Unpaginated      |      Vol_IIB-0052                                                                                                                  
EA-I. (Caterpillar Tractor Co.)

TRACTOR-TYPE TRANSPORTATION UNITS FOR ARCTIC OPERATIONS

       

CONTENTS

	Page
Commercial Usage	1
Military Usage	2
General Specifications of Commercially Available Track-Type Tractors.	3
Thickness of Ice	6
Type of Road	7
Maximum Grades and Grade Resistance	8
Sliding Resistances	8
Tonnage of Pay Load	9
Speed	9
Special Equipment Required for Arctic Tractors	11
Winch	11
Radiator Guard	11
Radiator Curtain	11
Cranckcase Guard	11
Front Pull Hook	11
Headlight Guards	11
Engine Side Shutters	12
Generator	12
Headlights	12
Exhaust-Pipe Extension	12
Cabs and Seat Enclosures	12
Tracks and Roller Frames	14
Fuel System	17
Instrument Panel Controls	18
Engine Heating Devices	18
Underchassis Heater	18
Hot-Air Heater	19
Water Heater	20
Open-Flame-Type Heaters	21
Operation and Maintenance	22
Sled Loading	24
Selecting the Route	25
Assembling the Train	25
On the Trail	26

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EA-I. Caterpillar Tractor Co.: Tractor-Type Unites

       

Contents #2

	Page
Fuels, Coolants, and Lubricants	28
Fuels	28
Engine Coolants	30
Lubricating Oils	31
Maintenance	32
Engine	33
Tractor Transmission and Final Drive	34
Tracks and Rollers	34
Sleds and Wanigans	35
Conclusions	35

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EA-I. Caterpillar Tractor Co: Tractor-Type Units ✓

       

LIST OF FIGURES

		Page
Fig. 1.	Steel and glass can on International TD-18 Tractor	12a
Fig. 2.	Canadian-type canvas enclosure on Caterpillar D-6 tractor	13a
Fig. 3.	Herman-Nelson hot-air generator, being used to warm up tractor engine	19a
Fig. 4.	Caterpillar D-7 tractor, equipped with two Vapor Car hot-water heaters	20a
Fig. 5.	Using an open-flame-type heater on Caterpillar D-7 tractor starting engine	21a
Fig. 6.	Caterpillar D-7 tractor pulling 24 sleighs (each carrying 4 cords) of pulpwood logs	22a
Fig. 7.	Caterpillar D-6 diesel tractors and 32 sleighs carrying approximately 300 tons of supplies	22b
Fig. 8.	A Caterpillar D-7 diesel tractor opening a road for spring traffic	25a
Fig. 9.	Caterpillar D-8 diesel tractor, pulling 3 sleds, each loaded with approximately 25 tons of lumber and other building materials, went through the ice	27a

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EA-I. (Caterpillar Tractor Co.)

       

TRACTOR-TYPE TRANSPORTATION UNITS FOR ARCTIC OPERATIONS

        The track-type tractor provides the most practical, and in some

circumstances the only means of transporting any sizable quantity of mate–

rials and supplies in those arctic areas unreached by roads or open water.

It has the ability to negotiate steep grades and rough country, breaking

its own trail as it goes. Over ice, snow, or deep mud, the wide planklike

tracks provide the necessary support and traction to enable it to maintain

a steady pace. Developed commercially to do the roughest kinds of work under

unfavorable conditions in all parts of the world, it has found a definite place

in arctic operations.

        Of course, the track-type tractor has its limitations in what it can do

under arctic conditions. It cannot travel over ice too thin to support its

weight, or in deep snow or mud too soft to keep the tractor and the load it

is pulling on the surface. Equipment is available to overcome, to a large

degree, the operational difficulties imposed by the extreme cold sometimes

encountered, but at the same time special maintenance practices must be carefully

employed if mechanical difficulties are to be avoided.

       

COMMERCIAL USAGE

        The track-type tractor is no newcomer to the Far North. Almost from the

time this machine first became commercially available it has found immediate

application in lumbering the pulpwood operations in the Subarctic, building

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and maintaining access roads, hauling supplies, and dragging the fallen

timber to points where it could be floated or hauled to market. There are

numerous mines in the Far North that have for years depended upon track-type

tractors for digging and hauling dirt and ore, bringing in fresh supplies,

and performing other tasks.

        From these early users of track-type tractors in northern regions comes

much of the present knowledge of design of special equipment to fit such

machines for service under the severe conditions encountered, and the suggestions

and recommendations that will be made later borrow freely from their experience.

       

MILITARY USAGE

        The possibility of future wars being fought in the Arctic has not escaped

the attention of the military strategists of various nations, and a great

amount of exploratory work has been done to determine the scope and usefulness

of track-type equipment in arctic military operations.

        Early successes of the Japanese in World War II indicated the immediate

need of Ordnance operations in arctic regions, and spurred construction of

the Alcan Highway by the U.S. Engineers. Much of the country traversed by

this highway is typically arctic, and track-type tractors were the major tools

used in construction. Due to the urgency of this project, the U.S. Engineers

had to rely on practices of local operators at first, but immediately launched

an organized test program to bring about improvements in equipment, lubricants,

fuels, and human comfort. Most of the work was done during warm weather and

many new methods and procedures for operating in muskeg were developed. In

the winter, tractors were used for repair and maintenance of the road, and these

operations added much to the store of knowledge of operating over snow, ice,

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and frozen ground at extremely low temperatures. The Alcan Highway project

became a proving ground for laboratory-developed equipment for arctic opera–

tions.

        As the war progressed, considerably more knowledge was gained from machine

performance in constructing air bases in Alaska, and in the Aleutian campaign.

Considerable work has also been done by the U.S. Navy, involving both explora–

tion and construction, using track-type tractors in Antarctica and at Point

Barrow, Alaska.

        Much work remains to be done to improve and expand further the usefulness

of track-type tractors in arctic regions. Both the U.S. Engineer Corps and

the Canadian Army are continuously investigating these problems in full-scale

field and laboratory tests, and much new knowledge is daily coming to light.

        The suggestions and specific recommendations made in this article come

principally from the reports and first-hand observations of factory engineers,

operators, and owners of track-type tractors engaged in arctic operations,

and military reports and personnel. More detailed information on specific

questions can usually be obtained by applying directly to:

1. Individual manufacturers of track-type tractors: Caterpillar Tractor
   
   Co., International Harvestor Co., Allis Chalmers Co., and Cleveland Tractor Co.
   
   
2. Military sources: U.S. Engineers (Fort Belvoir, Virginia), Bureau of
   
   Yards and Docks (Navy Department, Washington, D.D.), and F R oyal Canadian Army ✓
   
   Service Corps (Ottawa, Canada).
   
   
3. Major oil companies: Standard Oil Co. and Shell Oil Co.
   
   

       

GENERAL SPECIFICATIONS OF COMMERCIALLY AVAILABLE TRACK-TYPE TRACTORS

        Commercially available track-type tractors, as offered by the various

manufacturers come in a variety of sizes, ranging from a small machine weighing

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approximately 1.5 tons and powered with an 18-horsepower engine, to giant

construction tractors weighing up to 20 tons and rated at 163 horsepower.

Travel speeds provided on standard models are fairly uniform, with lowest

w s peeds ranging from 1.4 to 1.8 miles per hour and highest speeds from 4.8 ✓

to 6 miles per hour. Conventional gear-type transmissions are generally

used, although one manufacturer now offers a hydraulic torque converter on

his largest model. As engines are generally operated at a constant governed

speed, speed selection is made with the transmission, and the operator has

a choice of at least three, and on some models as many as six, forward speeds

within the high and low limits given above.

