Flow Rate Control Valve - Hitachi ZW180 Technical Manual

COMPONENT OPERATION / Hydraulic Fan Motor

FLOW RATE CONTROL VALVE

When temperature in the coolant or oil is less than the
set temperature, the flow rate control valve supplies
necessary amount of pressure oil from the fan pump to
the motor, and returns redundant amount of pressure
oil to the hydraulic oil tank. This controls to lower the
engine load and wind noise of the cooling fan.
Operation
1. Pressure oil from port P acts on side A as
upstream pressure and on side B as downstream
pressure of flow rate control valve spool (8), and
pressure difference acts on flow rate control valve
spring (12).
2. When pressure difference becomes higher than
the set force, flow rate control valve spool (8)
moves and redundant flow rate of pressure oil
flows to port T.
T3-3-6