The Oleoweb valves of the VBCT series are double overcenter valves with flanged body for installation in systems that require the use of cetop modular bases (Oleoweb BS3, BP3 or BM). The double counterbalance valves are suitable for applications in which it is necessary to guarantee stability in the working position and control the descent phase of a suspended load subject to gravitational force or in the presence of bidirectional loads as in reversible hydraulic motors. The installation requires that they be placed between the modular cetop base and the directional solenoid valve. The lines with controlled opening are connected to the return lines of the cylinder, while in delivery two unidirectional valves allow the supply in free flow. The control of the descent of a load is carried out by feeding the line on the opposite line and acting on the hydraulic pilot which has the task of managing the gradual opening of the valve, guaranteeing a back pressure sufficient to avoid too fast and potentially dangerous descents and avoiding the cavitation phenomenon. Counterbalance valves can also act as anti-shock valves when pressure peaks occur due to excessive load or accidental impacts. In these cases the valves open and discharge the excess pressure, safeguarding the circuit and the mechanical frame connected to it. This function is only possible if the directional valve of the system has a spool with uses connected to tank in the neutral position (open center). The VBCT is a semi-compensated counterbalance valve: the setting of the valve is not affected by any back pressure on the tank line, which instead influences the piloting ratio. The semi-compensated valves can be installed downstream of distributors with closed center spools, with users closed in neutral position. For load support, sealing is a key feature for this type of valve. For this reason, the internal components of the Oleoweb counterbalance valves are made of high-strength, hardened and ground steel and 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. VBCT counterbalance valves are parts in body valves: all the components are housed inside a hydraulic manifold. This solution allows you to manage high flow rates while keeping down the overall dimensions. The body and the external components are made of high-strength steel and are protected against corrosion by zinc-plati9ng. The machining of the body on the six surfaces 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 operating with operating pressures up to 350 bar (5075 PSI) and ensures a high resistance to wear to the benefit of reliability and valve life. VBCT valves can work with recommended flow rates up to 40 lpm (10,9 gpm). Different setting fields and different piloting ratios are available to better adapt to all types of applications. For optimal operation it is advisable to calibrate the counterbalance valve at a value 30% higher than the maximum work load.