pc78mr-6_sebm030601

00-1

MACHINE MODEL SERIAL NUMBER

PC78MR-6 1001 and up

This shop manual may contain attachments and optional equipment that are not available in yourarea. Please consult your local Komatsu distributor for those items you may require. Materials andspecifications are subject to change without notice.

PC78MR-6 mounts the S4D95LE-3-A engine.For details of the engine, see the 95-3 Series Engine Shop Manual.

SEBM030601

2003All Rights ReservedPrinted in Japan 12-03(02)

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00-2 PC78MR-6

CONTENTS

No. of page

01 GENERAL ................................................................................................................01-1

10 STRUCTURE AND FUNCTION, MAINTENANCE STANDARD......................................................................10-1

20 TESTING AND ADJUSTING .......................................................................20-1

30 DISASSEMBLY AND ASSEMBLY ..........................................................30-1

90 OTHERS ....................................................................................................................90-1

PC78MR-6 00-2-1

The affected pages are indicated by the use of thefollowing marks. It is requested that necessaryactions be taken to these pages according to thetable below.

Pages having no marks are those previously revisedor made aditions.

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SAFETY SAFETY NOTICE

00-3

SAFETYSAFETY NOTICE

IMPORTANT SAFETY NOTICE

Proper service and repair is extremely important for safe machine operation. The service andrepair techniques recommended by Komatsu and described in this manual are both effectiveand safe. Some of these techniques require the use of tools specially designed by Komatsu forthe specific purpose.

To prevent injury to workers, the symbol is used to mark safety precautions in this manual.The cautions accompanying these symbols should always be followed carefully. If any danger-ous situation arises or may possibly arise, first consider safety, and take the necessary actionsto deal with the situation.

GENERAL PRECAUTIONS

Mistakes in operation are extremely dangerous.Read the Operation and Maintenance Manual care-fully BEFORE operating the machine.1. Before carrying out any greasing or repairs, read

all the precautions given on the decals which arefixed to the machine.

2. When carrying out any operation, alwayswear safety shoes and helmet. Do not wearloose work clothes, or clothes with buttonsmissing. Always wear safety glasses when hitting

parts with a hammer. Always wear safety glasses when grinding

parts with a grinder, etc.3. If welding repairs are needed, always have a

trained, experienced welder carry out the work.When carrying out welding work, always wearwelding gloves, apron, hand shield, cap andother clothes suited for welding work.

4. When carrying out any operation with two ormore workers, always agree on the operatingprocedure before starting. Always inform yourfellow workers before starting any step of theoperation. Before starting work, hang UNDERREPAIR signs on the controls in the operator'scompartment.

5. Keep all tools in good condition and learn thecorrect way to use them.

6. Decide a place in the repair workshop to keeptools and removed parts. Always keep the toolsand parts in their correct places. Always keepthe work area clean and make sure that there isno dirt or oil on the floor. Smoke only in the areasprovided for smoking. Never smoke while work-ing.

PREPARATIONS FOR WORK

7. Before adding oil or making any repairs, park themachine on hard, level ground, and block thewheels or tracks to prevent the machine frommoving.

8. Before starting work, lower blade, ripper, bucketor any other work equipment to the ground. Ifthis is not possible, insert the safety pin or useblocks to prevent the work equipment from fall-ing. In addition, be sure to lock all the controllevers and hang warning signs on them.

9. When disassembling or assembling, support themachine with blocks, jacks or stands beforestarting work.

10.Remove all mud and oil from the steps or otherplaces used to get on and off the machine.Always use the handrails, ladders or steps whengetting on or off the machine. Never jump on oroff the machine. If it is impossible to use thehandrails, ladders or steps, use a stand to pro-vide safe footing.

SAFETY SAFETY NOTICE

00-4

PRECAUTIONS DURING WORK

11.When removing the oil filler cap, drain plug orhydraulic pressure measuring plugs, loosenthem slowly to prevent the oil from spurting out.Before disconnecting or removing componentsof the oil, water or air circuits, first remove thepressure completely from the circuit.

12.The water and oil in the circuits are hot when theengine is stopped, so be careful not to getburned.Wait for the oil and water to cool before carry-ing out any work on the oil or water circuits.

13.Before starting work, remove the leads from thebattery. Always remove the lead from the nega-tive () terminal first.

14.When raising heavy components, use a hoist orcrane.

Check that the wire rope, chains and hooks arefree from damage.Always use lifting equipment which has amplecapacity.Install the lifting equipment at the correct places.Use a hoist or crane and operate slowly to pre-vent the component from hitting any other part.Do not work with any part still raised by the hoistor crane.

15.When removing covers which are under internalpressure or under pressure from a spring,always leave two bolts in position on oppositesides. Slowly release the pressure, then slowlyloosen the bolts to remove.

16.When removing components, be careful not tobreak or damage the wiring. Damaged wiringmay cause electrical fires.

17.When removing piping, stop the fuel or oil fromspilling out. If any fuel or oil drips onto the floor,wipe it up immediately. Fuel or oil on the floorcan cause you to slip, or can even start fires.

18.As a general rule, do not use gasoline to washparts. In particular, use only the minimum ofgasoline when washing electrical parts.

19.Be sure to assemble all parts again in their origi-nal places.Replace any damaged parts with new parts. When installing hoses and wires, be sure

that they will not be damaged by contactwith other parts when the machine is beingoperated.

20.When installing high pressure hoses, make surethat they are not twisted. Damaged tubes aredangerous, so be extremely careful when install-ing tubes for high pressure circuits. Also, checkthat connecting parts are correctly installed.

21.When assembling or installing parts, always usethe specified tightening torques. When installingprotective parts such as guards, or parts whichvibrate violently or rotate at high speed, be par-ticularly careful to check that they are installedcorrectly.

22.When aligning two holes, never insert your fin-gers or hand. Be careful not to get your fingerscaught in a hole.

23.When measuring hydraulic pressure, check thatthe measuring tool is correctly assembled beforetaking any measurements.

24.Take care when removing or installing the tracksof track-type machines.When removing the track, the track separatessuddenly, so never let anyone stand at eitherend of the track.

FOREWORD GENERAL

00-5

FOREWORDGENERALThis shop manual has been prepared as an aid to improve the quality of repairs by giving the serviceman anaccurate understanding of the product and by showing him the correct way to perform repairs and make judge-ments. Make sure you understand the contents of this manual and use it to full effect at every opportunity.

This shop manual mainly contains the necessary technical information for operations performed in a serviceworkshop. For ease of understanding, the manual is divided into the following chapters; these chapters are fur-ther divided into the each main group of components.

STRUCTURE AND FUNCTIONThis section explains the structure and function of each component. It serves not only to give an under-standing of the structure, but also serves as reference material for troubleshooting.In addition, this section may contain hydraulic circuit diagrams, electric circuit diagrams, and mainte-nance standards.

TESTING AND ADJUSTINGThis section explains checks to be made before and after performing repairs, as well as adjustments tobe made at completion of the checks and repairs.Troubleshooting charts correlating "Problems" with "Causes" are also included in this section.

DISASSEMBLY AND ASSEMBLYThis section explains the procedures for removing, installing, disassembling and assembling each com-ponent, as well as precautions for them.

MAINTENANCE STANDARDThis section gives the judgment standards for inspection of disassembled parts.The contents of this section may be described in STRUCTURE AND FUNCTION.

OTHERSThis section mainly gives hydraulic circuit diagrams and electric circuit diagrams.In addition, this section may give the specifications of attachments and options together.

NOTICE

The specifications contained in this shop manual are subject to change at any time and without anyadvance notice. Use the specifications given in the book with the latest date.

FOREWORD HOW TO READ THE SHOP MANUAL

00-6

HOW TO READ THE SHOP MANUAL

VOLUMESShop manuals are issued as a guide to carrying outrepairs. They are divided as follows:

Chassis volume: Issued for every machine modelEngine volume: Issued for each engine seriesElectrical volume: Attachments volume:

These various volumes are designed to avoid dupli-cating the same information. Therefore, to deal withall repairs for any model , it is necessary that chas-sis, engine, electrical and attachment volumes beavailable.

DISTRIBUTION AND UPDATINGAny additions, amendments or other changes will besent to KOMATSU distributors. Get the most up-to-date information before you start any work.

FILING METHOD1. See the page number on the bottom of the page.

File the pages in correct order.2. Following examples show how to read the page

number.Example 1 (Chassis volume):

10 - 3

Item number (10. Structure andFunction)Consecutive page number for eachitem.

Example 2 (Engine volume):

12 - 5

Unit number (1. Engine)Item number (2. Testing and Adjust-ing)Consecutive page number for eachitem.

3. Additional pages: Additional pages are indicated by a hyphen (-) and number after the page number. File as in the example.Example:10-410-4-110-4-210-5

REVISED EDITION MARK

When a manual is revised, an edit ion mark(123....) is recorded on the bottom of the pages.

REVISIONS

Revised pages are shown in the LIST OF REVISEDPAGES next to the CONTENTS page.

SYMBOLS

So that the shop manual can be of ample practicaluse, important safety and quality portions aremarked with the following symbols.

Symbol Item Remarks

SafetySpecial safety precautionsare necessary when per-forming the work.

s

Caution

Special technical precau-tions or other precautionsfor preserving standardsare necessary when per-forming the work.

4 Weight

Weight of parts of sys-tems. Caution necessarywhen selecting hoistingwire, or when working pos-ture is important, etc.

3

Tighteningtorque

Places that require specialattention for the tighteningtorque during assembly.

2 CoatPlaces to be coated withadhesives and lubricants,etc.

5 Oil, waterPlaces where oil, water orfuel must be added, andthe capacity.

6 DrainPlaces where oil or watermust be dra ined, andquantity to be drained.

} Each issued as onevolume to cover allmodels

12-20312-203-112-203-212-204

Added pages

FOREWORD HOISTING INSTRUCTIONS

00-7

HOISTING INSTRUCTIONS

HOISTING

Heavy parts (25 kg or more) must be liftedwith a hoist, etc. In the DISASSEMBLYAND ASSEMBLY section, every partweighing 25 kg or more is indicated clearlywith the symbol 4

If a part cannot be smoothly removed from themachine by hoisting, the following checksshould be made:1) Check for removal of all bolts fastening the

part to the relative parts.2) Check for existence of another part causing

interference with the part to be removed.

