UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE TRACTOR ON CALIFORNIA FARMS L. J. FLETCHER AND C. D. KINSMAN BULLETIN 415 December, 1926 UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA 1926 Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://www.archive.org/details/tractoroncalifor415flet THE TRACTOR ON CALIFORNIA FARMS L. J. FLETCHEEi and C. D. KINSMAN2 INTRODUCTION The cost of power and labor for crop production in California amounts on the average to approximately a quarter of a billion dollars annually, or between 40 and 60 per cent of the total cost. Of this amount, approximately one hundred and five million dollars is expended for power and one hundred and forty-five million dollars for labor. This means an average annual cost for these items of about eighteen hundred dollars per farm, or twenty dollars per acre of improved land. For this reason, the farm operator is very much interested in utilizing the most effective labor saving devices and prac- tices available and in selecting that type and size of power equipment that will give him the most economical results. The gas tractor represents at the present time the principal source of power for field work in California. It is particularly well adapted for the types of farming now being followed and, under the majority of conditions, it has been found to be the most economical and satis- factory field power available. Lack of sufficient mechanical knowledge in the choice of tractors and lack of skill in their operation, together with the extremely dry and abrasive nature of the soil encountered in some parts of the State, however, have made their successful use somewhat difficult on certain farms. The purpose of this publication is to aid the farmers of California in the choice and successful operation of their field power and to impress upon manufacturers and dealers the need of supplying tractors of the proper design and type to meet the special require- ments for farming in California. The information contained in this bulletin is based on data obtained from replies to questionnaires mailed in 1924, to all known tractor owners in the State, and from contact with tractor owners at short courses and in connection with other extension activities. Many of the photographs in this bulletin illustrate the less common uses of tractors. In general, the tractor should be economically em- ployed more hours per year, thus reducing the cost per hour by distributing the fixed charges over a longer period of use. 1 Associate Professor of Agricultural Engineering and Agricultural Engineer in the Experiment Station. 2 Agricultural Engineer, Division of Agricultural Engineering, Bureau of Public Eoads, United States Department of Agriculture. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION CHOICE OF POWER Each farm is an individual problem when the power requirement and choice of equipment are being considered because of : 1. Variation in the managing and mechanical skill and personal likes and dislikes of the farm operator. 2. Differences in type of farming and in practices followed in caring for and handling the individual crops. 3. Size, topography, and soil conditions of the farm. 4. Plans for future developments. 5. Relative cost of labor and of the various kinds of available power. 6. Kind and availability of hired power and possibility of doing custom work. 7. The ability of any one kind of power to do all of the neces- sary field work. 8. Climatic conditions, such as high temperatures at time of power application. 9. Available capital. 10. Other occupations, if any, of the farm operator. Since each kind of power has its advantages and disadvantages, each factor should be weighed in proportion to its relative importance as applied to the particular farm in question. The personal factor is a very important item in the choice of power. Some farm operators are mechanically inclined and much prefer tractor poAver if the other factors nearly balance, while others have a personal liking for animals and prefer to use that type of power under the same circumstances. It is generally conceded that for some operations animal power is more practicable than tractors; while for others tractors are the more satisfactory. Animal power is frequently better adapted for working in corners and other cramped or difficult places, and is much more flexible than tractor power because of the ease with which the size and combination of the units may be changed. A horse or mule also has a great overload capacity, that is, the ability to exert, for short periods, a force several times greater than that normally exerted. On the other hand, there are some heavy operations, such as subsoiling, beet lifting, rice field checking, and deep plowing and cultivation, where animal power can seldom be employed satisfac- torily. Fencing demands may be somewhat less when tractor power Bul. 415] THE TRACTOR ON CALIFORNIA FARMS is employed. In pulling large machines such as combined harvesters, the tractor takes less room on the turns and can get in closer to the fences, thus reducing waste land around the fields. Less hired ~^^*«i Fig. 1. — Planting six rows of beans at one time with a small tractor on the Geo. H. Wilson farm near Clarksburg. A six-row cultivator will be used later. Fig. 2. — Rice binders are mounted in front of tractors and are used to open checks. Considerable rice is thus saved which would normally be tramped down during the first round. The binder pictured cuts a swath directly in front of the tractor. help also is necessary, as a rule, throughout the year. Where there is sufficient work to keep the entire power equipment busy the greater part of the year, the logical arrangement is to keep both tractors and animal power and to use each where it is most efficient. This can b UNIVERSITY OF- CALIFORNIA EXPERIMENT STATION be accomplished without much difficulty on the larger farms or ranches, but is frequently impracticable on the smaller ones. In some cases and particularly on the smaller fruit ranches, the farm operator devotes only a part of his time to his farm work, occasionally being engaged in some other occupation during the remainder of the year. In such cases, the tractor has an advantage over animal power, since this type of power requires no care or attention while idle. The hiring of a part of the power for field work is a common practice in some parts of the State. Some farmers keep horses and Fig. 3. — A small tractor supporting the frame and operating a duster for treating grape vines with calcium cyanide dust in the Imperial Valley. depend on hiring tractors to do a part or all of their heavy work. Others who keep one or more tractors and no animal power, depend upon hiring horses to do the light work that cannot be done con- veniently or economically with the tractor. Can I Make Profitable Use of a Tractor on My Farm? The profit derived from the use of a tractor may be due to decreas- ing