spool hydraulic directional control valve / pilot-operated / proportional
Bosch Rexroth - Industrial Hydraulics
2,800 l/min (740 us gal/min)
350 bar (5,076 psi)
Pilot-operated proportional directional valves type 4WRZ(E)… and 5WRZ(E).52…
Valves of type 4WRZ(E)... are pilot-operated 4-directional valves that are actuated by means of proportional solenoids. Their function is to control the flow direction and size.
Valves of type 5WRZ(E)... are equipped with an additional port "R" (only NG52).
The valve basically consists of:
Pilot control valve (9) with proportional solenoids (5 and 6)
Main valve (10) with main control spool (11) and centering spring (12)
With de-energized solenoids (5, 6), the main control spool (11) is held in the central position by means of the centering spring (12)
The main control spool (11) is controlled by the pilot control valve (9); the main control spool is proportionally moved, e.g. by actuating solenoid "b" (6)
→ The control spool (2) is moved to the right, pilot oil enters the pressure chamber (13) via the pilot control valve (9) and deflects the main control spool (11) proportionally to the electric input signal
→ Connection from P to A and B to T via orifice-type cross-sections with progressive flow characteristics
Pilot oil supply to the pilot control valve internally via port P or externally via port X
Switching off the solenoid (6)
→ The control spool (2) and main control spool (11) are moved back into the central position
Depending on the spool position, flow occurs from P to A and B to T or P to B and A to T (R)
An optional manual override (14 and 15) can be used to move the control spool (2) without solenoid energization.