WIRE ROPES1) Use adequate ropes depending on the

weight of parts to be hoisted, referring tothe table below:

Wire ropes(Standard "Z" or "S" twist ropes

without galvanizing)

The allowable load value is estimated to be one-sixth or one-seventh of the breaking strength ofthe rope used.

2) Sling wire ropes from the middle portion of thehook.

Slinging near the edge of the hook may causethe rope to slip off the hook during hoisting, anda serious accident can result. Hooks have max-imum strength at the middle portion.

3) Do not sling a heavy load with one rope alone,but sling with two or more ropes symmetricallywound onto the load. Slinging with one rope may cause turning

of the load during hoisting, untwisting ofthe rope, or slipping of the rope from itsoriginal winding position on the load, whichcan result in a dangerous accident.

4) Do not sling a heavy load with ropes forming awide hanging angle from the hook.When hoisting a load with two or more ropes,the force subjected to each rope will increasewith the hanging angles. The table belowshows the variation of allowable load kN {kg}when hoisting is made with two ropes, each ofwhich is allowed to sling up to 9.8 kN {1000 kg}vertically, at various hanging angles.When two ropes sling a load vertically, up to19.6 kN {2000 kg} of total weight can be sus-pended. This weight becomes 9.8 kN {1000 kg}when two ropes make a 120 hanging angle.On the other hand, two ropes are subjected toan excessive force as large as 39.2 kN {4000kg} if they sling a 19.6 kN {2000 kg} load at alifting angle of 150.

Rope diameter Allowable load

mm kN tons

1011.512.514161820

22.430405060

9.813.715.721.627.535.343.154.998.1176.5274.6392.2

1.01.41.62.22.83.64.45.6

10.018.028.040.0

SAD00479

41%71%79%88%100%

FOREWORD METHOD OF DISASSEMBLING, CONNECTING PUSH-PULL TYPE COUPLER

00-8

METHOD OF DISASSEMBLING, CONNECTING PUSH-PULL TYPE COUPLER

Before carrying out the following work, releasethe residual pressure from the hydraulic tank.For details, see TESTING AND ADJUSTING,Releasing residual pressure from hydraulictank.

Even if the residual pressure is released fromthe hydraulic tank, some hydraulic oil flows outwhen the hose is disconnected. Accordingly,prepare an oil receiving container.

Disconnection1) Release the residual pressure from the hydrau-

l ic tank. For detai ls , see TESTING ANDADJUSTING, Releasing residual pressure fromhydraulic tank.

2) Hold adapter (1) and push hose joint (2) intomating adapter (3). (See Fig. 1) The adapter can be pushed in about 3.5

mm. Do not hold rubber cap portion (4).

3) After hose joint (2) is pushed into adapter (3),press rubber cap portion (4) against (3) until itclicks. (See Fig. 2)

4) Hold hose adapter (1) or hose (5) and pull it out.(See Fig. 3) Since some hydraulic oil flows out, prepare

an oil receiving container.

Connection1) Hold hose adapter (1) or hose (5) and insert it in

mating adapter (3), aligning them with eachother. (See Fig. 4) Do not hold rubber cap portion (4).

2) After inserting the hose in the mating adapterperfectly, pull it back to check its connectingcondition. (See Fig. 5) When the hose is pulled back, the rubber

cap portion moves toward the hose about3.5 mm. This does not indicate abnormality,however.

Type 1

FOREWORD METHOD OF DISASSEMBLING, CONNECTING PUSH-PULL TYPE COUPLER

00-9

Type 2 Type 3D

isa

ssem

bly

1) Hold the mouthpiece of the tightening portionand push body (2) in straight until sliding pre-vention ring (1) contacts contact surface a ofthe hexagonal portion at the male end.

2) Hold in the condition in Step 1), and turnlever (4) to the right (clockwise).

3) Hold in the condition in Steps 1) and 2), andpull out whole body (2) to disconnect it.

1) Hold the mouthpiece of the tightening portionand push body (2) in straight until sliding pre-vention ring (1) contacts contact surface a ofthe hexagonal portion at the male end.

2) Hold in the condition in Step 1), and pushuntil cover (3) contacts contact surface a ofthe hexagonal portion at the male end.

3) Hold in the condition in Steps 1) and 2), andpull out whole body (2) to disconnect it.

Conn

ectio

n

Hold the mouthpiece of the tightening portionand push body (2) in straight until sliding pre-vention ring (1) contacts contact surface a ofthe hexagonal portion at the male end to con-nect it.

Hold the mouthpiece of the tightening portionand push body (2) in straight until sliding pre-vention ring (1) contacts contact surface a ofthe hexagonal portion at the male end to con-nect it.

FOREWORD COATING MATERIALS

00-10

COATING MATERIALS

The recommended coating materials such as adhesives, gasket sealants and greases used for disassemblyand assembly are listed below.

For coating materials not listed below, use the equivalent of products shown in this list.

Category Komatsu code Part No. Q'ty Container Main applications, featuresr

Adhesives

LT-1A 790-129-9030 150 g Tube Used to prevent rubber gaskets,

rubber cushions, and cock plugfrom coming out.

LT-1B 790-129-9050 20 g(2 pcs.)Polyethylene

container

Used in places requiring an imme-diately effective, strong adhesive.Used for plastics (except polyeth-ylene, polyprophylene, tetrafluor-oethlene and vinyl chlor ide),rubber, metal and non-metal.

LT-2 09940-00030 50 g Polyethylenecontainer

Features: Resistance to heat andchemicals

Used for anti-loosening and seal-ant purpose for bolts and plugs.

LT-3

790-129-9060(Set of

adhesive and hardening

agent)

Adhesive:1 kg

Hardening

agent:500 g

Can

Used as adhesive or sealant formetal, glass and plastic.

LT-4 790-129-9040 250 g Polyethylenecontainer Used as sealant for machined

holes.

HoltzMH 705 790-126-9120 75 g Tube

Used as heat-resisting sealant forrepairing engine.

Three bond1735 790-129-9140 50 g

Polyethylenecontainer

Quick hardening type adhesive Cure time: within 5 sec. to 3 min. Used mainly for adhesion of met-

als, rubbers, plastics and woods.

Aron-alpha201 790-129-9130 2 g


Quick hardening type adhesive Quick cure type (max. strength af-

ter 30 minutes) Used mainly for adhesion of rub-

bers, plastics and metals.

Loctite648-50 79A-129-9110 50 cc


Resistance to heat, chemicals Used at joint portions subject to

high temperatures.

Gasketsealant

LG-1 790-129-9010 200 g Tube Used as adhesive or sealant for

gaskets and packing of powertrain case, etc.

LG-5 790-129-9070 1 kg Can

Used as sealant for variousthreads, pipe joints, flanges.

Used as sealant for taperedplugs, elbows, nipples of hydrau-lic piping.

LG-6 790-129-9020 200 g Tube

Features: Silicon based, resist-ance to heat, cold

Used as sealant for flange sur-face, tread.

mab Used as sealant for oil pan,final drive case, etc.

FOREWORD COATING MATERIALS

00-11

Category Komatsu code Part No. Q'ty Container Main applications, featuresr

AdhesivesLG-7 790-129-9070 1 g Tube

Ftures: Silicon based, quick hard-ening type

Used as sealant for flywheelhousing, intake manifold, oil an,thermostat housing, etc.

Three bond1211 790-129-9090 100 g Tube

Used as heat-resisting sealant forrepairing engine.

Molybdenum disulphide lubricant

LM-G 09940-00051 60 g Can Used as lubricant for sliding por-tion (to prevent from squeaking).

LM-P 09940-00040 200 g Tube

Used to prevent seizure or scuf-fling of the thread when press fit-ting or shrink fitting.

Used as lubricant for linkage,bearings, etc.

Grease

G2-LI

SYG2-400LISYG2-350LISYG2-400LI-ASYG2-160LISYGA-160CNLI

Various Various

General purpose type

G2-CA

SYG2-400CASYG2-350CASYG2-400CA-ASYG2-160CASYGA-160CNCA

Various Various

Used for normal temperature,light load bearing at places in con-tact with water or steam.

Molybdenum disulphide lubricant

SYG2-400M400 g

(10 per case)

Belows type Used for places with heavy load

FOREWORD STANDARD TIGHTENING TORQUE

00-12

STANDARD TIGHTENING TORQUESTANDARD TIGHTENING TORQUE TABLE (WHEN USING TORQUE WRENCH) In the case of metric nuts and bolts for which there is no special instruction, tighten to the torque given in

the table below.

TABLE OF TIGHTENING TORQUES FOR FLARED NUTS In the case of flared nuts for which there is no

special instruction, tighten to the torque given inthe table below.

Thread diameter of bolt

Width across flats

mm mm Nm kgm

68101214

1013171922

13.2 0 1.431 0 366 0 7

113 0 10177 0 19

1.35 0 0.153.2 0 0.36.7 0 0.711.5 0 118 0 2

1618202224

2427303236

279 0 30382 0 39549 0 59745 0 83927 0 103

28.5 0 339 0 456 0 6

76 0 8.594.5 0 10.5

2730333639

4146505560

1320 0 1401720 0 1902210 0 2402750 0 2903290 0 340

135 0 15175 0 20225 0 25280 0 30335 0 35

Thread diameter of bolt

Width across flats

mm mm Nm kgm

681012

10131427

7.85 0 1.9518.6 0 4.940.2 0 5.9

82.35 0 7.85

0.8 0 0.21.9 0 0.54.1 0 0.68.4 0 0.8

Thread diameter Width across flat Tightening torque

mm mm Nm kgm

1418222430333642

1924273236414655

24.5 0 4.949 0 19.6

78.5 0 19.6137.3 0 29.4176.5 0 29.4196.1 0 49245.2 0 49294.2 0 49

2.5 0 0.55 0 28 0 2

14 0 318 0 320 0 525 0 530 0 5

SAD00483

Sealing surface


00-13

TABLE OF TIGHTENING TORQUES FOR SPLIT FLANGE BOLTS In the case of split flange bolts for which there is no special instruction, tighten to the torque given in the

table below.

