Counterbalance valves

Double overcenter valve for open center VBCD-SAE

In stock

Double counterbalance valve not compensated for in-line installation

With the Oleoweb VBCD-SAE counterbalance valves it is possible to support a suspended load and control its movement by eliminating vibrations or too fast and dangerous lowering. Equipped with a valve body with UNF-SAE threaded ports, the VBCD-SAE overcenter valves are designed to be installed in-line within the hydraulic system in compliance with the spaces available on the machine.



The VBCD-SAE series valves are double descent and movement control valves (also known as overcenter). Their action blocks the cylinder and controls its movement in both directions; and are therefore suitable for applications in which it is necessary not only to control the descent phase of a suspended load subjected to gravitational force, but also to guarantee stability in the actuator working position in the presence of bidirectional loads, as occurs for example in the reversible hydraulic motors. By feeding the line opposite the load, the pilot line manages the partial opening of the descent channel allowing control of the actuator movement and avoiding the phenomenon of cavitation thanks to the action of contrasting the gravitational force. A calibrated hole dampens the pilot signal so that the valve opens and closes proportionally, avoiding load oscillations. The VBCD-SAE double overcenter valve also works as an antishock valve in the presence of pressure peaks caused by impacts or excessive loads. For this to be possible, the return line on the distributor must be connected to the drain. The VBCD-SAE is a not-compensated valve: any residual pressures on the return line counteract the opening of the valve and rises its setting and piloting values. The use of this type of valve is therefore recommended in systems with DCV with an open center spool. The hydraulic leakproof is a fundamental feature for the overcenter valves. To ensure the best performance, Oleoweb manufactures the internal components of its valves in high-strength steel, hardened and grinded, and, during the production process, carefully checks the dimensions and geometric tolerances of the sealing elements, as well as the seal itself on the assembled valve. VBCD-SAE are parts-in-body valves: all components are housed inside a hydraulic manifold, a solution that allows to manage high flow rates while limiting overall dimensions. The manifold is made of steel for operating pressures up to 350 bar (5075 PSI) and high wear resistance; it is protected from corrosion by zinc plating treatment and it is machined on the six faces for a more effective execution of the surface treatment. For applications exposed to particularly aggressive corrosive agents (e.g. marine applications) Zinc-Nickel treatment is available on request. VBCD-SAE valves are available in size SAE4 to SAE8 for recommended working flow rates up to 120 lpm (31,7 gpm). Different calibration fields and pilot ratios and a calibration tamper system are available on request. For optimal operation, it is recommended to set the overcenter valves to a value 30% higher than the maximum working load.