TRAVEL CIRCUIT OPERATION TRAVEL MOTOR DEVICE R/G R/G OVERLOAD RELIEF VALVE CHECK VALVE COUNTER BALANCE VALVE P2(BW) P2(FW) P1(BW) P1(FW) TURNING JOINT TO/FROM MAIN CONTROL VALVE 900L3HC19 Valves are provided on travel motors to offer the following functions. 1) CHECK VALVE Stopping the motor, this valve sucks the oil from lower pressure passage for prevention the negative pressure and the cavitation of the motor. 2) COUNTER BALANCE VALVE When stopping the motor of slope descending, this valve to prevent the motor over run. 3) OVERLOAD RELIEF VALVE Relief valve limit the circuit pressure below 350 kgf/cm 2 (4980 psi ) to prevent high pressure generated at a time of stopping the machine.
Stopping the motor, this valve sucks the oil from lower pressure passage for preventing the negative pressure and the cavitation of the motor. 3-21