TABLE OF TIGHTENING TORQUES FOR O-RING BOSS PIPING JOINTS Unless there are special instructions, tighten the O-ring boss piping joints to the torque below.

TABLE OF TIGHTENING TORQUES FOR O-RING BOSS PLUGS Unless there are special instructions, tighten the O-ring boss plugs to the torque below.

Thread diameter Width across flat Tightening torque

mm mm Nm kgm

101216

141722

65.7 0 6.8112 0 9.8279 0 29

6.7 0 0.711.5 0 128.5 0 3

Norminal No.Thread diameter Width across flat Tightening torque

mm mm Nm kgm

0203, 0405, 0610, 12

14

1420243342

Varies depending on type of connector.

34.3 0 4.993.1 0 9.8

142.1 0 19.6421.4 0 58.8877.1 0 132.3

3.5 0 0.59.5 0 114.5 0 243 0 6

89.5 0 13.5

Norminal No.Thread diameter Width across flat Tightening torque

mm mm Nm kgm

08101214161820243033364252

08101214161820243033364252

141719222427303232n36nn

7.35 0 1.4711.27 0 1.4717.64 0 1.9622.54 0 1.96

29.4 0 4.939.2 0 4.949 0 4.9

68.6 0 9.8107.8 0 14.7127.4 0 19.6151.9 0 24.5210.7 0 29.4323.4 0 44.1

0.75 0 0.151.15 0 0.15

1.8 0 0.22.3 0 0.23 0 0.54 0 0.55 0 0.57 0 1

11 0 1.513 0 2

15.5 0 2.521.5 0 333 0 4.5


00-14

TIGHTENING TORQUE FOR 102 ENGINE SERIES 1) BOLT AND NUTS

Use these torques for bolts and nuts (unit: mm) of Cummins Engine.

2) EYE JOINTSUse these torques for eye joints (unit: mm) of Cummins Engine.

3) TAPERED SCREWSUse these torques for tapered screws (unit: inch) of Cummins Engine.

TIGHTENING TORQUE TABLE FOR HOSES (TAPER SEAL TYPE AND FACE SEAL TYPE) Tighten the hoses (taper seal type and face seal type) to the following torque, unless otherwise specified. Apply the following torque when the threads are coated (wet) with engine oil.

Thread diameter Tightening torquemm Nm kgm

681012

10 0 224 0 443 0 6

77 0 12

1.02 0 0.202.45 0 0.414.38 0 0.617.85 0 1.22

Thread diameter Tightening torquemm Nm kgm

68101214

8 0 210 0 212 0 224 0 436 0 5

0.81 0 0.201.02 0 0.201.22 0 0.202.45 0 0.413.67 0 0.51

Thread diameter Tightening torqueinch Nm kgm

1 / 161 / 81 / 43 / 81 / 23 / 4

1

3 0 18 0 212 0 215 0 224 0 436 0 560 0 9

0.31 0 0.100.81 0 0.201.22 0 0.201.53 0 0.412.45 0 0.413.67 0 0.516.12 0 0.92

Nominal size of hose

Width across flats

Tightening torque (Nm {kgm}) Taper seal type Face seal type

Range Target Thread size (mm)Nominal thread

size - Threads per inch, Thread series

Root diameter (mm) (Reference)

02 19 35 - 63 {3.5 - 6.5} 44 {4.5} 14 - 18UNF 14.3

0322 54 - 93 {5.5 - 9.5} 74 {4.5}

- 16UN 17.5

24 59 - 98 {6.0 - 10.0} 78 {8.0} 18

04 27 84 - 132 {8.5 - 13.5} 103 {10.5} 22 - 16UN 20.7

05 32 128 - 186 {13.0 - 19.0} 157 {16.0} 24 1 - 14UNS 25.4

06 36 177 - 245 {18.0 - 25.0} 216 {22.0} 30 1 - 12UNF 30.3

(10) 41 177 - 245 {18.0 - 25.0} 216 {22.0} 33 (12) 46 197 - 294 {20.0 - 30.0} 245 {25.0} 36 (14) 55 246 - 343 {25.0 - 35.0} 294 {30.0} 42

9161116

1316

316

FOREWORD ELECTRIC WIRE CODE

00-15

ELECTRIC WIRE CODEIn the wiring diagrams, various colors and symbols are employed to indicate the thickness of wires.This wire code table will help you understand WIRING DIAGRAMS.Example: 5WB indicates a cable having a nominal number 5 and white coating with black stripe.

CLASSIFICATION BY THICKNESS

CLASSIFICATION BY COLOR AND CODE

Norminalnumber

Copper wireCable O.D.(mm)

Current rating(A) Applicable circuitNumber of

strandsDia. of strands(mm2)

Cross section(mm2)

0.85 11 0.32 0.88 2.4 12 Starting, lighting, signal etc.

2 26 0.32 2.09 3.1 20 Lighting, signal etc.

5 65 0.32 5.23 4.6 37 Charging and signal

15 84 0.45 13.36 7.0 59 Starting (Glow plug)

40 85 0.80 42.73 11.4 135 Starting

60 127 0.80 63.84 13.6 178 Starting

100 217 0.80 109.1 17.6 230 Starting

Priori-ty

Circuits

Classi-fication

Charging Ground Starting Lighting Instrument Signal Other

1 Pri-maryCode W B B R Y G L

Color White Black Black Red Yellow Green Blue

2

Auxi-liary

Code WR n BW RW YR GW LW

Color White & Red n White & Black Red & White Rellow & Red Green & White Blue & White

3Code WB n BY RB YB GR LR

Color White & Black n Black & Yellow Red & Black Yellow & Black Green & Red Blue & Yellow

4

Code WL n BR RY YG GY LY

Color White & Blue n Black & Red Red & Yellow Yellow & GreenGreen & Yellow Blue & Yellow

5Code WG n n RG YL GB LB

Color White & Green n n Red & Green Yellow & Blue Green & Black Blue & Black

6Code n n n RL YW GL n

Color n n n Red & Blue Yellow & White Green & Blue n

FOREWORD CONVERSION TABLE

00-16

CONVERSION TABLE

METHOD OF USING THE CONVERSION TABLEThe Conversion Table in this section is provided to enable simple conversion of figures. For details of themethod of using the Conversion Table, see the example given below.

EXAMPLE Method of using the Conversion Table to convert from millimeters to inches1. Convert 55 mm into inches.

(1) Locate the number 50 in the vertical column at the left side, take this as A, then draw a horizontal linefrom A.

(2) Locate the number 5 in the row across the top, take this as B, then draw a perpendicular line downfrom B.

(3) Take the point where the two lines cross as C. This point C gives the value when converting from mil-limeters to inches. Therefore, 55 mm = 2.165 inches.

2. Convert 550 mm into inches.(1) The number 550 does not appear in the table, so divide by 10 (move the decimal point one place to the

left) to convert it to 55 mm.(2) Carry out the same procedure as above to convert 55 mm to 2.165 inches.(3) The original value (550 mm) was divided by 10, so multiply 2.165 inches by 10 (move the decimal point

one place to the right) to return to the original value. This gives 550 mm = 21.65 inches.

