ZDR
The valve type ZDR is a direct operated pressure reducing valve in sandwich plate design with pressure limitation of the secondary circuit. It is used to reduce the system pressure. The pressure reducing valve basically comprises housing, control spool, compression spring, adjustment type and an optional check valve. The secondary pressure is set via the adjustment type.
Product Description
Version “A”
The valve is open in initial position. Hydraulic fluid can flow from channel A to channel A without restrictions. The pressure in channel A is simultaneously applied via the control line at the piston area opposite the compression spring. If the pressure in channel A exceeds the value set at the compression spring, the control spool is pushed against the compression spring to control position and keeps the set pressure in channel A at a constant level. Control signal and pilot oil are supplied internally via the control line from channel A. If the pressure in channel A increases further due to an external force effect at the actuator, it pushes the control spool even further against the compression spring.
In this way, channel A is connected to the tank via the control edge at the control spool and the housing. So much hydraulic fluid is discharged into the tank that the pressure does not increase any further. The leakage oil drain from the spring chamber is always effected externally via the bore and channel T (Y). A pressure gauge connection allows for the control of the secondary pressure at the valve. A check valve can be used for free flow back from channel A to A with version “A”. Versions “P” and “B” With version “P”, the pressure reduction is effected in channel P.
Control signal and pilot oil are supplied internally from channel P. With version “B”, the pressure is reduced in channel P; but the pilot oil is extracted from channel B.