        The amount of tractive effort or drawbar pull the tractor exerts varies

with operating speed and the degree of traction afforded by ground conditions,

but a study of manufacturer’s published specifications shows that, in low gear

on level ground and with sufficiently good footing to prevent slippage, the

track-type tractor is able to exert a pulling force equal to about 90% of its

weight. At top speeds of 4.8 to 6 miles per hour the drawbar pull is reduced

to about 20 to 30% of the tractor’s weight. Complete data is obtainable from

the individual manufacturers.

        Most models of track-type tractors currently offered are powered by

semi high-speed diesel engines (1,000-1,800 r.p.m.), although gasoline engine

driven tractors are still made by two of the four major manufacturers. How–

ever, the lower fuel consumption of the diesel engine and its freedom e from ✓

electrical ignition difficulties make it a unanimous choice for arctic operations.

Reduced fire hazard and freedom e from radio static interference are also ✓

important factors.

        There is considerable variation in the methods used for starting the

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diesel engine. Battery-operated electric-starting systems are used on some

models, but are not favored for arctic operations because of the high rate

of depreciation of the storage battery under the travel conditions encountered

and its poor performance at low temperatures. Another method utilizes an

independent gasoline-operated starting engine, which finds considerable

favor because it can be hand-cranked, operated as long as necessary to start

the diesel, and while running adds its heat to the diesel engine to help

condition the diesel for easier starting. A third method utilizes an arrange–

ment whereby the diesel engine is started on gasoline as a conventional gasoline

engine, and when sufficiently warmed up is shifted over to full diesel operation.

        All of these methods have a low-temperature limitation, below which

satisfactory starting requires external means of applying heat to the engine,

or other special provision to permit the starting method to crank the diesel

engine fast enough to fire. Inasmuch as the frictional resistance of the

engine goes up and battery efficiency goes down with reduced temperatures,

diesel engines relying on conventional battery starting find need for special

aids at about 32°F. and lower. Diesel engines that start on gasoline, using

battery power for cranking, will start with fair reliability as low as 0°F.

The use of a hand-cranked gasoline engine for cranking the diesel permits

considerable lower starting temperatures, in the range of −20° to −30°F.,

before special aids are necessary.

        The track-type tractor is so well suited inherently for arctic operations

that few, if any, alterations are required in the basic design to fit it for

such service. There is, however, a wide choice of attachments and accessories

available from the manufacturer as special equipment to improve the usefulness

and reliability of the tractor under the operating conditions encountered, as

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EA-I. Caterpillar Tractor Co: Tractor-Type Units

well as equipment to combat the effect of the extremely low temperatures

sometimes encountered. Such items will be covered in detail later on.

        As for the selection of the best size of tractor to use for transport–

tation and freight hauling in arctic regions, there seems to be general

agreement that the larger machines are the most desirable, if operating

conditions permit their use. The easiest, and sometimes the only, route is

generally found by following lakes and rivers. The thickness of the ice

becomes the determining factor in selecting the best si x z e of tractor. ✓

Other factors involved are: type of road; maximum adverse grades; sliding

resistance; tonnage; and desired speed.

        The t T hickness of i I ce. The thickness will vary with every body of water. On lakes, if

there are currents or if the ice is under a considerable amount of snow, the

ice will generally be thin. Often on shallow lakes the ice will be poor due

to heat from the bottom. The color of ice is usually a good indication of

its thickness, light-blue being the strongest, and shading from gray to

black indicates less and less strength. Although specific information on

the bearing power of ice is not available, the rule-of-thumb data given in

Table I may be of interest.

Table I.

T R r actor model	Weight, lb.	Safe ice, in. ✓
D-2	6,870	10 to 14
D-4	10,430	12 to 18
D-6	17,330	16 to 24
D-7	24,330	28 to 32
D-8	34,360	36 to 40

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        Reconnaissance of the ice is recommended for winter hauling for there

are many possibilities of breaking through the ice: (1) Rocks near the

surface of lakes or streams give a thin ice sheet between the rocks and ice

surfaces. (2) Expansion and contraction of large ice areas produce “rents”

which result in thinner secondary ice. When covered by snow, these conditions

are not apparent to the vehicle operator. (3) Ice fatigue results from con–

stant travel over the same route.

        If the ice surface of a lake is not sufficiently strong, there are a

number of ways in which the road surface over the ice may be strengthened. (a) If the ✓

haul road is ice, the tanking may be continued over the lake ice. This will

build the natural ice up and will form an ice bridge across the lake, much

stronger than the surrounding ice. (b) If the road is snow plowed down to

the ice to a width of say 100-150 feet, the ice will thicken considerably

over this area as the insulating blanket of snow has been removed. With this

wide cleared area, if the ice gives at any one point, the road can be moved

fifteen to twenty feet to one side until the road can be repaired. It has

been found that a road grader pulled by a light tractor is very practical

for this purpose. (c) If holes are chopped in the ice the road area can be

flooded, with or without the use of pumps. Each application of water should

be allowed to freeze before more water is added. (d) Another method of rein–

forcing ice to increase its carrying capacity is by adding straw or boughs and

freezing them into the surface. However, being dark, they would be a drawback

in a spring thaw as they would cause faster thawing than normal. However,

occasions may arise where this method of reinforcement is practical.

        Type of Road . It is obvious that a tractor must have a firm well-packed

road in order to develop maximum output in the form of drawbar pounds pull.

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Usually several passes of tractors and trains will achieve this condition

but in this connection, the moisture content of the snow is of great

importance. Wet, heavy snow will pack down much quicker and provide more

thrust resistance than the dry, loose snow characteristic of very cold

temperatures.

        Maximum Grades and Grade Resistance . When a tractor train is hauled

over a grade, it is necessary to lifet a portion of the weight of the train ✓

in addition to negotiating forward movement. Grades are usually expressed

in percentages equal to 100 times the ratio of the vertical rise to the

horizontal distance, thus a 1% grade is one in which a vertical rise of one

foot is encountered in a horizontal distance of 100 feet. It is generally

accepted that each per cent of grade requires 20 additional drawbar pounds

pull per ton — over and above the pull required to overcome sliding

resistance.

        Sliding Rresistances of steel runners on ice and snow are not generally

very well known and the available figures are not completely usable because ✓

of the variety of conditions encountered — sometimes in a comparatively short

distance. The National Research Council of Canada has some of the most reliable

information on this subject. In logging sleds, of great importance are the

length of the runner in proportion to its width and the camber of the front

runner which should be such to achieve a lifting effect on loose snow. The

moccasin-type runner has achieved greatest popularity in the Province of Quebe d c ✓

for snow use. This type utilizes a runner twice the width of the steel shoe.

To give better flotation to the sled, the steel shoe is usually a ah ha lf oval, ✓

about 4 inches wide, and rolled of mild steel. The load weight per unit of

shoe surface should be as great as practical, as the sliding resistance of

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the steel on the snow is reduced by the heat created by friction of the

runner. Commercial freighters are of the opinion that tractive efficiency

is materially increased if the gauge of the sleds is the same as the gauge

of the tow vehicle.

        Tonnage of Pay Load . Larger tonnages obviously require more powerful

tow vehicles and increases in speeds bring about decreases in workable

tonnages.

        Speed . The available speeds in miles per hour and drawbar capacities

in pounds pull for five types of tractors in five different gears are

given in Table II. An examination of Table II indicates a model D-6 tractor

Table II.

