Proportional Pilot Operated
Pressure Relief Valves

HA 5117
5/2012

SR4P2-B2

7/8-14 UNF • pmax 350 bar (5076 PSI) • Qmax 60 L/min (15.85GPM)

Screw-in cartridge design
Pilot operated
Three pressure ranges
Pressure output proportional to DC current input

Functional Description
The valve is designed for continuous regulation of
pressure in the circuit.
The valve is pilot operated using the pilot stage of
SR1P2-A2 execution.
Due to two stage pilot design the valve is able to control
high hydraulic power in circuit.
The complete valve consist of pilot stage valve
SR1P2-A2 and main stage size 7/8-14 UNF.
In the basic position (with the coil de-energized) the
port P is fully open to the tank.
Connection to the pilot stage is realized with nozzles
(5) and (6) and the spring chamber (4) is unloaded to
the tank port.
When the DC current is applied to solenoid (10) at spring
(9) increases force to the seat (8) and it continuously
closes.
Build up pressure acts on spool (3) in spring chamber
(4) against the pressure line P thus closing the P line to
the Tank port.

Build up pressure P in system is proportional to the
energizing current at solenoid (10).
The minimum value of cracking pressure can be
adjusted using the screw (12), position of which is
secured with nut (11). The adjusting screw (12) can
be used as emergency control. Screw (13) is used to
air bleed the solenoid control system. To ensure self
bleeding of the valve it is recommended to install it in
a vertical position with the solenoid facing downwards.
Bleeding process is necessary for the proper function
of the valve.
Pilot stage valve SR1P2-A2 (catalogue no. HA 5122)
can be ordered separately as a built-in proportional
directly operated pressure relief valve. The main stage
of the valve can be also ordered separately – see spare
parts.
The valve body and the adjustment screw are zinc
coated.

The valve opens when the increasing pressure on P line
reaches value set by proportional solenoid (10).
In this situation the main spool (3) shift to open the Tank
line against the spring (4).

11

12
13

P

T

1