The excavator is an earth-moving machine that uses a bucket to excavate materials above or below the bearing surface and load them into transport vehicles or unload them to the stockyard.
The excavator is composed of a power unit, a working device, a slewing mechanism, a control mechanism, a transmission mechanism, a walking mechanism and other structures. It is mostly used for excavation of soil, coal, sediment and other materials.  Its three most important parameters are operating weight, engine power and bucket capacity.