It is the purpose of the author to analyze some of the factors that have influenced tractor development. He reviews a number of factors on which the usefulness of tractors depends, showing what the farmer is interested in when buying tractors and how the design should be worked out to secure the greatest general efficiency.
The paper then mentions certain general specifications that are required by tractor engines. The author finds that the conditions on about 90 per cent of all farms require a four-cylinder engine of between 16 and 40 hp., operating on the four-stroke cycle. The disadvantages of the two-cylinder horizontal-opposed engine are summarized. An empirical formula is given that can be used to calculate the most satisfactory operating speed of an engine.
In concluding the paper a number of the most important general themes of design are outlined. Particular mention is made of the lubrication system and of the special provisions required for kerosene burning engines.