Millimeters to inches

1 mm = 0.03937 in

0 1 2 3 4 5 6 7 8 9

010203040

5060708090

00.3940.7871.1811.575

1.9692.3622.7563.1503.543

0.0390.4330.8271.2201.614

2.0082.4022.7953.1893.583

0.0790.4720.8661.2601.654

2.0472.4412.8353.2283.622

0.1180.5120.9061.2991.693

2.0872.4802.8743.2683.661

0.1570.5510.9451.3391.732

2.1262.5202.9133.3073.701

0.1970.5910.9841.3781.772

2.1652.5592.9533.3463.740

0.2360.6301.0241.4171.811

2.2052.5982.9923.3863.780

0.2760.6691.0631.4571.850

2.2442.6383.0323.4253.819

0.3150.7091.1021.4961.890

2.2832.6773.0713.4653.858

0.3540.7481.1421.5361.929

2.3232.7173.1103.5043.898

B

A

C


00-17

Millimeters to Inches1 mm = 0.03937 in

Kilogram to Pound1 kg = 2.2046 lb

0 1 2 3 4 5 6 7 8 9

010203040

5060708090

00.3940.7871.1811.575

1.9692.3622.7563.1503.543

0.0390.4330.8271.2201.614

2.0082.4022.7953.1893.583

0.0790.4720.8661.2601.654

2.0472.4412.8353.2283.622

0.1180.5120.9061.2991.693

2.0872.4802.8743.2683.661

0.1570.5510.9451.3391.732

2.1262.5202.9133.3073.701

0.1970.5910.9841.3781.772

2.1652.5592.9533.3463.740

0.2360.6301.0241.4171.811

2.2052.5982.9923.3863.780

0.2760.6691.0631.4571.850

2.2442.6383.0323.4253.819

0.3150.7091.1021.4961.890

2.2832.6773.0713.4653.858

0.3540.7481.1421.5361.929

2.3232.7173.1103.5043.898

0 1 2 3 4 5 6 7 8 9

010203040

5060708090

022.0544.0966.1488.18

110.23132.28154.32176.37198.42

2.2024.2546.3068.3490.39

112.44134.48156.53178.57200.62

4.4126.4648.5070.5592.59

114.64136.69158.73180.78202.83

6.6128.6650.7172.7594.80

116.85138.89160.94182.98205.03

8.8230.8651.9174.9697.00

119.05141.10163.14185.19207.24

11.0233.0755.1277.1699.21

121.25143.30165.35187.39209.44

13.23 35.27 57.32 79.37101.41

123.46145.51167.55189.60211.64

15.43 37.48 59.53 81.57103.62

125.66147.71169.76191.80213.85

17.64 39.68 61.73 83.78105.82

127.87149.91171.96194.01216.05

19.84 41.89 63.93 85.98108.03

130.07152.12174.17196.21218.26


00-18

Liter to U.S. Gallon1l = 0.2642 U.S. Gal

Liter to U.K. Gallon1l = 0.21997 U.K. Gal

0 1 2 3 4 5 6 7 8 9

010203040

5060708090

0 2.642 5.283 7.92510.567

13.20915.85018.49221.13423.775

0.264 2.906 5.548 8.18910.831

13.47316.11518.75621.39824.040

0.528 3.170 5.812 8.45411.095

13.73716.37919.02021.66224.304

0.793 3.434 6.076 8.71811.359

14.00116.64319.28521.92624.568

1.057 3.698 6.340 8.98211.624

14.26516.90719.54922.19024.832

1.321 3.963 6.604 9.24611.888

14.52917.17119.81322.45525.096

1.585 4.227 6.869 9.51012.152

14.79517.43520.07722.71925.361

1.849 4.491 7.133 9.77412.416

15.05817.70020.34122.98325.625

2.113 4.755 7.39710.03912.680

15.32217.96420.60523.24725.889

2.378 5.019 7.66110.30312.944

15.58618.22820.87023.51126.153

0 1 2 3 4 5 6 7 8 9

010203040

5060708090

0 2.200 4.399 6.599 8.799

10.99813.19815.39817.59819.797

0.220 2.420 4.619 6.819 9.019

11.28113.41815.61817.81820.017

0.440 2.640 4.839 7.039 9.239

11.43813.63815.83818.03720.237

0.660 2.860 5.059 7.259 9.459

11.65813.85816.05818.25720.457

0.880 3.080 5.279 7.479 9.679

11.87814.07816.27818.47720.677

1.100 3.300 5.499 7.969 9.899

12.09814.29816.49818.69720.897

1.320 3.520 5.719 7.91910.119

12.31814.51816.71818.91721.117

1.540 3.740 5.939 8.13910.339

12.52814.73816.93819.13721.337

1.760 3.950 6.159 8.35910.559

12.75814.95817.15819.35721.557

1.980 4.179 6.379 8.57910.778

12.97815.17817.37819.57721.777


00-19

kgm to ft. lb1 kgm = 7.233 ft. lb

0 1 2 3 4 5 6 7 8 9

010203040

5060708090

100110120130140

150160170180190

0 72.3144.7217.0289.3

361.7434.0506.3578.6651.0

723.3795.6868.0940.3

1012.6

1084.91157.31129.61301.91374.3

7.2 79.6151.9224.2296.6

368.9441.2513.5585.9658.2

730.5802.9875.2947.51019.9

1092.21164.51236.81309.21381.5

14.5 86.8159.1231.5303.8

376.1448.5520.8593.1665.4

737.8810.1882.4954.81027.1

1099.41171.71244.11316.41388.7

21.7 94.0166.4238.7311.0

383.4455.7528.0600.3672.7

745.0817.3889.7962.01034.3

1106.61179.01251.31323.61396.0

28.9101.3173.6245.9318.3

390.6462.9535.2607.6679.9

752.2824.6896.9969.2

1041.5

1113.91186.21258.51330.91403.2

36.2108.5180.8253.2325.5

397.8470.2542.5614.8687.1

759.5831.8904.1976.5

1048.8

1121.11193.41265.81338.11410.4

43.4115.7188.1260.4332.7

405.1477.4549.7622.0694.4

766.7839.0911.4983.7

1056.0

1128.31200.71273.01345.31417.7

50.6123.0195.3267.6340.0

412.3484.6556.9629.3701.6

773.9846.3918.6990.91063.2

1135.61207.91280.11352.61424.9

57.9130.2202.5274.9347.2

419.5491.8564.2636.5708.8

781.2853.5925.8998.21070.5

1142.81215.11287.51359.81432.1

65.1137.4209.8282.1354.4

426.8499.1571.4643.7716.1

788.4860.7933.11005.41077.7

1150.01222.41294.71367.01439.4


00-20

kg/cm2 to lb/in21kg/cm2 = 14.2233 lb/in2

0 1 2 3 4 5 6 7 8 9

010203040

5060708090

100110120130140

150160170180190

200210220230240

0 142.2 284.5 426.7 568.9

711.2 853.4 995.6

11381280

14221565170718491991

21342276241825602702

28452987312932713414

14.2 156.5 298.7 440.9 583.2

725.4 867.6

101011521294

14371579172118632005

21482290243225742717

28593001314332863428

28.4 170.7 312.9 455.1 597.4

739.6 881.8

102411661309

14511593173518772020

21622304244625892731

28733015315833003442

42.7 184.9 327.1 469.4 611.6

753.8 896.1

103811811323

14651607174918922034

21762318246026032745

28873030317233143456

56.9 199.1 341.4 483.6 625.8

768.1 910.3

105311951337

14791621176419062048

21902333247526172759

29013044318633283470

71.1 213.4 355.6 497.8 640.1

782.3 924.5

106712091351

14931636177819202062

22052347248926312773

29163058320033433485

85.3 227.6 369.8 512.0 654.3

796.5 938.7

108112231365

15081650179219342077

22192361250326462788

29303072321433573499

99.6 241.8 384.0 526.3 668.5

810.7 953.0

109512371380

15221664180619492091

22332375251826602802

29443086322933713513

113.8 256.0 398.3 540.5 682.7

825.0 967.2

110912521394

15361678182119632105

22472389253226742816

29583101324333853527

128.0 270.2 412.5 554.7 696.9

839.2 981.4

112412661408

15501693183519772119

22622404254626882830

29733115325733993542


00-21

TemperatureFahrenheit-Centigrade Conversion ; a simple way to convert a Fahrenheit temperature reading into a Cen-tigrade temperature reading or vice versa is to enter the accompanying table in the center or boldface col-umn of figures.These figures refer to the temperature in either Fahrenheit or Centigrade degrees.If it is desired to convert from Fahrenheit to Centigrade degrees, consider the center column as a table ofFahrenheit temperatures and read the corresponding Centigrade temperature in the column at the left.If it is desired to convert from Centigrade to Fahrenheit degrees, consider the center column as a table ofCentigrade values, and read the corresponding Fahrenheit temperature on the right.

1C = 33.8F

C F C F C F C F

40.437.234.431.728.9

28.327.827.226.726.1

25.625.024.423.923.3

22.822.221.721.120.6

20.019.418.918.317.8

17.216.716.115.615.0

14.413.913.312.812.2

4035302520

1918171615

1413121110

9 8 7 6 5

4 3 2 1 0

1 2 3 4 5

6 7 8 9 10

40.031.022.013.0 4.0

2.2 0.4 1.4 3.2 5.0

6.8 8.6 10.4 12.2 14.0

15.8 17.6 19.4 21.2 23.0

24.8 26.6 28.4 30.2 32.0

33.8 35.6 37.4 39.2 41.0

42.8 44.6 46.4 48.2 50.0

11.711.110.610.0 9.4

8.9 8.3 7.8 7.2 6.7

6.1 5.6 5.0 4.4 3.9

3.3 2.8 2.2 1.7 1.1

0.6 0

0.6 1.1 1.7

2.2 2.8 3.3 3.9 4.4

5.0 5.6 6.1 6.7 7.2

1112131415

1617181920

2122232425

2627282930

3132333435

3637383940

4142434445

51.8 53.6 55.4 57.2 59.0

60.8 62.6 64.4 66.2 68.0

69.8 71.6 73.4 75.2 77.0

78.8 80.6 82.4 84.2 86.0

87.8 89.6 91.4 93.2 95.0

96.8 98.6100.4102.2104.0

105.8107.6109.4111.2113.0

7.8 8.3 8.9 9.410.0

10.611.111.712.212.8

13.313.914.415.015.6

16.116.717.217.818.3

18.919.420.020.621.1

21.722.222.823.323.9

24.425.025.626.126.7

4647484950

5152535455

56575859 0

6162636465

6667686970

7172737475

7677787980

114.8116.6118.4120.2122.0

123.8125.6127.4129.2131.0

132.8134.6136.4138.2140.0

141.8143.6145.4147.2149.0

150.8152.6154.4156.2158.0

159.8161.6163.4165.2167.0

168.8170.6172.4174.2176.0

27.227.828.328.929.4

30.030.631.131.732.2

32.833.333.934.435.0

35.636.136.737.237.8

40.643.346.148.951.7

54.457.260.062.765.6

68.371.173.976.779.4

81 82 83 84 85

86 87 88 89 90

91 92 93 94 95

96 97 98 99100

105110115120125

130135140145150

155160165170175

117.8179.6181.4183.2185.0

186.8188.6190.4192.2194.0

195.8197.6199.4201.2203.0

204.8206.6208.4210.2212.0

221.0230.0239.0248.0257.0

266.0275.0284.0293.0302.0

311.0320.0329.0338.0347.0

FOREWORD UNITS

00-22

UNITS

In this manual, the measuring units are indicated with Internatinal System of units (SI).As for reference, conventionally used Gravitational System of units are indicated in parentheses { }.

Example:N {kg}Nm {kgm}MPa {kg/cm2}kPa {mmH2O}kPa {mmHg}kW/rpm {HP/rpm}g/kWh {g/HPh}

PC78MR-6 01-1

Specifiaction dimensions drawing ...................... 01-2Working range drawing ....................................... 01-3Specifications ...................................................... 01-4Weight table ........................................................ 01-7List of lubricants and coolant .............................. 01-9

01 GENERAL

01-2 PC78MR-6

GENERAL

SPECIFICATION DIMENSIONS DRAWING

Item UnitPC78MR-6

Steel shoe spec. Road liner spec.

