Patent ID: 9702380
Date: 2017-07-11
CPC Classifications: E02F,F15B

Claim:
1. A fluid pressure control device for a power shovel, comprising: a first pump configured to supply working fluid to a first actuator; a second pump configured to supply working fluid to a second actuator; a first switching valve configured to enable or block communication between the first pump and the first actuator; a second switching valve configured to enable or block communication between the second pump and the second actuator; a third pump configured to be capable of supplying working fluid to the first and second actuators; a first merge control valve provided on a downstream side of the third pump, the first merge control valve having a tank communication position in which the third pump and a tank are in communication and a downstream-side communication position in which the third pump and a downstream side are in communication, the first merge control valve being configured to switch between the tank communication position and the downstream-side communication position; and a second merge control valve provided on a downstream side of the first merge control valve, the second merge control valve having a first actuator communication position in which the third pump and the first actuator are in communication and a first actuator blocked position in which communication between the third pump and the first actuator is blocked, the second merge control valve being configured to switch between the first actuator communication position and the first actuator blocked position, wherein the first merge control valve is maintained in the tank communication position by a biasing force of a biasing member, and the first merge control valve is switched from the tank communication position to the downstream-side communication position by a first pilot pressure for enabling communication between the first pump and the first actuator by the first switching valve, or a second pilot pressure for enabling communication between the second pump and the second actuator by the second switching valve, and the second merge control valve is maintained in the first actuator communication position by a biasing force of a biasing member, and the second merge control valve is switched from the first actuator communication position to the first actuator blocked position by the second pilot pressure.