Komatsu PC500LC-10R Shop Manual page 330

COMPONENT PARTS OF SWING SYSTEM
When stopping swing
1.
When the swing control lever is returned from swing
RIGHT position to NEUTRAL position, the pressurized oil
from the pump is not supplied to port (MA).
2.
Since the return circuit of the pressurized oil from the mo-
tor output to the tank is closed by control valve (6), the
pressure in port (MB) increases.
3.
When the pressure in port (MB) increases high, the oil re-
turns to the hydraulic tank through 2-stage swing relief
valve (1) and port (S).
4.
Rotational resistance occurs in the motor, and the brake
starts working.
5.
The pressure in port (MA) exceeding that in port (MA)
pushes the shuttle valve (4).
6.
The pressure in chamber (C) becomes the same with port
(MB) and increases to the set pressure of 2-stage swing
relief valve.
7.
High braking torque acts on the motor, and the motor
stops.
8.
While 2-stage swing relief valve (1) is in operation, the re-
lieved pressurized oil and the pressurized oil from port (S)
are supplied to port (MA) through check valve (3).
9.
Cavitation in port (MA) is prevented.
10-236
10 STRUCTURE AND FUNCTION
PC500LC-10R
AEP20509