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.

When using these valves, the center position of the upstream directional control valve to the tank must be relieved.

The valve enables static and dynamic control of the load by regulating the volume flow TO and FROM the consumer through the connections C1 and C2. 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 control ratio until the pressure relief valve opens and prevents the load from moving backwards.

Pressure relief valve opens and enables a controlled flow from C2 to V2 or from C1 to V1. The spring chambers of the DBVs are relieved towards the respective connection V1 or V2. Back pressure at V1 and V2 is added to the presetting of the corresponding pressure relief valve in all functions. To keep this effect as low as possible, the connections of the upstream directional control valve should be relieved to the tank in the middle position.

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

Controlled flow from “C1” to “V1” and from “C2” to “V2”.

Order 1 schemes:

Order 2 schemes:

Order 3 schemes:

Order 4 schemes:

Order 5 schemes:

Order 6 schemes:

Order 7 schemes: