Komatsu PC500LC-10R Shop Manual page 329

10 STRUCTURE AND FUNCTION
OPERATION OF CHECK VALVE, SHUTTLE VALVE, AND 2-STAGE SWING RE-
LIEF VALVE OF SWING MOTOR
When starting swing
1.
When swing RIGHT operation is performed, the pressur-
ized oil from the pump flows through control valve (6) into
port (MA).
2.
The pressure in port (MA) increases, starting torque is
generated, and the motor starts rotating.
3.
The pressure is supplied to port (PU) of the motor, and the
set pressure of the motor increases.
4.
During swing acceleration, the pilot pressure from the 2-
stage swing relief solenoid valve is added to port (PU), and
the relief rate is limited.
5.
The pressurized oil from the motor outlet returns to the
tank through port (MB) and control valve (6).
PC500LC-10R
COMPONENT PARTS OF SWING SYSTEM
10-235