

0 .8 1 /16 3 /32 1 /8 3/16 3 /32 < 00 s 9/32

1 .0 1/16 3 /32 1 /8 3/16 3 /32 1 /8 3/16 7/32

1 .5and over 1/16 3 /32 1 /8 3/16 3/32 1 /8 3/16 3/16

BELT SELECTION PROBLEMS

Example 1 . S e le c t io n o f s u i t a b le b e l t in g f o r underground

main h au lag e .

The fo llo w in g in fo rm a tio n i s p ro v id ed .

1 . R ig id -fram e c o n v e n tio n a l b e l t conveyor w ith 20 deg . tro u g h in g i d l e r s .

6 3

; ' 2 . /L e n g th of h au l: 3000 f t .

.:3• .Bulk w t. o f c o a l : . 50 lb s p er cub ic f t .

4 . S ize of. lumps: up to 1 2".

5 . G rad ien t o f road-w ay: 1 in 50 a g a in s t th eloaded b e l t .

6 . B e lt speed r e s t r i c t i o n s : ' n o t more th a n 4-50f .p .m .

7* Two lo a d in g p o in ts on th e b e l t w ith peak lo ad in g o f 3°0 tp h and 350 tp h r e s p e c t iv e ly . Ho t r ip p e r i s n e c e s s a ry .

S tep I D eterm ine th e t o t a l b e l t c a p a c ity , speed , w id th ,

and a llo w ab le lu m p -s iz e .

The Peak c a p a c ity of b e l t » 300 / 350 s 750 tp h or

1 2 .5 to n s /m in u te . 15

Assuming a b e l t speed o f 4-50 f . p .m . , th e b e l t w id th

in in ch es - j ;

=1 10,000P .f s x U * 5 (fo rm ula 1)

= 1 3 - 6 aAl0 ,000 x 12 .5 ,

J 4-50 x 50

- 30.4- / 5 = 35.4- o r 36 in ch es

1 ' ; ■ W - 6 'A llow able lu m p -size * — r — (form ula 2)

36 - 615 in ch es

2

6 4

Step I I D eterm ine th e t o t a l b e l t horsepow er to convey th e

c o a l under th e g iv en c o n d it io n s .

C x Q x (L / L0 ) x S( i ) he =

(11) hm ~

33,000

_ 0 .03 % 36 x (3000 / 150) x 4503 3 ,0 0 0

= 4 6 .5 0 hp.

- 0 X (L / Lp) x T

(form ula 6)

® 990

_ 0 .03 x (3000 / 150) x 750

(form ula 7)

990

( i i i ) hp

= 71*50 hp.

- y x H990

(form ula 8)

- (S ince g ra d ie n t = 1 in 50,

th e r e f o r e ,

_ L _ 3000 _ ,H ' " I T " 6 0 f t '

- 45*50 hp.

( iv ) h t = ze ro (S ince no t r ip p e r i s co n s id e red ).2

(v) ha -_ (Q / M) x (L/100) x (S /100)'

6 3 .8 x t

(36 / 55*5) x (3000/ 100) x (450/100)

(form ula 10)

2

63 .80 x 3

29 hp.

Because t h i s a c c e le ra tio n , horsepower i s l e s s th a n .50%: of th e

sum of he, hg,, and hr i t may be ig n o red .

6 5

T h e re fo re , t o t a l b e l t motor horsepower a t 80% motor

e f f ic ie n c y : ' * ,

_ 4 6 .5 0 / 7 1 .5 0 / 4 5 .5 0 _QOfto " 200 hp*

Step I I I D eterm ine th e p roper, b e l t s p e c i f i c a t io n s .

U sing a th ree -d ru m d r iv e (an g le of wrap = 660 d eg .)

w ith p la in drums and p .v . c . b e l t in g , F = 1 .1 1 (from

i : v.

t a b le X ). ;

- S in c e , TV = 1 .1 1 x ^ 3 ^ ° x 33,000 ■ - .. -450

= 13,200 lb s .

(N ote: The s lo p e te n s io n Ts of th e b e l t i s n o t con­

s id e re d h ere as i t does n o t exceed th e s la c k s id e

te n s io n T2 )

Now ' f x p = JL (fo rm ula 21)

= M i f -0.0 = 367 lb s p er in c h o f b e l t •5 • 3d , w id th

Taking v a lu e s o f p (number o f p l i e s in th e b e l t ) -

5, 6 , 7, ...... . . . . . . . ..... ;

The p .w .s . /p ly / in c h - w id th = .........5 6 7

= 7 3 .3 , 6 1 .1 , 5 2 .4 , . . . .

f

66

R e fe rr in g to t a b l e X l : t h e fo llo w in g b e l t ty p e s can

be s e le c te d :

(a) 7 -P ly , *+8 oz. c o tto n or heavy rayon b e l t in g

(b) No. 100 campass cord b e l t in g

(c) No. 150 s t e e l c a b le b e l t in g

The a c tu a l s e le c t io n o f b e l t to be used i s

p o s s ib le on ly a f t e r c o n s id e r in g o th e r f a c to r s such

. as takeup d e v ic e , b e l t jo in t in g method, p h y s ic a l

w orking c o n d itio n s in th e mine and o th e r f a c t o r s .

Example 2 . F ind th e g r e a t e s t le n g th o f conveyor p e rm is s ib le

u s in g 6 -p ly , b2 o z. c o t to n f a b r ic c a rc a ss b e l t in g of 36

in ch es in w id th w ith ru b b e r covering and conveying 400 tp h

a t a speed of 350 f .p .m . up an in c l in e 1 in 50. The system

u ses m e ta l l ic hook jo in t s 'a n d au to m atic co u n te rw e ig h t takeup

d ev ice w ith no t r i p p e r .

S tep I D eterm ine th e t o t a l b e l t horsepow er.

H ere,

( i )

C = 0 .0 3 ; .Q = 36; L ~ ?; L0 I 150; S = 350;

T = 400; H =. Jr,-..; 5 0 ' :: -

hQ z 0 .03 x 36 x (L / 150) x 350 3 3 ,0 0 0

; ( W 150) x hP- 100

( l i ) hm = 0-03 X (L / 150) X 400k . ... l.,- - . - - • ..............

(L / 1^0) x1.21100

( i l l ) hr400 x L _ 0.82L 990 X 50 *■ 100“

The t r i p p e r and a c c e le r a t io n horsepow ers a re n o t con­

s i d e r e d . ' ’ ' ' '

T h e re fo re , th e t o t a l b e l t horsepow er:

= l . l 4 ( L / 150) / 1.21(1, / 150) / 0.82L

= I r m / 3 2 h p .100

Step I I D eterm ine b e l t s t r e s s e s and th e b e l t le n g th .

From t a b le XI th e maximum a llo w a b le t e n s io n f o r a 42 o z .

c o t to n b e l t in g i s 45 lb s per in c h -w id th per p ly .

S ince —& = f x p (form ula 21)W

T h e re fo re , T^ = f x p x W z 45 x 6 x 36 = 9 ,500 lb s

Assuming a two-drum d r iv e (an g le of wrap z 440 d e g .)

w ith p la in drums, F = 1 .1 7 (from ta b le X)

S ince T^ = F x Te (form ula 17)

T h e re fo re , T0 = T^/ F = 9 ,5 0 0 /1 .1 7 = 7 ,600 lb s

6 8

A lso , Le =t o t a l b e l t h p ,(h ) x 33,000

8(form ula 16)

T o ta l b e l t hp . = Te x 8 . , 7,600 x 3503 3 ,0 0 0 3 3 ,0 0 0

T h e re fo re , 3 _ - /. 353 = Zj . 92. x....3i £ (from p rev io u s100 33,000 p a g e :)

On s im p lify in g , th e le n g th of th e conveyor L, i s

2 ,200 f t . ' : ' * '

CHAPTER VI

DISCUSSION ON BELT HAULAGE ECONOMICS AND COST ESTIMATION

........ The' f in a l d e c is io n to employ a b e lt conveyor w i l l

o ften depend upon the r e la t iv e c o s ts o f a l l methods of

tra n sp o r ta tio n . When used under the proper co n d itio n s , b e lt

conveyors can move m a ter ia l more econom ically than most

other methods. They consume l e s s power per u n it o f work and

the handling c o s ts in comparison w ith other system s are l e s s .

However, b e lt conveyors have c e r ta in operating l im ita t io n s ,

and th e ir use i s not th e so lu t io n to every haulage problem;

they have the a b i l i t y to handle la rg e tonnages a t low u n it

c o s t s . S ince they have a high c a p ita l co st they are not

e f f i c i e n t fo r p art-tim e operation or fo r handling sm all

tonnages. Hence, in planning a haulage system , i t should be

determined f i r s t whether s u f f ic ie n t tonnages are a v a ila b le

fo r a number of. years to j u s t i f y the in s t a l la t io n o f b e lt

conveyors and, secon d ly , to determine the approximate break­

even p o in ts between conveyors and other types o f mine .

haulage. Here a model technique i s developed which b a s ic a lly

i s intended to enable the engineer to estim ate the output

and approximate co st of owning and operating a conveyor

haulage system . These c o s ts can then be compared w ith other

system s of mine haulage to . determine which .system or:

69 .. • ' ,.

com bination of system s i s most l i k e l y to p ro v id e th e lo w est

70

u n i t co s t: f o r - t h e t r a n s p o r ta t io n o f c o a l under th e con­

d i t io n s being in v e s t ig a te d . No a ttem p t has been made in

t h i s s tudy to compare th e u n i t c o s ts o f o th e r hau lage sy s­

tems w ith th o se of conveyors; such a com parison i s beyond

th e scope o f th e p re s e n t s tu d y .