Machine weight (with blade) kg 8,270 8,300

Bucket capacity m 0.28

Engine model KOMATSU S4D95LE-3-A Diesel engine

Rated engine output kW {HP}/rpm 40.5 {54.0}/1,850

A Overall length mm 6,200 6,230

B Overall height mm 2,730 2,750

C Overall width mm 2,330

D Shoe width mm 450

E Tail swing radius mm 1,310

F Overall length of track mm 2,840 2,900

G Distance between tumbler centers mm 2,235

Minimum ground clearance mm 360 400

Travel speed (Low/High) km/h 2.8/4.2

Continuous swing speed rpm 10.0

SPECIFICATION DIMENSIONS DRAWING

PC78MR-6 01-3

GENERAL

WORKING RANGE DRAWING

Working range (mm) Steel shoe spec.

A Max. digging reach 6,960

B Max. digging depth 4,160

C Max. digging height 6,570

D Max. vertical wall depth 2,900

E Max. dumping height 4,515

FMin. swing radius of work equipment 2,775

Min. swing radius at boom swinging 2,125

G Max. reach at ground level 6,750

H Max. blade lifting height 380

I Max. blade lowering depth 245

WORKING RANGE DRAWING

01-4 PC78MR-6

GENERAL

SPECIFICATIONS

Figures (steel shoe specification) are common to the all specifications unless otherwise specified.( ) Figures in ( ): Road liner specification

Machine model PC78MR-6

Serial Number 1001 and up

Bucket capacity m3 0.28

Machine weight kg 8,270 (8,300)

Per

form

ance W

orki

ng ra

nge

Max. digging depth mm 4,160

Max. vertical wall depth mm 2,900

Max. digging reach mm 6,960

Max. reach at ground level mm 6,750

Max. digging height mm 6,570

Max. dumping height mm 4,515

Boom swing (left side/right side) mm 580/930

Max. blade lifting height mm 380

Max. blade lowering depth mm 245

Max. digging force (Bucket) kN {kg} 61.3 {6,250}

Continuous swing speed rpm 10.0

Max. slope angle for swing deg. 16.0

Travel speed (Low/High) km/h 2.8/4.2

Gradeability deg. 35

Ground pressure kPa {kg/cm2} 37.3 {0.38}

Dim

ensi

on

Overall length (for transport) mm 6,200

Overall width mm 2,330

Overall height (for transport) mm 2,730 (2,750)

Overall height (for operation) mm 2,710 (2,750)

Ground clearance of counterweight mm 735 (780)

Min. ground clearance mm 360 (400)

Tail swing radius mm 1,310Min. swing radius of work equipment(at boom swinging) mm 2,125

Height of work equipment at min. swing radius mm 5,210 (5,230)

Overall width of track mm 2,320

Overall length track mm 2,840 (2,900)

Distance between tumbler centers mm 2,235

Track gauge mm 1,870Machine cab height mm 1,745 (1,795)

Blade width height mm 2,320 470

SPECIFICATIONS

PC78MR-6 01-5

GENERAL



Eng

ine

Model S4D95LE-3-A

Type 4-cycle, water-cooled, in-line, direct injection

No. of cylinders - bore stroke mm 4-95 115

Total displacement l {cc} 3.26 {3,260}

Perfo

rman

ce

Rated output kW/rpm {HP/rpm}40.5/1,850

{54.0/1,850}

Max. torque Nm/rpm {kgm/rpm}337/1,500

{24.2/1,500}Max. speed at no load rpm 2,020

Min. speed at no load rpm 1,130

Min. fuel consumption g/kWh {g/HPh} 227 {169}

Starting motor 24 V, 3.0 kw

Alternator 24 V, 25 A

Battery 12 V, 48 Ah 2 (55D26R)

Type of radiator core CF29-3

Und

erca

rria

ge Carrier roller 1 on each side

Track roller 5 on each sideTrack shoe (Steel shoe)

(Road liner)(Rubber shoe)

Assembly-type triple grouser, 39 on each sideAssembly-type road liner, 39 on each side

Unit-type rubber crawler

Hyd

raul

ic s

yste

m

Hyd

raul

ic p

ump Type No.

Variable-capacity piston pump 1Gear pump 2

Discharge l {cc} 802+60+12.7Set pressures

(Work equipment, travel)(Swing, blade)(Control)

MPa {kg/cm2}

26.5 {270}21.1 {215}3.1 {32}

Con

trol

valv

e Type No. 9-spool type 1

Control method Hydraulically assisted

Hyd

raul

icm

otor

Travel motorVariable-capacity piston motor(with brake valve, parking brake) 2

Swing motorFixed-capacity piston motor(with safety valve, pivot shaft brake) 1

Hydraulic tank Box-shaped, open

Hydraulic oil filter Tank return side

Oil cooler Air-cooled

SPECIFICATIONS

01-6 PC78MR-6

GENERAL



Hyd

raul

ic s

yste

m

Wor

k eq

uipm

ent c

ylin

der

Boo

m c

ylin

der

Type Reciprocating piston

Inside diameter of cylinder mm 115

Diameter of piston rod mm 65

Stroke mm 988

Max. distance between pinsmm mm 2,393

Min. distance between pinsmm mm 1,405

Arm

cyl

inde

r

Type mm Reciprocating piston



Stroke mm 865

Max. distance between pins mm 2,193

Min. distance between pins mm 1,328

Buc

ket c

ylin

der




Stroke mm 710



Boo

m s

win

g cy

linde

r Type mm Reciprocating piston



Stroke mm 658



Bla

de c

ylin

der




Stroke mm 130

Max. distance between pins mm 679

Min. distance between pins mm 549

SPECIFICATIONS

PC78MR-6 01-7

GENERAL

WEIGHT TABLEk This mass list is for reference in handling or transporting these components.

Unit: kg

Figures (steel shoe specification) are common to the all specifications unless otherwise specified.[ ] Figures in [ ]: Rubber shoe specification



Engine assembly (without water and oil) 403

Engine (without water and oil) 300

Engine mount 30

PTO 7

Hydraulic pump 66

Cooling assembly (without coolant and oil) 29

Radiator (without coolant) 6.3

Oil cooler (without oil) 5.2

Revolving frame 1,220

Operator's cab 260

Operator's seat 18

Fuel tank (without fuel) 8.3

Hydraulic tank (without hydraulic oil) 70

Control valve 62

Counterweight 950

Additional counterweight 220

Swing motor (Including brake valve) 22

Swing circle 104

Swing machinery 47

Center swivel joint 16

Track frame assembly (without track shoe) 1,067 [1,048]

Track frame 704

Idler assembly 54 x 2

Recoil spring assembly 40 x 2

Carrier roller 3.4 x 2

Track roller 13 x 10

Travel motor (with reduction gears) 81 x 2

Sprocket 19 x 2

WEIGHT TABLE

01-8 PC78MR-6

GENERAL

Unit: kg

Figures are common to the all specifications unless otherwise specified.



Track shoe assembly

City pad shoe (450 mm) 410 X 2

Road liner (450 mm) 450 X 2

Rubber shoe (450 mm) 385 X 2

Triple grouser (600 m) 495 X 2

Boom assembly 365

Swing bracket 234

Arm assembly 147

Bucket link assembly 56

Bucket assembly (with side cutter) 210

Blade assembly 374

Boom cylinder assembly 95

Arm cylinder assembly 72

Bucket cylinder assembly 51

Boom swing cylinder assembly 65

Blade cylinder assembly 46

WEIGHT TABLE

PC78MR-6 01-9

GENERAL

LIST OF LUBRICANTS AND COOLANT

*1: ASTM D975 No. 1 Unit: l

ReservoirPC78MR-6

Specified capacity Refill capacity

Engine oil pan 7.5 7.0

PTO gear case 0.4 0.4

Swing machinery case 2.0 2.0

Final drive case (each) 1.3 1.3

Hydraulic system 120 64

Fuel tank 125

Cooling system 10.5

RESERVOIRKIND OF

FLUID

AMBIENT TEMPERATURE

22 4 14 32 50 68 86 104 122F

30 20 10 0 10 20 30 40 50C

Add antifreeze

SAE 30

SAE 30

SAE 10W

*1

SAE 10W-30

SAE 10

ASTM D975 No. 2

SAE 15W-40

SAE 10W-30

SAE 15W-40

NLGI No. 2

Engine oil pan

Swing machinery caseFinal drive casePTO gear case

Hydraulic system

Fuel tank

Greasing system

Cooling system

Engine oil

Diesel fuel

Diesel fuel

Water

LIST OF LUBRICANTS AND COOLANT

PC78MR-6 10-1

PTO ........................................................................... 10- 2Cooling system.......................................................... 10- 3Power train system.................................................... 10- 4Swing circle ............................................................... 10- 5Swing machinery ....................................................... 10- 6Track frame and idler cushion ................................... 10- 8Idler ........................................................................... 10-10Track roller..................................................................10-11Carrier roller .............................................................. 10-12Sprocket .................................................................... 10-13Track shoe................................................................. 10-14Arrangement of hydraulic components...................... 10-19Hydraulic tank and oil filter ........................................ 10-20Center swivel joint ..................................................... 10-21Travel motor .............................................................. 10-22Work equipment cylinder ........................................... 10-30Solenoid valve ........................................................... 10-34Multi-Control Valve .................................................... 10-40Accumulator for Brake............................................... 10-41Hydraulic pump ......................................................... 10-42Control valve ............................................................. 10-56CLSS ......................................................................... 10-68Swing motor ............................................................ 10-100Work equipment and swing PPC valve ................... 10-108Travel PPC valve......................................................10-114Boom swing PPC valve, blade PPC valve ...............10-118Boom hydraulic anti-burst valve (For EU spec.) ... 10-121-1Work equipment ...................................................... 10-122Dimensions of each part of work equipment ........... 10-124Air conditioner piping (Optional) .............................. 10-128Electric control system ............................................ 10-129System components ................................................ 10-146Monitor system ........................................................ 10-154Sensors ................................................................... 10-158

10 STRUCTURE, FUNCTION ANDMAINTENANCE STANDARD

(1)

