The Oleoweb overcenter valves of the VBCA series are dual descent control valves, thus controlling cylinder movement in both directions. The double counterbalance valves are suitable for applications in which it is necessary to guarantee stability in the working position and to control the movement of a hydraulic actuator on both supply sides. Examples of applications can be the telescopic extension of a wheel loader or the blocking of the rotation of a hydraulic motor. In a hydraulic circuit these valves are installed so that the branches with controlled opening are connected to the return of the cylinder. In the delivery phase two check valves allow the supply in free flow. 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 on the opposite side to the load, the pilot line acts to manage the partial opening of the descent line thus allowing to control the movement of the actuator counteracting the gravitational force and avoiding the cavitation phenomenon. The VBCA double counterbalance valve also functions as a pressure relief valve: when pressure peaks occur due to impacts or excessive loads, the valve protects the mechanical structure from damage. For this to be possible, the return line on the distributor must be connected to the drain. The VBCA is a non-compensated counterbalance valve: any residual pressure on the return line is added to the setting value and pilot pressure. 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. The hydraulic seal is a fundamental characteristic for supporting the load. Oleoweb takes particular care with the construction of the components, made of high-strength, tempered and ground steel. During the production process, the dimensions and geometric tolerances of the sealing parts are accurately checked, as well as the seal itself when the valve is mounted. VBCA counterbalance valves are parts-in-body valves: all 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 are protected against corrosion by galvanizing treatment. 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 also ensures high wear resistance to the benefit of valve reliability and durability. VBCA valves are available in BSPP 3/8” size. They can work with a maximum pressure up to 350 bar (5075 PSI) and are recommended for use up to 40 l/min (10,6 lpm). For optimal operation it is advisable to calibrate the counterbalance valve at a value 30% higher than the maximum work load. Different setting fields and different piloting ratios are available to better adapt to all types of applications. Using a plastic cap it is also possible to seal the setting, protecting it from tampering.