This SAE Surface Vehicle Electromagnetic Compatibility (EMC) Standards Manual provides a comprehensive compilation of the SAE documents pertaining to the measurement of electromagnetic characteristics of vehicles, motorboats, agricultural machinery, earthmoving machinery, and other internal-combustion- engine-driven equipment. The documents also apply to electrically driven vehicles including boats, golf carts, and similar equipment. (Aircraft, trains, and electric trolleys are specifically excluded.)
MUCH study has been given by the author to the history and development of the pneumatic tire in preparation for the writing of this paper. He found in THE JOURNAL of the Society a great wealth of detailed information in papers extending back to 1913 and gives a comprehensive and interesting review of the earliest patent, taken out in England in 1845, and later patents on fundamental ideas. Successive improvements are described, progressively increased section size and reduced inflation-pressures are set forth, truck and motorcoach tire developments and trends are discussed at length and new types of tire that have made their advent in the last two years are described and illustrated. Among these new tires are the airplane and passenger-car airwheel or super-balloon, the lug-type pneumatic for industrial tractors and road-building machines, the startling development of the airwheel or super-balloon for farm tractors and the pneumatic tire for rail-cars.
A tract comprising several acres of “tamarack” swamp, drained with tile the previous fall and cleared of stumpage the following spring, was utilized to obtain accurate information regarding the tractor and the plowing equipment required for the heavy operations of first breaking of the peat soil, which was from 5 to 7 ft. deep. The paper describes the equipment used, gives details of the procedure and presents the data that were obtained. Three different types of tractor and two types of plow, the latter having either a marsh or a breaker bottom and equipped both with and without a furrow pusher were used. Specifications of the tractors and the plows are given and commented upon, graphs and tabulations of the results being presented also. Power requirements on timbered peat and on grass marsh are compared and the efficiency of the plowing equipment is discussed.
Rapid wearing out of the engines of farm tractors, trucks and automobiles led the University of California to undertake a study of the dust problem and the efficiency of air-cleaners in removing field and road dust from the air before it passes into the engine. Work was begun in 1922 and several reports have been made on the methods devised and the progress made during the last 2 years. Results to June, 1924, were given in the paper published in August, 1924. The present paper gives results of the studies to the end of 1924 and includes data from tests of 12 new makes or models of air-cleaner not previously tested or not fully tested. Of outstanding importance is the discovery that the quantity of dust inspired by any cleaner or carbureter is greatly reduced if the intake is placed high and faces away from the direction of motion of the vehicle.
Inasmuch as horses cannot meet the demand for increased farm power, the tractor must come at once. So far the supply of tractors has been entirely inadequate to meet the demand. The author specifiies some of the problems that confront designers of farm tractors. To make the tractor immediately available for farm work, it must be adaptable to practically all of the existing types of horse-drawn implements, besides furnishing belt power for a wide variety of present power-driven farm machinery. In designing tractors it must be remembered that the horse is a very flexible unit, capable of a wide variation in power output. Designing a tractor to furnish the necessary power for the majority of farm conditions, requires an intimate knowledge of crops, soils and farm management. These must be analyzed carefully so as to make the machine have as wide a range of usefulness as possible.
The author first points out how increasing population and rising standards of living have increased the demand for foodstuffs and how such industrial activities as are brought about by the present conflict magnify the seriousness of the food problem, not only by withdrawing workers from the farms, but also by increasing food consumption on the part of those engaged in the speeded-up industries in order to supply the increased human energy required. The author then passes to a discussion of the tractor as a means for increasing the food supply by taking the place of withdrawn labor and cheapening production. Several charts show the effect of increased individual activity on food consumption, the relation of food consumption to standards of living and the growth of population, the variation of food demand during political activities during the past century, and the relation of the cost per calorie of various cereals.
The author first considers the size of farm on which tractors can be used profitably. Confining his remarks to certain of the central and north central states, he points out the fact that there is a strong tendency for farms from 20 to 100 acres to be combined with others to make units of a more efficient size for the application of modern farming methods. Farms from 100 to 500 acres, representing 65 per cent of the total farm acreage, are the greatest users of tractors. Farms over 500 acres contain 25 per cent of the farm land, and also represent an important tractor market. Efficient sizes of tractors are next treated; three and four-plow sizes are generally preferred. Belt work, representing 50 per cent of a typical tractor's work, and other special duties performed by the tractor are next referred to.
After a few general introductory remarks the author outlines the operating requirements for tractors, and takes up the matter of the proper sizes of tractors, stated in horsepowers per given number of plows. The use of lower-grade fuels, value of water in the engine, cylinder construction, methods of lubrication and design of drive-wheels are the subjects covered by the balance of the paper.
The farm tractor is finding itself among the most essential of mechanical agricultural devices; the industry is young, and controlling basic factors of design are not yet completely crystallized, nor has research had its proper share in the development. Some further factors of the author's earlier article on tractor plowing speeds2 are discussed in this paper. The earlier article dealt chiefly with plowing data on the assumption that there was delivered at the drawbar of the tractor a constant horsepower. This paper starts with a normal condition of a constant engine power which is to be delivered to the crankshaft under governor control for any of the travel speeds analyzed. The tractor is considered as powered by a given brake-horsepower engine, this power being transmitted through sets of gears in which the net bearing and gear efficiency is taken to be 73 per cent.
The paper relates to some of the methods and apparatus which can be used to advantage in large-scale farming operations. The laying out of a production program, the transportation of men and supplies, special implements for raw-land preparation, tractor dynamometers, large tractors, special plowing and tilling implements, four-wheel-drive tractors and road haulage are discussed. An operation chart applying to an area of 40,000 acres is first presented and analyzed. Regarding hours of operation, the author maintains that with a suitable organization and proper selection of motive power and implements, tractors can be kept in motion 20 hr. per day and gives a time-table. Consideration is then given in some detail to the problems of electric lighting, the implements used in raw-land preparation, the power required for various operations, types of tractor construction, plowing and harrowing, harvesting, hauling and tractor-train schedules, the whole being copiously illustrated.
Kerosene has advanced to the front rank as a fuel for the farm tractor within a decade. A heavily preponderating majority of tractors burn kerosene. The history of early oil engines is reviewed and some comparative costs of kerosene and gasoline fuel for tractors, obtained from tests made in January, 1920, are given. Kerosene tractor-engine development is then discussed. The conditions required for complete combustion are the same in principle for both kerosene and gasoline, but in actual practice a wider latitude in providing ideal conditions is permissible for gasoline than for kerosene. The four classes of commercial liquid fuels usable in internal-combustion engines are the alcohols, the gasolines, the common kerosenes and the low-cost heavy-oil fuels. The alcohols rank lowest in heating value per pound of combustible. Under existing economic conditions neither alcohol nor the fuel oils require consideration as available fuels for the tractor.
TWO methods of oversizing basic tires are available, each with advantages and disadvantages. Extensive field test data presented here correlate very well with laboratory work performed by others. Based on data gotten from the tests and test conditions described, low section height tires provide the many advantages resulting from the use of bask and oversize tires with common outside diameters and rolling radii, without sacrificing tractive performance, when compared with oversize tires of conventional configuration.
As the internal combustion engine began to replace the horse, the Ackermann non-turning front axle came into its own. With increasing front-end loads, reducing gears replaced simple tiller connections between hands of driver and front wheels. The story of manual steering gears is that of continued engineering effort to increase efficiency within the gear-box, to hold down steering effort and amount of “wheeling” required, as loads have gone up and tire pressures down. In the last few years, power steering for passenger cars has been introduced. At the start a luxury, it is fast becoming a necessity.
Application of integral implements to larger sizes of farm tractors poses new problems in design of a standardized hitch. Interchangeability is a major problem. New concepts of control must be used. These include suitable regulation of the hitch and provision for added control functions. Greater attention must be paid to providing adequate hydraulic power, to tractor stability and to operator convenience, according to the author.
This paper discusses individually and collectively the several factors which will affect future fuel trends in the farm tractor field. These factors are (1) past and present fuel consumption trends, (2) fuel manufacturing trends, (3) engine design and production trends, (4) economic trends. On the basis of this analysis it is concluded that the predominating farm tractor fuel of the immediate future will be regular grade gasoline, followed by LP-gas and diesel fuel. Future consumption of kerosine-type distillate will be insignificant. Gasoline tractors will continue to increase in compression ratio in order to take full advantage of the high octane number level of present gasoline. Gasoline tractors designed to burn premium grade fuel represent a trend in the more distant future.