expense of farm power operation, to a better quality of work accomplished, or to doing some seasonal work more quickly and at more nearly the proper time than was possible with methods pre- viously employed. Many successful farmers, before considering definitely the pur- chase of any certain tractor, have carefully listed all of the work BUL. 415] the TRACTOR ON CALIFORNIA FARMS 7 which they expect it to do. The relative cost of performing this work by means of the tractor, as compared with the present methods, is next determined as accurately as possible. Owing to the extensive use of tractors in California, most dealers can now give a close estimate of the amount of the different kinds of work that their tractors will do per hour under the conditions encountered in each locality. It is advisable also for prospective purchasers to visit other farms where tractors are used and gain first-hand information concerning the size of implements operated and the amount of work done, as well as the general satisfaction given by the tractor, and its performance after Fig. 4. — Kidger and tapper used by Mr. Paul H. Gray in his citrus grove near Covina. With the outfit shown above, one man can ridge and tap ten acres a day. a few years' use. Sometimes it is well to discount somewhat the owner's statements of what he can accomplish with his tractor, although as a rule reliable information can be obtained after an explanation of the purpose of the inquiry. However, it is well to keep in mind the fact that the size of the tractor must be determined to a large extent by its ability to handle satisfactorily the heaviest load that will be assigned to it during the year. After a certain tractor is tentatively decided upon, it is well to determine next the approximate number of hours that it will be used annually in doing the work on the farm. In many cases, the sound- ness of the investment depends very much upon the amount of time the tractor is to be used. 8 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Data secured from questionnaires and other sources indicate that the average tractor in California is operated about 650 hours per year. However, many of the more successful farmers keep their tractors busy from 1000 to 2000 hours per year, thus materially reducing the cost of operation per hour. Studies made of tractors in use in the State indicate that the owner's estimate of the life of a tractor in years is, to a large extent, independent of the amount it is used per year. When a tractor is used only 300 or 400 hours per year, the fixed charges such as interest, depreciation, and repairs due to age, housing, and taxes, amount to . 5. — A tractor pulling a rice binder. Note that the binder mechanism is being operated by means of a power take-off from the tractor engine. This is one of the more recent tractor developments which is now being adapted to the operation of combines as well as of binders. This system of drive will undoubtedly be extended to many other farm machines whose mechanism is now operated by ground driven wheels. more than the operating costs ; while tractors used for from 1000 to 1500 hours per year show fixed charges amounting to somewhat less than one-half of the operating cost. There are occasions also when the tractor's ability to do a large amount of work in a short time is the deciding factor in its favor. This applies particularly to tillage in the spring or after rains or irrigation, as well as in some harvesting operations. Where sheep are allowed to graze in the field during the winter months, longer feeding periods are secured because of the fact that spring plowing may be delayed. The tractor is every year finding new ways of serving on the farm more efficiently. Belt power is taken from the tractor to drive Bul. 415] THE TRACTOR ON CALIFORNIA FARMS more stationary farm machines, while many new attachments are proving labor savers. The power take-off is being rapidly adapted to many farm tools. This device consists of a flexible extension shaft fitted with suitable couplings, universals, and sliding joints for transmitting power from the tractor engine directly to the mechanism of field machines as they are pulled by the tractor. When such machines as binders and potato diggers are driven through a power take-off, their operation is much steadier and the total power requirements are less than when Fig. 6. — A recent tractor development. This machine not only plows and operates other common tillage tools, but is also adapted to such practices as cultivating row crops and mowing. The mower shown above is operated by a power take-off. Practically all machines used with this tractor are designed for one man control. they are driven through a ground wheel. The use of this power take- off on such machines as spray pumping outfits also saves the cost of a portable engine. A modified type of tractor with high clearance has recently been developed to cultivate row crops in addition to performing the usual operations. Each year sees the development of new and more efficient farm tools especially built for use with tractors, and implement manu- facturers are finding it necessary to change from the making of animal drawn tools to special tractor tools in order to meet the demand. 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION What Should I Consider in Buying a Tractor? If a careful survey of all conditions indicates that a tractor is likely to be a profitable investment, the next question is the make and type to buy. The more important factors influencing the make of the tractor purchased are : 1. The cost of power during the life of the tractor, based upon initial cost, operating expense, repairs, and probable life. 2. The design and construction of the tractor itself, including quality of materials, workmanship, accessibility, and dust exclusion. Fig. 7.— Dust is the principal enemy of the tractor in California. This scene is quite typical of tractors operating tillage machinery on loose, dry soils where an efficient air cleaner is essential for low operating cost. If used without air cleaners, tractor motors may wear out in a few days of operation. Other parts of the machine, sucli as wheel and track bearings, should also be designed to exclude dust. 3. General suitability of the tractor to the kind of work to be done. 4. The general satisfaction given by the tractor after working, for a considerable period, under similar conditions on other farms. 5. Nearness of a dependable dealer who keeps a good stock of repair parts. 