Komatsu Galeo PC138US-8 Shop Manual page 122

SEN02548-01
Action of spring
Load of springs (4) and (6) on the PC valve is
q
determined by the swash plate position.
As servo piston (9) moves to left, spring (6) is
q
retracted.
If the servo piston moves further, it will be con-
q
tacted again seat (5) and spring (6) will be
fixed.
After that, spring (4) alone will operate.
q
The spring load is changed by servo piston (9)
q
as it extends or compresses springs (4) and
(6).
If the command current (X) to PC-EPC valve
q
solenoid (1) changes, so does the force push-
ing piston (2).
22
10 Structure, function and maintenance standard
Spring load of springs (4) and (6) is also
q
affected by the command current (X) to PC-
EPC valve solenoid.
Port (C) of the PC valve is connected to port
q
(E) of the LS valve.
Check valve output pressure (PP1) enters port
q
(B) and the small diameter end of servo piston
(9), and shuttle valve output pressure (PP2)
enters port (A).
When pump pressures (PP1) and (PP2) are
q
small, spool (3) will be positioned in the right
side.
Port (C) and (D) are connected, and the pres-
q
sure entering the LS valve becomes drain
pressure (PT).
PC138US, USLC-8