SOME APPLICATIONS OF CHRONOCYCLEGRAPHY

IN AGRICULTURAL WORK STUDY *

INTRODUCTION

The principle of photographicallyrecording work routines on a slow film(200 ASA or lower) by time exposurewas developed over fifty years ago byFrank B. and Lillian Gilbreth (1) thepioneers of Method Study. They developed the idea of attaching small electriclight bulbs to moving parts or bodymembers so that a trace of light on aphotographic plate could be obtained.An elaboration of this is to flash the

lights off and on about ten times persecond, so that an interrupted trail oflight is produced. The interruptions ofthe light source enable it to be interpreted in terms of distance, direction,acceleration, and velocity with considerable accuracy.

The basic technique has been described in most texts on Industrial

Engineering (2) (3) (4). The use ofa polaroid camera was suggested byNadler (5) for general method studyapplication. It can now be extended tochronocyclegraphy using the newerslow types of film. The main advantageof the polaroid camera is that theoperative and the engineer can see thephotograph while the method is stillfresh in their minds. This considerablyaids their interpretations of the photograph.

The purpose of this paper is to drawattention to the simplicity and speed ofthe techniques and to its relatively lowcosts.

APPLICATION AND DISCUSSION

The agricultural engineering uses ofthe technique including the polaroidcamera, which can produce a print inunder half a minute, include:

1. Training designers in the recognition of desirable and hence undesirable features of manual controls and fixtures; so that theymay be positioned and arrangedfor the optimum convenience ofoperators.

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by

T. A. Preston

Member C.S.A.E.

Department of Agricultural EngineeringUniversity of Alberta, Edmonton, Alberta

2. Group training of farm machineryoperators in the recognition of theprinciples of motion economy andadvantages of various types of fixture, and also of manual methods.

3. As a vehicle for interesting machinery operators in the principlesof motion economy (3). Thesethe technique illuminates in themicro scale, whereas the principles are appropriate to both themacro and micro scales: theanalogy between the pattern ofhand movements and the patternof machinery operation in a largefield is easily recognized and thebest method of operation for bothcan be illustrated.

The photographic technicalities ofobtaining a print which will includedetails both of the background and ofthe light traces has been described ina report (6). The examples given infigures 1 to 4 have been compiled withequioment costing in total less than$250.00. The cost of each print isunder $.50 which allows for 10 percentphotographic failures. The equipmentused is:

A f 4.7 Polaroid "120" 3.5 inch x2.5 inch camera.

1 tripod.

1 chronocyclegraph unit (by Fosterof Chiswick, London).

1 light meter, preferably calibratedin foot candles.

1 mirror, 2 feet x 3 feet, for 3dimensional effects and to circumvent obstacles.

It will be seen from the accompanying photographs in figures 1 to 4 thatit is an easy matter to detect awkwardmovements and to count the light"blips" to show the extra time savedby the more convenient designs. Fromthis, the cost comparison can be madeas well as methods improvements.

The formula below indicates thesimple calculations needed to convert

chronocyclegraphy to cost detail.

C/ 3600 \

1

where C = the extra cost of the improvements to the design.

T = the time saved by the newmethod as found bycounting the chronocyclegraph "blips" at 10 persecond.

N = number of times the appliance is used in its working life.

S = the hourly wage rate indollars.

The above formula ignores the valueof the machine time saved in extrauseful output and also any direct interest chargeable on the investment.These will normally more than offsetthe extra cost of the chronocyclegraphand film. A simple calculation willshow that with labour at $1.00 perhour, the number of "blips" countedfor a saving in time, for an item whichwould be used once daily for a ten yearworking life, are equal to the dollarsmaximum investment which could beexpended on improving the design. Obviously if more than one item of theequipment to be improved are in use,then the dollars are multiplied by thenumber of items in use.

