Patent ID: 11891779
Assignee: HITACHI CONSTRUCTION MACHINERY CO., LTD.
Field: Civil engineering (Other fields)
Classification: CPC E  F | IPC E  F

Claim 2:
3. The hydraulic excavator according to claim 2, further comprising:
pressure sensors that detect arm crowding operation pressure outputted from the arm pilot valve, boom raising operation pressure outputted from the boom pilot valve, bucket crowding operation pressure outputted from the bucket pilot valve, and bucket dumping operation pressure outputted from the bucket pilot valve, wherein
the spool stroke limitation device includes
a first solenoid proportional pressure reducing valve that has a primary pressure port connected to a secondary pressure port on an arm crowding side of the arm pilot valve and a secondary pressure port connected to an operation pressure port on an arm crowding side of the second directional control valve, and
a controller that is configured to control secondary pressure of the first solenoid proportional pressure reducing valve on a basis of a target meter-in opening area having a lowest value among target meter-in opening areas of the second directional control valve, the target meter-in opening areas being determined on a basis of the arm crowding operation pressure, the boom raising operation pressure, the bucket crowding operation pressure, and the bucket dumping operation pressure, respectively.