Also known as an excavator, it is a type of earthmoving machinery that uses a bucket to excavate materials that are higher or lower than the bearing surface, and loads them into transport vehicles or unloads them into a storage yard. Excavators are composed of power devices, working devices, rotary mechanisms, control mechanisms, transmission mechanisms, walking mechanisms, and other structures, and are commonly used for excavating materials such as soil, coal, and sediment. The three important parameters are operating weight, engine power, and bucket capacity.