For practical purposes such hairbreadth fine timing may seem ultra-theoretical; nevertheless ten light"blips" per occasion saved on an itemin use for ten years is equivalent to$100.00 if the item is used only tentimes per day. There appears to beevidence that some farmers are prepared to purchase leisure time by introducing mechanization of farm chores,and other tedious work, without anydirect economic justification of theirinvestment, such as can be providedby formula 1.

CANADIAN AGRICULTURAL ENGINEERING, JAN. 1967

Agricultural illustrations of the usesof the technique include the followingrepetitive manual operations which arecontrolled by the basic design of minorfurnishings of equipment:

1. The positioning of drivers' controls on tractors, self - poweredimplements and accessories wherean operator is needed.

2. Studies of the method of attachingfencing wire to posts; particularlyfor electric fencing associated withstrip grazing.

3. Instructing milkers in the bestroutine for grasping milking machine teat-cups for positioningthese on the cow.

4. Examine the time needed to position bags and sacks on spouts andstands. Hooks can be comparedwith clamps versus belts versusexpanding bars for use with potatoes, grain, seeds, fertilizer, fruitand vegetables.

5. Gate fastening attachments inwhich bolts, for example, couldbe compared with catches andbarbed wire entanglements.

The connections ofpipes and laterals.

irrigation

7. As a psycho-motor test analogousto driving in fatigue studies.

It will be recognized that much photography is needed to collect andcompare the full range of work proposed in the above seven projects.

Other photographic techniques alsohave a place in machine design. Notable has been the 360 degree motorized camera developed for the ChryslerCorporation (7) to simulate the driver's eye to obtain full visibility. Thisreplaces the older technique of placinga light source on a model in the position of the operative's eye so that anyarea found in shadow will be known tobe obscured from view (8).

It is the aspects of fitting the job tothe worker, rather than adapting theworker to the machine which can beillustrated by the use of Chronocyclegraphy in forms which can be readilyunderstood by both designers and operatives.

The four illustrations show:—

Figure 1—Marble dropping and thehigh cost of time needed for unnecessary precision.

Figure 2—The natural arcs of movement in a well designed control lever.

Figure 3—The movement betweencontrols on certain routines used innormal operation of a tractor.

Figure 4—The improvement of anoperators performance in the use ofmachinery by training in the correctand quickest method.

Marble Dropping

This example is taken from a laboratory exercise in which marble agates

Figure J

are taken from predetermined positionsoff two inclined ramps and droppedthrough a hole of V2, 1, 1Vi or 2 inchesdiameter in a plywood bridge placedcentrally in front of the operator.

The time taken to locate the handabove the holes and then release theagate can be seen quite clearly. Thetime required to release the agate overthe 2 inch hole, on the right side, (figure 1) was 3/10 of a second, whilethat for the \Vi inch hole was 7/10of a second. The extra time taken maythen be calculated by subtraction. Thenext size took 8/10 of a second andthe smallest 14/10 of a second, despite the fact that these were performed

CANADIAN AGRICULTURAL ENGINEERING, JAN. 1967 29

with the right rather than the left handof a non-ambidextrous operator. Thedifference between the extremes is over1 second in favour of the absence ofprecision, which should only be required of an operator when it is goingto make some genuine contribution tothe work he performs. This principleof avoiding precision wherever possiblecan be extended to the design of thesize and locations of levers and controlson any item of farm machinery.

Natural Arcs of Movement

Figure 2 is a view of a driver on theseat of a Massey Ferguson 175 Tractorusing a steering wheel (SW) and hydraulic control (HC). The contracts inspeed between the lower arc, SW-HCand the upper arc, HC-SW can be seen.This is a reflection of the known fixedlocation in the field of view of the SWand the unseen variable position of theHC. Note also the smooth arc ofmovement of the very well designedHC lever.

The comet tails point in the direction of actual movement. The blackarrows show the position of "blips"which have nearly become invisibleagainst a light background.

Movements Between Controls

Figure 3 contains three photographsof a driver on an International Harvester B414 Diesel tractor.

