An excavator is an earth moving machine that uses a bucket to excavate materials above or below the plane of the bearing and load it into the transportation vehicle or unload it to a stockyard. The material excavated by the excavator are mainly soil, coal, sediment, and pre-loose soil and rock. Judging from the development of construction machinery in recent years, the development excavator is relatively fast, and the excavator has become one of the most important construction machinery in engineering construction.

The excavator mainly uses the hydraulic system to control the swing arm to complete the excavation work. Now we understand the principle of hydraulic transmission through experiments.