Motor truck logging methods

Front matter

K5 Copy 1 jati.

BULLETIN ^ UNIVERSITY OF WASHINGTON

GINEERING EXPERIMENT STATION

Contents

Page INTRODUCTION 4

HISTORY OF TRUCK LOGGING 4

First use of motor truck in logging — Development of logging trailer—Possibilities in the use of motor trucks.

Introduction

In this paper an attempt has been made to bring together some useful facts concerning the apphcation of the motor truck to the logging industry. The term "motor truck" as here used is applied to the ordinary truck type of motor vehicle with trailer adapted to carrying logs, and does not include the "tractor" and the "caterpillar tractor." These latter types present special problems of their own. In the following pages the discussion of motor truck logging is premised upon conditions as they exist in the forests of the Pacific Northwest.

HISTORY OF TRUCK LOGGING

Motor trucks in the logging industry are a comparatively recent development. As nearly as can be determined, the first use of a truck in a logging operation was made in this region by Palms and Shields near Covington, Washington, in the spring of 1913. Since that time various types of road construction suitable for heavy trucks have been devised and the used of the motor truck for logging has steadily increased until at the present time there are about six hundred trucks operating in the woods in the Northwest.

The first real progress in the use of the motor truck for logging purposes came with the development of the trailer. Although the motor truck has been brought to its present high state of perfection in eastern factories the problem of adapting it to the hauling of massive logs was solved in Seattle, Washington, with the perfecting of a trailer which could carry unprecedented loads and stand up under the speed attained by a motor truck. In the early attempts to design a trailer, it was found that too great tractive effort on the part of the truck was required if the trailer was patterned after older types with simply increased dimensions in all of its parts. Through successive improvements the modern form of heavy duty trailer was finally evolved. It has solved a serious problem by permitting the hauling of heavier weights with the aid of the trailer than is possible with the use of the truck alone. With the help of the trailer and an adjustable reach, the motor truck has successfully entered the logging field.

In the Pacilic Northwest tracts of timber of sufficient area well situated for economical logging by old established methods are no longer plentiful. Almost every logging chance which exists today presents its own peculiar conditions and individual problems. An operator must therefore analyze the situation thoroughly before arriving at a decision as to the most economical logging methods that will apply in any particular case. Even in diiferent sections of the same operation it is often necessary to use different methods. Since proper cost accounting systems are not usually kept by logging companies, particularly the smaller concerns, these companies often do not know that they are losing money upon one part of an operation because the success of the whole absorbs this loss.

Pioneer log-g-ing with a motor truck in 1913.

The use of a motor truck has proved to be practicable in many instances, and bids fair to become of increasing importance. It will therefore be advantageous for every operator to inquire into its possible applications. It should be emphasized, however, that the motor truck is not economically adapted to all conditions. There have been many failures. Each projected application of the motor truck in the logging field must be thoroughly analyzed and if a doubt as to its successful performance exists, expert advice should be sought.

TRANSPORTATION OF LOGS— RAILROADS VERSUS MOTOR TRUCKS

The principal methods of transporting logs are by rail, by motor truck and by animal power. The last of these methods is, for obvious reasons, impracticable in the Northwest, and so needs no further comment. While it is impossible to give specific details in a general discussion of this kind to show where the motor truck may be more economically suited to the conditions at hand than the railroad, a comparison of the fundamental principles involved should enable any operator familiar with logging to determine whether or not to use the truck for his particular chance.

In general the choice between railroad and motor truck logging depends, fundamentally, upon two things : ( 1 ) comparative cost, and (2) adaptability. Sufficient motive power and rolling stock can be obtained much more cheaply for motor truck logging than for a railroad. There are, of course, many situations where the locomotive and car costs, as well as those of constructing a logging railroad, are obviously prohibitive, and the question revolves entirely upon the adaptability of the motor truck to existing conditions. There is no question at all that the logging railroad is not adapted to small, isolated and scattering tracts, and to certain portions of larger operations. There are almost innumerable tracts situated close to public highways, or where temporary roads can be built, which may be veiy serviceable during the summer months, giving ample time to clean up the timber before wet weather sets in. In such instances, road construction and maintenance costs are of very minor importance. In the larger operations and in the use of the motor truck as an auxiliary to railroad logging, there are many opportunities for the reduction of logging costs. However, it is impossible to discuss these problems specifically in a paper of this kind. They will need to be worked out on the ground with each case as a distinct problem. The fundamental problems covered in this paper will sen^e as a basis for the more detailed problems that must be solved on the ground.

