Komatsu PC200-8M0 Shop Manual page 131

401 Hydraulic system, Part 1
Hydraulic pump
Action of spring
Load of springs (4) and (6) on the PC valve is
q
determined by the swash plate position.
q As servo piston (9) moves to right, spring (6) is
retracted.
q If the servo piston moves further, it will be con-
tacted again seat (5) and spring (6) will be
fixed.
After that, spring (4) alone will operate.
q
q The spring load is changed by servo piston (9)
as it extends or compresses springs (4) and
(6).
The spring load changes as the servo piston
(9) extends and contracts the 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).
Spring load of springs (4) and (6) is also
q
affected by the command current (X) to PC-
EPC valve solenoid.
q Port (C) of the PC valve is connected to port
(E) of the LS valve.
PC200, 200LC, 220, 220LC-8M0
Self pressure (PP1) enters port (B) and the
q
small diameter end of servo piston (9), and
other pump pressure (PP2) enters port (A).
When pump pressures (PP1) and (PP2) are
q
small, spool (3) will be positioned in the left
side.
q Port (C) and (D) are connected, and the pres-
sure entering the LS valve becomes drain
pressure (PT).
q If port (E) and port (G) of the LS valve are con-
nected, the pressure entering the large diame-
ter end of the piston from port (J) becomes
drain pressure (PT), and servo piston (9)
moves to the left side.
The pump discharge will be set to the increas-
q
ing trend.
q Accompanied with move of servo piston (9),
springs (4) and (6) will be expanded and the
spring force becomes weaker.
SEN06119-00
19
10-401