The 4/2 and 4/3 proportional directional valves are designed as direct operated devices in plate design. Operation by means of
proportional solenoids with central thread and detachable coil. The solenoids are controlled by external electronics.
Set-up:
The valve basically consists of:
Housing (1) with connection surface
Control spool (2) with compression springs (3 and 4) and spring plates (5 and 6)
Solenoids (7 and 8) with central thread
Position transducer (9)
Function:
With de-energized solenoids (7 and 8), central position of the control spool (2) due to compression springs (3 and 4) between the
spring plates (5 and 6)
Direct actuation of the control spool (2) by the control of one proportional solenoid, e. g. solenoid "b" (8)
Control spool (2) is moved to the left in proportion to the electrical input signal •
Connection from P to A and B to T via orifice-type cross-sections with progressive •
Flow characteristics •
Switching off of the solenoid (8)
Control spool (2) is returned to the central position by the compression spring (3) •
In the de-energized state, the control spool (2) is held in a mechanical central position by the return spring of the solenoids.
With control spool symbol "V", this position does not correspond to the hydraulic central position! When the electric Valve
control loop is closed, the control spool is positioned in the hydraulic central position.