Wherever the item of road construction is important, it may be stated in general that the time required and the cost of building roads for motor trucks are very much less than for a logging railroad. This is due to the lesser importance of grades, curves, ballasting, bridges and other construction work, all of which is much cheaper and takes less time. In case a pole road is built the material found adjacent to the right of way can be utihzed for what it costs to fell it.

From the standpoint of adaptability the motor truck is very flexible. It can operate on grades and curves that are impossible with the railroad. The whole logging equipment, including the donkey engine, can be loaded on the truck and trailer and easily moved from one setting to another. By replacing the log bunk with a platform the truck can take out all the smaller marketable material, such as shingle bolts, poles and cordwood. The modern truck can also be provided with the necessary equipment for use in snaking out the logs in stands of small timber and when used with a winch and an "A" shaped boom, will load itself. If the truck becomes mired in a mud hole, the winch may be used to pull it out. Finally, the item of fire risk is practically negligible.

COSTS

In order to arrive at definite figures as a basis for a comparison between railroad and motor truck transportation costs, the following case is cited as an example representing average good conditions :* A 5-ton truck with trailer was used, operating on a seven and one-half mile haul over ordinary unpaved roads. An average of four trips a day were made and the actual running expense for hauling was $.90^/^ per thousand feet. Adding to this the overhead expenses of interest, depreciation, etc., the total cost of hauling was $1.44 per thousand feet. The statement of this cost is as follows :

AcTUAi, Cash Outlay in Hauling 128,420 Board Feet oe Logs

Gasoline, 284 gallons @ $.19 $ 53.96

Incidentals — One electric light globe .35

Hardware 4.03

Blacksmith 3.00

* West Coast Lumberman, Nov. 1, 1916, page 266. Labor, g-as and oil have since advanced in cost.

ToTAi^ Expense of Hauung 128,420 Board Feet oe Logs Investment :

Trailer 700.00

Total Investment $5,600.00

Variable Charges

Gasoline, 284 gallons @ $.19 $ 53.96

Tires, $.07>4 per mile on 615 miles 46.12

Incidentals 7.43

Total variable charges $118.54

Depreciation — (based on 15% per annum on $5,600, less

Interest on amortized value at 7% .63

Storage, $5.00 a month .20

Driver @ $4.00 a day 4.00

Total fixed charges $6,179

Total variable charges $118.54

Total fixed charges at $6,179 a day for

Total cost $186.51

Follov^ing is a recapitulation of the work performed by a 5-ton logging truck, Jan. 20 to Jan. 31, 1916, inclusive. The logs were hauled from O'Neill's Camp on the Bothell-Everett road 7^ miles and dumped into Lake Washington at Bothell.

Date Trips Mileage No. Ft. Hauled Gas Used Oil Used

1/23/16 Did not haul. Roads in bad condition.

1/24/16

1/25/16

1/26/16

1/27/16

1/28/16

1/29/16

1/30/16

1/31/16

Total

8,894

2.25

5,200

*1.00

16,174

2.25

11,276

2.25

15,514

2.25

15,511

2.25

9,152

**2.25

12,336

2.25

128,420 284 23.50

Many loggers who have used both the steam railroad and the motor truck claim that the latter is preferable in some cases and often is the only method by means of which logs can be gotten to the mill at a reasonable cost. Where the stand is scattered and of poor quality, the building of a railroad is not practical. In such a case the motor truck may offer the only solution.

The motor truck makes the best showing when hauling from one "side." With a two or three side operation the railroad is by far the more practical. It must be remembered, however, that the railroad and the motor truck are not competitors in the logging industry — they are allies.

ROLLING STOCK EQUIPMENT

In general two plans are followed in building a motor truck. The first is to build a rigid truck so that it will resist all shocks and distortions that come from rough and uneven roads. The second plan is to build a flexible body so that the chassis will "give" rather than resist when subjected to hard strains. Although the rigidlybuilt truck may be entirely satisfactory for most forms of trucking, it is practically impossible to build one on the rigid principle that will stand up under the heavy strains to which a logging truck is subjected unless it is to be operated over good paved roads. When only ordinary unpaved public roads are available, flexibility is one of the most important characteristics to look for when selecting a truck. Where the operator is hauling over his own pole or plank road this consideration does not play so important a part, as the roaH bed then is more likely to be free from holes and irregularities.

* Freight truck in the ditch. Pour hours lost getting the road cleared. **Two hours lost at the landing due to a spring slipping out of place, whicli made it necessary to iinload and load again.

