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

Claim 0:
1. A hydraulic excavator drive system comprising:
a boom cylinder;
a first pump connected to a head-side chamber of the boom cylinder by a head-side line and driven by an electric motor;
a second pump that supplies hydraulic oil to at least one of an arm cylinder or a bucket cylinder;
a first switching valve located on a rod-side line that connects a rod-side chamber of the boom cylinder to a tank, the first switching valve being a switching valve that opens the rod-side line at a boom raising operation, but blocks the rod-side line at a vehicle body lifting operation; and
a second switching valve located on a relay line that connects a part of the rod-side line, the part extending between the rod-side chamber and the first switching valve, to a supply line extending from the second pump, the second switching valve being a switching valve that blocks the relay line at the boom raising operation, but opens the relay line at the vehicle body lifting operation.