Hydraulic Valves

Double counterbalance valve flanged for open center VBCF

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Overcenter valve double effect not compensated flanged installation


With counterbalance (or overcenter) valves is possible to support suspended loads and control their movement during lowering, excluding oscillations or too fast and dangerous movements. Through the flanged surface, the VBCF series valves can be installed directly on the actuator.

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Counterbalance valves are a fundamental component for the hydraulic circuits of those applications that manage suspended loads. The Oleoweb VBCF counterbalance valves are designed to obtain the best control of the loads in working conditions that foresee gravitational forces on the actuators, such as cylinders or hydraulic motors. The VBCF overcenter valves are double-acting, ie they control the load in both delivery directions; they are flangable valves, which can therefore be applied directly on the actuator with consequent reduction of the hysteresis phenomenon. Sustaining a gravitational load is one of the fundamental tasks of counterbalance valves. To ensure the best performance in terms of load holding, Oleoweb takes particular care of the hydraulic seal of its counterbalance valves, making the components in high-strength steel, hardened and grinded and carefully checking dimensions and tolerances as well as the sealing of the valves once assembled. Another main task of the overcenter valves is the control of the actuator movement. Thanks to the piloting ratio, it is possible to release the load at a pressure lower than the valve setting pressure. For the Oleoweb counterbalance valves, different piloting reports are available. The contrast spring also allows a gradual opening of the fluid passage area allowing the control of the actuator movement even in the presence of negative loads and thus avoiding the onset of cavitation. For optimal operation it is advisable to set the counterbalance valve at a value 30% higher than the maximum work load. Using a plastic cap it is also possible to seal the setting, protecting it from tampering. The VBCF counterbalance valves can also perform the function of shock-proof valves, protecting the structure connected to the actuator from damage caused by sudden pressure peaks due, for example, to excessively high loads or accidental impacts. For this to be possible, the return line on the distributor must be connected to the drain. The VBCF is a non-compensated counterbalance valve: any residual pressure on the return lines counter the opening of the valve by raising the setting and pilot pressure necessary to open it. For this reason this type of valve is better suited to be installed downstream of distributors with open center spool, with uses connected to discharge in neutral position. Oleoweb VBCF counterbalance valves are parts in body valves: the components are housed inside a hydraulic manifold. This solution allows you to manage high flow rates while keeping down the overall dimensions. The valve body and external components are made of high-strength steel and are protected against corrosion by galvanizing. The processing of the body on the six faces guarantees an optimal execution of the surface treatment to the advantage of its effectiveness. For applications exposed to particularly aggressive corrosive agents (eg marine applications) the zinc-nickel treatment is available on request. The steel body allows working with operating pressures up to 350 bar (5075 PSI) and ensures a high resistance to wear to the benefit of valve reliability and durability. VBCF valves are available in sizes from BSPP 1/4 "to BSPP 1/2" for flow rates up to 60 lpm (15,9 gpm).

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