Bulldozers are one of the main machines of earthwork machinery. They are divided into crawler type and tyre type according to the way of walking. Because tyre type bulldozers are few. This paper mainly describes the structure and working principle of crawler bulldozer. The basic operation of bulldozer excavation is: A. shovel soil B. soil C. unloading.

Most of the crawler bulldozers with power greater than 120KW use hydraulic mechanical transmission. This kind of bulldozer comes from the introduction of Japan Komatsu Manufacturing Institute D155, D85, D65 three basic bulldozer manufacturing technology. After the localization, the TY320 bulldozers are type TY220, TY160 and basic bulldozers. In order to meet the needs of users in various working conditions, the bulldozer manufacturers in China have expanded the product variety and formed three series of bulldozers on the basis of the above three basic bulldozers. TY220 bulldozer series products, including TSY220 wetland bulldozer, TMY220 desert bulldozer, TYG220 plateau bulldozer, TY220F forest cutting bulldozer, TSY220H environmental protection bulldozer and DG45 pipe crane. TY320 and TY160 series bulldozers are also developing similar products. In the TY160 series, there are TSY160L super wet bulldozers and TBY160 push and pull machines.

The development and expansion of bulldozer products, not only to meet the working adaptability of different working conditions, but also to maintain the maximum universality (or interchangeability) of components with the basic model, which brings great convenience for users to use and maintain. In order to facilitate users to buy accessories, the manufacturers have retained the parts number of Komatsu, Japan. Only the parts designed by themselves in the modification are crowned with the number of their own manufacturers.

Crawler bulldozer is mainly composed of engine, transmission system, working device, electrical parts, cab and hood. The mechanical and hydraulic transmission system includes hydraulic torque converter, coupling assembly, planetary gear transmission, central transmission, steering clutch and brake, final transmission and running system.

The power output mechanism drives the working pump, the variable speed variable torque hydraulic system variable speed pump and the steering pump of the steering and braking hydraulic system in the hydraulic system of the working device by means of gear transmission and spline connection; the sprocket represents the final transmission mechanism of the secondary spur gear transmission (including the left and right final transmission assembly); the caterpillar plate includes the caterpillar assembly, the steering and braking hydraulic system steering pump; The frame and suspension assembly are included in the walking system.