10-2 PC78MR-6

STRUCTURE, FUNCTION AND MAINTENANCE STANDARD

PTO

1. Drain plug2. Coupling3. Flywheel4. Pump case5. Cage6. Level plug7. Breather/Oil filler plug

PTO

PC78MR-6 10-3


COOLING SYSTEM

1. Fan guard 2. Radiator inlet hose 3. Drain valve 4. Radiator outlet hose 5. Radiator cap 6. Oil cooler 7. Radiator 8. Shroud 9. Oil cooler inlet10. Reservoir tank11. Oil cooler outlet

SPECIFICATIONS

Radiator Oil cooler

Type of core CF29-3 CF40-1

Fin pitch (mm) 4.0/2 4.5/2

Total heat dissipation area (m2) 16.53 6.15

Pressure valve cracking pressure (kPa {kg/cm})

88.314.7(0.90.15)

Vacuum valve cracking pressure (kPa {kg/cm})

4.9(0.05)

COOLING SYSTEM

10-4 PC78MR-6


POWER TRAIN SYSTEM

1. Idler2. Control valve3. Center swivel joint4. Swing motor5. Travel motor6. Control pump (for pilot control)7. Hydraulic pump (for swing and blade)8. Hydraulic pump

(For travel and work equipment)9. Engine

10. Boom RAISE stop EPC valve11. Arm IN stop EPC valve12. Left offset stop EPC vaolve13. Swing holding brake solenoid valve14. 2-stage travel speed selector solenoid valve15. PPC lock solenoid valve16. Swing machinery17. Swing circle

POWER TRAIN SYSTEM

PC78MR-6 10-5


SWING CIRCLE

Unit: mm

2. Greasing for swing circle bearing3. Greasing for swing circle pinion4. Outer race5. Inner race6. Ball7. Seal

a. Position of inner race soft zoneb. Position of outer race soft zone

Specifications

No. Item Criteria Remedy

1 Axial clearance of bearingStandard clearance Allowable clearance

Replace0.20 0.80 2.0

Reduction ratio 80/10=8.0Grease G2-LI

Quantity of grease ( ) 5.5

SWING CIRCLE

10-6 PC78MR-6


SWING MACHINERY

1. Swing pinion (Number of teeth: 10) 2. Swing machinery case 3. No. 2 planetary carrier 4. Ring gear (Number of teeth: 58) 5. No. 2 sun gear (Number of teeth: 14) 6. No. 1 planetary carrier 7. No. 1 sun gear (Number of teeth: 14) 8. Swing motor 9. Oil filler10. Level gauge11. No. 1 planetary gear (Number of teeth: 22)12. No. 2 planetary gear (Number of teeth: 22)13. Drain plug

Specification

Reduction ratio (14+58)/14X(14+58)/14 = 26.45Swing reduction ratio 26.45X8.0 = 211.59Swing speed (rpm) 10

SWING MACHINERY

PC78MR-6 10-7


Unit: mmNo. Item Criteria Remedy

1Backlash between swing motor shaft and No. 1 sun gear

Standard clearance Allowable clearance

Replace

0.03 0.11

2Backlash between No. 1 sun gear and No. 1 planetary gear

0.10 0.27 0.6

3Backlash between No. 1 planetary gear and ring gear

0.12 0.38 0.6

4Backlash between No. 1 planetary carrier and No. 2 sun gear

0.10 0.26

5Backlash between No. 2 sun gear and No. 2 planetary gear

0.10 0.27 0.6

6Backlash between No. 2 planetary gear and ring gear

0.12 0.38 0.6

7Backlash between No. 2 planetary carrier and swing pinion

0.07 0.21

8Backlash between swing pinion and swing circle

0.27 0.83 2.0

9Wear of sliding surface of swing pinion collar against oil seal

Basic dimension Allowance Allowable LimitPlating with hard chromium or replace75 0- 0.074 74.8

SWING MACHINERY

10-8 PC78MR-6


TRACK FRAME AND IDLER CUSHION


PC78MR-6 10-9


Unit: mm

4. Idler 5. Track frame 6. Carrier roller 7. Travel motor 8. Sprocket 9. Track roller10. Track shoe11. Idler cushion

11a.Support11b.Yoke11c.Recoil spring11d.Cylinder11e.Collar11f.Lubricator

12. Idler guard (Road liner specification, steel shoespecification)

13. Bracket to secure machine body for transporta-tion (for USA spec. only)

Specification


1 Vertical width of idler guide

Basic dimension Allowable limitOverlay

Track frame 74 78Idler support 73 69

Overlay or replace

2 Lateral width of idler guide

Track frame 158 162 Overlay

Idler support 156 152 Overlay or replace

3 Recoil spring

Basic dimension Allowable limit

Replace

Free length Installed lengthInstalled

load Free lengthInstalled

loadRoad liner, steel shoe 412 323

47.4 kN{4,835 kg} 402

42.2 kN{4,305 kg}

Rubber shoe 412 283 69.2 kN{7,061 kg} 40261.6 kN

{6,284 kg}

Grease G2-LI

Quantity of grease (cc) 96 (Steel shoe, road liner)233 (Rubber shoe)


10-10 PC78MR-6


IDLER


1 Outside diameter of projected partBasic dimension Allowable limit

Overlay or replace

460 2 Outside diameter of tread 415 4073 Depth of tread 22.5 26.54 Width of projected part 43 375 Overall width 100 926 Width of tread 28.5 32

7 Clearance between idler shaft and bushing

Basic dimension

Allowance Standard clearance

Allowable clearance

Replace

Shaft Hole

44 -0.250-0.290+ 0.062

0 0.250 0.352 1.5

8 Interference between idler and bushing

Basic dimension

Allowance Standard interference

Allowable interferenceShaft Hole

50 +0.117+0.087+0.025

0 0.062 0.117

9 Side clearance of idler (Each side)Standard clearance Allowable clearance

0.190 0.395 1.5

10 Thickness of tread (at cen-ter of width of tread)Basic dimension Allowable limit

Overlay or replace13.8 9.8

Quantity of oil 60 cc (Engine oil: SAE30CD)

IDLER

PC78MR-6 10-11


TRACK ROLLER


1 Outside diameter of projected partBasic dimension Allowable limit

Overlay or replace 149

2 Outside diameter of tread 120 1133 Width of flange 43 36.64 Overall width 129 5 Width of tread 43 47.3 Overlay or replace

6 Clearance between idler shaft and bushing

Basic dimension


Allowable clearance

Replace

Shaft Hole

38 -0.250-0.270+ 0.075- 0.025 0.225 0.345 1.5

7 Interference between idler and bushing

Basic dimension


Allowable interferenceShaft Hole

48 +0.117+0.087+0.030

0 0.057 0.117

8 Side clearance of track roller (Each side)Standard clearance Allowable clearance

0.38 0.73 1.5

9 Thickness of tread (at cen-ter of width of tread)Basic dimension Allowable limit

Overlay or replace36 32.5

Quantity of oil 210 230 cc (Gear oil: G0140)

TRACK ROLLER

10-12 PC78MR-6


CARRIER ROLLER


1 Outside diameter of treadBasic dimension Allowable limit

Overlay or replace 82 72

2 Width of tread 100

3 Interference between shaft and bearing

Basic dimension


Allowable interference

Replace

Shaft Hole

30 +0.009-0.0040

- 0.010-0.004

0.019

4 Interference between roller and bearing 620

- 0.013+ 0.018- 0.012

-0.031 0.012

5 Thickness of tread Basic dimension Allowable limit

Overlay or replace10 5

Quantity of oil 47 52 cc (Grease: ALVANIA EP-2)

CARRIER ROLLER

PC78MR-6 10-13


SPROCKET


1 Wear of root diameterBasic dimension Allowance Allowable limit

Overlay or replace

433.004 +1.0-2.0 421

2 Wear of tip diameter 483.7 2.0 4723 Wear of dip width 28 - 23

4 Wear of root width 38 +0.5-2.5 33

5 Thickness of root 84.002 +0.475-1.150 78

SPROCKET

10-14 PC78MR-6


TRACK SHOECITY PAD SHOE, ROAD LINER, AND TRIPLE SHOE

*1. City pad shoeTriple shoe (OPT)

*2. Road liner (OPT)

a Part P is the link on the press fitting side of bushing.

TRACK SHOE

PC78MR-6 10-15


Unit: mm

Items marked with * are for the dry track.


1 Link pitchBasic dimension Allowable limit

Reverse or replace154.25 157.252 Outside diameter of bushing 41.2 37.23 Height of link 74 70

Repair or replace4 Thickness of link (Press fit-ting part of bushing) 20 16

5Shoe bolt pitch

89Replace6 73

7 57

8

Link

Inside width 45

Repair or replace9 Overall width 30

10 Width of tread 26.3

11 Projection of pin 3

Adjust or replace

12 Projection of regular bush-ing 3.15

13 Overall length of pin 131

14 Overall length of bushing (Master bushing) 74.6

15 Thickness of bushingBasic dimension Allowable limit

8.4 4.416 Thickness of spacer 17

Press fitting pressure

Bushing 19.6 98.1 kN {2 10 ton}

18 Regular pin 49.0 117.7 kN {5 12 ton}

*19 Master pin 39.2 78.5 kN {4 8 ton}

TRACK SHOE

10-16 PC78MR-6


Unit: mm

Items marked with * are for the dry track.


20Shoe bolt

a. Regular link

Tightening torque (Nm {kgm}) Retightening angle (deg.)