A—is the start up routine followedby steering and movement ofthe hand to the rear hydraulics.

B—is the start up routine followeddirectly by hand movement tothe rear hydraulics.

C—is the operation of front mounted hydraulics into a definitelocation. Note the three positions of the control lever knob.Note also the convenient location and short arc of movementrequired for this control.

The arcs of movement of the handsbetween the starter and the hydraulicsare, to the uninitiate, a surprisinglycurved arc, which would naturally circumvent an obstacle placed by a designer in a straight line between thetwo.

The series also shows how themachine times between the start andthe movement of the front hydraulicsor movement of the rear hydraulicscan be recorded by noting the opera

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tive's reactions. It should also be notedthat the time required for manual control selection is not directly related tothe distance between controls butrather to their visibility and predictablepositioning.

Operators Methods and Training

The assembly of a clinch-pin ontothe lower hydraulic link connecting a 3bottom plow onto a David Brown tractor is shown in figure 4. The flasheswere taken at 250 per minute. The firstsequence is of a two handed methodand the second of a single handedmethod. The second sequence is obviously the faster. The faster methodwas identified by motivating the operative to perform the work as quickly aspossible and this showed that he wassubconsciously aware of the fact thatthe single-handed method was fasterthan the method he had demonstratedfirst.

Once he had seen the substantialdifference in the times he was convinced of the need to consciously concentrate on the one handed method,which he now teaches to other drivers.

CONCLUSION

Chronocyclegraphy may be regardedas a technique for teaching primarily,and secondarily for contrasting thepractical aspects of different types andlocations of control levers on agricultural implements. The value will lie asmuch in the actual time saving benefitsas in the psychological effect of theoperators knowing that designers havean awareness of the workers' needs.

REFERENCES

1. Gilbreth, F. B. Applied MotionTime Study, MacMillan, 1919.

2. Maynard, H. B., Industrial Engineering Handbook, 2nd Edition,McGraw-Hill, page 2-71 andpage 2-80 to 82, 1963.

3. Morrow, R. L., Motion Economyand Work Measurement, RonaldPress, New York, page 126 andchapter 10, 1957.

4. Murrell, K. F. H. et al, Fitting theJob to the Worker, British Productivity Council, 1960.

5. Nadler, G, Work Design, Irwin,pages 189 to 195, 1964.

6. Preston, T. A. Chronocyclegraphy-Polaroid Photography, Depart

ment of Agricultural Engineering,University of Alberta, 1965.

7. Serratoni, Angelo, Industrial Photography, New York, page 42,March, 1965.

8. Shaw, Anne G., The Purpose andPractice of Motion Study, London: Columbine Press, Pages 92-131, 1960.

. . . CRANKCASE OILS

continued from page 21

(3). They found that high enginespeeds rather than load were responsible for the vscosity loss.

SUMMARY

1. Many multi-graded 5W-20 and10W-30 oils were found to beviscometrically equal to straightgraded oils at low shear rates.

2. Multi-graded oils of the 5W-30designation need to be tested athigh shear rates to determineengine cranking characteristics.

3. Pumpability characterstics of 5W-30 oils at 0°F were not equal to5W and 5W-20 oils.

4. Permanent viscosity loss of 12 to13 S.U.S. @210° (or 30%) wasobtained during sixteen hours ofengine operation with a 5W-30oil.

REFERENCES

1. Walker K. M., The Falling BallViscometer. Unpublished B.Sc.Thesis, University of Manitoba,1962.

2. Wilson, N.D., Low TemperatureProperties of Multi-Grade Lubricating Oils. Unpublished B.Sc.Thesis, University of Manitoba,1966.

3. West, J. P. and T. W. Selby.Multi-Grade Oils Lose ViscosityWith Time and Engine Speed.SAE Journal, 74, No. 3; 42-45,1966.

CANADIAN AGRICULTURAL ENGINEERING, JAN. 1967