Komatsu PC88MR-10 Shop Manual page 168

10 Structure and function
Control valve
Surface area ratio of pressure compensation valve
S1: Area of flow control valve (2) - Area of piston (3)
S2: Area of pressure reducing valve (1) - Area of piston (3)
Function
The pressure compensation valve finely adjusts the ratio of area (S1) on the left side of flow control valve
(2) to area (S2) on the right side of pressure reducing valve (1) (S2/S1) to determine the compensation
characteristics corresponding to the characteristics of each actuator.
Surface area ratio (S1):(S2) and compensation characteristics
When ratio is 1.00:
[Pump (discharged) pressure (PP) - Upstream pressure of spool notch (PPB)]
- Actuator circuit pressure (PA) = (A)], thus oil flow is supplied corresponding with the open area ratio of
the spool.
When ratio is above 1.00:
[(PP) - (PPB)] > [(PLS) - (PA (= A))], thus less oil flow is supplied to the compensated side for the open
area ratio of the spool.
When ratio is below 1.00:
[(PP) - (PPB)] < [(PLS) - (PA (= A))], thus more oil flow is supplied to the compensated side for the open
area ratio of the spool.
10-90
[LS circuit pressure (PLS)
PC88MR-10