Retighten

City pad Triple

117.7 19.6{12 2} 90 10

Road liner 117.7 19.6{12 2}

60 10(Torque after retightening)

Min. 343 Nm {35 kgm}

b. Master linkTightening

torqueRetightening angle (deg.) Lower limit torque

Number of shoes (Each side) 39

21 Number of shoes(Each side)

Basic dimen-sion


Adjust or replace

Shaft Hole

41 +0.214+0.174+0.062

0 0.112 0.214

22 Interference between regular pin and link 24+0.150

0-0.198-0.250 0.198 0.400

23 Clearance between regular pin and bushing

Basic dimen-sion

Allowance Standard clearanceShaft Hole

24 +0.1500+0.830+0.330 0.180 0.830

*24 Interference between master pin and link

Basic dimen-sion

Allowance Standard interferenceShaft Hole

24 +0.020-0.020-0.198-0.250 0.178 0.270

*25 Clearance between master pin and bushing

Basic dimen-sion

Allowance Standard clearanceShaft Hole

24 -0.150-0.250+0.630+0.230 0.380 0.880

26 Height of grouserBasic dimension Allowable limit

ReplaceRoad liner 42 19

TRACK SHOE

PC78MR-6 10-17


TRIPLE SHOE AND CITY PAD SHOE


1 Height of grouserBasic dimension Allowable limit

Overlay or replace

20 122 Overall height of shoe 26 183 Thickness of plate 64

Length of base of grouser20

5 166

Length of upper side of grouser14

7 108 12

TRACK SHOE

10-18 PC78MR-6


RUBBER SHOE (OPTIONAL)


1 Wear of lug heightBasic dimension Allowable limit

Replace30 5

2 Wear of roller guide 42 58

3 Wear of meshing part of sprocketBasic dimension Allowance Allowable limit

22.5 0.5 27

TRACK SHOE

PC78MR-6 10-19


ARRANGEMENT OF HYDRAULIC COMPONENTS

1. Bucket cylinder 2. Arm cylinder 3. Boom cylinder 4. Boom swing cylinder 5. Hydraulic tank 6. Control valve 7. Swing motor 8. Hydraulic pump 9. Oil cooler10. Travel motor11. Left work equipment PPC valve

12. Blade PPC valve13. Right work equipment PPC valve14. Center swivel joint15. Service PPC valve (Machine to which attach-

ments can be installed)16. Travel PPC valve17. 6-spool solenoid valve18. Boom swing PPC valve19. Blade cylinder20. Boom hydraulic anti-burst valve (For EU spec.)

(1)

ARRANGEMENT OF HYDRAULIC COMPONENTS

10-20 PC78MR-6


HYDRAULIC TANK AND OIL FILTER

1. Hydraulic tank2. Sight gauge3. Strainer4. Drain plug5. Filter6. Bypass valve7. Oil filler cap

Specification

Tank capacity ( ) 80

Quantity of oil in tank ( ) 64

Bypass valve set pressure (kPa {kg/cm})

0.15 0.03{1.53 0.3}

Pressure valve cracking pressure (kPa {kg/cm})

38 15{0.39 0.15}

Vacuum valve cracking pressure (kPa {kg/cm})

0 5{0 0.05}

HYDRAULIC TANK AND OIL FILTER

PC78MR-6 10-21


CENTER SWIVEL JOINT

1. Cover2. Rotor

3. Slipper seal4. Shaft

Unit: mm

A1: From right travel control valve A2: To right travel motorB1: From right travel control valve B2: To right travel motorC1: From left travel control valve C2: To left travel motorD1: From left travel control valve D2: To left travel motorE1: From blade control valve E2: To blade cylinder bottomF1: From blade control valve F2: To blade cylinder headG1: From 2-stage travel speed selector solenoid valve G2: To 2-stage travel speed selector solenoid valve

DR1: To tank DR2: From travel motor drain port


5Clearance between rotor and shaft

Basic dimension Standard clearance Allowable clearanceReplace

70 0.056 0.105 0.111

CENTER SWIVEL JOINT

10-22 PC78MR-6


TRAVEL MOTOR

A. From travel control valveB. From travel control valveD. To tankP. From 2-stage travel speed selector solenoid

valve

TRAVEL MOTOR

PC78MR-6 10-23


1. Check valve2. Counterbalance valve3. Valve plate4. Cylinder5. Brake piston6. Plate7. Disc8. Piston9. Swash plate10. Regulator piston11. RV gear12. RV gear13. Case

14. Shaft15. Drive gear16. Cover17. Crankshaft18. Drain plug19. Driven gear20. Pivot21. Spindle22. Floating seal23. End cover24. Regulator valve25. Check valve

TRAVEL MOTOR

10-24 PC78MR-6


Specification

Outline

1. Reduction gearsThe reduction gears consists of spur gear unit(1a) and differential gear unit (1b) which usespericycloid gears and converts the high speedrevolution of the hydraulic motor into low-speedand high-torque revolution.

2. Hydraulic motorThe hydraulic motor is a swash plate-type axialpiston motor, which converts the power of thehydraulic oil sent from the hydraulic pump intorevolution.

3. Brake valveThe brake valve consists of various valves andhas functions of stopping the hydraulic motorsmoothly, preventing the hydraulic motor fromrunning away, and preventing generation ofabnormally high pressure when the hydraulicmotor is stopped suddenly.

4. 2-stage travel speed changeover mechanismThe 2-stage travel speed changing mechanismconsists of a changeover valve and a piston,which change the displacement of the hydraulicmotor to either of 2 stages.

5. Parking brakeThe parking brake is a friction plate brake, whichis built as a part of the hydraulic motor.

Model GM09VN-E

Theoretical displacement (cm/rev)

Hi 24.1Lo 36.3

Rated speedHi 3,211Lo 2,154

Brake releasing pressure (MPa {kg/cm})

0.47{4.8}

Speed changeover pressure(MPa {kg/cm})

2.94{30}

Reduction ratio 66.5

TRAVEL MOTOR

PC78MR-6 10-25


OPERATION

Operation of motor

At low speed (With swash plate angle at maximum)

1. 2-stage travel speed selector solenoid valve 2. Regulator valve 3. Spring 4. Check valve 5. End cover 6. Regulator piston 7. Swash plate 8. Pump merge-divider valve 9. Travel control valve10. Brake valve

Since 2-stage travel speed selector solenoidvalve (1) is de-energized, the hydraulic oil fromthe control pump does not flow into port Pi.

Accordingly, regulator valve (2) is pressed to theleft by spring (3).

Under this condition, the main hydraulic oil fromthe control valve pushes check valve (4) andflows into end cover (5) and then is shut off byregulator valve (2).

The hydraulic oil in control chamber (a) flowsthrough passage (b) of regulator valve (2) intothe motor case.

As a result, swash plate (7) is pushed toward themaximum swash plate angle by the main hydrau-lic oil in chamber (P) of the cylinder and themotor capacity is increased to the maximum andthe travel speed lowers.

TRAVEL MOTOR

10-26 PC78MR-6


At high speed (With swash plate angle at minimum)

1. 2-stage travel speed selector solenoid valve 2. Regulator valve 3. Spring 4. Check valve 5. End cover 6. Regulator piston 7. Swash plate 8. Pump merge-divider valve 9. Travel control valve10. Brake valve

If 2-stage travel speed selector solenoid valve(1) is energized, the pilot pressure from the con-trol pump flows into port Pi and pushes regulatorvalve (2) to the right.

Accordingly, the main hydraulic oil from the con-trol valve flows through passage (c) of regulatorvalve (2) into control chamber (a) and pushesregulator piston (6) to the left.

As a result, swash plate (7) is pushed toward theminimum swash plate angle and the motorcapacity is decreased to the minimum and thetravel speed rises.

TRAVEL MOTOR

PC78MR-6 10-27


Operation of brake valve The brake valve consists of check valves (1a)

and (1b) and counterbalance valve spool (2) asshown in the following figure.

Function When the machine travels downhill, its speed

may become higher than the motor speedbecause of its momentum. If the engine speed islow at this time, the motor runs idle and themachine runs away, and this situation is verydangerous. The brake valve prevents this phe-nomenon and limits the travel speed accordingto the engine speed (pump discharge).

Operation when oil is supplied If the travel lever is operated, the hydraulic oil

from the control valve flows in port PA, pushesvalve (1a) open, and flows through motor inputport MA to motor outlet port MB.At the same time, the hydraulic oil also flowsthrough orifice c of spool (2) to chamber D. If itspressure becomes higher than the pressure ofspring (3), spool (2) is pushed to the left. As aresult, port MB is connected to port PB and themotor outlet side opens and the motor starts rev-olution.Since port PA is connected to port E, too, thehydraulic oil operates parking brake piston (4) torelease the parking brake force.

TRAVEL MOTOR

10-28 PC78MR-6


Operation when oil is shut off If the control lever is returned to neutral, the

hydraulic oil from the control valve is shut off andspool (2) is returned to the right by the reactionforce of spring (3).At this time, the oil flows through orifice (c) ofchamber D into port PA and back pressure isgenerated by the throttle effect of orifice (c). Thisback pressure controls the speed of spool (2)returning to the right.

Even after the hydraulic oil in port PA is shut off,the motor continues revolution by inertia.

At this time, the returning oil is reduced graduallyaccording to the changing speed and shape ofspool (2) to stop the motor smoothly.

The motor continues revolution by inertia andcan cause cavitation. Since valve (1a) is oper-ated by very slight negative pressure, however, itopens ports PA and MA to prevent cavitation.

Operation of brake during downhill travel If the machine starts running away while travel-

ing downhill, the motor revolves idle and thepressure on the motor inlets side lowers, thenthe pressure in chamber D also lowers throughorifice (c).If the pressure in chamber D lowers below thepressure of spring (3), spool (2) is pushed backto the right.At this time, the oil in chamber G flows throughorifice (f) into port PB. The throttle effect of ori-fice (f) generates back pressure, and spool (2)returns to the right to control the returning speedof spool (2). Port MB on the outlet side is nar-rowed.As a result, the pressure on the outlet side risesand revolving resistance is generated in themotor to prevent the machine from running away.To put it concretely, spool (2) moves to a positionat which the machine weight and the pressure onthe inlet side are balanced with the pressure atport MB on the outlet side to narrow the outletcircuit. Consequently, the speed is controlledaccording to the pump discharge.

TRAVEL MOTOR

PC78MR-6 10-29


Operation of parking brake

When travel lever is operated If the travel lever is operated, the hydraulic oil

from the pump moves spool (1) to the left andflows through port E into chamber A of brake pis-ton (2), then pushes brake piston (2) to the left.

As a result, the pressing force of spring (5) givento plate (3) and disc (4) is lost, then plate (3) anddisc (4) are separated and the brake force isreleased.

