Pressure valves of type DB and DBW are pilot-operated pressure relief valves. They are used for the limitation (DB) or limitation and solenoid-actuated unloading (DBW) of a system pressure.
The pressure relief valves basically consist of the pilot control valve (1) with pressure adjustment element (2), main valve (3) with main spool insert (4) and directional valve (5), optional.
Pressure relief valve type DB
The pressure applied by the system acts on the main spool (4). At the same time, pressure is applied to the spring-loaded side of the main spool (4) and to the pilot control valve (1) via the control lines (6) which are equipped with nozzles. If the system pressure exceeds the value set at the spring (7), the poppet (10) of the pilot control valve opens. The hydraulic fluid on the spring-loaded side of main spool (4) now flows via the spring chamber of the pilot control valve (1) to the tank, either internally via port T, or externally, via port Y. Due to the nozzle combination in the control lines, a pressure drop results at the main spool, the connection from P to T is thus released. The hydraulic fluid flows from channel P to channel T maintaining the set operating pressure.
The pressure relief valve can be unloaded by means of remote control or switched to another pressure value via port X (8).
Pressure relief valves type DBW
The function of this valve is basically the same as that of valve type DB. The unloading of the main spool (4) is, however, achieved by controlling the mounted directional valve (5).
To reduce the tank pressure peaks when switching to depressurized circulation by operating the directional valve, the main spool in spool version (4.1) can be used.\