Komatsu PC600LC-7 Manual page 111

STRUCTURE, FUNCTION AND MAINTENANCE STANDARD
SWING PRIORITY VALVE
Function
• When the swing and arm are operated at the
same time, a large amount of the pressure oil
flows to the arm circuit where the load is small, so
little pressure oil flows to the swing circuit.
• This makes the arm speed too fast for the swing
speed, and causes poor combination in simulta-
neous operation.
1) When swing is at HOLD
Operation
• No pilot pressure oil flows from the travel shuttle
valve, so the swing priority valve is not actuated.
• For this reason, all the pressure oil from the front
main pump passes through port PR and flows to
the arm Lo control valve.
PC600, 600LC-7
• To overcome this, the swing priority valve is ac-
tuated to throttle the pressure oil flowing to the
arm Lo control valve in order to restrict the arm
speed and improve the simultaneous operation
performance.
CONTROL VALVE
10-79