6. Stability and business reputation of the manufacturer. Protection of the tractor's mechanism from dust is an important consideration under all field conditions, particularly where the soil is of an especially abrasive nature. An efficient air cleaner is the first essential in protecting a tractor from dust, and regardless of the type, should not require attention more often than once a day. The BUL. 415] THE TRACTOR ON CALIFORNIA FARMS 11 location of the air intake has been found to have an important bearing on the amount of dust encountered. Wherever possible, a "peri- scope" should be placed on the air intake so that the supply will be drawn in above or in front of the tractor where the air is relatively free of dust. On most tractors, the crank case breather should also be equipped with a cleaner, and special means should also be provided to prevent dust from entering the wheel bearings, starting mechanism, magneto drive-shaft bearings, and housings of all moving parts. Means for proper and convenient lubrication of all parts are essential. However, there is a marked tendency in tractor design Fig. 8. — A tractor pulling a plane on sandy soil. The long spade lugs used on the tractor have proved very efficient on loose soils. toward the reduction of the number of lubricating places requiring frequent attention from the operator. The tractor motor should be provided with a positive devise for distributing oil to all wearing surfaces. An oil pressure gauge is desirable, to give a check on the pump operation, as well as an indication of the relative viscosity of the oil, and means should be provided for easily draining the crank case of all used oil. Oil niters and cleaners, which remove such con- tamination as dust and dilution from excess fuel, will reduce the engine wear considerably. These devices are now being perfected and will be available for attachment to the tractor engine. One of the most important matters in the selection of wheel tractors is the proper lug equipment so as to insure satisfactory traction. This especially applies to farms having sandy or very light soils. Owing to the fact that many tractors are now manufactured 12 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION for a world market and may be equipped with a wide variety of tractive devices, it is important that proper types be secured. In most parts of California, a fairly long spade lug has proved most efficient on wheel machines. Track type tractors need no additional lugs or special tracks except on marshy land or very soft soil. Many operators do not realize the loss due to wheel slippage. If this is due to overloading, the tool may be narrowed in many cases and the load thus lightened. Whenever a tractor wheel slips, the effect on the tractor as far as fuel and oil consumption and wear are concerned is practically the same as though the tractor had pulled the load an additional distance equal to the slippage. Positive steering control on both wheel and track type tractors is very essential in orchard or vineyard work. High bands on front wheels, proper weight distribu- tion, and properly designed swinging drawbars aid considerably in steering. Tractors with individual drives or clutches for the wheels or tracks can usually be turned shorter and are more positive of control. In this type of machine, however, it is essential that the steering clutches be of ample capacity and that they operate without slipping or grabbing. It is also necessary that, when turning, one driver be able to pull the load. "What are the relative advantages of track and wheel tractors?" This is a question frequently asked by the prospective tractor buyer. The opinions of about 500 of the owners who answered the question- naire are reflected by their replies to the question, "Which type of drive do you prefer — wheel or track?" The farmers who preferred wheel tractors listed the following reasons, which are given in the order of frequency: First cost lower. Wheels less complicated than tracks. Expense of up-keep less on the wheel tractor. Riding easier on rough ground for the operator. Those preferring the track type give as their reasons: Better traction on loose soils. No packing of the soil. Quicker and shorter turning. Less damage to road surfaces. It is quite evident from these replies that many of the owners had had experience with only the one type of tractor, that is, wheel or track. Recent developments in tractor design and construction are tending to improve the tractive ability of wheel machines by the Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 13 Fig. 9. — Tractors for orchard operation should have all projecting parts cov- ered, thus avoiding damage to trees. High bands on the front wheels and a swinging drawbar aid in steering. Note also the scrapers provided for cleaning the space between the spade lugs. This is one of the most effective methods of keeping the gr outers clean and thus aiding traction. Fig. 10. — Tractors may often be efficiently employed to pull a series of tools. On the tractor illustrated above, notice how the swinging drawbar aids the tractor in turning while pulling the heavy orchard disc harrow and clod masher. Note also the electric lights provided on the tractor for night operation. During cer- tain times of the year a very large amount of work may be obtained from a tractor by operating day and night without increasing the farm investment for equipment. 14 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION use of better types of lugs, and steering is made more positive by the use of better designed swinging drawbars and high bands on the front wheels. The life of the tracks on track machines is being materially lengthened by the use of more wear-resisting materials, by re-designing the track bearings to eliminate dust more effectively and by general improvements resulting from observation of types of track construction which have given trouble on previous models. A tractor should be equipped with an ignition system well enclosed against dust and provided with a rugged enclosed impulse starter coupling or other means of making starting easy under such adverse Fig. 11. — Because of its mobility and power, the tractor is the most common type of drive used for operating ensilage cutters. A good governor for the tractor engine is required for dependable and efficient operation. conditions as cold weather or stiffness from recent overhauling. The radiator should also be of rugged design and so made that the core may be removed and easily cleaned. Accessibility for the adjustment of parts, lubrication, and repair- ing are items which should be given careful attention by the pros- pective buyer. The parts which usually receive the most frequent attention are spark plugs, carbureter, moving parts of the ignition system, valve tappets, crank-shaft bearings, and fan belts. Fan belts should be eliminated wherever possible in the design. Provisions for efficient servicing of the tractor are important. This refers to large and easily manipulated openings in fuel tanks, radiator drains, air cleaners, and places receiving oil or grease. Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 15 For most classes of work an engine governor is very desirable. It prevents the racing of the engine ; makes field operation easier ; in stationary work insures a constant speed, which is often essential; and also provides protection from the racing of both the engine and belt-driven machine. Fig. 12. — Subsoiling 30 inches deep with a tractor in a foothill citrus grove. The ability to operate implements on steep grades is one of the requirements of tractors for foothill orchard work. Fig. 13. — Cultivating twelve rows of beans at one time on the Sutter Basin Company farm. Note that extension axles are used to place the driving tracks between the roAvs. In order that the cultivator may register with the rows, the common practice is to plant at one operation as many rows as are to be cultivated. It is well to consider the comfort of the operator. This relates particularly to the ease of steering, convenience of the control levers, sunshades, foot rests, location of the exhaust outlet, direction of fan discharge, which should not be toward the operator, and the use of fenders to protect the driver and guard him from dust. The line 16 UNIVERSITY OP CALIFORNIA EXPERIMENT STATION of vision should not be blocked by engine or radiator, and last but not least, a comfortable and properly located seat should be provided. There is usually a more or less direct relationship between the weight of a modern tractor and the amount of draft that can be exerted at the drawbar. Most of the modern tractors exert a pull equal to from 60 to 80 per cent of their weight. In other words, a tractor weighing 5000 pounds can usually exert a pull on the draw- bar of from 3000 to 4000 pounds. As a rule, however, a tractor operating in loose soil should not be expected to pull in excess of 60 per cent of its weight and still steer well and not suffer from slipping of the drivers. What are the Most Important Factors Influencing the Cost of Operating a Tractor f With very few exceptions the success of a tractor seems to be largely independent of the make, working conditions, or implements used, its success being influenced, rather, by (1) the ability of the farm operator to utilize the tractor to the best advantage, and (2) the character of the mechanical attention given the tractor. Many prospective tractor OAvners, when discussing costs of oper- ation, seem to be concerned chiefly with the fuel and oil costs. The replies to questionnaires sent to California tractor owners indicate that fuel and oil constitute on the average only about one-half of the total operating costs, the other operating costs being made up largely of interest, depreciation, and repairs. Some of the more successful operators, however, have found that these last items con- stitute only about one-third of the total expense. A number of the latter were questioned as to what they considered the most essential factor in the efficient utilization of a tractor. The following are typical answers: "Do not overload the tractor, but at the same time see that it is pulling the proper load. Avoid racing the engine and starting loads with jerks. This invariably causes rapid wear and breakage." ' ' Plan the work so that tractors will run as many hours as possible, and at the same time see that each tractor is made to pull the proper load and is doing the proper kind of work. The use of tools especially built for the work being done will increase the efficiency of the tractor and reduce the cost of doing the work." "Keep the tractor clean. We have a special rack and wash our tractors every night. We are certain this keeps a large amount of BUL. 415] THE TRACTOR ON CALIFORNIA FARMS 17 dust from working into the bearings, and it gives us a chance to inspect our tractors completely every day." ' ' Have but one man operate and care for the tractor. This insures more careful attention to lubrication and adjustment and permits the placing of responsibility, which it is difficult to do when more than one man operates the machine." Where a number of tractors are operated in a group or fleet, as on the larger farming enterprises, experience has shown that the best results are obtained by employing men who are familiar with farming operations to drive the tractors, entrusting to one or more well trained mechanics all mechanical care from minor adjustments to complete overhauling. Occasionally tractors are used to operate implements intended for either larger or smaller tractors or animal power units. This often results in overloading, with its attendant rapid wear or breaking of parts, or underloading and high cost per acre per unit of work accom- plished. Tractor owners may reduce the cost of operation materially by using combinations of implements, especially where one implement alone will not make a sufficient load. By carefully planning the work of the tractor in advance, one man saves much time which is otherwise lost in making extra trips to the machine shed for other implements or in traveling considerable distances between fields. A tractor service wagon in which fuel, oil, and grease, and certain spare parts are kept will prove a good investment. There is, however, little doubt concerning the importance of the operator in keeping down repair costs and loss of time. Regular and conscientious attention to such matters as lubrication and cleaning, and a knowledge of farm practices are qualifications as important as mechanical skill. There are, moreover, sections of California where severe dust conditions are encountered. Wear is more rapid in such sections, although proper design and construction of the tractor and careful maintenance tend to decrease the wear. That attention to mechanical details is important is evidenced by the following suggestions from successful tractor owners: 1 ' Keep the fuel and oil cans clean ; drain the crank case often, the frequency depending upon the dustiness of the work." " Watch the air cleaner. This is the most important part of the tractor as far as keeping down engine wear is concerned. See that it is functioning properly; time spent in caring for the cleaner is well invested." 18 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION "Watch the adjustment of the carbureter; keep the fuel mixture as lean as possible without heating the engine and causing lack of power. This will, to a large extent, prevent oil dilution and the forming of carbon." "Keep all bearings in proper adjustment. Do not wait for crank- shaft bearings to pound and wheel bearings to get so loose that they interfere with operation." Practically all of the 1800 tractor owners who answered the questionnaire gave definite information concerning certain features of tractor design. Owners were practically unanimous in mentioning the desirability of inspection plates on the engine, the value of engine governors, and adjustable drawbars; 83 per cent desired a service brake, and 90 per cent a clutch brake ; 50 per cent preferred three forward speeds, 45 per cent two, and only 5 per cent were satisfied with one speed. That easy starting is favored was evidenced by the fact that 98 per cent of those answering the questionnaire desired an impulse starter coupling on the magneto. Less than one-half of the replies indicated a desire that the tractor be suitable for row crop cultivation. Fourteen per cent stated that their service manuals were not satisfactory, some having received no manual at all. The main reasons given were that the books were : 1. Too technical, not being clear enough for average operator. 