B efo re an a ly z in g ow nership and o p e ra tin g c o s ts of

b e l t hau lage system , c e r t a in o th e r im p o rtan t economic

f a c to r s must be d is c u s s e d . The economic l i f e o f th e con­

veyor equipm ent depends on ( i ) th e r a t e a t which th e equip­

ment i s am o rtized and ( i i ) th e r a t e a t which th e m ain ten­

ance and r e p a i r c o s ts in c re a s e w ith th e age o f th e equipm ent.

These f a c t o r s a r e d isc u sse d below .

The d e p re c ia t io n c o s t i s a fu n c tio n o f th e f i r s t

c o s t and l i f e o f th e equipm ent. The i n i t i a l c a p i t a l in v e s t ­

ment must be determ ined on ly a f t e r c o n s id e ra t io n of a l l th e

c o s t f a c to r s in v o lv e d . As re g a rd s th e l i f e of th e conveyor

equipm ent, i t i s d i f f i c u l t to p r e d ic t t h i s l i f e a c c u ra te ly .

However th e American Mining Congress Conveyor Committee in

t h e i r r e p o r ts over th e p a s t 8 y e a rs have c o n s is te n t ly used

a d e p re c ia t io n p e r io d of 10 y e a rs f o r conveyor fram e-w ork

and a l l m echan ical and e l e c t r i c a l equipm ent. The ru b b er

b e l t in g i s d e p re c ia te d on a 5 y ea r b a s i s . The b e l t manu­

f a c t u r e r s c o n s id e r th e above f iv e - y e a r l i f e o f b e l t in g to

be to o s h o r t , b u t ex p e rien ce has shown th a t i t i s a f a i r

71

average l i f e ' f o r b e l t in g used In th e main and In te rm e d ia te

hau lage s e rv ic e . A number of d e p re c ia t io n methods a re •

a v a i la b le to d e te rm in e y e a r ly d e p re c ia t io n c o s t of th e equ ip­

m ent. The most im p o rtan t o f th e s e a re th e s t r a i g h t - l i n e ,

s in k in g fu n d , p ro d u c tio n u n i t s and d e c lin in g b a lan ce m ethods.

I t i s ex trem ely d i f f i c u l t to keep up to d a te w ith th e U. S.

Bureau of I n te r n a l Revenue1s re g u la tio n s .g o v e rn in g th e use

of p roper m ethods.

The m aintenance c o s ts , in c lu d in g r e p a i r s , p lay a

dom inant r o le in th e economic l i f e o f th e equipm ent. The

annua l r e p a i r c o s ts may r i s e w ith th e age of th e equipm ent.

Even th o u g h "th e r e p a i r c o s ts do r i s e each year - th ey r i s e

on ly u n t i l th e f i r s t heavy r e p a i r s a re made. At. t h i s tim e

i t i s p o s s ib le to show th a t as th e number o f cy c le s of

heavy r e p a i r s in c r e a s e , th e r a t e of r i s e of m aintenance c o s ts

over th e t o t a l e lap se d tim e may le s s e n . E v en tu a lly o v e r a l l

m ain tenance c o s ts w i l l l e v e l o f f . Hence a uniform r a t e of

o p e ra tin g m ain tenance c o s t may be co n s id e red .

R egarding I n t e r e s t , ta x e s and in su ra n c e c o s ts of. . . . : . .

th e equipm ent, w hether money i s or i s n o t borrowed i n i t i a l l y. f ' :

to buy th e new conveyor equipm ent, a 6^ i n t e r e s t r a t e i s a

f a i r av erag e to be in c lu d ed in th e an n u a l ow nership c o s ts .

The an n u a l c o s t o f ta x e s and in su ran c e may be tak en a s eq u a l

to bfo o f th e A v erag e Investm ent* c a lc u la te d as fo llo w s :

A verage Investm en t = n / 1 (29)2 x n

Where:n%= th e l i f e o f th e conveyor equipm ent (10 y e a rs f o r

conveyor fram e, m echan ica l and e l e c t r i c a l p a r t s , and 5 y e a rs

fo r th e ru b b er b e l t i n g ) .

ESTIMATION 0£ BELT HAULAGE COSTS ;

I . Ownership C o sts :

A r u le of thumb fo r e s tim a tin g c o s t o f a com plete

conveyor system i n s t a l l e d i s ab o u t S 1 5 0 .0 0 p er f o o t o f le n g th

f o r a c o n v e n tio n a l b e lt '.co n v ey o r .u sing a 24 -in c h b e l t . The;

c o s t change i s about $50 .00 f o r each 6 - in c h change in th e

b e l t w id th .

A more a c c u ra te method of c a lc u la t in g ow nership c o s ts i s

g iv en below:

(a) Cost o f Equipm ent: T h is .in c lu d e s th e c o s t of

p u l le y s , speed re d u c t io n tr a n s m is s io n , m o to r s ,c o n t r o l s ,

ta k e u p s , b ra k e s , e t c . The eq u ip m en t-co st v a r ie s w ith th e

s iz e o f . th e conveyor. The fo llo w in g c o s t in fo rm a tio n has

been su p p lie d to th e au th o r by th e Goodman M anufacturing

Company, H a ls ted S t r e e t , Chicago 9 , I l l i n o i s :

Up to 6o hp.. = $220.00 per hp.$ " ..

61 to 75 hp. = • $160.00 per hp.$I ______ (30)

76 to 200 hp. z $145.00 p er h p .I

over 200 hp. ' :Z $140.00 p er hp.$

(b) Cost o f S t ru c tu r e s , I d l e r s , and o th e r S upporting

Equipment: •

72

For c o n v e n tio n a l b e l t hau lage s t r u c tu r e s ( r ig id - f r a m e ) , th e

c o s t in d o l la r s

' - ' z (0 .8 0 x b e l t w id th in in ch es x le n g th of

s t r u c tu r e in f t . ) - - ______________ (31)

For ro p e-fram e b e l t conveyor s t r u c tu r e s , th e c o s t in d o l la r s

,Z (0 .50 x b e l t w id th in in ch es x le n g th of

s t r u c tu r e in f t . ) ______________ (32 )

(c) Cost of B e lt in g : The c o s t of b e l t in g v a r ie s

w ith th e duck w eig h t, number o f p l i e s , ty p e of b e l t con­

s t r u c t io n m a te r ia l , m a n u fa c tu re r , fo o tag e to be purchased

and o th e r f a c t o r s . The a c tu a l c o s t o f a b e l t f o r any p a r t ­

i c u la r du ty can be determ ined w ith accuracy and i f th e

a c tu a l c o s t i s known, th en t h i s should be u sed . However,

a f a i r e s tim a te o f th e c o s t o f b e l t in g can be found as

fo llo w s : • : ) ‘ '

The c o s t of b e l t in g (p ly ty p e ) p er f t . in d o l la r s

= (0 .0006 x T-l / 0 .2 0 ) x W ___________ (33)

Where: T j z maximum o p e ra tin g te n s io n of b e l t in

lb s / in c h -w id th .

W Z b e l t w id th in in ch es

(d) E re c tio n c o s ts : .U vvr:; .. i

( i ) C leaning o ld mine openings and e la b o ra te

73

7 4

s i t e p re p a ra t io n s a re excluded c o s t s . When th e b e l t con­

veyor can be extended as th e working fa c e advances, th e

e r e c t io n c o s ts may be ta k en a t l i $ to 2$ of th e c a p i t a l to

be in v e s te d f o r e x te n s io n under id e a l c o n d itio n s .

(11) I f w ir in g , c le a n in g , g rad in g and f i l l

fo o tin g c o s ts a re in c lu d e d , th e i n s t a l l a t i o n c o s t may v ary

from V5$ to 40$ of th e sum of th e equipment (item , a t

above) and b e l t ( item rc* above) c o s ts depending on th e

amount o f work to be done.

(e) C o n tin g en c ie s : The c o n tin g e n c ie s a re in c lu d ed

to cover th e u n fo re see n c o s ts . These c o s ts may be tak en as

eq u a l to 2$ o f th e sum of th e equipm ent, b e l t , and e re c t io n

c o s ts . .

