Komatsu PC88MR-10 Shop Manual page 185

Hydraulic oil cooler bypass valve
Function
(PC88MR-B8PB-042-K-00-A)
The oil cooler bypass valve prevents breakage of oil cooler (3) when the return oil flow from the control
valve increases and oil cooler inlet pressure (PB) increases consequently.
The oil cooler bypass valve drains the return oil from the control valve directly to the tank without via oil
cooler (3).
Operation
(PC88MR-B8PB-044-K-00-A)
Oil cooler inlet pressure (PA) acts on the left surface of piston (1). Piston (1) moves to the right.
Piston (1) balances so that the oil cooler inlet pressure (PA) is as follows.
(PA) - (PT) = Reaction force of spring (2) / Pressure receiving area (S2-S1) of piston (1)
PC88MR-10
(PC88MR-B8PB-041-K-00-A)
10 Structure and function
Control valve
10-107