Model	Weight, lb.				Gear
		1st m.p.h. lb.	2nd m.p.h. lb.	3rd m.p.h. lb.	4th m.p.h. lb.	5th m.p.h. lb.
D-2	6,870	1.7-6,250	2.5-4,700	3.0-3,800	3.6-3,070	5.1-1,950
D-4	10,430	1.7-9,450	2.4-6,990	3.0-5,470	3.7-4,180	5.4-2,690
D-6	17,330	1.4-15,500	2.3-10,750	3.2-7,320	4.4-4,730	5.8-3,130
D-7	24,330	1.4-21,351	2.2-13,454	3.2-9,090	4.6-5,994	6.0-4,550
D-8	34,360	1.7-28,700	2.3-21,300	2.8-16,800	3.7-12,600	4.8-9,550

        in fourth gear at 4.4 m.p.h. has as much pulling ability as a D-2 in second

gear. Similarly, a D-8 in high gear (4.8 m.p.h.) has greater pulling capacity

than a D-4 in low gear.

        In regions where the tractors operate over frozen ground or heavy ice,

large tractors in the class of the Caterpillar D-7 or D-8 are used, but in areas

where most movements have to be made over river or lake ice, and there is a

limited number of days in the year when the ice is thick enough to safely support

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EA-I. Caterpillar Tractor Co: Tractor-Type Units

a D-8, more work is accomplished with a medium size tractor, such as the

Caterpillar D-6. For comparative purposes, brief specifications of the

Caterpillar D-8, D-7, and D-6 tractors are given in Table III.

Table III.

Over-all dimensions		D-8	D-7	D-6 (wide gauge)
Length		15 ft. 3 in.	13 ft. 6 ¼ in.	12 t. 5 3/16 in.
Height		7 ft. 6 in.	6 ft. 8 in.	6 ft. 3 1/4 in.
Width		8 ft. 7 3/4 in.	8 ft. 1 in.	7 ft. 10 1/2 in.
Weight		34,360 lb.	24,330 lb.	17,330 lb.
Horsepower
Belt		144	92	75
Drawbar		130	80	65
Drawbar pull (at various travel speeds, and rated engine speed)
Forward:		m.p.h. lb.	m.p.h. lb.	m.p.h. lb.
	1st	1.7-28,700	1.4-21,350	1.4-15,500
	2nd	2.3-21,300	2.2-13,454	2.3-10,750
	3rd	2.8-16,800	3.2-9,090	3.2-7,320
	4th	3.7-12,600	4.6-5,994	4.4-4,730
	5th	4.8-9,550	6.0-4,550	5.8-3,130
Tracks
Width (standard shoe)		22 in.	20 in.	16 in.
Length track on ground		97 5/8 in.	93 1/4 in.	85 5/8 in.
Area ground contact		4,296 sq.in.	3,730 sq.in.	2,740 sq.in.
Ground pressure (standard tracks)		8 p.s.i.	6.6 p.s.i.	6.28 p.s.i.

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EA-I. Caterpillar Tractor Co: Tractor-Type Units

       

SPECIAL EQUIPMENT REQUIRED FOR ARCTIC TRACTORS

        Because of the extreme variations in operating conditions that are to

be found in various arctic regions through both summer and winter, it would

be impossible to equip a tractor so that it would give best possible per–

formance under all conditions. Experience has shown, however, that certain

items are generally required or desirable, regardless of season or ground

conditions.

        Winch . A rear-mounted winch is essential. When the tractor encounters

ground conditions where there is insufficient traction to move the load, the

winch permits the tractor to be uncoupled from the drawn sleds and move on to

firmer ground, where it acts as an anchor while the winch pulls the load over

the soft area.

        Radiator Guard . This is a heavy metal plate, perforated to permit

passage of air, that mounts directly in front of the radiator. It prevents

damage to the radiator when passing through wooded areas. As any damage to

the radiator may result in loss of coolant, and enforced shutdown of the engine,

radiator guards are considered to be essential.

        Radiator Curtain . This attachment aids in keeping the engine up to the

proper operating temperature during cold weather.

        Crankcase Guard . This is a heavy steel plate that armors the underside

of the engine and transmission case, to prevent damage from stumps, hidden rock, etc.

        Front Pull Hook . Principal use of the front pull hook is as a means of

coupling two tractors together, on those occasions when it becomes necessary

to double-head the tractors.

        Headlight Guards . These are heavy wire mesh guards to protect the head–

light lens from damage when traveling through wooded country.

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        Engine Side Shutters . These serve two purposes: they keep snow from

blowing in on the engine, and they help conserve the heat of the engine to

keep it at the proper operating temperature. Sheet-metal shutters, tailored

to fit snugly, are usually obtainable from the tractor manufacturer. Another

type that has found favor is made locally from canvas. The top edge is clamped

to the engine hood, and the bottom edge is simply weighted to keep it from

flapping. The canvas type has the advantage of making it extremely simple

to get to the engine as it requires no clamps.

        Generator . A generator is required to furnish power for the headlights

for night travel. The batteryless-type generator is favored, because of the

previously mentioned objections to batteries. A generator of sufficient

capacity to handle all the lights required should be specified.

        Headlights . Each tractor should be equipped with a pair of headlights on

both the front and rear of the tractor. The rear lamps assist the operator

when winching the load at night. In addition, there should be a pair of

spotlights, mounted on the highest point of the tractor seat enclosure. These

spotlights are chiefly used shining to the rear, with the beams converging on

the sled train.

        Exhaust-Pipe Extension . At low temperatures, the moisture in the engine

exhaust condenses to form a dense cloud of vapor, and may seriously obscure

the operator’s vision. Eliminating this operational hazard may require suitable

alterations or extensions to the exhaust stack.

        Cabs and Seat Enclosures . To afford the tractor operator as much protection

as possible from the elements, one of two types of enclosure is generally used:

( 1 ) a regular tractor cab, made of sheet metal or plywood and with glass

windows totally enclosing the operator’s compartment (see Fig. 1) , or ( 2 ) simple canvas —

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shields, sometimes with a glass windbreaker, that transform the operator’s

compartment into an open cockpit . (see Fig. 2). Holes cut in the dash allow engine heat —

to circulate around the operator. Each arrangement has its advantages and

disadvantages.

        The standard tractor cab has the advantage that it gives the operator

maximum protection from wind, snow, sleet, and rain, and in the summer months,

from insects. On the other hand, it is subject to rather rapid depreciation

under rough operating conditions, and inclined to be somewhat noisy. Visi–

bility is poor due to frost forming on the glass and the wood or sheet-metal

frame, which unavoidably blocks the operator’s view in certain directions.

Also, cabs make it difficult for the operator to escape in the event the

tractor should fall through the ice when crossing lakes or rivers.

        Open cockpits, with canvas sides and windshield, offer maximum visibility,

low maintenance, and easy escape in case of accident. However, there is no

protection from the elements or from insects in the summer months. There

is also a problem of keeping pieces of ice, etc., thrown up by the tracks

from filling the cockpit.

        The opinion of commercial haulers seems to favor the open cockpit,

canvas-shrouded enclosure over the totally enclosed cab, especially for

cold-weather operation, because of the better visibility and safety features.

It should be noted, however, that most of the objections to cabs could be over–

come by improved design, and investigation in this direction is continuing.

Escape hatches on the cab roof can be provided rather simply. An efficient,

dependable window defroster and windshield wiper, and the use of double-pane,

sealed glass (Thermopane) would improve visibility, as would careful location

of the windows. Such improvements could quite conceivably result in the cab

being given operator preference.

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        Whether cab or enclosure is used, it should be of sufficient width to

comfortably seat two men dressed in arctic clothing. A width of 48 inches

is about minimum.

