Introduction proportion of large tractors,and wheeled tractors are mainly two-wheel drive.With the development of national economy and scientific and technological progress in recent years,the power range of tractors is wider,100 horsepower four-wheel drive tractor models of large-scale increase and in the level of overall design and manufacture of the tractor is generally improved.New materials,and advanced technology are in general applied.Meanwhile,tractor products have entered the international market. 1.3 The overview of internal combustion engine development The development of internal combustion engines and that of automobile and tractor was similar.In the 100 years of development history,two important landmark development stages are:the early 20th century,the rise of the supercharger 50 in the extensive application of internal combustion engine products; 20th century,70 starting age of computer technology and electronic technology in the development of internal combustion engines. (1)The overall performance is continuously improved. 械电子工程学 Automobile and Tractor Northwest A&F University Automobile and Tractor Northwest A&F University Introduction proportion of large tractors, and wheeled tractors are mainly two-wheel drive. With the development of national economy and scientific and technological progress in recent years, the power range of tractors is wider, 100 horsepower four-wheel drive tractor models of large-scale increase and in the level of overall design and manufacture of the tractor is generally improved. New materials, and advanced technology are in general applied. Meanwhile, tractor products have entered the internationalmarket. 1.3 The overview of internal combustion engine development The development of internal combustion engines and that of automobile and tractor was similar. In the 100 years of development history, two important landmark development stages are: the early 20th century, the rise of the supercharger 50 in the extensive application of internal combustion engine products; 20th century, 70 starting age of computer technology and electronic technology in the development of internal combustion engines. (1) The overall performance is continuously improved