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Self-pressure reducing valve
Function
It reduces the main pump discharge pressure and provides it as control pressure to the solenoid valves,
EPC valves, etc.
Operation
If normal
When pressure (PR) exceeds the set pressure, poppet (1) opens.
The pressurized oil flows from port (PR) to orifice (a) in spool (4), and then flows through the opening of
poppet (1) to seal drain port (TS).
Differential pressure is generated over orifice (a) in spool (4) and spool (4) moves to close the opening
between ports (P) and (PR).
Pressure (P) is reduced and adjusted to constant pressure (set pressure) by the opening area at this time
and supplied as pressure (PR).
When abnormal high pressure occurs
If pressure (PR) of the self-pressure reducing valve becomes abnormal, ball (6) compresses spring (5)
and separates from the seat.
The pressurized oil flows through port (PR) to (TS) to reduce pressure (PR).
Thus, the hydraulic components such as the PPC valves and solenoid valves are protected from abnormal
pressure.
PC88MR-10
(PC138-PL30-042-K-00-A)
10 Structure and function
Control valve
10-97
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