        Glasspanels, if used, should be of safety glass. Glass on the forward

part of the cab should be protected with some type of metal guard to prevent

the possibility of breaking the glass when removing engine side panels or

doing other work around the engine.

        If a canvas enclosure is used, the windshield should be hinged so that

it can be folded down during calm, mild weather.

        Tracks and Roller Frames . As has been mentioned before, the great variety

of operating conditions encountered in the Arctic makes it impossible to

equip a tractor so that it will perform equally well, without equipment changes,

in all situations. This is especially true in regard to selecting the type and

size of track plates for such service.

        In operating over soft snow or muskeg, the important consideration is to

keep the machine from sinking or digging its way beneath the surface, which

requires that track plates having the maximum obtainable area be used.

Experience has shown that, for satisfactory operation over packed snowdrifts

or average muskeg, the ground pressure (total weight divided by area of track

plates actually on the ground) of the tractor should not be more than 2 to 3

p.s.i. This is less than half the ground pressure ordinarily found with

conventionally equipped track-type tractors (specifications previously given

for the Caterpillar D-6 tractor, with standard 16-inch shoes, show ground

pressure of 6.28 p.s.i. To operate under such conditions, the track-plate

area must be increased by using wider-than-standard plates, or by attaching

to the regular plates auxiliary track pads. The p [ c?] atter means, while successful ✓

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in decreasing the tractor ground pressure, has its limitations, as can be

judged from the following excerpt from a report on U.S. Army Task Force

Williwaw at Adak, Alaska (1947).

        “Two track-type tractors were reworked to decrease the ground pressure

on each unit. This was accomplished by replacing the standard track pads

with angle iron section pieces. A Caterpillar D7 tractor track was built

up with 6 × 6 inch 5/8 thick angle iron 40 inches in length, which reduced

the ground pressure of this tractor to 2.7 psi. The angle iron type grouser

had an overhang from the outside track link of 25 1/2 inches. An International

TD14 tractor was reworked in similar manner. The angle sections were 5 × 5

inch 1/2" thick angle iron 30 inches long, which reduced the ground pressure

to 4.5 psi. B e y increasing the track pad size as described, the tractors ✓

were found to be very mobile and the units were considered good prime movers.

Trouble may develop in the units as an overload is produced on the steering

system, track frames, links, roller, etc. because of the extra wide grousers.

In rocky sections of the terrain, it was found that the angle iron grousers

became quite badly bent.”

        In order to provide as much clearance as possible for the use of extra

wide track plates, wide-gauge tractors should be specified, if available.

Wide-gauge tractors differ from standard tractors only in that the track frames

are spread farther apart, with a corresponding increase in the distance from

the track chains to the side of the tractor chassis. It is desirable that

extra long track plates be attached to the track chain as near the center of

the plate as possible, with equal overhang on each side of the track chain,

which indicates the desirability of the widest gauge obtainable. In addition,

the increased width of the tractor gives it additional stability when travelling

over rough or sloping ground.

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        Some tractor manufacturers also offer, as special or optional equipment,

extra long track roller frames. As longer frames increase the number of

links in the track chain, with a corresponding increase in the area of

track in contact with the ground, they should be specified if available.

        Under some operating conditions, low ground pressure is not an advantage,

and may even be un desirable. For example, when travelling over ice or hard-

packed snow, higher ground pressure may be required to secure sufficient

penetration of the track grousers to give the required traction. Furthermore,

the extra wide shoes required for low ground pressure reduce the maneuverability

of the tractor, and are subject to considerable bending of the ends when rocky

ground is encountered.

        Fortunately, in actual practice most of the difficulties mentioned above

can be avoided, by careful choosing of the trail to avoid low, s e w ampy areas ✓

in warm weather. In a report on the joint operations of the U.S. Army and

the Canadian Army near Fort Churchill, Canada, an observer reported.

        “By selecting the proper routes, a tractor with a higher ground pressure

can be used and more work done than if a straight cross-country route is taken.

        “Commercial freighters are very careful in selecting their routes for

winter time hauling. For terrain as found in the Churchill area, even greater

care must be taken as to route selection during the summer months because the

muskeg becomes very soft, with the water level near the surface.”

        The design of the track plates, as well as the size, is of considerable

importance. Over the years, a great amount of experimental work has been done

by tractor manufacturers and commercial haulers alike in an attempt to develop

the “perfect” track plate for snow and ice. While no single answer has been

found, and tractor manufacturers offer a variety of sizes and shapes of track

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plate for snow and ice. While no single answer has beenfound, and tractor [?] ✓ cf. original p. 25 line 7 from bottom

manufacturers offer a variety of sizes and shapes of track plate to meet

varying conditions, the so-called “snow and ice semi-skeleton” track plate

seems to be most popular for arctic winter operations. The center of the

shoe is open, so that snow that packs in the chain is punched out by the

track sprocket. The grousers have both single spikes and double spikes,

and the plates are attached alternately to the track chain — first a single–

spiked plate, then a double-spiked plate.

        As a general recommendations for equipping a tractor for year-round

transportation service in the Arctic, as far as the track running gear is

concerned, it should have the widest gauge and the longest track frames

obtainable from the manufacturer. The track plates should be of the type

described above, in the widest width furnished. If it is possible to avoid

soft, marshy ground or deep snow by careful selection of the travel route, the

track-plate area can be augmented by bolting on extra wide pads made from such

material as heavy angle iron.

        Fuel System. One of the commonest difficulties encountered in operating

tractors in extremely cold weather is the formation of ice in fuel lines. It

is extremely difficult to keep the fuel absolutely free of water, and only a

very small quantity is required to cause trouble.

        Fuel tanks and filter housings are customarily equipped with drain cocks,

settling bowls, or other provision so that accumulated water can be periodi–

cally removed from the fuel system. In addition, it is good insurance to

replace all fuel lines of small size with oversized lines (approximately

½ inch inside diameter), and use fittings that have smoothly rounded inside

passages.

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        Instrument Panel Controls. All control knobs, handles, keys, etc., that

the operator uses should be spaced and of suitable shape so that they can be

worked by the operator without removing his heavy gloves.

       

Engine Heating Devices

       

ENGINE HEATING DEVISCES

✓

        As mentioned before, the low-temperature limit for satisfactory starting

of the engine on commercial crawler tractors without special eating equipment

is about 0° to −10°F., assuming that the engine is in good operating condition

and has been properly services with correct fuels and lubricants for low–

temperature operation (see “Operation and Maintenance” section). For lower

temperature it is usually necessary to apply heat to the engine from some

external source.

        The most obvious solution is to keep the tractor in a heated enclosure

when it is not in operation, but under arctic conditions such a solution is

not often practicable, and the tractor must be parked in the open.

        There are several means of applying auxiliary heat to the engine to

facilitate starting. In general, the selection of the most satisfactory

arrangement to meet existing conditions depends upon two factors: how low

a temperature the engine reaches, and how fast a start is desired.

        Underchassis Heater. Perhaps the simplest scheme for maintaining the

temperature of a tractor parked in the open high enough to permit starting

consists basically of a tarpaulin closely fitted around the tractor or engine,

and a conventional-type gasoline-burning space heater which is hung beneath

the tractor chassis. Such an arrangement was furnished for military machines

for arctic service during World War II, as part of a so-called “winterization

kit.”

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        On paper, this arrangement would appear to be capable of doing a

satisfactory job. It is simple, lightweight, and operating principle

is obviously sound. However, actual tests brought cut a number of objections.

