Hyundai HX145LCR Manual page 185

SWING CIRCUIT OPERATION
AU
DR
MB
TO / FROM MAIN CONTROL VALVE
1)
MOTOR BRAKE VALVE
Motor brake valve for the swing motor limits to cushion the starting and stopping pressure of swing
operation and controls the swing motor operating pressure.
2) MAKE UP VALVE
The make up valves prevent cavitation by supplying return oil to the vacuum side of the motor.
3) PARKING BRAKE
This is function as a parking brake only when the swing control lever and arm in control lever are
not operated.
PARKING BRAKE "OFF" OPERATION
The parking brake is released by the pilot pressure oil from the pilot pump.
When the swing control lever or arm in control lever placed in the operating position, the pilot oil
flows into SH port through the MCV. This pressure transferred to the brake release valve and the
brake release valve is change over. Then the pilot oil pressure PG lift the brake piston and release
the parking brake.
PARKING BRAKE "ON" OPERATION
When the swing control lever and arm in control lever placed in the neutral position, the pressure of
the pilot oil passage down.
Then the brake release valve returned to the neutral position and the oil is returned from the brake
piston to the hydraulic oil tank. And the brake is set to 'ON'.
4) ANTI-INVERSION VALVE
This anti-inversion valve absorbs shocks produced as swing motion stops and reduced oscillation
cause by swing motion.
REG
VA(CW)
VB(CCW)
PARKING BRAKE
SH
BRAKE OFF
BRAKE RELEASE VALVE
PG
BRAKE ON
SPRING 4k
MAKE UP VALVE
MOTOR BRAKE VALVE
MA
MAKE UP PORT(MU)
ANTI-INVERSION VALVE
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140L3HC18A