2. Written to cover older models and made no reference to new parts. 3. Lacking in detail and did not explain how to get at and repair inaccessible parts. 4. Without lubrication chart, there being oiling places mentioned which could not be found on the tractor. It is the manufacturer's duty to furnish each owner with a book containing complete instructions for operation, care, and repair of his tractor; in turn, the operator should study the book carefully and thus become thoroughly familiar with his machine. There are instances where unusual wear has resulted from the operator's over- looking some important place requiring lubrication or allowing some parts to get out of adjustment even when the manual of operation sent with the tractor contained complete instructions as to lubrication and adjustment. Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 19 Fig. 14. — The stationary gas engine furnishes 7 per cent of all power used on the farms in California. In many places these engines serve to eliminate a large amount of hand labor, thus materially reducing the cost of production or handling of farm products. I Fig. 13. — A small tractor adapted for cultivation of onions, wheel axle extensions and spade lugs. Note the drive 20 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION ANALYSIS OF FARM POWER COSTS The total amount of primary power used on farms in California amounts to approximately two million horsepower, and the horse- power hours developed annually by this power are over one billion. Though the cost of this power varies considerably, according to the kind and quantity being used, the average is just about nine cents per horsepower-hour and the total cost for all kinds used amounts then to approximately one hundred million dollars per year. 3 TABLE 1 Approximate Amount and Cost of Power Used on Farms in California ' Number of units Average primary H.P. per unit Total primary horse- power Average H.P. hours per primary H. P. per year H. P. hours per year* Cost per H.P. hour, cents] Total annual cost Type of power Total Per cent (in mil- lions) Horses and mules.. Electric motors Tractors Stationary engines.. Windmills 305,500 35,000 35,000 30,000 26,000 25,000 1 14 13t 6 V* 20 305,500 490,000 455,000 180,000 13,000 500,000 650 1,130 600 § 450 800 100 198,575,000 553,700,000 273,000,000 81,000,000 10,400,000 50,000,000 17 47.5 23 7 1 4.5 23 3 10|| 6 5 20 45.7 16.6 27.3 4.9 .5 10.0 Totals 1,943,500 600 1,166,675,000 9 105.0 * Tractors and animals furnish practically all the power used directly for field work. About 95 per cent of the power developed by tractors and 75 per cent of the animal power are used for this purpose. t The cost figures given include fixed and operating charges but not operator's time. Wages for the operator were excluded in these computations because they vary indirectly with the size of unit used, and also because in many operations much of the time of tne operator is devoted to manipulation of the machinery used rather than caring for the power unit. % Drawbar rating. § Includes belt work, which is a small percentage of the total. || Cost per drawbar horsepower-hour. Belt power is approximately half of the amount shown. 3 Power is the term used for indicating the rate of developing energy or of doing work, and is usually measured in foot pounds. One horsepower represents the power equivalent to performing work at the rate of 33,000 foot pounds per minute. For example, a horse walking two and a half miles per hour or 220 feet per minute and exerting a pull of 150 pounds on the singletree would be developing power at the rate of one horsepower (220 X 150 1= 33,000 foot pounds). A tractor traveling three miles per hour or 264 feet per minute and exerting a pull of 1500 pounds on the drawbar would be developing 12 horse- power (264X1500 = 396,000 foot pounds. And 396,000-^33,000 = 12 horse- power). An ordinary farm horse will be developing power at the rate of approxi- mately one horsepower while doing heavy plowing or disking. A horsepower-hour is equal to 33,000 X 60 = 1,980,000 foot pounds and is the common unit used for measuring quantity of work done. An ordinary farm horse will develop, on the average, approximately five horsepower-hours of work during a ten-hour work day. The term "horse hour" is used frequently in farm accounts and should not be confused with the term horsepower hour. A "horse hour" is the time of one horse for one hour and has no connection with the amount of work done during the hour. Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 21 Table 1 shows the approximate amount and cost of each principal kind of power used on farms in California. It will be seen from this table that animal power furnishes about 17 per cent of the total power, electric motors, 47 per cent, tractors, 23 per cent, stationary engines 7 per cent, windmills 1 per cent, and motor trucks 5 per cent. Fig. 16. — Tractor cultivating five rows of cotton with cultivators originally designed for two rows each. Note center extension shovels so that a fifth row is included. Two men cultivate 60 acres per day. .-".-- 1 Fig. 17. — Plowing and operating combined harvesters on large grain ranches were two of the first uses for tractors in California. Smaller combines with auxiliary engines are now being used, the tractor serving only to pull the machine. 22 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Of the kinds of power shown, horses, mules, and tractors are those used primarily for field work. About 75 per cent of the animal power and 95 per cent of the tractor power developed are being used for this purpose. Electric motors represent the largest quantity of any kind of power used on farms in California, but its use consists almost entirely of stationary work such as pumping for irrigation and drainage. A small amount of stationary engine power is utilized for field work by means of cable outfits. This application, however, is confined almost entirely to preparing the ground for sugar beet production and the cultivation and harvesting of this crop. Cost of Field Power The cost of using any kind of power is made up of two major items, namely, fixed costs and direct operating costs. The fixed costs are those items which occur independently of the amount the power unit is used; the direct operating costs are those that vary with the amount of power that is developed. In the case of tractor power, the fixed charges consist of interest on investment, housing, taxes, insurance, and depreciation, repairs and replacements due directly to obsolescence or