Connection sizes: 

Order 1:G 1/2” BSP (D1 + D2 + U1 + U2) G 1/4” BSP (M1 + M2)

Order 2: G 3/8” BSP (D1 + D2 + U1 + U2) G 1/4” BSP (M1 + M2)

The purpose of lowering brake valves, also known as overcenter valves, is to prevent pulling loads on hydraulic cylinders or hydraulic motors from leading in an uncontrolled manner. The consumers are preloaded on the outlet side via the adjustable pressure valve. If necessary, this preload is released via an internal control bore, so that controlled movement is possible. The valves must always be set for the respective application.

The valve enables static and dynamic control of the load by regulating the volume flow TO and FROM the consumer through the connections U1 and U2. The valve consists of two units, each unit containing a non-return valve and a pressure relief valve. The pressure relief valves are each opened by the control pressure on the opposite side. The non-return valves allow free flow into the consumer and then block the load against unintentional reverse movements.

The pressure setting of the opposite DBV is reduced proportionally to the specified boost ratio until the pressure relief valve opens and allows a controlled flow from U2 to D2 or from U1 to D1.

The spring chambers of the DBVs are relieved towards the atmosphere. This means that a possible back pressure at D1/D2 does not affect either the upstroke behavior or the presetting of the respective DBVs. The control lines contain adjustable hydraulic damping for fine-tuning stability and response behavior.

The setting value of the DBV should be at least 1.3 times the maximum expected load pressure.

Additional information:

Controlled flow from “U1” to “D1” and from “U2” to “D2”.

Pressure setting must be at least 1.3 times higher than the load pressure. Both opening pressure and control pressure are independent of any back pressure.

Normally used when the ports A+B of the upstream directional control valve are blocked in neutral position. In addition, the working connections of the directional control valve must be fitted with shock and suction valves. The control lines contain adjustable hydraulic damping for fine-tuning stability and response behavior.

Schemes: