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 power required for operations in connection with various crops, is outlined, as are also the conditions that must be met in plowing and cultivating corn, wheat, oats and other crops. The power required for pulling plows varies from 250 to 1500 lb. per bottom, depending upon the condition and kind of soil, depth and type of plow.
The author reviews what the tractor must show in the way of economical operation, pointing out that for permanent success it must show higher returns on the investment than horses. Information is also given in regard to the mechanical efficiency, engine efficiency, friction losses, rolling resistance and general design requirements. Other factors peculiar to farm tractor work, which must be taken into account, are treated. In conclusion photographs and a brief description are given of representative tractors.