T h ere fo re th e t o t a l Ownership C osts

= (a ) / (b) / (d) / (e) p lu s (c ) ;

Using th e s t r a i g h t l i n e method, th e y e a r ly de­

p r e c ia t io n c o s t :

- (a) / (b) / (d) / (e ) _ (c)- ------------ ----------------------- p lu s -----------

10 y e a rs 5 y e a rs

Y early f ix e d c o s ts z y e a r ly d e p re c ia t io n c o s t / c o s t of

i n t e r e s t , ta x e s and in su ra n c e ,

z y e a r ly d e p re c ia t io n c o s t / 10/5 of

“Average Investm ent"

7 5

WOTS: There a re many more c o s ts o f owning a com­

p le te b e l t conveyor system . These in c lu d e t r a n s f e r s t a t i o n s ,

supp ly t r a c k , c a r s , and lo co m o tiv e s , and, i f needed , su rge

b in s , f e e d e r s , and l in in g s in them, power s t a t io n s f o r b e l t

d r iv e s , in te rcom m unication and r e l a t e d f a c i l i t i e s , and equip­

ment c a r r i e r s . The c o s ts o f a l l th e se item s a re n o t con­

s id e re d in th e above c o s t e s tim a tio n p ro ced u re .

I I O perating C osts:

U nlike ow nership c o s ts , th e o p e ra tin g c o s ts , excep t

f o r power c o s t , a re n o t p ro p o r t io n a l to th e b e l t le n g th ,

c a p a c ity , g ra d ie n t and so f o r t h . A ll th e o p e ra tin g c o s t

f a c to r s of conveyor hau lage a re g iv en below.

(a) Power C ost: G en e ra lly a l l th e roadway con­

veyors a re e l e c t r i c a l l y d r iv e n . There a re v e ry few con­

veyors in England t h a t a re now ru n by o th e r meansv A ttem pts

to o b ta in a c tu a l consum ption o f power proved u n s u c c e s s fu l .

T h e re fo re , th e energy req u irem e n ts must be d e riv e d on a

t h e o r e t i c a l b a s is assuming a known runn ing tim e . Lacking

th e l o c a l power r a t e j $0,008 per k ilo w a tt-h o u r may be used

as an average power r a t e , and th e t h e o r e t i c a l power c o s t may

be dete rm in ed a s fo llo w s :

Y early power c o s t in d o l la r s

a t o t a l m otor h p x 0 .7^6 x hours o p e ra te d /y e a r

x 0 .008 ..■v;:: __________OH)

7 6

■ . (b) O p era tin g ;L ab o r C o sts i For a l l ty p e s of con­

veyo rs th e o p e ra tin g la b o r c o n s is ts o f one man a t each t r a n s ­

f e r p o in t f o r every s h i f t th e conveyor i s in o p e ra t io n . The

wage r a te s :v a r y from p la c e to p la c e . At p r e s e n t , an average

o f $ 2 .5 0 per hour i s assum ed. T his r a t e in c lu d e s a l l

f r in g e b e n e f i t s .

; (c) M aintenance and R ep a irs C ost:

( i ) M aintenance la b o r c o s t : Only ro u t in e

la b o r on conveyors may be c o n s id e re d . N on-rou tine la b o r

f o r m ajor b e l t rep lacem en ts and o th e r works must be con­

s id e re d s e p a r a te ly . This r o u t in e la b o r f o r d a i ly m aintenance

i s o f two k in d s . F i r s t , u n s k i l le d la b o r i s used fo r

p a t r o l l in g and c lean in g th e s p i l la g e ; f o r t h i s purpose one

or two men per m ile o f conveyor p e r s h i f t i s a f a i r av e ra g e .

Secondly , s k i l l e d la b o r i s used f o r th e m aintenance of th e

m echan ical and e l e c t r i c a l p a r t s o f th e conveyor equipm ent.

One m echan ical f i t t e r and one e l e c t r i c i a n per m ile of th e

conveyor per s h i f t a re s u f f i c i e n t . This t o t a l m ain tenance

fo rc e o f 3 to 4 men per m ile p e r s h i f t i s a ls o expected to

do some o th e r odd jo b s , such a s s m a ll-b e l t rep lacem en ts

and b e l t s p l i c i n g . . The wage r a te s , may be ta k e n f o r a l l men

as $2 .50 p er hour as s t a te d .

( i i ) M a te r ia l c o s t f o r m ain tenance: From th e r e ­

cords o f components and b e l t s re p la c e d in th e p a s t an

a ttem p t i s made to dete rm in e th e l i v e s of th e m ajor components

77

of th e conveyor system ; b u t t h i s v e n tu re i s f u r th e r com­

p l ic a te d , in some c a s e s , by th e ever changing d es ig n of

c e r t a in p a r ts of th e conveyor equipm ent. Hence an average

m aintenance c o s t may be u sed . . '

The main c o s t o f m aintenance i s , of c o u rse , th e r e ­

placem ent o f th e b e l t in g . The b e l t i s co n s id e red to have a

l i f e of 5 y e a r s , w hereas th e l i f e of th e o th e r elem ents of

th e e n t i r e i n s t a l l a t i o n i s 10 y e a r s . This means th e re w i l l

be one rep lacem en t o f th e whole b e l t in g in 10 y e a rs . Using

th e c o s t of th e o r ig in a l b e l t in g (item *c? in ow nership

c o s t s ) , th e y e a r ly b e l t rep lacem en t c o s t can be c a lc u la te d .

I t w i l l be eq u a l to o n e - te n th o f o r ig in a l b e l t c o s t .

B esides y e a r ly b e l t rep lacem en t c o s t , th e re w i l l be

sm all c o s t f o r sp a re p a r ts on th e conveyor s t r u c tu r e , lu b ­

r i c a t i o n s , e t c . This c o s t may be tak en to be eq u a l to 2$

of th e equipm ent c o s t ( item *31 in th e ow nership c o s t s ) .

The t o t a l y e a r ly o p e ra tin g c o s ts % (a) / (b) / (c)

U n it c o s t / to n = YeaTly ow nershlp and o p e ra tin g c o s tst o t a l to n s moved p er y ea r

PROBLEM ON TgE COST ESTIMATION ££ & BELT HAULAGE SYSTEM

Example: C a lc u la te th e u n i t c o s t of conveying c o a l f o r

example ( l ) on page 62 . :

I Ownership c o s ts :

7 8

(a) Cost o f equipm ent @ $1^5*00 per hp. =

200 x Ik? = $29,000

( b ) " Cost o f s t r u c tu r e = (0 .80 x b e l t w id th x le n g th

o f s t r u c tu r e )

= (0 .8 0 x 36 x 3 ,000) = $86,500

(c ) Cost o f b e l t in g * (0 .0006 x / 0 .2 0 ) x 36 x

(3000/ 3000/ 1 5 0 )

, - r (0.0006 x 367 / 0 .2 0 ). x 36 x ,

6150

= $93,000

- ■ (d) Cost of i n s t a l l a t i o n z 20^ of (equipm ent / b e l t )

c o s t

r 20^ of (29,000 / 93,000)

z $24,400

(e) C o n tin g en c ies z 2% o f (equipm ent / b e l t /

i n s t a l l a t i o n )

= 2% o f (29,000 / 93,000 / 24 ,400)

’ -c ; r :: : / . = $2,928 . :'y : ,

T o ta l ow nership c o s ts z 29,000 / 86,^00 / 93,000 /

24,400 / 2 ,928

= $237,828

Y early d e p re c ia t io n based on s t r a i g h t l i n e method

. ( a ) / ( b ) / ( d ) / ( e ) , (c)5 y e a rs10 y e a rs

7 9

_ 144,828 , 93,000 10 5

= 133,083

Average Investm en t (ex c lu d in g b e l t c o s t) = 144,828 x I P - / —.. ... .. 2 x 5

(form ula 29)

•= $ 79,500

Average in v estm en t f o r b e l t in g 93,000 x dJ—2 x 5

:: - - = #55i75o

T o ta l average in v estm en t - z 79,000 / 55,750

: : - • - = 1135,250

Yearly in t e r e s t , ta x es and insurance co st = 10^ of t o t a l ave­

rage investm ent- • - - ' .• ;■ . 1

= 10;S of 135,250 =

■ - ®13,525

Yearly f ix e d c o s ts = yea r ly d ep rec ia tio n / y ear ly in t e r e s t ,

ta x e s , e t c .

/ 33 ,083 / 13,525 : $46,608

I I Operating c o s ts :

(a) Y early power c o s t (based on 2000 hours per year)

= $(200 x 0.746 x 2000 x 0 . 008)

* -$ 2 ,4 9 0 : ' : : " .

8 0

(b ) Y ea r ly o p e r a tin g la b o r c o s t

= S ( 2 .5 0 x 2000)

= $ 5,000 . •:

( c ) Y ea rly m ain tenance and r e p a ir c o s t s : . '

( i ) M aintenance la b o r c o s t - (3 men)

= 3 x 2 .5 0 x 2000 = $ 1 5 ,0 0 0

( i i ) M aintenance m a te r ia l c o s t f o r r e ­

p lacem en t and lu b r ic a t io n -

r 10$ o f b e l t c o s t / 2$ o f equipm ent

C O S t . . . : : v : L . : . .