Under conditions of extreme cold the heater may go out, either from the wind

or from the heater fuel line freezing up. The products of combustion of the

fuel condense on the ignition system of cold engines. If the engine has

reached an extremely low temperature before the heater is lit, the heat is

slow in penetrating and an excessively long period of time is required to

achieve starting temperature.

        Hot-Air Heater . One of the developments of World War II was a high–

capacity hot-air generator, specifically designed for warming aircraft

engines. Perhaps the best-known machine of this type is the Herman-Nelson

heater (see Fig. 3) , which consists basically of a high output (100,000 B.t.u. per hour), —

gasoline-fired burner, and a 4-cycle air-cooled gasoline engine, which drives

a fan to force the hot air through flexible conduits to the point where heat

is needed. The whole machine is mounted on a portable, four-wheeled cart.

        Operational reports indicate that this type machine does a very satis–

factory job of warming up cold engines, even under extreme conditions. By

using canvas shields around the engine, it is a simple matter to insert the

hot-air conduit to direct the heat where most needed. However, the problem

remains of getting the engine on the heat generator started, assuming the

tractor is on the trail and there is no heated shelter for the heater.

        It would seem, then, that the Herman-Nelson type heater is very satis–

factory for arctic operations where the machines to be started are bivouacked

near permanent or temporary headquarters, and the heater can be put into

operation without much difficulty. On the trail, such an arrangement presents

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the fuel condense on the ignition system of cold engines. If

the engine has reached an extremely low temperature before the

heater is lit, the heat is slow in penetrating and an excessive–

ly long period of time is required to achieve starting temperature.

       

Hot Air Heater

        One of the developments of World War II was a high capacity

hot air generator, specifically designed for warming aircraft

engines. Perhaps the best known machine of this type is the

Herman-Nelson heater, which consists basically of a high output

(100,000 B.T.U./hr.) gasoline fired burner, and a 4-cycle air

cooled gasoline engine which drives a fan to force the hot air

through flexible conduits to the point where heat is needed.

The whole machine is mounted on a portable, four wheeled cart.

        Operational reports indicate that this type machine does a

very satisfactory job of warming up cold engines, even under ex–

treme conditions. By using canvas shields around the engine, it

is a simple matter to insert the hot air conduit to direct the

heat where most needed. However, the problem remains of getting

the engine on the heat generator started, assuming the tractor

was on the trail and there was no heated shelter for the heater.

        It would seem, then, that the Herman-Nelson type heater is

very satisfactory for Arctic operations where the machines to be

started are bivouacked near permanent or temporary headquarters,

and the heater can be put into operation without much difficulty.

On the trail, such an arrangement presents an additional engine

starting problem, and in addition it becomes another piece of

freight to be transported by the tractor train, deducting just

that much from the pay load.

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an additional engine starting problem, and in addition it becomes another

piece of freight to be transported by the tractor train, deducting just that

much from the pay load.

        Water Heater. This arrangement consists basically of a gasoline burner and

a hot water coil, generally mounted on the exterior of the engine. The water

coil is directly connected to the cooling system of the engine, and in addi–

tion there may be auxiliary heating coils in the oil sump and around the

battery box. The burner and hot water coil are mounted low on the engine,

and act as a thermosiphon to maintain circulation. As the engine coolan d t is ✓

heated, it rises in the system, forcing cold coolant into the heater. The

best-known heaters of this type are the Vapor Car Heater (See Fig. 4) and the Superfex. —

        This type heater, if put into operation immediately upon shutting off

the engine, will maintain a sufficiently high engine temperature for immediate

starting. If the engine is cold to begin with, it may take from 6 to 8 hours’

operation of the heater to bring the engine up to a satisfactory starting

temperature.

        Field tests indicate that this type heater, if it operates properly,

gives very satisfactory results. In a test at Fort Churchill, a Caterpillar

D-7 tractor was started in slightly more than one minute in a temperature of

−38°F. However, numerous operational difficulties sometimes arise, and in

this same test it was reported that the operators were somewhat discouraged

by the heater fuel lines freezing up, snow being blown into the heater, and

the uncertainty that proper circulation was taking place, due to the formation

of vapor locks.

        Development work is still progressing and undoubtedly most of these

operational problems will eventually be overcome. If so, this type heater

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Water Heater

        This arrangement consists basically of a gasoline burner and

a hot water coil, generally mounted on the exterior of the engine.

The water coil is directly connected to the cooling system of the

engine, and in addition there may be auxiliary heating coils in

the oil sump and around the battery box. The burner and hot water

coil are mounted low on the engine, and act as a thermo-siphon to

maintain circulation. As the engine coolant is heated it rises

in the system, forcing cold coolant into the heater.

        The best known heaters of this type are the Vapor Car Heater,

and the Superfex.

        This type heater, is put into operation immediately upon

shutting off the engine, will maintain a sufficiently high engine

temperature for immediate starting. If the engine is cold to be–

gin with, it may take from 6 to 8 hours operation of the heater to

bring the engine up to a satisfactory starting temperature.

        Field tests indicate that this type heater, if it operates

properly, gives very satisfactory results. In a test at Fort

Churchill, a Caterpillar D7 tractor was started in slightly over

1 minute in a temperature of −38°F. However, numerous operational

difficulties sometimes arise, and in this same test it was report–

ed that the operators were somewhat discouraged by the heater fuel

lines freezing up, snow being blown into the heater, and the un–

certainty that proper circulation was taking place, due to the

formation of vapor locks.

        Development work is still progressing and undoubtedly most

of these operational problems will eventually be overcome. If

so, this type heater will undoubtedly become very popular for

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will undoubtedly become very popular for cold-weather operation, especially

on engines that rely on storage batteries or hand cranking for starting. It

was the opinion of test officers at Fort Churchill that engines should be

equipped with a coolant-type heater that would function as either a stand-by

or a fast heater, and could be considered to be dependable and not a fire

hazard. Heater capacity should be at least 50,000 B.t.u. per hour.

        Open-Flame-Type Heaters. Gasoline-burning blowtorches, acetylene-gas

torches, and the like are not, in themselves, capable of heating large engines

to starting temperatures in conditions of extreme cold, although they are

useful for applying heat to local areas, such as the intake manifold. However,

where the diesel engine is equipped with an independent gasoline-starting

engine (Caterpillar), this is oftentimes the only external heating device

required to make a cold start, even in temperatures of −40°F. or lower.

The open flame is applied to the crankcase and intake manifold of the

starting engine and, if the starting engine is in good condition, it will

usually start readily . (See Fig. 5). The starting engine is tied in with the diesel engine —

in such a way that the starting-engine heat is added to the common cooling

system and to the intake air of the diesel engine. Motoring the diesel

engine with the starting engine from 5 to 8 minutes is usually sufficient

to start the diesel.

        The use of an open flame on the starting engine is not especially

desirable, because of the fire hazard, and the danger of the localized heat

causing unequal expansion with resulting cracking of the metal parts. In

general, however, the method is successful, and has led some operators to

comment that, with the Caterpillar diesel starting system, the only heating

aid required for cold starts in the lowest temperatures is a bottle of acetylene

gas and a torch.

021a      |      Vol_IIB-0084                                                                                                                  

Unpaginated      |      Vol_IIB-0085                                                                                                                  
cold weather operation, especially on engines that rely on storage

batteries or hand cranking for starting. It was the opinion of

test officers at Fort Churchill that engines should be equipped

with a coolant type heater that would function as either a stand–

by or a fast heater,, and could be considered to be dependable and

not a fire hazard. Heater capacity should be at least 50,000 B.T.U.,

hr.