All makes of trucks are more or less alike in general construction, differing only in minor details, so that the personal whims of the buyer will largely determine the kind he will select. It is advantageous to have as long a distance as possible between the driver's seat and the bunk over the rear axle, in order to allow more of the load to be carried by the truck, and less by the trailer, giving better traction to the drive wheels, but necessitating extra strong rear springs and axles.

The type of power transmission best suited to the use of the logging truck is a question that has received a great deal of attention. There are three general methods of transmitting the power : (1) by chain; (2) by worm drive, and (3) by internal gear drive. Each has its advantages. It is claimed by many that the chain drive saves many hours of "shut-down time" due to the fact that if anything breaks in the transmission, it will be a link in the chain as this is the weakest point. It is then only a matter of a few minutes to insert another link. With the worm driven vehicle, a break in the transmission requires an expensive shut-down before the matter can be repaired. The worm drive, on the other hand, very seldom breaks if proper care is used.

The chain drive also allows the replacement of the sprocket with one of a larger or smaller diameter thereby giving a higher or lower gear ratio, which cannot be done with the worm gear. This seems to be of some advantage to an operator when changing his setting from one with a short haul and steep grades where a low gear ratio is required, to one where the haul is long and fairly level, and where speed in transit is an advantage.

On the other hand, in starting on slippery grades or wherever the traction is poor, the worm drive will give better traction than a chain drive because there is difficulty in taking up the slack that is always present in the chain before letting in the clutch fully. The slightest jerk given to the wheels when the slack is taken up is likely to cause them to spin, thereby losing all the tractive power of the drive wheels. In the worm gear there is no slack to take up and the power can be applied more gradually, thus reducing the chances of spinning the wheels and losing the traction.

The question of the weight of the truck used for logging purposes is not as important now as it will be in the future. Laws are being passed in nearly every state limiting the maximum weight to be carried on each wheel by trucks using state or county roads so that the total weight of the truck without load will be important. When operating over state or county roads the load is limited to from 2400 to 3000 feet, B. M., of Douglas fir, depending upon the locality. In such cases, it is an advantage to have a lighter truck, say one of 3^ tons capacity. By adding additional leaves to the rear springs of a truck of this capacity it may be made to carry a larger load than it would be possible to put on a 5-ton truck and still comply with the law. The pulling power of the 3j/2-ton truck and the 5-ton truck is practically the same so that the difference in dead weight between the two may be carried in a profitable manner by adding four or five hundred feet B. M. of logs. Another advantage of the lighter weight truck is speed. The 3^/2 -ton truck is geared to make from 14 to 16 miles an hour, while the 5-ton truck is usually limited to from 10 to 12 miles an hour.

Whenever the legal weight limit does not enter into the problem, as in operating over a pole or plank road for the entire distance, is it, of course, advantageous to carry the largest loads possible. In such cases a 5-ton truck with an 8^ -ton trailer is the most profitable investment. This allows a much larger load to be carried in proportion to the overhead charges. The disadvantage of fhe 5-ton truck is that it is very heavy and unless the roads are good, it will easily sink into the ground and cause trouble. A common fault of the 5-ton truck today is the overweight of the front end, which is too heavy for the width of tire on the front wheels. This can be very easily overcome by the use of wider tires.

LIFE AND DEPRECIATION

The life of a truck is directly proportional to the care that it receives, hence, a good driver is a most important consideration. If the right man can be secured his wages should be a ^secondary consideration.

The charge to be made for the depreciation of a truck is an uncertain question. Some loggers figure on the basis of four and a half years, others on as much as seven years. The depreciation charge on a truck used in the logging industry should depend largely upon the type of road over which it is operated. Loggers in general over-rate the life of their equipment because they do not fully realize the severity of the work. Over a fore and aft plank road or a cement road, where the jar and vibration are reduced to a minimum, the wear and tear on the equipment is very much less than where the truck is operated over a cross-plank road or an unpaved public road. The matter of depreciation, then, will depend largely upon the type of road over which the truck is to operate. In general a four-year depreciation charge less 25% sale value at the end of that time should be used as a basis for figuring costs unless the hauling conditions are very favorable. Only under very rare circumstances should more than four years be allowed. It should be remembered that the depreciation on a truck is very heavy during the first year, and the sale value at the end of a year is only half the original price. INIany truck operators now hauling over good roads who are depreciating on the basis of five years say that a four-year depreciation would be more nearly correct. Another factor in favor of a .four year depreciation charge is that methods of logging are changing constantly and that trucks in that time may be improved upon to such an extent that the use of the old equipment would be unprofitable and inefficient.

