Komatsu Galeo PC138US-8 Shop Manual page 125

10 Structure, function and maintenance standard
As a result, the pressure on port (C) (= J) is
q
decreased and the rightward move of servo
piston (9) is stopped.
The position in which servo piston (9) stops at
q
this time is further to the left than the position
when pump pressures (PP1) and (PP2) are
low.
The relationship between the average pump
q
pressure (PP1 + PP2)/2 and servo piston (9) in
terms of their positions can be represented by
the broken line in the figure because springs
(4) and (6) form the double springs.
The relationship between the average pump
q
pressure (PP1 + PP2)/2 and average pump
delivery (Q) becomes as shown below.
If command current (X) sent to PC-EPC valve
q
solenoid (1) increases further, the relationship
between average pump pressure (PP1 + PP2)/
2, and pump delivery (Q) is proportional to the
force of the PC-EPC valve solenoid and moves
in parallel.
Namely, the force of PC-EPC valve solenoid
q
(1) is added to the pushing force to the left
because of the pump pressure applied to the
spool (3), so the relationship between the aver-
age pump pressure (PP1 + PP2)/2 and the
pump delivery (Q) moves from (A) to (B) as the
command current (X) is increased.
PC138US, USLC-8
SEN02548-01
25