non-use; and the direct operating costs include such items as fuel, lubricating oil, grease, wages of the operator, and depreciation, repairs and replace- ments due directly to wear. If animal power is being considered, the fixed charges include interest on investment, housing, taxes, insurance, the value of feed consumed, and care required when not used for work, and the depreciation due directly to aging ; while the direct operating costs consist of the extra feed and care required, operator's wages, and the extra depreciation that will take place w T hile the animal is being worked. Since the fixed costs must be prorated against the power actually developed in order to determine the cost per unit of power utilized, the number of hours the power equipment is u§ed annually has a very decided bearing upon the total cost per horsepower-hour. If the power equipment is used only a few hours each year, the fixed costs represent the larger part of the cost of the power ; while if the annual use is large, the fixed charges become small compared with the direct operating costs. Table 2 shows the approximate cost per horsepower-hour and the annual cost per rated drawbar horsepower of using tractors in California under 1926 conditions, wages for the operator not being included. Table 3 shows similar figures for animal Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 23 power. The data for cost of tractor operation is based upon replies obtained from about 500 tractor owners, practically all prominent makes of tractors being represented, while the animal power costs are based on data from various farm management and other cost- production studies. Figure 18 shows graphically the data contained in tables 2 and 3. TABLE 2 Approximate Cost of Tractor Power in California under 1926 Conditions* Average annual fixed cost of keeping a tractor per rated drawbar horsepower $21.00f Average direct operating costs per drawbar housepower-hour developed by tractor: Fuel, lubricating oil and labor for servicing tractor $.04 Depreciation and repairs due directly to use 02 Total $.06 Total fixed and direct operating costs per drawbar horsepower-hour and per year for different amounts tractor is used annually: Power developed annually per rated drawbar horse- power of tractor Fixed costs per horse-power-hour of power developed Direct operating costs per horse- power-hour of power developed Total costs per horsepower-hour of power developed* Total annual cost per drawbar horsepower of tractor H . P. hours Cents Cents Cents Dollars $21.00 100 21.0 6.0 27.0 27.00 200 10.5 6.0 16.5 33.00 300 7.0 6.0 13.0 39.00 400 5.3 6 11.3 45.20 500 4.2 6.0 10.2 51.00 600 3.5 6.0 9.5 56.00 800 2.6 6.0 8.6 68.80 1000 2.1 6.0 8.1 81.00 1200 1.8 6.0 7.8 93.60 1500 1.4 6.0 7.4 111.00 2000 1.1 6.0 7.1 142.00 2500 0.8 6.0 6.8 170.00 * Wages of operator while in field not included. t The fixed costs include interest, taxes, insurance, and housing computed at 10 per cent on an average investment of $57.00, and depreciation and repairs due to age, at 14 per cent on an average first cost of $105.00 per rated drawbar horsepower of the tractor. It should be noted that in the case of tractors and animals the cost figures shown are only for a single drawbar horsepower. The approximate cost of operating any certain size of power unit may be obtained by multiplying the costs given by the rated drawbar power of the tractor or by the number of animals in the size of team being used and adding to this the wages paid or allowed for the operator. For example, if we take a tractor of ten drawbar horsepower used an average of 500 hours annually, and an operator who is paid or 24 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION TABLE 3 Approximate Cost of Animal Power in California under 1926 Conditions* Average annual fixed costs of keeping each work animal $92.00f Average direct operating cost per horsepower-hour developed by each work animal .09 Total average fixed and direct operating costs per horsepower-hour and per year for different amounts of time work animals are used annually: Power developed annually per work animal Fixed costs per horsepower-hour of power developed Direct operating costs per horse- power-hour of power developed! Total costs per horsepower-hour of power developed Total annual cost per work animal H. P. hours Cents Cents Cents Dollars $92.00 100 92 9.0 101 101.00 200 46 9.0 55 110 00 300 31 9.0 40 120 00 400 23 9.0 32 128.00 500 18 9.0 27 135.00 600 15 9.0 24 144.00 800 11 9.0 20 160.00 1000 9 9.0 18 180.00 1200 8 9.0 17 204.00 1500 6 9.0 15 225.00 2000 5 9.0 14 280.00 * Wages of driver not included. t The fixed costs include cost of feed and care while idle, shelter, interest, taxes, insurance, equip- ment and depreciation due to age. (See California Agricultural Experiment Station Bulletin 401.) t Direct operating costs include additional feed and care required while in use and increased depre- ciation and mortality due to use. 1000 1500 2000 Horsepower-Hours Developed Annually Fig. 18. — Approximate operating cost of horse and tractor power for different amounts of work performed annually. Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 25 allowed 50 cents an hour or $250 for operating the tractor during the season, then the approximate cost of operation per hour and per year may be obtained as follows: From table 2 or figure 18, w^find that the average cost for using a tractor 500 hours annually is 10.2 Fig. 19. — Land leveling is one of the common tractor operations in California. Small levelers are made for one man operation and are placed either behind or in front of the tractor. Fig. 20. — A tractor performing an operation formerly requiring three trips of a team and man through the vineyard. The sharp-edged bands on the wheels cut the sucker vines, a float levels the soil between the vine rows, and a scraper forms a ridge along one side. Later, trays containing the drying raisins are placed with one edge on the ridge, thus allowing more rapid drying. 