: = 10$ o f 9 3 , 0 0 0 / 2 $ o f 2 9 ,0 0 0

= 9,300 / 580 s 9,880 '

T h erefo re t o t a l m aintenance and r e p a ir c o s t

Z item ( i ) / item ( i i ) above

= 15,000 / 9,880 = $ 2^,880 ■

T o ta l o p e r a tin g c o s t s = 2 ,4 0 0 / 5 ,0 0 0 / 2 4 ,8 8 0

= $ 3 2 ,3 7 0

T h erefo re t o t a l ow nersh ip and o p e r a tin g c o s t s per

■ year .

= 4 6 ,6 0 8 / 32,370 = $ 78,978

T o ta l to n s moved per year @ 750 tp h * 2000 x 750

1 , 500,000

T h erefo re c o s t / t o n o f c o a l hau led = =1 , 500,000

$0,053 per to n

81

Or c o s t /to n /m ile = 0 .053 x 28° . e.e t .3 ,0 0 0 (len g th of haul)

Z $0.093 per to n per m ile .

NOTE: A ctu a lly the c o s t /to n -m ile w i l l be l e s s than

th e above f ig u r e s in c e maintenance labor co st i s not

d ir e c t ly p rop ortion a l to len g th of haul.

COST CHARACTERISTICS OF BELT HAULAGE SYSTEM

Based on the above c o s t estim ation procedure, a

range o f “hypothetical*1 d u tie s rep r ese n ta tiv e o f co n d ition s

under which the conveyors w i l l run are in v e s t ig a te d to de­

term ine the b e lt haulage co st c h a r a c te r is t ic s . The use of

th e term “h ypothetica l" should be c le a r ly understood th a t i t

i s the conveyor in s t a l la t io n s which are h y p o th e tica l. The

c o s ts are r e a l , based on the above co st estim ation procedure

which i s developed from a c tu a l conveyor in s t a l la t io n s and

manufacturers* q u o ta tio n s.

With a l l th ese and the fo llo w in g assum ptions ty p ic a l

c h a r a c te r is t ic curves have been constructed (see F ig s . 5 and

6) from ca lcu la ted u n it c o s ts a t f iv e p o in ts fo r each curve:

(1) C onventional type b e lt haulage system ( i . e . ,

rig id -fram e supporting s tru c tu res) w ith 20 deg. troughing

id le r s .

(2) S tra ig h t l in e d ep rec ia tio n method i s u sed .

(3) No sa lvage or r e s a le va lu e of the equipment i s

82

co n s id e red .

(M-) I n t e r e s t , ta x e s and in su ran c e c o s t i s ta k en a t■ „ ■ :Vyfo of th e "Average In v e s tm e n t" . ■

; ; (5) M aintenance la b o r - t o t a l of th r e e men as

s p e c if ied: below:

one e l e c t r i c i a n •. ; one m echan ica l f i t t e r

. : ! one man f o r p a t r o l l in g and c le a n in g s p i l la g e

(6) Labor r a t e f o r a l l c a te g o r ie s i s ta k e n a t $2 .50

per hour in c lu d in g a l l f r in g e b e n e f i t s .

(7) A ll o th e r c o s t f a c t o r s a re tak en as s p e c if ie d

in th e c o s t e s tim a tio n p ro ced u re .

HOW TO REDUCE CONVEYOR COSTS?

I t has a lre a d y been s t r e s s e d th a t f o r co n tinuous

o p e ra t io n , h ig h p ro d u c tio n , and low u n i t c o s t th e b e l t

haulage system i s th e b e s t s o lu t io n f o r t r a n s p o r ta t io n of

c o a l in m in es. But h ig h e r u n i t c o s t may r e s u l t because of

im proper d e s ig n and i n s t a l l a t i o n or poor m aintenance and

o p e ra t io n . W ith c a r e f u l d e s ig n o f th e b e l t hau lage system

and p ro p er m ain tenance , most o f th e b e l t hau lage c o s ts can

be kep t to a minimum. The fo llo w in g a re some of th e o th e r

ways of f u r th e r red u c in g th e b e l t hau lage u n i t c o s t w herever

p r a c t ic a b le and p o s s ib le .

( l ) Use o f narrow b e l t w id ths and in c re a se d sp eed s.

A c tu a l lo a d in g t r a n s p o r t req u irem e n ts must be s tu d ie d

f o r each in d iv id u a l c a s e . The s iz e and shape o f th e m a te r ia l

HnXlZTS EECAIT' T -

- L i _ 1.

r 1 - - r

„ u!

Ifkisai T i-r-ri t ig a a r ii icOUTPUT:Tons p er Hour

rrrT

i LLi

OUTPUT* TONS Per HOUR

may p la c e some r e s t r i c t i o n s on th e ch o ice of b e l t speed . To

f in d ou t w hether h ig h e r speeds r e a l l y red u ce th e conveyor

c o s ts , a h y p o th e tic a l case can be s e t up as fo llo w s by assum­

ing a s e t o f norm al conveyor c o n d i tio n s :

( a ) ib e l t le n g th : 2000 f t .

(b) 1000 tp h w ith maximum lum psize r .o .m . c o a l of

12 in ch es

(c) l e v e l g rad e w ith no l i f t s or d e c l in e .

(d) s ta n d a rd 20 deg . tro u g h in g id l e r s on r i g i d -

fram e s t r u c t u r e s .

8 5

Now r e f e r r in g to F ig . 5 , th e fo llo w in g co n c lu s io n s can be

drawn:

h2" b e l t conveys |iood]j@5l*0 "1 w ith u n i t c o s t of $ 0 ,0 2 6 /|_ tp tu |f .p .m j to n

48“ " |io o o ] |4 o o 1 " ".p .m j

" " $ 0 ,0 2 9 /to n

" " $0 , 031/to n

Ltphjf.i54" " " E006I I 320 "I » »

[ tph] (C.p.mj

The n e t sav ing o f having a n arrow -w id th b e l t o f 42" a t th e

h ig h er speed o f 540 f .p .m . i s 11^ and 20% over t h a t o f a

48" b e l t a t 400 f .p .m . and a 54" b e l t a t 320 f .p .m .

r e s p e c t iv e ly .

(2) Use o f deep tro u g h id l e r s -

For some y e a rs th e Germans in t h e i r s t r i p m ining

o p e ra tio n s have made use o f i d l e r s w ith a 30 deg. tro u g h in g

an g le in p la c e o f commonly used 20 d e g . tro u g h in g i d l e r s in

th e U nited S ta te s . The d es ig n of deep tro u g h in g i d l e r s

8 6

r e q u ir e s b e l t in g th a t w i l l be a b le to w ith s ta n d sev e re t r a n s ­

v e rse f le x in g .

A 48 m b e l t a t 400 f .p .m . can hand le 1000 tp h w ith

20 deg . tro u g h in g i d l e r s . The same o u tp u t can be handled

by a 42" b e l t a t th e same speed o f 4-00 f .p .m . bu t w ith 35

deg. tro u g h in g i d l e r s . The n e t sav ing in c o s t w i l l be , in

t h i s c a se , about 10%.

(3) M u ltip le s h i f t o p e ra t io n in s te a d o f one s h i f t

per day -

O pera ting th e b e l t a t two s h i f t s per day in s te a d of

one s h i f t , a n e t sav ing of 5% to 8% in u n i t c o s t can be

accom plished . This i s because th e o u tp u t i s d i r e c t l y p ro ­

p o r t io n a l to number o f hours worked, whereas th e d e p re c ia t io n

p e r io d or th e l i f e o f th e equipm ent i s n o t .

(4) I n s t a l l i n g long s in g le conveyors -

W herever p o s s ib le and n ec e ssa ry th e f e a s i b i l i t y of

u sing one long conveyor u n i t as compared to s e v e ra l s h o r te r

f l i g h t s should be s tu d ie d . For in s ta n c e , a 4 0 0 0 - f t . long

s in g le conveyor u n i t w i l l r e q u ir e an expensive and h igher

s t r e n g th b e l t in g o f s y n th e t ic f ib e r o r s t e e l cab le con­

s t r u c t io n . However, th e i n i t i a l c o s t o f t h i s long b e l t in g

as a whole w i l l be app ro x im ate ly 6% l e s s th a n th e t o t a l c o s t

of 4 s h o r te r u n i t s o f 1000 f t . each . A lso th e i n i t i a l

c a p i t a l in v estm en t (w ith o u t b e l t in g ) f o r a 4000 f t . long

8 7

s in g le u n i t w i l l be about 20^ l e s s th a n f o r fo u r s h o r te r

u n i t s . T his sav ing i s due to th e e l im in a tio n o f th r e e t r a n s ­

f e r p o in ts w ith t h e i r i n s t a l l a t i o n s o f m o to rs, t r a n s f e r

g e a rs , takeup d e v ic e s , e t c . , as compared to on ly one t r a n s ­

f e r p o in t o f th e lo n g e r u n i t . , A lso t h e r e .w i l l be reduced

breakage and d e g ra d a tio n o f c o a l c a r r ie d on a: longer, s in g le

u n i t . . : - : : ; v .; - : . . : - ■ :■

(5) Use of m u lti-m o to rs in s te a d of s in g le motor

f o r la r g e r u n i t s -

On long h o r iz o n ta l conveyors a tw o -p u lley ty p e of

d r iv e o f te n p e rm its low er b e l t o p e ra tin g te n s io n and th e re ­

fo re low er b e l t c o s t . A m u lti-m o to r d e s ig n w i l l a llo w a

w ider cho ice in th e s e le c t io n o f th e low er horsepower

m oto rs. A lso th e c o s t o f sp a re motor u n i t s i s much lo w er.

