Komatsu PC200-8M0 Shop Manual page 193

402 Hydraulic system, Part 2
Functions and operation by valve
When engine is running (other than swing or
travel operation)
The pressurized oil from self-pressure reduc-
q
ing valve (1) flows to variable back pressure
solenoid valve (3).
q Since drive signal (IS3) of variable back pres-
sure solenoid valve (3) is "ON", the pressur-
ized oil (PR) from self-pressure reducing valve
(1) flown to spring chamber (C) of variable
back pressure valve (4) is drained through
variable back pressure solenoid valve (3).
q Only the reaction force of spring (5) pushes
valve (6) to the right.
Pressure (PA) of drain circuit (A) of the control
q
valve acts on the right end face of valve (6)
(surface of fd1) to push valve (6) to the left.
Valve (6) balances at a position where it cre-
q
ates back pressure (PA) determined as fol-
lows; PA = Reaction force of spring (5) / Area
of surface fd1
Accordingly, the oil flow rate from drain circuit
q
(A) of the control valve to port (T) is limited. In
other words, the set pressure of variable back
pressure valve (4) is adjusted.
PC200, 200LC, 220, 220LC-8M0
SEN06120-00
51
10-402