Komatsu PC88MR-10 Shop Manual page 167

Pressure compensation valve
Function
When the load pressure of an actuator is lower than that of other actuator and the flow to the actuator is
going to increase during combined operation, this valve allows the load pressure to be compensated. [At
this time, the load pressure of the other actuator under combined operation (right side) is higher than that
of the actuator on this side (left side).]
Operation
When the load pressure of the other actuator (right side) increases during combined operation, flow to the
actuator circuit (A) on this side (left side) is going to increase.
In this case, LS pressure (PLS) of the other actuator is applied to spring chamber (PLSS) and pushes
pressure reducing valve (1) and flow control valve (2) to the left.
Flow control valve (2) reduces the open area between pump circuit (PP) and spool upstream (PPA) to
generate a pressure loss between (PP) and (PPA).
The flow control valve (2)and the pressure reducing valve (1) balance each other at the place where the
pressure difference between (PA) and (PLS) which applies to the both end surfaces of the pressure
reducing valve (1) becomes the same as the pressure loss between (PP) and (PPA) around the flow
control valve.
The pressure differences between upstream pressure (PPA) and downstream pressure (PA) of both
spools operated for combined operation becomes the same and the pump flow is divided in proportion to
the opening area of notch (a) of each spool.
PC88MR-10
(PC88MR-L6D0-040-K-00-A)
10 Structure and function
Control valve
10-89