When travel lever is set to neutral position If the travel lever is set to the neutral position, the

hydraulic oil from the pump is shut off.The hydraulic oil in chamber (a) of brake piston(2) is drained into the case and piston (2) ispushed to the right by spring (5).As a result, plate (3) and disc (4) are pressedand the braking force is applied.

TRAVEL MOTOR

10-30 PC78MR-6


WORK EQUIPMENT CYLINDERBoom cylinder

Arm cylinder

Bucket cylinder

WORK EQUIPMENT CYLINDER

PC78MR-6 10-31


Boom swing cylinder

Blade cylinder


10-32 PC78MR-6



1 Clearance between piston rod and bushing

Cylinder name

Basic dimension


Allowable clearance

Replace bushing

Shaft Hole

Boom 65 -0.030-0.104+0.250+0.055

0.085 0.354 0.654

Arm 60 -0.030-0.104+0.163+0.006

0.036 0.267 0.567

Bucket 55 -0.030-0.104+0.163+0.006

0.036 0.267 0.567

Boom swing 60

-0.030-0.104

+0.163+0.006

0.036 0.267 0.567

Blade 65 -0.030-0.104+0.250+0.055

0.085 0.354 0.654

2Clearance between piston rod support shaft and bushing

Boom 60 -0.030-0.100+0.174+0.100

0.130 0.274 1.0

Replace pin and

bushing

Arm 60 -0.030-0.100+0.174+0.100

0.130 0.274 1.0

Bucket 60 -0.030-0.100+0.174+0.100

0.130 0.274 1.0

Boom swing 65

-0.030-0.100

+0.174+0.100

0.130 0.274 1.0

Blade 70 -0.030-0.104+0.174+0.100

0.130 0.278 1.0

3Clearance between

cylinder bottom support shaft and bushing

Boom 65 -0.030-0.100+0.174+0.100

0.130 0.274 1.0

Arm 55 -0.030-0.100+0.174+0.100

0.130 0.274 1.0

Bucket 50 -0.030-0.100+0.142+0.080

0.110 0.242 1.0

Boom swing 65

-0.030-0.076

+0.174+0.100

0.130 0.250 1.0

Blade 70 -0.030-0.104+0.174+0.100

0.130 0.278 1.0

4 Tightening torque of cylinder head

Boom 961 96.1 Nm {98 9.8 kgm}

Retighten

Arm 785 78.5 Nm {80 8.0 kgm}

Bucket

Procedure 1) Tighten to 1.18 1.37 kNm {120 140 kgm}.2) Loosen to 0 Nm {0 kgm}.3) Tighten to 0.39 kNm {40 kgm}.4) Control tightening of cylinder head by

turning angle (Turning distance: 3.5 4.5 mm).Boom swing 981 98.1 Nm {100 10.0 kgm}

Blade 1.030 103.0 Nm {105 10.5 kgm}

5 Tightening torque of cylinder piston

Boom 3.33 0.33 kNm {340 34.0 kgm} (2 Width across flats: 70 mm)Arm 2.65 0.26 kNm {270 27.0 kgm} (2 Width across flats: 65 mm)

Bucket 2.16 0.22 kNm {220 22.0 kgm} (2 Width across flats: 60 mm)Boom swing 2.6 0.26 kNm {265 26.0 kgm} (2 Width across flats: 70 mm)

Blade 3.14 0.31 kNm {320 32.0 kgm} (2 Width across flats: 75 mm)


10-34 PC78MR-6


SOLENOID VALVE

Serial No.: 1001 1094

SOLENOID VALVE

(1)

PC78MR-6 10-35


A: From control pumpA4: PlugA5: From left work equipment PPC valve "ARM IN"A6: From right work equipment PPC valve "BOOM RAISE"B1: To PPC valveB2: To 2-stage travel speed selection valveB3: To swing holding brakeB4: PlugB5: To control valve "ARM IN"B6: To control valve "BOOM RAISE"

T: To hydraulic tank

1. Left boom swing stop EPC valve2. Right boom swing stop EPC valve3. Not used4. Swing holding brake solenoid valve5. 2-stage travel speed selector solenoid valve6. PPC lock solenoid valve

Solenoid valve7. Coil (ON-OFF type)8. Push pin9. Valve spool

10. Return spring11. Valve body

EPC valve12. Return spring13. Guide14. Valve spool15. Push pin16. Coil (Proportional)

Check valve17. Plug18. Spring19. Ball

Control relief valve20. Adjustment screw21. Locknut22. Guide23. Return spring24. Valve spool

SOLENOID VALVE

10-35-1 PC78MR-6


Serial No.: 1095 and up

SOLENOID VALVE

(1)

PC78MR-6 10-35-2


A: From control pumpA5: From left work equipment PPC valve "ARM IN"A6: From right work equipment PPC valve "BOOM RAISE"B1: To PPC valveB2: To 2-stage travel speed selection valveB3: To swing holding brakeB4: PlugB5: To control valve "ARM IN"B6: To control valve "BOOM RAISE"

T: To hydraulic tank

1. Left boom swing stop EPC valve2. Right boom swing stop EPC valve3. Swing holding brake solenoid valve4. 2-stage travel speed selector solenoid valve5. PPC lock solenoid valve

Solenoid valve6. Coil (ON-OFF type)7. Push pin8. Valve spool9. Return spring

10. Valve body

EPC valve11. Return spring12. Guide13. Valve spool14. Push pin15. Coil (Proportional)

Check valve16. Plug17. Spring18. Ball

Control relief valve19. Adjustment screw20. Locknut21. Guide22. Return spring23. Valve spool

(1)

SOLENOID VALVE

10-36 PC78MR-6


PPC LOCK SOLENOID VALVE2-STAGE TRAVEL SPEED SELECTOR SOLENOID VALVESWING HOLDING BRAKE SOLENOID VALVE

Operation

When solenoid is de-energized (circuit is broken) While a signal current does not flow from the

PPC hydraulic lock switch or travel speed boostpedal, solenoid (1) is de-energized.Accordingly, spool (2) is pressed up by spring(3).

Under this condition, port A is closed and thepilot hydraulic oil does not flow into the actuator.At the same time, the oil from the actuator isdrained through ports B and T into the tank.

When solenoid is energized (circuit is made) If a signal current flows from the PPC hydraulic

lock switch or travel speed boost pedal to sole-noid (1), solenoid (1) is energized.

Accordingly, spool (2) is pushed down by pushpin (4).

Under this condition, the pilot hydraulic oil flowsthrough port A, spool (2), and port B into theactuator.At the same time, port T is closed and the oildoes not flow into the tank.

SOLENOID VALVE

PC78MR-6 10-37


LEFT BOOM SWING STOP EPC VALVERIGHT BOOM SWING STOP EPC VALVE

Operation

When signal current is maximum (When coil isenergized and circuit pressure is maximum) If the signal current flows from the controller into

coil (1), coil (1) is energized.At this time, the thrust of coil (1) is maximum.

As a result, spool (2) is pushed down by push pin(3).

Accordingly, all the pressurized oil from the PPCvalve flows through port A, spool (2), and port Bto the control valve.At this time, port T is closed and any oil does notflow in the tank.

When signal current is reduced (When coil isenergized and circuit pressure is low) If the signal current flowing from the controller

into coil (1) is reduced, coil (1) is still energizedbut its thrust is lowered in proportion to the signalcurrent.

As a result, push pin (3) pushes down spool (2)and the pressurized oil from port A flows to portB.

If the pressure in port B rises and the forceapplied to face "a" of spool (2) becomes largerthan the thrust of coil (1), spool (2) is pushed upand port A is disconnected from port B and con-nected to port T.

Accordingly, spool (2) moves up and down sothat the thrust of coil (1) will be balanced with thepressure in port B.

As a result, the circuit pressure between thePPC valve and control valve is controlled in pro-portion to the signal current.

SOLENOID VALVE

10-38 PC78MR-6


When signal current is 0 (When coil is de-ener-gized and circuit cut out) If the signal current flowing from the controller

into coil (1) becomes 0, coil (1) is deenergized. As a result, spool (2) is pressed up by return

spring (4). Accordingly, port A is closed and the pressurized

oil from the PPC valve does not flow into thecontrol valve.At this time, the oil from the control valve isdrained through ports B and T into the tank.

Signal current is 0 o increased o maximum The valve operates in the order of 3, 2, and 1

explained above.

SOLENOID VALVE

PC78MR-6 10-39


Control relief valve

If the pressure of the hydraulic oil from the con-trol pump rises, the oil in port A pushes spool (1).The reaction force of spool (1) compressesspring (2) and moves spool (1) to the right toopen ports A and T to relieve the circuit. Set pressure: 3.1 MPa {32 kg/cm}

SOLENOID VALVE

10-40 PC78MR-6


MULTI-CONTROL VALVE(OPTIONAL)

(1) JIS Pattern (2) Backhoe Pattern* Operation pattern selection drawing (Port names correspond to symbols in drawing)

MULTI-CONTROL VALVE

PC78MR-6 10-41


ACCUMULATOR FOR BRAKE(If equipped)

1. Cap2. Core3. Guard rubber4. Lid5. Plug6. Shell

SpecificationType of gas Nitrogen Gas

Gas volume ( ) 0.48Sealed gas pressure

(MPa {kg/cm}) 0.1 {1} (at 80 C)Max. actuating pressure

(MPa {kg/cm}) 6.86 {70}

(1)

ACCUMULATOR FOR BRAKE

10-42 PC78MR-6


HYDRAULIC PUMP

Model: LPD45 + 45

P1 : Pump dischargeP2 : Pump dischargeP4 : Pilot pump dischargePD : DrainPM : PC mode changeover pressure pickup portP1T : Travel deviation adjustment orificeP2T : Travel deviation adjustment orifice

PD2 : Pump drain (plug)PDA : Air bleederPEN : Control pressure pickup portPLS : LS pressure input (From control valve)PPT : PTO oil fillerPS1 : Main pump suctionPEPC : EPC main pressure pickup portPPLS : Pump pressure input (From control valve)

pc78mr-6_sebm030601

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