       

Open Flame Type Heaters

        Gasoline burning blow-torches, acetylene gas torches and the

like are not, in themselves, capable of heating large engines to

starting temperatures in conditions of extreme cold, although they

are useful for applying heat to local areas, such as the intake

manifold. However, where the Diesel engine is equipped with an

independent gasoline starting engine (Caterpillar), this is often–

times the only external heating device required to make a cold

start, even in temperatures of −40°F. or lower. The open flame

is applied to the crankcase and intake manifold of the starting

engine, and if the starting engine is in good condition it will

usually start readily. The starting engine is tied in with the

Diesel engine in such a way that the starting engine heat is add–

ed to the common cooling system and to the intake air of the

Diesel engine. Motoring the Diesel engine with the starting

engine from 5 to 8 minutes is usually sufficient to start the

Diesel.

        The use of an open flame on the starting engine is not es–

pecially desirable, because of the fire hazard, and the danger

of the localized heat causing unequal expansion with resulting

cracking of the metal parts. In general, however, the method is

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        Utilizing the same principle and procedure, but in a more acceptable

manner, is a hand-cranked gasoline-fired blower that throws a blast of hot

air on the entire starting engine, including the magneto. When tested at

Fort Churchill, this attachment made it possible to consistently start the

starting engine in from 5 to 9 minutes after the heater was started, in

temperatures ranging from −27° to −38°F. This heater was developed by the

Caterpillar Tractor Co. in conjunction with the U.S. Engineer Corps.

        While discussing cold-weather starting, mention should be made of

investigations now going on of the use of other as an aid in low-temperature

starting of diesel engines. Ether in liquid form is squirted into the intake

manifold by a special device, and has the effect of promoting immediate firing

of the diesel engine. This new development is past the experimental stage,

and should soon be commercially available as an attachment for diesel engines.

       

OPERATION AND MAINTENANCE

        The usual means of utilizing track-type tractors as transportation units

in the Arctic is the so-called “tractor train.” The material to be moved is

loaded on sled platforms, which are towed in tandem by the tractor. Ordinarily,

each tractor pulls three sled units, and this combination is termed a “swing.”

The train may consist of one or a number of swings, depending upon circumstances

and the nature of the operation. The load-moving capacity of each swing, or

tractor, depends upon the condition of the trail and the size of tractor used . (see —

Figs. 6 and 7).

Over an established but infrequently used trail, the tonnage figures given in

Table IV are considered a close working estimate.

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022b      |      Vol_IIB-0089                                                                                                                  


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Table IV.

Tractor	Gross weight of tractor s , tons	Gross weight load of ✓ cargo and sleds, tons ✓
Caterpillar D-4	5.75	12
International TD-14	8.5	20
Caterpillar D-6	9	25
International TD-18	15	40
Caterpillar D-7	13	40
Caterpillar D-8	18.4	50

        The sled units towed by the tractor may be of various sizes and designs.

Cargo-carrying sleds usually have two sets of runners, joined by cross-chains

so that the rear set track with the front set when negotiating a curve. Both

sets of runners pivot with respect to the sled platforms. All parts are ex–

tremely rugged and reinforced with steel.

        Tractor trains ordinarily include one or more utility sleds, known as

“wanigans”. These are small buildings mounted on sled runners and provide

quarters, cooking facilities, and a repair shop for the train crew. They are

constructed of ply - wood or sheet metal on a strong metal frame, with the —

interior insulated with Celotex or some similar material. Inside height is

a minimum of 7 feet, and the width is usually about 8 feet, but cannot exceed

the width of the tractor. Length is usually from 16 to 24 feet.

        Table V gives brief specifications of some of the better known commer–

cially available sleds and wanigans.

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Table V.

Manufacturer	Weight, lb.	Size, ft.	Pay - load capacity, tons —
McLaren	5,000	8½ × 20½	10
Otaco	6,000	8½ × 20½	10
Michler (large)	10,000	8 × 24	10
Michler (small)	6,000	8 × 16	10
Otaco sled ( W w anigan equipped)	10,000	8 × 16	4 men —
Michler (large) sled ( W w anigan equipped)	18,000	8 × 24	6 men —

        Another commonly used cargo carrier, known as a “go-devil” sled, con–

sists of a heavy platform rigidly mounted on a single pair of heavy runners.

They are simple and easy to construct, and provide great load capacity with

a low center of gravity, reducing the possibility of tipping. However, more

power is generally required to pull a “go-devil” than a bobsled, which limits

their use to hauling such items as heavy pieces of machinery, etc., than

cannot be safely loaded on a bobsled.

        Sled Loading. Proper sled loading requires experience and knowledge of

the condition of the trail. The height of the load is generally governed by

its tipping tendency rather than its weight. For any but old, smooth trails

the height from the ground to the top of the load should not exceed the width.

        Loads should be secured before the train starts. A shifting load not only

wastes precious time on the trail, but it distracts the operator when he

should be concentrating on running the tractor. Loose loads should be boxed

in with lumber, and larger items should be spiked to the sled platform, or

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otherwise secured. At each stop along the route every load should be checked

for shifting.

        Selecting the Route. A straight-line route is the most desirable but

very seldom the most practical. In those areas of the North covered with

rivers and lakes, the usual practice is to take full advantage of them by

laying out the route to follow the relatively smooth the flat ice surface pro–

vided. Ascending grades exceeding 10% is slow and difficult, requiring

considerable winch work. Zigzagging up steep grades is dangerous, because

of the possibility of the sleds tipping.

        Obviously, selection of the route is about the most important step in

assuring the success of a tractor-train operation. Careless or hasty

selection can result in delays and even loss of equipment and men. All

available means, such as serial reconnaissance, maps, and photographs

should be utilized, as well as experienced guides.

        The usual practice in establishing new trails is to send out an advance,

or trail-breaking, party. The usual outfit for trail-breaking consists of

two tractors, equipped with bulldozers, and a utility wanigan, and operating

about a day in advance of the train. Usually, it is advisable to break trail

only in daylight, except in open country.

        Trail-breaking in deep snow simply requires that the tractor move along

the selected route, with dozer blade raised, compacting the snow . (see Fig. 8). Where the —

surface is uneven, or blocked by trees or rocks, the bulldozer blade is used to

clear and level the T t rail. —

        Assembling the Train. All the sleds pulled by each tractor should have

the same gauge, or distance between the runners, so that all runners follow

in the same track. The sleds will pull more easily if the heaviest loaded sleds

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are to the front. Wanigans and “go-devil” type sleds should always follow

the loaded conventional-type sleds. If the sleds stand in the open for any

length of time, the runners may freeze to the ice or snow. They should be

broken free with a sledge or mallet, to reduce the starting strain on the

runners.

        On the Trail. Tractor trains usually travel at the highest speed pro–

vided by the tractor, if trail conditions permit. Counting routine stops,

delays for minor repairs, time lost in negotiating bad spots, etc., the

average speed, figured on the basis of total elapsed time between two points

connected by an established trail, is from two to three miles per hour.

Operation is around the clock, to permit greater distances to be covered

and to avoid restarting cold engines.

        During arctic winters, the limited amount of daylight means that most

of the time the train is operating in darkness, when the driver can see only

the sled immediately following the tractor. For obvious reasons, the most

experienced men should have the night duty, where possible. Each tractor

should carry an extra gasoline lantern, and there should be an ample supply

of flashlights in the wanigan for night emergencies. Kerosene flares should

also be available for marking the rear sled when the train stops, or disabled

equipment left along the trail.

