Komatsu PC500LC-10R, Shop Manual, Page: 189 / 758

1: Valve
2: Spring
3: Piston
4: Piston
5: Swing valve spool
6: R.H. travel valve spool
7: Arm valve spool
8: LS shuttle valve
9: LS circuit
• It prevents entry of the high LS pressure from the swing
circuit into the LS circuit of the work equipment valve at the
combined operation of swing and travel RIGHT.
• It prevents high pressure which is generated when the ma-
chine swings, and improves operability of the work equip-
ment.
OPERATION OF LS SELECT VALVE
When pilot pressure (BP) is cut off (OFF)
1.
Since pilot pressure (BP) is cut off, piston (3) is pressed to
the left by the reaction force of spring (2).
2.
When the swing operation is performed, swing LS pres-
sure (P1) passes through swing spool (5) and enters port
(A).
3.
Swing LS pressure (P1) pushes valve (1) to the left, and
port (A) is connected to port (B).
4.
Swing LS pressure (P1) flows from port (A) through port
(B) to LS shuttle valve.
When pilot pressure (BP) is supplied (ON)
1.
When pilot pressure (BP) is supplied, it moves piston (3) to
the right against the reaction force of spring (2).
2.
When piston (3) moves to the right, valve (1) disconnect
port (A) from port (B).
3.
Since port (A) is disconnected from port (B), swing LS
pressure (P1) does not flow to LS shuttle valve.
4.
Even swing LS pressure (P1) increases, it does not affect
other LS circuits.
10 STRUCTURE AND FUNCTION CLSS
PC500LC-10R 10-95