(1) the backhoe: digging is characterized by "back down, forced cut soil", its not shovel digging force is small, can stop the following one to three kinds of soil excavation, appropriate is used for no more than 4 m of the foundation pit excavation depth, base trough, pipe trench, wet soil, water content are also applicable to the larger and underground water level below the soil excavation and soil of underground water level is relatively high. There are two ways of backhoe excavator: trench end excavation and trench side excavation.

(2) Drag shovel: soil excavation is characterized by "backward downward, self-weight cutting soil", its excavation radius and depth are large, can excavate the soil below the shutdown surface, should be used for excavation of large and deep foundation pit or underwater excavation. 

(3) Grasp shovel: Excavation is characterized by "straight up and down, self-weight soil cutting", which is suitable for excavation of narrow and deep foundation pits or silt in water, especially suitable for underwater excavation, hard soil can not be used to grasp the shovel construction.