        Stops for refueling and maintenance are usually made at noon, when light

and temperature are at a maximum. Tractor maintenance consists of lubrication,

inspection and adjustment, and general tightening of nuts, bolts, and fittings.

On hauls of less than 100 miles, or over new trails, the tractor train usually

carries its fuel with it. On long hauls over established trails, it may be

more economical to establish fuel caches along the route. Fuel requirements

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per tractor range from 2 to 4 gallons per hour, depending upon travel condi–

tions, load, and size of tractor used. On one typical test it was found that

a Caterpillar D-8 tractor consumed 53 gallons, or 500 pounds of fuel in 15

hours running time. Obviously, for a long trip the fuel carried will account

for an appreciable part of the starting load unless there is provision

for refueling along the route.

        The six basic rules of tractor-train operation established by the

Canadian Army at Fort Churchill are as follows:

1. Tractors must follow the prepared trail at all times unless otherwise
   
   ordered. If this is not done the object of trail-breaking, which is to facili–
   
   tate floatation, is nullified and, in effect, each tractor cuts its own trail
   
   with consequent loss of tractive effort. Additionally, more than one trail
   
   can be extremely confusing on return journeys, especially at night or in
   
   conditions of poor visibility.
   
   
2. As in every other transport operation, the speed of the column is
   
   dictated by the speed of the slowest vehicle. Thus in conformity with accepted
   
   practice the slowest tractor should lead the column.
   
   
3. When travelling in swings, the operator of the first tractor must keep
   
   the tractor following in sight in order to provide mutual assistance. Thus the ✓
   
   two operators of a swing work as a team.
   
   
4. When crossing thin ice, tractors should be in the highest gear possible
   
   and operate with reduced throttle. Sleights should be connected to the hook
   
   of the winch cable in order that they may be released and the load spread if
   
   cracks in ice appear.
   
   
5. To minimize strain, intervals of 100 yards should be maintained on
   
   ice at all times . (see Fig. 9).
   
   


027a      |      Vol_IIB-0098                                                                                                                  


Fig. 9. Caterpillar D-8 diesel tractor, pulling 3 sleds, each

loaded with approximately 25 tons of lumber and other

building materials, went through the ice.



027a      |      Vol_IIB-0099                                                                                                                  


[Figure]



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6. There should be no closing up of tractors when halted on ice.
   
   Intervals must be maintained.
   
   

       

FUELS, COOLANTS, AND LUBRICANTS

        Fuels for cold-weather operation of engines do not present much of

a problem, as satisfactory fuels are commercially available. Diesel fuels

conforming to U.S. Specification 2-102C - Grade C (Arctic) have been found

to give good performance in extremely low temperatures (Table VI).

Table VI. Diesel fuel, U.S. Specification 2-102C - Grade C (Arctic).

Test	Requirement
Cetane No., min.	40
Flash point, °F.	110
Pour point, °F.	−50
Cloud point, °F.	−40
Distillation:
90% recovery temperature, °F.	600
End point temperature, °F.	650
Carbon residue (10% bottoms), %, max.	0.15
Sulfur, % by weight, max. (preferably not more than 0.5%)	1 ✓
Kinematic viscosity at 100°F., centistokes	1.5-4.28
Water and sediment	Nil
Corrosion	Pass

        In selecting a diesel fuel for extremely cold weather operation, the

specifications of greatest importance are cetane number, pour point, and water.

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Cetane number correlates directly with ignition quality, or the ability of

the fuel to ignite and continue to fire. In general, the higher the Cetane

number, the more readily the engine will start. Pour point is important,

as the fuel must obviously be in a fluid state at the operating temperatures

encountered, so that it can flow freely from the fuel tank to the engine.

If the fuel contains water, the water will freeze in the fuel lines and

cause difficulty.

        Even if the fuel is free of water to begin with, it is rather difficult

to prevent entirely the entrance of snow and ice when refueling, or condensa–

tion from adding water to the fuel. It is common practice to add denatured

alcohol (½ pint to each 20 gallons of fuel) to the fuel, as the al d c ohol will ✓

mix with any water present and keep it from freezing in the lines. The alcohol

should always be added after the fuel is in the engine tan i k . If added in the ✓

storage drums or containers, it will dissolve ice and water in the container

and carry it to the fuel tan i k . ✓

        The first time alcohol is added, run the engine long enough to clean all

nontreated fuel out of the fuel lines, and clean any sediment bowls or settling

compartments.

        Servicing the fuel tank at the end of the day’s run will also help keep

water out of the fuel, as filling the tank drives out any moisture-laden air.

Never let a partially filled tank stand overnight or during a long halt on

the trail.

        Gasolines conforming to U.S. Specification 2-103C - Type C are recommended

for operations below 0°F., and have been found satisfactory for extremely low

temperatures (Table VII).

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Table VII. Gasoline, U.S. Specification 2-103C - Type C.

Test	Requirement
Octane No. (A.S.T.M.), min.	80
90% distillation temperature, °F.	302
Distillation residue, %, max.	2
Reid vapor pressure, lb./sq.in., max.	12
Gum, mg./100 ml., max.	4
Sulfur, %, max.	4
Corrosion	None
Tetraethyllead content, ml./gal., max.	3
Oxidation stability, minutes	430
Water and sediment	None

        Precautions for avoiding difficulty due to water in the fuel are the

same as those given above for diesel fuel.

        Development work is continuing on improving motor fuels for arctic

service, and significant discoveries have been reported. There are indi–

cations that the use of additives such as ethyl ether to diesel fuel will

greatly improve ignition quality. Other investigations now in progress

show promise of providing improved fuels for subzero work as time goes on.

        Engine Coolants . An antifreeze mixture containing 60% ethylene glycol ✓

glycol (Prestone, Peak, Zerex, etc.) and 40% water will give protection down

to −62° E F . The solution should be mixed thoroughly before being poured into ✓

the radiator. Check periodically with a hydrometer, and if additional coolant

is required always add thoroughly mixed 60% solution.

        Ethyl alcohol can also be used, but because of its relatively low boiling

point (173°F.) an appreciable amount may be lost due to evaporation. For this

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reason the more permanent type antifreezes are universally preferred.

        Lubricating Oils . Not too satisfactory an answer has yet been found to

the problem of lubricating machines at low temperatures. The principal

difficulty is in providing lubricants that are viscous enough to protect

working parts, yet fluid enough to afford reasonable ease in starting cold

engines, shifting gears in transmissions, and operating clutches.

        For example, good engine performances with maximum life and minimum

maintenance requires the use of a lubricating oil conforming to U.S. Speci–

fications 2-104B, which can be obtained in S.A.E. 10, 30, and 50 viscosity

grades. S.A.E. 10, the lightest, has a pour point of −10° to 20°F. This

means that for lower temperatures this oil must be dilute s d (preferably with ✓

kerosene) to achieve the required fluidity for starting. As the engine warms

up, most of the diluent is burned off, requiring the addition of fresh oil.

Before the engine is shut down, additional diluent must be added while the

oil is still hot in order that the engine can be started on the next occasion.

At best, this is an uncertain, rule-of-thumb pr e o cedure, but lacking a better ✓

solution, it gives fairly satisfactory results. The problem would be con–

siderably simplified by the availability of reliable heaters to warm the

crankcase oil, but the best answer would be engine oils that would remain

fluid at −60°F. and yet provide the required lubrication characteristics at

engine operating temperatures.

        A very thin oil has been developed for arctic service, designated S.A.E. 5

viscosity grade, which has a pour point of about −50°F., but this is a straight

mineral oil without the additives required for peak performance of heavy-duty

engines.