(6) S h if t .f ro m r i g i d to ro p e -su p p o rted equipment -

The ro p e -su p p o rte d conveyor hau lage can be in ­

s t a l l e d , ex tended and r e lo c a te d f a s t e r th an th e co n v e n tio n a l

ty p e of conveyor system . Hence th e re w i l l be a n e t sav ing

in th e u n i t c o s t o f h au lin g c o a l when compared to r i g i d -

fram e b e l t h au lag e . However, th e s h i f t from r i g i d to ro p e -

supported s t r u c tu r e s f o r main l i n e b e l t hau lage i s v e ry slow

owing to i t s somewhat n o n - r ig id i ty f o r perm anent hau lage and

to random breakdow ns.

8 8

S im ila r to ro p e -su p p o rte d conveyor h au lag e , th e

c a b le - b e l t conveyors (see page 7) a ls o do n o t compare fa v o r­

ab ly w ith co n v e n tio n a l co n v ey o rs . The e f f e c t iv e rope l i f e

i s one of th e im p o rtan t f a c to r s in de te rm in in g th e o p e ra tin g

c o s ts of c a b le - b e l t co n v ey o rs . These u n i t s may be expected

to be removed from s e rv ic e sooner th an co n v e n tio n a l b e l t s

f o r two main re a s o n s : (a) a c c id e n ta l damage may occur w ith

g r e a te r freq u en cy or (b) w earing down of b e l t and ca b le may •

ta k e p la c e a t a g r e a te r r a t e : '

W ith a l l th e s e s h o r t comings of ro p e-fram e ( i . e . rope

su p p o rted i d l e r s t r u c tu r e s ) and c a b l e - b e l t . ( i . e . c a b le or

ro p e -su p p o rte d b e l t s t r u c tu r e s ) u n i t s , i t i s d o u b tfu l w hether

th e s e conveyor system s w i l l be. more co m p e titiv e f o r a w ider

ran g e of d u t ie s in c o a l t r a n s p o r ta t io n . A d d itio n a l r e - .

s e a rc h work must be u n d ertak en by en g in eerin g e s ta b lish m e n ts

to de term ine b reak -ev en p o in ts f o r d i f f e r e n t k in d s of b e l t

hau lage sy stem s. ..... : . . .

CHAPTER V II

INSTALLATION AND MAINTENANCE OF CONVEYOR BELTS FOR EFFICIENT OPERATION

A v/ell designed conveyor, which, has been properly in s ta lled and maintained, w ill lower subsequent maintenance, repair and replacement costs. The benefits of good main­tenance, regular inspection and proper housekeeping of the belt conveyor w ill re su lt in increased production, efficiency and ease of operation. Like a l l machinery, how­ever, they can be an endless source of trouble when neg­lected . Lack of periodic checking and maintenance of alignment, leveling , cleaning, correct loading, lubricating of the moving p a rts , e t c . , may cause severe damage or may ru in a be lt th a t frequently has a dollar value greater than any piece of equipment in the mine. By following simple ru les and procedures, smooth running of the conveyor can be expected with few or no breakdowns.

INSTALLATION PROCEDURE ' ' : ' : v

Success with the be lt haulage system comes from proper in s ta lla tio n according to the recommendations of belt manufacturers. The services of competent consultants

89 ::: ' .

90

a re u s u a lly j u s t i f i e d on Im p o rtan t i n s t a l l a t i o n s .

.... , F i r s t l y , th e d e te rm in a tio n of re q u ire d b e l t le n g th

i s made a f t e r ta k in g in to c o n s id e ra t io n th e c e n te r - to - c e n te r

d is ta n c e of te rm in a l p u lle y s and-number and le n g th of b e l t

s p l i c e s . . Then an o rd e r i s s e n t to th e m anufactu rer f o r i t s

p u rch ase . ... .......

...........Secondly , some p re c a u tio n s in hand ling and s to r in g

of conveyor b e l t r o l l s must be ta k en when th e y a re re c e iv e d

from th e m a n u fac tu re r . The b e l t r o l l s must be s to re d in a

co o l d ark p la c e where o i l s , g a s o lin e and p a in t in g m a te r ia ls

a re n o t p r e s e n t . The p la c e s where ozone i s produced: by

e l e c t r i c a l equipm ent or w elding must be avoided f o r b e l t

s to ra g e . 'New as w e ll as o ld b e l t s must be handled c a r e f u l ly

w ith o u t d ro p p in g . I f r o l l s a r e handled w ith s l i n g s , a bar

th ro u g h th e c e n te r f o r l i f t i n g i s used and th e b e l t edges

a re p ro te c te d w ith p la n k s . In hand ling and i n s t a l l a t i o n th e

b e l t must n o t be b en t more sh a rp ly th a n minimum p u lle y d ia ­

m e te r ....P roper equipm ent and methods must be used in moving

a b e l t in to '-th e m ine, such a s w inding i t on a h o r iz o n ta l

sp ind le" 'and moving i t u p r ig h t in to th e m ine.

T h ird ly , th e fo llo w in g p re c a u tio n s must be ta k en

d u r in g , i n s t a l l a t i o n of b e l t conveyors: , ... , _ 1

(1) S ince th e a lignm en t i s c r i t i c a l w ith under­

ground b e l t s , p ro p er a lignm en t i s n e c e s s a ry .

91

(2) Keep b e l t l e v e l t r a n s v e r s e ly .

(3) P rov ide p ro p er c le a ra n c e . T his f a c i l i t a t e s

in s p e c tio n and m aintenance as w e ll as avo id ing damage or

f a u l ty o p e ra t io n .

0+) A lign i d l e r s p ro p e r ly . P rov ide added in ­

surance by ju d ic io u s use of s e l f a l ig n in g i d l e r s a t in ­

t e r v a l s of 200 f e e t on r e tu r n and 400 f e e t on c a rry in g

s id e , and c lo s e to head and t a i l p u lle y s f o r c e n te r in g .

(5) Make su re t h a t lo a d in g and d isc h a rg e ch u tes a re

p ro p e r ly c o n s tru c te d and a lig n e d and th a t p ro v is io n i s made

to e l im in a te or red u ce th e im pact to a minimum.

(6) S e le c t c o n t ro l equipm ent f o r s t a r t i n g th e

m otors and f o r a u x i l ia r y c o n t ro ls on th e b a s is o f th e type

and s iz e of m otor u sed , th e to rq u e re q u ire d to a c c e le r a te

th e conveyor, and v a r io u s p ro te c t io n s a g a in s t overflow of

m a te r ia l , a c c id e n ta l r e v e r s a l and o v ersp eed in g , ro o f f a l l s ,

m isa lig n m en t, e x c e ss iv e b e l t s l ip p a g e , ch u te c logg ing and

p i l in g o f m a te r ia l a t d isc h a rg e p o in ts , conveyor f i r e s , e t c .

A ll th e s e c o n tro ls a re n e c e ssa ry on b e l t conveyor in ­

s t a l l a t i o n from th e s tan d p o in t o f s a fe and e f f i c i e n t

o p e ra t io n .

(7) Do n o t use o ld b e l t in g f o r s k i r t i n g . The in ­

g ra in e d c o a l p a r t i c l e s make i t a c t l i k e sand p ap e r. Use

s p e c ia l s k i r t in g m a te r ia l a v a i la b le from b e l t m an u fac tu re rs .

(8) Check conveyor p a r ts th o ro u g h ly b e fo re b e l t

i n s t a l l a t i o n . These in c lu d e : s t r u c t u r e , p u l le y s , i d l e r s ,

92

lo ad in g equipm ent and s k i r t b o ard s. '■ . / : r-

■ •": (9) P o s i t io n b e l t in g r o l l p ro p e r ly , w hether on a

h o r iz o n ta l or v e r t i c a l s p in d le . ' v »

(10) Unwind b e l t r o l l by power i f p o s s ib le - - from

to p of r o l l i f fe d in to c a rry in g r o l l s , or from th e bottom

i f onto th e r e t u r n ' i d l e r s A w ire -ro p e and p u l l in g p la te

may be used or -the new b e l t may be a tta c h e d to th e o ld in

re p la c e m e n t. - ' ; - . ' .i- ' - : ' ; "

:(11);...-Keep:';t e i t t i g h t a s i t i s u n ro lle d to p rev en t

tw is t in g or te le s c o p in g . Avoid sharp tw i s t s , bends and hard

p u l l in g . - Unwind s lo w ly . • -•-- • - ' :

• (12) P u l l b e l t ' i n t o p o s i t io n by-'w inch;or s im ila r

equipm ent. P u l l even ly a c ro s s e n t i r e w id th of b e l t .