26 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION cents per horsepower hour, or $51.00 per year per drawbar horse- power. Then, the total cost of operating a ten-horsepower tractor under these conditions will be ten times $51.00 plus $250, or $760 per year. If, on the other hand, the tractor is used 1000 hours annually, we find from table 2 or figure 18 that the cost will be 8.1 cents per horsepower-hour or $81.00 per drawbar horsepower. Ten times $81.00 plus 50 cents times 1000 for the operator gives a total cost of $1310 per year. Computations for animal power may be obtained in a similar way by using the data from table 3 or figure 18. It will be noticed from these examples and from the tables that as the number of hours the power unit is used annually increases, the cost per hour of operation decreases. Depreciation and Upkeep of Field Power Depreciation of either tractors or animal power is due to two principal factors, namely, aging or obsolescence, and wear and tear, when in use. The useful life of the average farm work animal is probably about ten years, and the average amount such an animal is used annually in California is about 1300 hours, during which time it develops an average of one-half horsepower-hour of power per hour, or 650 horsepower-hours of power per year. If the animal were worked continuously for eight or ten hours per day during each day of the year, it would probably develop at least 2000 horsepower hours of power during the year, but it would be practically worn out and useless at the end of three or four years of such service. On the other hand, if it were worked only a few hours a year or not at all, its period of usefulness would probably not exceed twenty or twenty-five years. This means that a depreciation of 4 or 5 per cent of the maximum value of the work animal should be included under the item of fixed charges and that sufficient additional amounts should be included under the item of fixed charges and operating charges to take care of the depreciation due to use. In the case of tractor power, a determination of the depreciation charges is much more complicated than with animal power because of the variation in the design of the tractor and the quality of materials entering into the construction of the different designs and makes of tractors, the radically different conditions under which tractors are required to work, and the great difference in the Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 27 mechanical skill of the operator and his conscientiousness in caring for his machine. In the reports obtained, 465 tractor owners gave their estimate of the life of their machines, together with information as to the amount they were being used annually. The amount the tractors were used varied from less than a hundred to more than twenty-five hun- dred hours per year and the estimated life from three years to more than thirty. Grouping the reports according to the number of hours the tractors were used annually and averaging the estimates of the length of life of the tractors in each group give some idea of the relation existing between these two factors. The results of this grouping is shown in table 4 and figure 21. TABLE 4 Estimated Life of Tractor as Influenced by Annual Use* Number of hours used per year Number of reports Average age at time of reporting, years Estimated life, years Hours used in 1923 Estimated life in hours of use 200 and less 61 3.49 8.72 154 1,346 201- 400 149 3.23 8.09 312 2,524 401- 600 112 3.39 7.83 497 3,894 601- 800 53 3.17 7.49 695 5,207 801-1000 36 3.57 6.96 920 6,402 1001-1400 37 2 80 7.54 1160 8,745 1401-1800 12 2.66 6.38 1525 9,728 1801-2200 2 2.75 6.50 2075 13,488 2201-2600 3 3.19 5.66 2441 13,814 3.27 7.84 547 4,287 * This table is based on data from 465 of the 1800 answered questionnaires received. Only the questionnaires which were completely filled out were used in this computation. It will be seen from this table that while the average amount the tractors in each group were used varies from 154 hours to 2441 hours a year, the average estimated life only varies from 8.72 years to 5.66 years, and that the average tractor becomes obsolete after about nine years, even if it is not used at all. This means that an amount equal to about 11 per cent of the first cost of the tractor should be included under fixed charges to cover obsolescence and that a sufficient addi- tional amount should be included under the operating charges to take care of the direct wear. 28 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 15,000 ^10,000 ■-55,000 y < / Z ±s / ° /o -7 .- a. < LV / \ e^ L £E IT ± Y^ ^RS ■ ^e / / / / / t 1000 Hours Used Annually 2000 Fig. 21. — Kelation between the hours tractors are used annually and average total life in years and hours of use. the DETERMINING SIZE OF TRACTOR The size of tractor best suited for any certain farm depends partly upon the amount of work to be done and partly upon the nature of the operations to be performed. It is shown under the discussion of cost of operation that the more a tractor is used annually, the cheaper will be the cost per hour of use. Since it usually requires more time to accomplish a given piece of work with a small tractor, such a tractor would prob- Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 29 ably be used a greater number of hours in a year, resulting in a lower cost per unit of work done than when a larger tractor is used. This rule will not hold true in every case, however, because the wages of the operator are usually greater per unit of work accomplished with a small power outfit than with a large one. Up to a certain point, therefore, as the size of power unit employed is increased, the cost per unit of work done is decreased because of a saving in oper- ator's wages. Beyond this point, however, the extra cost of operating the tractor more than offsets the saving in wages. This is illustrated 1250 1000 833 667 Total Hours Tractor is Used per Year 500 400 333 286 250 222 200 1500 1000 500 8 10 12 20 25 30 35 40 Size of Tractor - Drawbar Horsepower Fig. 22.— Comparative cost of doing 10,000 horsepower hours of field work per year with tractors of various sizes. in figure 22 for a specific case of 10,000 horsepower-hours of work to be performed with a tractor annually. In this particular case, the most economical size of tractor would be about 15 drawbar horse- power. It should be noted, however, that if more or less work per year were to be done, that if a considerable part of the work were such that a 15 horsepower tractor could not be used efficiently, or if the wages of the operator were different, the most economical size of tractor would also probably be somewhat different. There are two other factors which also may have an important bearing on the size of power unit : In the production of most crops, there are some operations that affect the crop yield materially if they are not done at the proper time. In such cases, it is possible that 30 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION a larger outfit than the most economical one would prove more profit- able because of the possibility of its doing the work faster. In other cases, there are such necessary operations, as subsoiling, which may require a greater minimum amount of power than is the most economical for the remainder of the work. Usually under such con- ditions, not economy but operations to be performed control, to a considerable extent, the size of power unit to be selected. Other factors influencing the size of the tractor to be purchased are : amount Fig. 23. — A five-standard subsoiler operating on a farm of the California Packing Corporation. Subsoilers and deep tilling cultivators are used extensively on California farms. Owing to their deep penetration draft requirements are high and they are operated almost altogether by tractors. of custom work, if any, to be done ; the value of that part of the operator's time not devoted to the driving of the tractor; possibility of hiring other power ; belt uses, such as operating a pump or ensilage cutter; and the number of horses replaced or disposed of. There is sometimes a tendency to purchase too light or too small a tractor, because the work of the machine is based upon the existing practices rather than upon the probable developments in the use of heavier machinery and deeper tillage, which frequently follow the purchase of a tractor. Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 31 Fig. 24. — A large tractor pulling a "V" crowder which is constructing in one operation a levee for rice growing. The speed with which levees may be built by this method is a great advantage. Fig. 25. — Steam cable outfit pulling a six-row beet lifter on a ranch near Spreckels, California. This outfit consists of two large steam tractors, one placed at each side of the field. The implement is pulled across the field by cables connected to drums on the tractors. 32 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION RESPONSIBILITY FOR THE SUCCESS OF THE TRACTOR The manufacturer, dealer, and owner all have a responsibility in the success of the tractor. Responsibility of the Manufacturer The manufacturer, in the design of his tractor, should consider the incorporation of proved features which will lower the operating costs, such as 1. Accessibility of parts for lubricating, adjusting, and replacing. 2. The reduction of wear by better dust protection, and the use of wear-resisting materials. 3. The reduction of the cost of parts most frequently replaced because of wear. 4. The introduction of devices for better economy in the use of fuel and oil. The comfort and safety of the operator should be considered. An easy starting system for the engine is highly desirable. In keep- ing with the price, all materials and such accessory parts as magnetos, carbureters, and spark plugs of high quality should be provided, together with accurate workmanship to allow ease in the replacing of repair parts. Manufacturers, as far as it is practicable to do so, should adapt their tractors to meet successfully special conditions which are encountered in the production of certain crops. A complete, well-illustrated service manual and list of repair parts should be furnished with each tractor. The manufacturer should select dealers carefully and insure good repair stocks and service. Responsibility of the Dealer The dealer should know the farm conditions in his territory so that he can advise the farmer accurately as to the suitability of his tractor for various types of soils and crops. He should also keep on hand all repair parts likely to be needed by the owner and should establish means of obtaining, without delay, other parts from the manufacturer. Competent, courteous service men should be employed, and each new owner should be given complete directions and instruc- tions as to the care and operation of his tractor. BUL. 415] THE TR ACTOR ON CALIFORNIA FARMS -33 Responsibility of the Owner The owner also has a certain responsibility. He should not use a new tractor for his heaviest work but should break it in gradually, just as he would care for a new automobile. At no time should a tractor be overloaded, overspeeded, or jerked. Care should be taken to provide ample lubrication, and the working parts should be in- spected at intervals and adjusted, if necessary. All owners should become familiar with the instruction book and attempt to carry out the directions of the manufacturer. TRACTOR COST RECORDS The real value of keeping records of tractor operating costs and performance is emphasized by the following excerpt from a report by a tractor expert after he had visited a number of farms in Cali- fornia : "I was especially impressed with the fact that in successful tractor operation a competent operator and good bookkeeping were factors of equal or greater importance than any other two factors entering into the situation. Almost without exception where the tractor was in the hands of a good operator and careful records of its performance were being kept, the owner was well satisfied with the work of the machine." Many starting to keep records on a tractor make the mistake of trying to use a very complicated system. A few suggestions for keep- ing a tractor record follow: 1. Plan a system simple and easy to keep. 2. Enter daily an account of hours of work, kind and amount of work done. 3. Record the amount and cost of supplies used by the tractor, such as fuel, oil, and grease, as well as repair parts, labor, and repairing. If these items are purchased separately, entries may be made when the supplies or repair bills are received or when payments are made. If fuel and oil, how- ever, are drawn from a common storage, some convenient system should be provided for indicating their use. Taxes should be included on this record. 34 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 4. Record the total time of operator in driving, servicing, or repair- ing the tractor, including the amount of wages plus the value of board, lodging, or other perquisites. 5. Enter for later reference first cost of tractor and tools or extras purchased for use in repairing or operating of tractors. Fig. 26. — On larger ranches, factory production methods may be used to advantage. Above is a reproduction of a typical daily chart taken from one of the tractors used on the James Mills Orchard Company ranch near Hamilton City. A mechanic is placed in charge of all tractors on this ranch. A certain amount is agreed upon at the beginning of the year as a reasonable hourly cost for each tractor. The mechanic then receives a bonus at the end of the year if the operat- ing cost is less than that previously agreed upon. Operators are paid on the time clock basis, and when their tractor is in the shop for repairs they draw only the current day laborer's wage. This system provides an incentive to keep their machines in good repair and operating in the field, thus securing a very low cost per hour for tractor operation. Bul. 415] THE TRACTOR ON CALIFORNIA FARMS 35 The following is a convenient form for a tractor record: Tractor Work Eecord Month Day Hours worked Kind of work Amount Remarks If a common fuel supply is used for tractor, truck, and automobile, list fuel for tractor on a separate card. Where the tractor is filled with fuel daily, the entire work and field record may be kept on a card placed in some convenient location near the fuel tank. Tractor Cost Eecord . 1. Make of tractor Model Serial No Engine No 2. Cost of tractor Cost of tools or extras purchased for use in repairing or operating a tractor 3. Taxes on tractor 4. Supplies, repairs, etc., used by tractor: Month Day Item (such as fuel, oil, grease or repairs) Bill number Cost Remarks Fig. 27. — Making nine irrigation furrows in one operation in an orange grove. 15w-12,'26