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        The current recommendations of one tractor manufacturer for engine

lubrication are: For operating temperatures above 30°F., use S.A.E. 30

(U.S. Specification 2-104B oil in the crankcase); 0° to 32°F., use S.A.E. 10;

−20° to 0°F., use S.A.E. 10 diluted with 25% kerosene; below −20°F., use S.A.E. ✓

10 diluted with 40% kerosene.

        These recommendations apply to all engine compartments where engine

lubricating oil is ordinarily used. In the case of oil bath air cleaners,

dilution is not recommended, as it is preferable to leave the oil cups empty

for temperatures below the pour point of S.A.E. 10 be oil. ✓ S

        The same difficulties which affect engine oils at low temperatures

apply to transmission oils and greases used in other parts of the tractor.

The general practice is to use S.A.E. 10 engine oil or S.A.E. 90 transmission

oil in transmissions, final drives, track rollers, etc., diluting as required

to establish fluidity or permit the shifting of gears.

        The individual manufacturer’s recommendations for oil change periods,

lubrication intervals, etc., should be followed.

       

MAINTENANCE

        Machine maintenance, of great importance on heavy machinery under any

operating conditions, takes on additional significance in the Arctic. Taking

a machine that is not in tiptop condition out on the trail in subzero weather

is taking a chance on not getting back home with it. Rigid adherence to

schedules is of extreme importance, and the extent of emergency repairs or

adjustments that have to be made in bitter cold, without shelter or established

repair facilities, is very limited. It must also be remembered that, should

failure of a critical part occur due to lack of maintenance or advance planning,

it might be weeks or months before a replacement can be secured.

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        Maintenance for individual machines is thoroughly covered in the published

literature of the various manufacturers, and with some elaboration these

recommendations hold true for arctic operations.

        Operators and mechanics should school themselves thoroughly in the

manufacturer’s recommendations, remembering the extraordinary need for

adhering to the letter to the specific instructions given. The following

suggestions supplement the manufacturer’s instruction books, to cover abnormal

maintenance required by the climate and trail conditions.

        Engine . Set up a service schedule to insure that the engine is properly

lubricated at all times with the correct lubricant for existing conditions.

Make sure the radiator is filled with the right antifreeze mixture, and

check the entire cooling system for leaks.

        Check periodically for loose or missing cap screws, bolts, fittings, and

wires, and make all required adjustments regularly. Replace immediately any

parts that show damage or deterioration, such as frayed fan belts and hose

connections. Remember that extreme cold shortens the service life of parts

made from rubber and fabric. It causes copper wire to become brittle, and

may have the same effect on iron and steel parts. Take care to avoid rough

handling.

        In general, ignition and electrical systems perform satisfactorily down

to −30°F. Below this temperature, cracking of the insulation on ignition

wires, excessive burning of distributor points, failure of condensers, and

the fouling of spark plugs occur and become maintenance problems. Check,

clean, and tighten all wiring connections, especially battery and starter

terminals. Check for breaks and shorts in high-tension ignition wiring.

        Clean distributor thoroughly, and adjust or replace breaker points.

It may be necessary to remove practically all lubricant from the breaker

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arm, to make sure that the points will close properly. Sluggish action

will cause pitting and failure to start at low temperatures.

        Clean and replace spark plugs, making sure that the porcelain is not

chipped or cracked and the point gap is correct. Setting the points about

0.005 inch closer than normally recommended seems to promote easier starting

under conditions of extreme cold. Check the battery, if one is required,

and make sure it is fully charged to a hydrometer reading of 1.275 to 1.300.

a battery with a reading less than 1.125 will freeze and crack at 0°F.

Check the generator and starting motor to see that the commutator is clean

and the brushes make good contact. Make sure the voltage regulator is

functioning properly.

        Remove and clean all fuel sediment bowls and water traps, and clean the

strainers. Drain any settling compartments in the fuel filters. Drain the

fuel tank periodically, and blow out the fuel lines.

        Tractor transmission and Final Drive . Except for the dilution of

lubricants at low temperatures, as already covered, transmissions and final

drives usually require only the regular maintenance and adjustments recommended

for ordinary operation in more temperate regions.

        Care should be taken to see that the drain plugs provided in dry clutch

compartments are in place. Keep clutches and brakes in proper adjustment at

all times.

        Tracks and Rollers . Tracks should be kept in proper adjustment. Too

tight adjustment causes rapid wear, absorbes additional engine power, and

places excessive loads on track parts should rock or chunks of ice get caught

in the tracks. When mud or deep snow is encountered, the track chains will

usually increase their tension and should be slackened to avoid damage.

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        Track carrier rollers may fail to turn due to a comb us ina tion of snow ✓

or mud packing around the rollers, and the stiffness of the lubricant.

When this happens, the heavy track chain drags over the immobile roller

and rapidly cuts a flat spot. A common remedy is to replace the carrier

rollers with a hard wood skid block.

        To simplify the lubrication of track rollers and idlers while on the

trail, it is customary to carry the lubricant pump in the heated wanigan to

keep the lubricant warm.

        Sleds and Wanigan s . Sled and wanigan running gear must be checked regu–

larly, and adjustments and repairs made as required. When traversing rough

terrain, constant attention should be given to bolts and chains, and to

adjustments, to reduce repairs and insure minimum drag on the tractors.

       

CONCLUSIONS

        While numerous improvements remain to be made in both equipment and

technique, the use of tractors and sleds for transportation and freight–

carrying in arctic regions will probably be for some time to come the most

dependable and economical solution to the supply problem for remote, inland

points. It is interesting to note the increases in tractor-train hauling

accomplished by the U.S. Navy in conjunction with their operations surround–

ing their petroleum reserve in the vicinity of Point Barrow. The net tons

transported by tractor train (per winter freighting season) increased from

4,676 tons in 1946 to 10,288 tons in 1949. The net ton-miles traversed

during the same period increased from 826,222 in 1946 to 1,265,884 in 1949.

In this period, one of the largest single freighting operations was accomplished. ✓

In the winter of 1946-47, three trains, totaling 13 miles in length, traveled ✓

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In the winter of 1946-47, one of the largest single freighting operations

was accomplished, when three trains traveled from Point Barrow, along the

Arctic Sea and up the Colville River to Umiat, a distance of 280 miles.

The three tractor trains, each made up of a series of units and each unit

consisting of a tractor towing five to seven sleds, with a track-laying

personnel carrier preceding the first train, stretched out for a distance

of 13 miles while in operation. Each train when closed up for refueling or

other purposes had a length of about 1,500 feet, while the closed-up length

of the three trains was possibly one mile.

        Basically, problems of operation and maintenance are not radically

different than those encountered in more temperate areas. Although the

employment of skilled and experienced operators would doubtlessly reduce these

problems, it should be noted than an entire tractor train was manned by

Eskimos (operators, trail scouts, and crew members) in the movement of material

over roughly 50 miles of sea ice from Point Barrow to a site east of Cape

Simpson, during the winter of 1947-48. Special equipment is available to

overcome, to a reasonable degree, the effect of extreme cold, deep snow, ice,

and muskeg. Machine maintenance is higher, principally for the reason that

for safety’s sake machines must be kept in tiptop condition at all times. The

maintenance problem is further complicated by the lack of access to complete

stocks of replacement parts and organized repair shops.

        When the investigations now in progress are completed, they will undoubtedly

bring into being new lubricants, improved fuels, and better designed machines

to cope with the unusual problems of the Arctic. This will mean additional

reliability and a simplification of the operational problems of using tractors

for transportation in the Far North.

       

Caterpillar Tractor Co.