Swivel bunk on tiuck equipped for motor truck logging. The base on which the bunk rests is made of two heavy timbers about 18 inches by 24 inches in section and 4 feet long, bolted togetlier and clamped to the frame of the truck b.v means of lieavy N-bolts, (D). The bunk is fastened by a king-pin (E) to the base and is free to rotate upon a steel center plate and two side-bearing plates (F).

INSURANCE

The insurance rates on trucks depend upon the use to which they are put. The insurance usually carried by loggers covers fire and theft, although some companies also cany liability /and either collision or property damage insurance. The equipment can be insured for only ninety per cent of its value.

Fire and theft insurance is based upon the list price of the truck and body when new and the usual premium for the logging truck is one dollar for every hundred dollars of insured value. Theft rates on the trailer are based on a flat charge of twenty-five cents per hundred dollars of insurance taken, regardless of age, list price, etcetera.

Collision insurance is based upon the list price of the equipment and covers full value at the time of loss of the damage to the truck by colliding with anything movable or immovable.

The liability rate for logging trucks is $33.75 and is based upon occupation alone. This covers the public as well as the employee and is limited to $5,000 for one person and $10,000 for two persons or more.

The property damage rate for logging trucks is $13.50, and covers the damage done to the property of others. It is arrived at in the same way as liability insurance. The usual limit for property damage is $1,000.

TRUCK EQUIPMENT

Bunks. All trucks for use in log hauling are equipped with a patent bunk over the rear axle on which the logs rest (see illustration on page 13). This is essentially a steel I-beam (A) which grips the logs so that they will not slip. At each end of the bunk are V-shaped iron chock-blocks (B) held by chains which run under the I-beam and are fastened by an iron gooseneck hook (C) so that the load is kept from spreading. These blocks may be adjusted to any width of load. The whole bunk is mounted on a swivel so that it will turn with the logs when rounding a sharp turn in the road. When dumping the logs at the landing, each block is loosened from the opposite side so that the danger of the logs rolling ofif on the men is greatly lessened.

Tires. Solid rubber tires are generally conceded to be the best suited for the heavy dut\' required in logging. The use of steel tires is rapidly declining. The jar on the equipment is in itself enough to condemn their use. Rubber tires double the mileage of a day's work, more than double the life of the equipment, allow the weight of the equipment to be cut in half, and work well on dirt, cement, or any other type of road. The saving on the life of a pole or plank road by the use of rubber tires is also an item of considerable impqrtance. There are three general types of solid rubber tires in use on the logging truck : the so-called giant tires, the duals, and the non-skid or caterpillar tires. It is a question as to which of the three is the best. Traction for the drive wheels and also for the trailer wheels, if the latter are equipped with brakes, is the problem to be solved.

The duals are satisfactory with light loads and easy grades, on cement, brick, or other perfect surface road, but when the haul is heavy and the braking difificult on account of heavy grades, the larger single-tread giant tires are more efficient. During dry weather it is safe to work with the single-tread tires on grades as high as nine or ten per cent, but in wet weather a seven per cent grade should be the maximum unless some extra means are taken to secure traction, and even then the wheels will skid if particles of soil get on the surface of a plank i-oad, unless chains are used or the wheel is wrapped with a light cable.* For very heavy-duty trucking, where resiliency and long ser\'ice are prime considerations, the giant type is rapidly superseding the old dual type as the former contains more rubber and gives more mileage with the least truck vibration.

The non-skid or caterpillar tire may well be used on heavy grades or where the traction is very poor, the general opinion being that it gives a firmer grip on the road and makes it safer to handle the truck in wet weather.

There is no standard width of tread for truck wheels. The w^idths usually used on the drive w^heels of the logging truck and the wheels of the trailer are twelve and fourteen inches, respectively. The use of tires of smaller width on either trailer or truck cannot be recommended. The wider the tires on the trailer, the better it is both for the life of the equipment and for ease in handling the load. When the surface of the giant tires becomes worn down so that the grooves become very shallow, it is desirable to have the tires re-grooved. They will last a great deal longer if this is

* West Coast Lumberman. October, 1919. Page 25.

done and will also give better traction on the road. The groove makes the tire lobes act separately on the uneven places in the road so that only one lobe is subjected to the strain of the irregularities instead of the whole tire. This is also trvie with reference to the strains that are set up internally due to the twisting the the rubber.

LAWS GOVERNING THE OPERATION OF MOTOR VEHICLES

The Laws governing' the operation of motor veliicles upon tlie public highways of the State of "Washington are contained and summarized in Senate Bill No. 220, Session of 1921 of the Legislature of the State of Washington. They include the following provisions governing the operation of motor trucks and trailers:

(a) Chapter 153 of the laws of 1913 and Chapter 142 of the laws of 1915 are repealed.