(13) -Exert s u f f i c i e n t te n s io n • in pul-ling th e b e l t

to g e th e r so t h a t th e screw ty p e takeup i s in p roper p o s i t io n

when s p l ic e s a re made. W ith coun terw eigh t g ra v i ty - ty p e

ta k e u p , app ly s u f f i c i e n t f o rc e to move takeup p u lle y from

maximum p o s i t io n to c o r r e c t p o s i t io n . ' .

( I1*) - Check t r a in in g o f b e l t , in c lu d in g r e tu r n ru n

and t a i l p u l le y . : on .

- - (15) Check f o r a lignm en t and ru b b in g -a g a in s t .

lo ad in g and d isc h a rg e ch u te s and s k i r t i n g .

PROTECTION OF BELTS

A fte r p ro p er i n s t a l l a t i o n o f a b e l t conveyor- system ,

i t i s "necessary to ta k e c a re o f a b e l t from p o s s ib le damage

during i t s norm al o p e r a t io n . - The fo llo w in g " p o in ts a re .w orth

n o tin g :"

' (1) P rovide p ro p er ro o f and r ib - s u p p o r ts .

’• • (2) K eep -b e lt head ings f r e e o f w ater and p r o te c t

th e b e l t from dir ip s . ;;

(3 ) V e n t i la te b e ltw a y s"p ro p e r ly .

(4) Reduce f i r e hazards by u sin g approved f i r e -.................................... ...... ' - ' ' - - - " - ' ' - ' - ' - " : X . . . u i

r e s i s t a n t .b e l t s and f i r e - r e s i s t a n t m a te r ia l f o r p u lle y

la g g in g , im pact i d l e r s , s k i r t i n g , e t c . Guard a g a in s t

" fro zen " or hot runn ing r o l l e r s by re g u la r in s p e c t io n .

E s ta b l i s h c o r r e c t te n s io n in th e b e l t . - E lim in a te s p i l la g e

and over lo a d in g . P rev en t p i le u p s a t lo ad in g and t r a n s f e r

p o in t s . ■

(5) P ro v id e p ro p er lu b r ic a t io n , p e r io d ic in s p e c tio n

and prompt r e p a i r to th e damaged b e l t .

BELT MAINTENANCE GUIDES

The beg inn ing and a ls o end of p ro p er b e l t m ain tenance

i s good housekeep ing . T h is does n o t mean c lean in g u p .a

conveyor roadway m onthly or every two m onths. But i t means .

m a in ta in in g a c le a n conveyor system a t a l l t im e s ; th a t i s ,

d a i ly and w eekly in s p e c tio n sch ed u les must be a rran g ed . The

patro lm en on th e conveyor system must be made re s p o n s ib le f o r

making qu ick d a i ly exam inations" to d e te c t dangerous c o n d it io n s .

A ll em ergencies shou ld be re p o r te d im m ediately so t h a t th e

conveyor can be sh u t down and r e p a i r e d . Im proper m aintenance

93

may r e s u l t in conveyor f i r e s . Good m aintenance i s n e c e ssa ry

n o t only from th e s tan d p o in t o f red u c in g breakdow ns, bu t

a ls o from th e s ta n d p o in t o f s a fe ty and c o n t in u i ty of opera­

t i o n . The fo llo w in g check l i s t can be used as a gu ide to

d a i ly and weekly in s p e c t io n s . A d d itio n a l ch eck p o in ts may be

needed to f i t p a r t i c u l a r s i t u a t i o n . .

9 4

(1) TROUBLE: B e lt ru n s o f f

clim bs side-w ays on some id le

Cause

(a) Off c e n te r lo a d in g

(b) Conveyor fram e n o t

• s t r a i g h t J

(c) I d le r s ta n d s n o t

cen te red . . , - v

(d) I d le r s s t i c k -

(e ) Loose i d l e r s

( f ) One s id e o f conveyor

i s low

(g) M a te r ia l b u ild s on

i d l e r s a t te rm in a l

p u l le y s .

c e n te r a t a s p e c i f ic p o in t or

\. ; . v ' .y/ vi

Remedy

A d ju st ch u tes and o th e r lo a d ­

ing d ev ices to p u t lo a d in th e

c e n te r and in th e d i r e c t io n of

b e l t movement.

S tra ig h te n acco rd in g to need .

Same c o r r e c t io n as above.

L u b ric a te p ro p e r ly .o r r e p la c e .

R e p o s itio n and f a s te n s e c u re ly .

L evel up and s e c u re . , •: v

Improve m a in te n an ce ;and r i n s t a l l

b e l t c le a n in g equipm ent r.v.”

95(2) TROUBLE:: B e lt ru n s o f f a t t e rm ln a l..

Cause Remedy,

■ P u lle y or approach ing : v . .

i d l e r s n o t in l i n e . A lig n p ro p e r ly . •. , , .

(3) TROUBLE: B e lt w anders a t random.

(a) Too s t i f f because of Use b e l t w ith more t r a n s v e rs e

d es ig n f l e x i b i l i t y o r add e x tra

a l ig n in g a id s and t i l t tro u g h -

ing id l e r s ahead n o t over 2

v : v;: ;: ; , d e g re e s . -

(b) Too s t i f f because o f Allow; p roper .b reak -in tim e ,

new ness. Reduce b re a k - in tim e by l e t t i n g

b e l t s tan d loaded over n ig h t .

(4) TROUBLE: B e lt s t r e t c h e s e x c e s s iv e ly . S p lic e s weaken

p rem a tu re ly . Cuts or b reak s e n la rg e q u ic k ly . .

E xcess s t a r t i n g te n s io n In c re a s e speed . Keep tonnage

or excess b e l t te n s io n th e same or red u ce tonnage a t

th e same speed . Even up fe e d -

in g r a t e . D ecrease drag by p ro ­

p er i d l e r lu b r i c a t io n , r e p la c e ­

ment of worn ou t i d l e r s and

rem oval of s p i l l a g e m a te r ia l .

Use minimum w eight o f co u n te r

b a lan c in g w e ig h ts . R ep lace w ith

low er e lo n g a tio n b e l t .

96(5) TROUBLE: B e lt edges worn or gouged. .

Cause

(a) Rubbing.

(b) O ff-c e n te r lo a d in g .

M isalignm ent, d e f e c t -

(: ) i v e .s e l f - a l i g n i n g

• ■ i d l e r s . . '

(6) TROUBLE: E x cess iv e to p

(a) Poor- cover., q u a l i ty .

(b) Slow ru nn ing or s tu c k

m isa lig n ed r e tu r n

r o l l s .

(c) Poor lo a d in g .

/ '• \ . , . —\ ! i ti ■■ . . ' . » - . • ‘ •, -

(d) P i l in g up a t head

■ ) and t a i l p u l le y s .

Remedy

R e a lig n b e l t i f n e c e ssa ry .

Remove a l l o b s t r u c t io n s .

R e p o s itio n lo a d in g and

t r a n s f e r c h u te s . A lign

b e l t s ; R epair or r e p la c e ;

f a u l t y ; i d l e r s .

cover w ear.

R eplace b e l t w ith one

having a*, h ea v ie r cover

o r h igh q u a l i ty cover

m a te r ia l . : , .

C le a n ;up b e l t w i th .b e l t •

c le an in g d e v ic e s .: R ea lig n

r e tu r n r o l l e r s . Use ru b b er

d is c r e tu r n r o l l s , i f ;•

n e c e s s a ry .

Feed c o a l onto b e l t in th e i

s a m e .d ire c tio n and a t th e

same speed o f th e b e l t .

Keep c lean in g and lo ad

p ro p e r ly .

9 7

(7) TROUBLE: E x cess iv e bottom cover w ear.

Cause

(a) B e lt s l ip p in g o f f

d r iv e p u l le y .

(b) S tic k in g r o l l e r s . -

(c) Excess tro u g h in g

i d l e r s .

(d) B o lt heads pro-,

tru d in g above

lag g ed d r iv in g

drum s.

(e) M a te r ia l b u ild s up

due to s p i l l a g e or; ‘ ’ r 1" " • ‘ "V - k-' ‘.j. '

o th e r re a s o n s .

Remedy

A djust takeup d ev ices to in ­

c re a se te n s io n . In c re a s e a rc

of c o n ta c t w ith snub p u lle y

o r tandem d r iv e .

' S e rv ice and lu b r i c a t e p ro p e r ly .

T i l t n o t over 2 d eg rees from

u p r ig h t .

T ig h ten b o l t s , r e p la c e worn

o u t la g g in g .

Do n o t lo ad b e l t to o h e a v ily .

Use good ch u te lo ad in g

f a c i l i t i e s . Use s c ra p e rs ( to

c le a n b e l t ) ahead of t a i l

p u lle y on r e tu r n ru n . Use

p la te or v u lc a n iz e d s p l ic e s to

check le a k a g e . In sp e c t and

c le a n r e g u la r ly .

(8) TROUBLE: The c a rc a s s b re a k s .

(a) -Im pact. ~ < Load a t f l a t an g le a t b e l t

speed and In l i n e w ith b e l t .

Use cush ion i d l e r s .

98

Cause

(b) M a te r ia l trap p e d

betw een ;b e l t a n d ,

p u lle y ..

(c ) M a te r ia l b u ild in g up

on p u l le y s .

