The pressure valve type DA 6 V is a pilot-operated pressure cut-off valve with steplessly adjustable switching pressure differential. It basically consists of pilot control stage and main stage of the screw-in cartridge valve (1), check valve (2) and housing (3).
The pump flow in P is introduced into the accumulator of the system via port B. If the pressure at the actuator in port B exceeds the set top switching pressure, the pilot control valve opens and pilot fluid discharge is enabled via port A (Y). The check valve (2) closes the connection from port B to port P and the pump flow is switched to depressurized circulation (from P to T).
Type DA 6 VP
- Switching of the pump flow from P to B (pump → actuator) to P to T (pump → tank).
The pump delivers via the check valve (2) into the hydraulic system (P to B). The pressure in channel B acts via the control line (4) and the bore (5) on the pilot control of the screw-in cartridge valve (1). Simultaneously, the pressure in channel P is applied via the bore (7) to the spring-loaded side of the main spool (8). As soon as the top cut-off pressure set via the adjustment spindle (6) in the screw-in cartridge valve (1) is reached in the hydraulic system (channel B), pilot control of the screw-in cartridge valve (1) opens the connection from the spring-loaded side of the main spool (8) to the control line (9) and the external connection via port A (Y) into the tank. Due to the bore (7), a pressure drop occurs at the main spool (8). The main spool (8) is lifted from the seat and opens connection P to T. The check valve (2) closes the connection B to P and pilot control of the screw-in cartridge valve (1) is held in open position by the actuator pressure in B.
- Switching of the pump flow from P to T (pump → tank) to P to B (pump → actuator).
If the actuator pressure in B compared to the cut-off pressure has fallen according to the lower bottom pressure value set at the adjustment spindle (10), pilot control of the screw-in cartridge valve (1) is set back to its initial position.
This way, a pressure is built up on the spring-loaded side of the main spool (8). It closes the connection from P to T by means of the spring (11) and the pump delivers via the check valve (2) into the hydraulic system from P to B.
Type DA 6 VA
At this valve type, the pump connection is not designed in P but in A. The valve directs the pump flow from A to P or from A to T. The drain port is located in B (Y).
The switching processes correspond to version "VP" (this valve version supports connection with manifolds).
Type DA 6 VP…
Notices!
- Only indirect pressure limiting function:
A pressure limiting function of the pump pressure (to the tank) is not directly provided but only indirectly via the check valve (2) and the control line (4) in the actuator channel.
- Setting the switching pressure differential:
At the factory, the valves are set at nominal pressure to a switching pressure differential of approx. 10 % to 12 %. A setting of 50 % of the nominal pressure is possible.
On delivery, the adjustment spindle (6) is set to the minimum adjustable top switching pressure, i.e., the adjustment spindle (6) is screwed out up to the limit stop.
By screwing in the adjustment spindle (6), the top switching pressure may be increased.
By screwing in the adjustment spindle (10), the bottom switching pressure is increased and the switching pressure differential reduced. Screwing out the adjustment spindle (10) reduced the bottom switching pressure and the switching pressure differential is increased.
The pressure adjustment is secured via a clamping screw (12) and a lock nut (13).