(b) Motor truck vehicles weighing less than 1,500 pounds must pay an annual license fee of ten dollars ($10.00); Trucks weighing more than 1,500 pounds and not to exceed 6,500 pounds, ten dollars ($10.00) plus forty cents per hundredweight for all in excess of 1,500 pounds and in addition thereto fifty cents per hundredweight at the rated carrying capacity. Motor trucks weighing more than 6,500 pounds must pay a license fee of ten dollars ($10.00) plus fifty cents per hundredweight for all in excess of 1,500 pounds and in addition tliereto fifty cents per hundredweight at the rated carrying capacity. Trailers used as trucks sliall be classified and rated as, and shall pay the same fees as liereinbefore provided for motor trucks of like weiglit and capacity.

(c) No vehicle of four wheels or less whose gross weight with load is over 24,000 pounds is permitted to operate over or along a public higliway. Any vehicle having a greater weight than 22,400 pounds on one axle, or any vehicle having a combined weight of 800 pounds per inch-widtli of tire concentrated upon the surface of the highway (said width of tire in the case of solid rubber tires to be measured between the flanges of the rim) is also barred by the provisions of tliis law, with the following exception:

PROVIDED, that in special cases vehicles whose weight including loads whose weiglit exceeds those herein prescribed, may operate under special written permits, wliich mvist be first obtained and under such terms and conditions as to time, route, equipment, speed and otherwise as sliall be determined by tlie director of licenses if it is desired to use a state liighway; the county commissioners, if it is desired to use a county road; the city or town council, if it is desired to use a city or town street; from each of wliich officer or officers such permit sliall be obtained in the respective cases. Provided, tliat no motor truck or trailer shall be driven over or on a public highway with a load exceeding tlie licensed capacity.

Chain Drive. Trucks equipped with a chain drive should be supplied with an extra set of chains so that they may be changed and cleaned every week. To clean the chains, they should be soaked in kerosene which removes the dirt, grease and gum that has accumulated. By doing this the life of the chains will be quadrupled. The small amount of time that it takes will pay.

Top. The truck should come equipped with a top over the driver's seat that is easily detachable. In bad weather the driver should be protected from the elements, but the top should be removed in good weather as it is in constant danger of being broken during loading. Many operators leave the top off entirely and the driver must dress for the weather. A good demountable top will add to the comfort of the men and often helps to keep a good man at his job.

TRAILERS

The development of the trailer has made motor truck logging practical. Every truck has greater tractive power than it can utilize in the propulsion of the ordinar}^ load. Its limitations are due to a short-bulk carrying capacity and not to any lack of pulling power. The ordinary truck has a draw-bar pull of 2600 pounds. The draw-bar pull per ton of load varies from the minimum of 50 pounds on a level pavement to 250 pounds on a level dirt road, depending upon the character of surface.* Twenty pounds of additional pull are required for each degree of gradient. For example, a fore and aft plank road offers a resistance of about 60 pounds pull to a ton of load. If this were located on a seven per cent grade, it would require a 60 pound pull to overcome the load resistance plus seven times twenty or 140 pounds additional pull for the grade, a total of 200 pounds to pull one ton. Dividing 2600, the draw-bar pull of the truck, by 200, the resistance offered by road and grade, gives 13 tons as the load that can be pulled by the truck over this surface and grade. As this must include the weight of the trailer, which when equipped for logging is about three tons, it leaves a total of 10 tons that the truck can pull. This is equivalent to about 3000 feet B. M. of Douglas fir logs, the average load that is hauled. While such an adverse grade as cited in this illustration is avoided if possible with a loaded truck, the illustration will serve to show the pulling capacity of the truck. The hauling of loads of this size would be impossible without the use of the trailer. The normal load, then, may be increased two, three, or even four times, by the use of the trailer, over the maximum load that can be carried by the truck alone.

Objection to the trailer that it tends to shorten the life of the truck is hardly worth consideration. According to a careful analysis it has been estimated that the use of the trailer does not shorten the life of the truck by more than one 'year, which is of little consequence when the saving due to the size of the load that can be carried is taken into consideration.

Description of the Trailer: The frame of the trailer is constructed of heavy steel channel bars which support the twin bunks used for logging, and for the substructure to carry the body when used for other service. The steel frame is supported by semi-

* Operating Cost of Motor Truck Computed. Timberman. Feb., 1918. Page 60.

elliptic springs held by shackles similar to those of the truck. The springs rest secvn^ely upon the axle, are clamped to it by U-bolts, and are relieved from side stresses by radius rods which connect the axle to the frame.