Excavator is a moving machine that uses a bucket to dig material up and down the bed and load it into a conveying vehicle or dump it into a storage yard. The excavator is composed of power device, working device, rotary mechanism, control mechanism, transmission mechanism, walking mechanism and other structures. It is mainly used for the excavation of soil, coal, silt and other materials.  The three most important parameters are operating weight, engine power and bucket capacity. Bulldozer is a kind of engineering vehicle, which is composed of torque converter, transmission and other components. It is divided into crawler bulldozer, wheel bulldozer and so on. Bulldozer can independently complete the work of digging, transporting and unloading soil, with flexible operation, convenient rotation, the required working face is small, driving speed and other characteristics, can be used for site cleaning or leveling, excavation depth of the foundation pit and backfill, push the height of the roadbed.