Pressure relief valve Bosch Rexroth art. R900424297

Pressure valves of type ZDB and Z2DB are pilot-operated pressure relief valves in sandwich plate design.
They are used for limiting a system pressure.
The valves basically consist of the housing (7) and one or two pressure valve cartridges.
The system pressure can be set via the adjustment type (4).
Example version “VA”:
In the initial position the valves are closed. The pressure in channel A acts on the spool (1). At the same time, pressure is applied to the spring-loaded side of the spool (1) via nozzle (2) and to the pilot poppet (6) via nozzle (3). If the pressure in channel A exceeds the value set at the spring (5), the pilot poppet (6) opens.
Hydraulic fluid flows from the spring-loaded side of the spool (1), nozzle (3), channel (8) into channel T. The resulting pressure drop moves the spool (1) and thus opens the connection from A to T while maintaining the pressure set at spring (5).
Die pilot oil drain from the two spring chambers is effected externally, via channel T.
Type ZDB 6 VA2-…
➀ = component side
➁ = plate side