Komatsu Galeo PC138US-8 Shop Manual page 124

SEN02548-01
2) When load on actuator is large and pump discharge pressure is high
Outline
When the load is large and pump discharge
q
pressures (PP1) and (PP2) are high, the force
pushing spool (3) to the left becomes larger
and spool (3) will be moved to the position
shown in above figure.
Part of the pressure to be conducted from port
q
(C) to LS valve flows from port (A) to port (C)
and (D) through LS valve. At the end this flow,
level of this pressure becomes approximately
half of the main pump pressure (PP).
24
10 Structure, function and maintenance standard
Operation
When port (E) and port (G) of the LS valve are
q
connected, this pressure from port (J) enters
the large diameter end of servo piston (9),
stopping servo piston (9).
If main pump pressure (PP) increases further
q
and spool (3) moves further to the left, main
pump pressure (PP1) flows to port (C) and acts
to make the pump delivery the minimum.
When servo piston (9) moves to the left,
q
springs (4) and (6) are compressed and push
back spool (3).
When spool (3) moves to the right, the opening
q
of port (C) and port (D) becomes larger.
PC138US, USLC-8