Patent ID: 11926986
Assignee: KAWASAKI JUKOGYO KABUSHIKI KAISHA
Field: Civil engineering (Other fields)
Classification: CPC E  F | IPC E  F

Claim 9:
10. The hydraulic excavator drive system according to claim 9, wherein
a fourth switching valve is located on the suction/delivery line, such that the suction/delivery line is divided into a tank-side passage and a pump-side passage,
the regenerative line connects the pump-side passage of the suction/delivery line to the part of the rod-side line, the part extending between the rod-side chamber and the first switching valve,
the fourth switching valve is connected to the tank by a parallel line on which a check valve having a predetermined cracking pressure is located, and
at the boom lowering operation, the fourth switching valve brings the pump-side passage into communication with the parallel line, but except at the boom lowering operation, the fourth switching valve brings the pump-side passage into communication with the tank-side passage.