Hydraulic valves

Single counterbalance valve flanged for open center VBLF

In stock

Overcenter valve simple effect not compensated flangeable on the cylinder


With counterbalance valves it is possible to sustain a suspended load and manage its movement free from vibrations or avoiding potentially dangerous sudden drives. The counterbalance valves of the VBLF series are equipped with flanged ports which allow their installation directly on the cylinder.

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The Oleoweb VBLF series includes single counterbalance valves with flanged ports for installation on the actuator. The actuator movement is controlled in one direction only, while the opposite one is fed by a free flow. These valves are suitable for all systems where a gravitational load requires sustenance and control in its movement. Flanged ports make the VBLF series valves suitable for direct installation on hydraulic cylinders with benefits on hysteresis of the system which is extremely reduced. The correct installation of these valves in the hydraulic system requires that the line with controlled opening is positioned on the return line of the cylinder. A check valve allows the actuator to be powered in the opposite direction. By feeding the line opposite to the load, the counterbalance valve is unlocked by the pilot line. A reduction ratio (pilot ratio) allows the valve to be opened with lower pressure than the setting. The pilot line manages the partial opening of the descent branch by counteracting the gravitational force induced by the load and thus allowing its control without cavitation. An orifice on the pilot line allows a gradual opening and closing of the valve avoiding load oscillations. The VBLF single balancing valve can also work as anti-shock valve to protect the structure connected to the actuator in the event that the load pressure exceeds the valve setting, for example in the event of accidental impacts. The anti-shock function is only possible if the return line on the distributor is connected to the tank. The VBLF is a non-compensated overcenter valve: in presence of residual pressures on the return line, the setting values and pilot pressure are increased accordingly. The use of not compensated counterbalance valves is therefore recommended in systems where the downstream distributor has spool with users connected to tank in neutral position (open center). Sealing is a key feature for supporting a load. To obtain the best performance in terms of sealing, Oleoweb manufactures the internal components of counterbalance valves in high-strength, hardened and grinded steel, and during the production process accurately checks dimensions and geometric tolerances of the sealing parts, as well as the seal itself valve mounted. The VBLFs are parts in body balancing valves: the components are housed inside a hydraulic manifold. This solution allows you to manage high flow rates while keeping down the overall dimensions. Body and external components are made of high-strength steel and protected against corrosion by zinc plating. The valve body is machined on the six faces for an optimal execution of the surface treatment. Zinc-nickel treatment is available on request for applications exposed to particularly aggressive corrosive agents (eg marine applications). The steel body allows working with operating pressures up to 350 bar (5075 PSI) and ensures high wear resistance to the benefit of valve reliability and durability. Oleoweb offers VBLF valves in sizes BSPP 3/8 "and BSPP 1/2", for recommended operating flows up to 60 lpm (15,9 gpm). For optimal operation it is advisable to set counterbalance valves at a value 30% higher than the maximum work load. Many setting ranges and pilot ratios are available to better adapt to all types of applications. Using a plastic cap, the seting can be sealed, protecting it from tampering.

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