Hydraulic valves

Single counterbalance valve for closed center, flanged VCLF

In stock

Overcenter valve simple effect semi-compensated flanged installation

Within a hydraulic circuit the counterbalance (or overcenter) valves have the task of supporting a suspended load and controlling its downward movement eliminating vibrations or too fast and potentially dangerous lowering. The VCLF series valves, thanks to the flanged surface, allow installation directly on the hydraulic cylinder.



The Oleoweb valves VCLF series are single overcenter valves. Their function, within a hydraulic circuit is to support a load subject to gravitational force and to control its movement in only one direction (usually the lowring phase). The actuator movement in the opposite direction is powered by free flow. The single counterbalance valves are suitable for applications in which it is necessary to guarantee stability and control of a load and find large employement in the mobile sector mainly. Correct installation requires the controlled opening line to be connected to the actuator return line. In the delivery phase, a check valve allows free flow supply. Thanks to a reduction ratio between the load line and the hydraulic pilot line (pilot ratio), the pressure required to open the valve is lower than the setting pressure. Powering the line opposite to the load, the pilot piston modulates the opening of the descent line allowing to control the movement of the actuator and avoiding the cavitation phenomenon. A calibrated orifice on the pilot line also ensures that the valve is opened and closed proportionately, avoiding load oscillations. The VCLF single counterbalance valve can work as an anti-shock valve to protect the structure connected to the actuator in the presence of pressure peaks caused by excessive loads or accidental impacts. For this to be possible, the return line on the distributor must be connected to the drain. The VCLF is a semi-compensated counterbalance valve: any residual pressure on the return line has no influence on the valve setting value, but increases the pilot pressure necessary to open it. This type of valve can be installed in systems with directional control valves with closed center spool, with users closed in a neutral position. Oleoweb have particular care to the production and check of components in order to ensure high performance in terms of hydraulic sealing: fundamental characteristic for sustaining the load. The internal components of the VBCL counterbalance valve are therefore constructed in high-strength, hardened and grinded steel and during the production process the dimensions and geometric tolerances of the sealing parts are accurately verified, as well as the seal itself when the valve is mounted. VCLF counterbalance valves are parts in body valves: all the components are housed inside a hydraulic manifold. This solution allows to manage high flow rates while keeping down the overall dimensions. Valve body and external components are made of high-strength steel and protected against surface corrosion by zinc-plating. The machining 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 pressures up to 350 bar (5075 PSI) and ensures a high resistance to wear to the benefit of reliability and durability of the valve. Its shape allows easy installation of pipes with banjo bolts. VCLF valves are available in sizes from BSPP 3/8 "and BSPP 1/2" for recommended operating flows up to 60 lpm (15,9 gpm). Different setting ranges and different pilot ratios are available to better adapt to all types of applications. For optimal operation it is suggestes to set the counterbalance valves 30% higher than the maximum work load.