(9) TROUBLE: C rescen t b:

Mildew

Remedy

P lace s c ra p e rs ahead of t a i l

p u lle y on r e tu r n s id e .

Use p roper b e l t c le a n e rs .

:s , o r mushy s p o t s .

Use mildew in h ib i te d b e l t s .

(10) TROUBLE: C rossw ise

(a) B e lt edges fo ld in g

up.

(b) Poor p o s i t io n in g of

i d l e r s n ex t to head

p u lle y - to o c lo se

or to o h ig h .

(c) Too sharp v e r t i c a l

cu rv e . 11

(11) TROUBLE: Lengthw ise

to p co v ers i n t a c t .

ak a t edge.

Use l im i t sw itch es to s to p

ex c ess iv e s h i f t in g of b e l t .

Remove o b s tru c t io n s and p ro ­

v id e ample s id e c le a ra n c e .

R e lo ca te or r e a d ju s t i d l e r s

or p u lle y p o s i t io n .

In c re a s e curve r a d iu s to r e ­

duce s t r e s s e s on i d l e r s and

b e l t .

c a rc a s s b reak bu t bottom and

99

Cause Remedy

(a) B e lt ru n n in g o f f

and fo ld in g back . Use l i m i t sw ith c e s .

(b) Im pact. . : Reduce im pact.

(12) TROUBLE: S hrinkage of b e l t .

M o is tu re . ... ;' S p l ic e - in e x tra p ie c e w ith -

- v .1 tak eu p d e v ic e . h a l f down. -

(13) Bowing up th e E lim in a te o i l sou rce or use

c e n te r o r sp o t an o i l r e s i s t a n t b e l t . To

s w e l l in g . r e l i e v e c o n d itio n in th e

e x is t in g b e l t , groove le n g th -

- - l v . - w ise w ith t i r e -g ro o v in g to o l .

(14) TROUBLE: B l i s t e r in th e c o v e r .

F in e m a te r ia l working

U n to c u ts or p u n c - . ; Spot r e p a i r and v u lc a n iz e

• 1 t u r e s . . ' .. th e p a r t .

(II?) TROUBLE: C rossw ise b reak s of m e ta l f a s te n e r b e l t

jo in t s . ... 1 v... ■

B e lt f a s te n e r Use s h o r te r f a s te n e r s or

p la te s to o lo n g . in c re a s e p u lle y s iz e , or b o th .

_ i - ; CHAPTER V II I - - : : .

CONCLUSIONS; AND SUGGESTIONS FOR FUTURE STUDY ' ‘

CONCLUSIONS

: : ; (1) ;.¥ h en f i r s t c o n s id e r in g th e i n s t a l l a t i o n o f b e l t

conveyors, one shou ld c a r e f u l ly e s tim a te th e c o a l r e s e rv e s

a v a i la b le in o rd er to a s s u re t h a t d e p re c ia t io n c o s ts w i l l

h o t be e x o rb i ta n t and to d ec id e w hether to i n s t a l l com plete

b e l t conveyor hau lage or a com bination of b e l t s and o th e r

hau lage system s.

(2) G reat c a re must be ta k en w ith th e i n s t a l l a t i o n

of a l l m a in - lin e and o th e r im p o rtan t conveyor s t r u c t u r e s .

These should be equipped w ith p ro p er e l e c t r i c a l o verload

d ev ices and sequence and s lip p a g e c o n tro ls to p re v e n t “p i l e -

ups'* of c o a l a t t r a n s f e r p o in ts . The o p e ra tin g c o s ts of th e

b e l t hau lage system w i l l be h ig h e r w ith f a u l ty i n s t a l l a t i o n

and m ain tenance . v. ■ •

(3) For econom ical o p e ra tio n o f conveyor h au lag e ,

th e b e l t w id th shou ld n o t be w ider th a n n e c e ssa ry and I t

should be ru n as f a s t as p o s s ib le w ith in th e ran g e of r e - c - n r : r .

commended b e l t sp eed s .

100

-U (h) A ll th e b e l t hau lage c o s t components v a ry w ith

th e b e l t le n g th ; some v ary d ir e c t ly ^ -T o r example th e owner­

sh ip and energy c o s ts ; some v a r y : p a r t i a l l y and in s te p s , as

w ith o p e ra tin g ex p en ses . T h ere fo re ,' th e c o s t per to n w i l l

be somewhate p ro p o r t io n a l to th e le n g th , and th e c o s t p e r

to n -m ile w i l l be re a so n a b ly c o n s ta n t , ten d in g to d ec rease

s l i g h t l y - i f a t a l l - w ith in c re a s e in le n g th .

(5) The ow nership and energy c o s ts a re d i r e c t l y

p ro p o r t io n a l to th e tonnage c a r r ie d ; however, th e o p e ra tin g

and m ain tenance c o s ts rem ain f a i r l y s te a d y . Hence w ith in ­

c re a s in g tonnage c a r r ie d , th e c o s t per to n w i l l f a l l

s t e a d i ly .

(6) The e f f e c t o f in c re a s in g g ra d ie n t a g a in s t th e

lo ad w i l l be to in c re a s e c a p i t a l and energy ch a rg es as in ­

i t i a l c o s t o f equipm ent r i s e s because of th e more c o s t ly

b e l t r e q u ire d to w ith s ta n d th e h ig h er s t r e s s e s and e x tra

horsepower needed to e le v a te th e m a te r ia l .

(7) The o p e ra tin g c o s ts f o r o p e ra tin g la b o r and

m ain tenance la b o r w i l l rem ain f a i r l y c o n s ta n t up to a

hau lage d is ta n c e o f abou t one m ile ; beyond t h i s , th e la b o r

c o s t may in c re a s e in s te p s f o r each a d d i t io n a l m ile or

f r a c t i o n th e r e o f .

The o p e ra tin g and m ain tenance la b o r c o s ts depend,

a l s o , upon th e d eg ree o f au tom ation a t th e lo a d in g and

101

d isc h a rg e p o in ts and on th e number of s e p a ra te conveyor u n i t s

o p e ra tin g in th e same v i c i n i t y . This i s because more u n i t s

can be o p e ra ted ' and m a in ta in ed by th e sam e.crew of men and

i f th e s e u n i t s a r e c o n c e n tra te d a t one p la c e , th e r e s u l t in g

o p e ra tin g and m aintenance c o s ts can be d i s t r ib u t e d among a l l

u n i t s . I f th e d is ta n c e between s e p a ra te u n i t s in c re a s e s ,

s e p a ra te m ain tenance crews must be employed as i t w i l l n o t be

p o s s ib le f o r th e same crew to lo o k a f t e r a l l th e u n i t s .

FUTURE TRENDS ./ • ’

(1) As la rg e r c o a l m ining m achines a re used and

p ro d u c tio n becomes more c o n c e n tra te d , more a t t e n t io n must be

p a id to hau lage problem s to red u ce u n i t c o s ts .

(2) New p o ly e s te r s y n th e t ic f i b e r m a te r ia ls w i l l be

developed in th e f u tu r e to w ith s ta n d h ea v ie r s t r e s s e s , whence

i t w i l l be p o s s ib le to use lo n g e r s in g le conveyor u n i t s .

A lso , th e in v e n tio n of.som e kind o f m a te r ia l to be used in

b e l t s must be made to guard a g a in s t e l e c t r o s t a t i c sp a rk s

produced when th e b e l t s a re o p e ra ted a t h igh speeds and

th e reb y overcoming one cause o f conveyor f i r e s .

(3) I t w i l l become a s ta n d a rd p ro ced u re in th e

f u tu r e to use on ly f i r e - r e s i s t a n t b e l t in g f o r a l l under­

ground conveyor hau lage i n s t a l l a t i o n s .

(^ ) Use of deeper tro u g h in g i d l e r s f o r underground

t r a n s p o r ta t io n o f c o a l w i l l be in tro d u c e d in th e n ea r f u tu r e .

102

(5) Improvements and. m o d if ic a tio n s in th e e x te n s ib le

b e l t s , a r t i c u l a t e d and cascade ty p e conveyor equipm ent; and

s in g le b e l t conveyor u n i t s -which can c lim b , tu rn and have an

alm ost u n lim ite d number of d isc h a rg e p o in ts w i l l be used f o r

co a l t r a n s p o r ta t io n in m ines.

(6) The rope-fram e conveyor hau lage (n o t c a b le - b e l t )

system may become alm ost s ta n d a rd fo r many underground s e r ­

v ic e s and may f in d growing use in o th e r in d u s t r i e s f o r t r a n s ­

p o r ta t io n o f b u lk m a te r ia l s .

(7) . . . . I t i s expected th a t c a b le - b e l t conveyors w i l l

be used in th e U. S. c o a l m ining in d u s try .

SUGGESTIONS FOR FUTURE STUDY

The fo llo w in g s tu d y shou ld be made re g a rd in g con­

veyor hau lage in m ines:

(1) P re c is e in fo rm a tio n must be o b ta in ed f o r es­

ta b l i s h in g s ta n d a rd c o s t e s tim a tio n p ro ced u res f o r o th e r

ty p e s of conveyor hau lage system s such as ro p e -fram e , c a b le -

b e l t , pan or p l a t e , sh a k e r , b r id g e , c h a in , a r t i c u l a t e d and

cascade conveyors. The l im i ta t io n s o f th e s e ty p e s o f con­

veyor hau lage system s f o r e f f i c i e n t and economic o p e ra t io n

must a ls o be a s c e r ta in e d .

(2) A com parison o f owning and o p e ra tin g c o s ts of

d i f f e r e n t k in d s of conveyor and o th e r hau lage methods should

103

be made f o r v a r io u s le n g th s , c a p a c i t i e s , g r a d ie n ts and o th e r

■working c o n d itio n s ; and economic l im i ta t io n s f o r each type

of hau lage shou ld be d e te rm in ed .

(3) The modern e le c t r o n ic com puters shou ld be in ­

v e s t ig a te d f o r p o s s ib le a p p l ic a t io n s in th e s o lu t io n of con­

veyor hau lage p rob lem s, e s p e c ia l ly th o se th a t a re r e p e t i t i v e

or i t e r a t i v e in n a tu r e . These in c lu d e d e te rm in a tio n of

b reak -even p o in ts f o r owning and o p e ra tin g conveyor haulage

system s f o r d i f f e r e n t com binations of g ra d e s , le n g th s , w id th s ,

sp eed s, e t c . , and th e s e must be compared w ith o th e r haulage

system s. A ll th e s e r e s u l t s shou ld enable management to make

b e t te r d e c is io n s in th e s e le c t io n and d e s ig n o f d i f f e r e n t

haulage system s. .

104

BIBLIOGRAPHY AND SELECTED REFERENCES

PERIODICALS

1 . “New p ro d u c ts d ig e s t - .C lim b in g and tu rn in g con­

v e y o rs ," E n g in eerin g and Mining J o u r n a l . Vol 163 ,

No h, A p r i l 1962, p . 53.2. E. R . T r a x l e r , "Conveyor b e l t horsepow er and o p e ra tin g

d is ta n c e s co n tin u e to In c re a se in f u tu r e . "

E n g in ee rin g and Mining J o u r n a l . V ol 162, No 8 ,

August 1961 , pp . 86- 7 .

3 . A. W. Asman, "B e lt hau lage econom ics," Coal Age.

Vol 65 , No 10, O ct. I9 6 0 , pp. 112-14 , 116.

•4 . D. C. Jo n es , "H andling lump co a l on b e l t s , "

M echan iza tion . Vol 24, No 9, S ep t. I9 6 0 , pp. 73 -5 .

5. H. W. Meador, "New developm ent in b e l t h au lag e ,"

: : . Mining Congress J o u r n a l . Vol 4 6 , No 9 , S ep t, i 960 ,

p p . 86-9. .. . , . ■•6 . W. A. McCurdy, "Track fo r long h a u l ," M echan iza tion ,

Vol 2 4 , No 8 , August i 960 , pp . 69- 7 2 . . ;

7* W. A. McCurdy, "Problem s o f new mine d e s ig n ,"

M ech an iza tio n . V ol 25, No 6 , June i 960 , pp. 43-53*

8. W. G. H allam , "L ab o ra to ry assessm en t o f conveyor b e l t

p erfo rm ance." C o l l ie ry G uard ian . Vol 200, No 5 l6 4 ,

A p r i l 7 , I9 6 0 , pp. 391-4 .

105

“C ontinuous t r a n s p o r ta t io n in s p e c ia l mine la y o u t

paces high, p r o d u c t iv i ty ,” Coal /lee . Vol 65 , No 4 ,

A p r i l I9 6 0 , pp . 72 -8 .

J . R. Brandon, “T ips on b e l t conveyor m a in te n an ce ,”

G oai Age. Vol 65, No 3 , March I9 6 0 , pp. 100-2 , 104.

D. S,. Kedick and T. Furman, "Review of b e l t conveyors

w ith s t e e l hau lage m embers,” C o l l ie ry E n g in e e rin g ,

Vol 37, No 431 , J a n . I9 6 0 , pp. 17-24 .

N. Brook, “E s tim a tio n of conveyor s p e c i f i c a t i o n s ,”

C o l l ie ry E n g in e e rin g . Vol 36, No 429 , Nov. 1959,

pp. 480-92 .

G. H. V ulcan , “Changes in conveyor,b e l t p r o p e r t ie s

w ith s e r v i c e ,” C o l l ie ry E n g in ee rin g . Vol 36,

No> 2 4 , June 1959, pp . 2 4 l-6 .

D.. B; Shupe, "E xperience w ith flam e r e s i s t a n t b e l t in g

Mining Congress J o u r n a l . Vol 45 , No 4 , A p r i l 1959,

-PP* 59-62.

“Low. speed and low c o s t b e l t s f o r h o is t in g m en,"

Coal Age, Vol 63 , No 7A, M id-July 1958, p . 79-

"Three y e a rs of h o is t in g w ith P r in c e s s C a b le -b e l t ,"

Coal Age, Vol 6 3 , No 9 , S ep t. 1958, pp. 106-8 .

" E le c tro n ic conveyor c o n t r o l s , ” Coal Age. Vol 63 ,

No 8 , August 1958, pp . 106-7 .

H. J . A tk in so n , J . F . C arr and E. H oyle, "Development

and use of f i r e - r e s i s t a n t b e l t i n g ," C o l l ie ry

G uard ian , Vol 196 , No 5072, May 8 , 1958, pp . 567-73

107

19. T. D. E l l i o t , “Development of c a b le - b e l t co n v e y o rs ,”

I ro n and Coal T rades Review. V ol 176, No 4689,

A p ri l 4 , 1958, pp. 809-13.

20. "B e ltm an 's g u id e ,” Coal Age, Vol 6 ^ T No 3 , March 1958,

pp. 122-27.

21. A. E. F lo w ers , "Rope b e l t s b o o stin g e f f ic ie n c y a t

Peabody," Coal Age, V ol 62 , No 2 , Feb. 1958,

pp. 124-34.

22. E. F . H ew ett, " C a b le -b e lt conveyor and i t s a p p l i ­

c a t io n s ,"

P ro c eed in g s . No l8 4 . Dec. 1957, PP. 4 4 -8 .

23. R. F . Knobloch, "How to g e t more and b e t t e r s e rv ic e

from b e l t co n v ey o rs ," Coa^ ^ g e . Vol 62 , No 8 ,

August 1957, pp . 76-9•

24. "B e lt t h a t goes around c o rn e r s ," M echan iza tion .

Vol 20, No 10, O ct. 1956, pp. 72-3•

25. R. U. Jackson , "Conveyors V s. t r a c k h a u la g e ,"

Mining E n g in e e rin g . V ol 4 , No 9 , S ep t. 1952,

pp. 866-9 . .

BOOKS AND MISCELLANEOUS ARTICLES

1 . E. R. D revdah l, P r o f i ta b le use of ex cav a tio n eq u ip - >

d e n t , Tucson, A r iz . , D ese rt L a b o ra to r ie s , T ec h n ica l

P u b l ic a t io n s , 1961 .

2 . J . J . S h ie ld s and J . J . Dowd, "M echanical m ining in

bitum inous c o a l m in e s ." P ro g re ss r e p o r t No 9 -

Face h a u la g e , USBM I n f e r . C irc . No 7978, I9 6 0 .

108

3. J . ¥ . Hardy, B e lt conveyor co m p u ta tio n s . H a ls ted

S t r e e t , C h icago-9> Goodman M anufacturing Co . , I9 6 0 .

U-. ,,RopexH - Goodman*s e x te n s ib le b e l t conveyor and

R o p e-b e lt conveyorT Goodman*s c a ta lo g No G-123

and G-150.

5. M a te r ia ls h and ling handbook, New York, Ronald P re ss

Co. , 1958.

6 . C. E. B u l l in g e r , E n g in ee rin g economy. New York,

McGraw-Hill Book Co. , 1958.

7 . R e la tin g roadway conveyors to i t s d u ty . N.C.B. I n f o r .

B u l le t in No 58 /197 , Grosvenor P la c e , London, S.W. 1 ,

N a tio n a l Coal B oard, 1958.

8 . L in k -b e lt C atalog No 1000. 233, Broadway, New York 7 ,

L in k -B e lt Co. , 1958. /:...

9 . H. E. P ru n e r , AH about b e l t in g r Handbook M, 63lH—B -l

and 17 , R o c k fe lle r C e n te r , New York 20, U nited

S ta te s Rubber Co. , 1957.

10. N a tio n a l E l e c t r i c a l M anufactu rers A sso c ia tio n

s ta n d a rd s f o r m ining b e l t conveyors, C irc. No MB-1,

1956.

11. P e rm iss ib le mine equipm ent approved du ring th e

ca len d e r y e a rs 1955-56. USBM I n f o r . C i r c . No 7840.

12. R/M E n g in eerin g gu ide f o r conveyor b e l t i n g T P a s s a ic ,

' New J e r s e y , R aybestos-M anhattan , I n c . , 1956.

1 3 . W. G. Hudson, Conveyors and r e l a t e d equipm ent. New

York, John W iley , 1949•