A counterbalance valve is commonly used when high-pressure events are expected or when controlled manipulation at high pressures is required, such as hydraulic overloading or lowering suspended loads. During normal operation, pressure is typically applied to a separate port, normally taken from the other side of the actuator, where the area is larger than the relief seat area. 2013/0233409, are provided … For example if the pressure of the spring is set on 260 bar and the valve has a pilot ratio R=10, the required pilot pressure is 26 bar. Functional Group: Products : Cartridges : Counterbalance : 3-Port Non-vented : Standard, 3:1 Pilot Ratio Model: CBEA-LHN Product Description Counterbalance valves with pilot assist are meant to control an overrunning load. When backpressure exceeds pilot pressure, it adds to the setting of the valve at a rate of 1 plus the pilot ratio times the backpressure, i.e. But it also finds application in other situations, including variable pump and motor controls. Top Rated Seller Top Rated Seller. Figure 3 shows the relief performance of three different manufacturers��� overcenter product fittings in the same cavity. Other names for this valve include motion control valve and over center valve. It is recommended for applicaitons where the load indiced pressure varies during the motion with resulting instability of the machine. This action causes the valve to open at a lower pressure. The pilot pressure at Z, required to open the valve in case of an unloaded cylinder depends on the valve pilot ratio R and the pressure setting of the spring. Most counterbalance valves come with a pilot ratio anywhere from 1.75:1 to 12.0:1. In this case, the min. Each series has multiple pilot ratio options, adjustment styles, and available pressure ranges. by the pilot ratio. ADJUSTMENT TYPE Parker offers counterbalance valves with adjustable and non-adjustable pressure settings. A lower pilot ratio requires a greater pilot pressure difference to fully open the valve, and any given load pressure change does not affect the valve as much as it does for a high pilot ratio (See Figure 2). Pilot assist at port 3 lowers the effective setting of the relief Pilot assist at port 3 lowers the effective setting of the relief valve at a rate determined by the pilot ratio. Figure 2 shows the pressure drop curves of two valves with different pilot … The stiffness of the spring increases the pressure override when used as a relief valve. Required fields are marked *. This is likely to be about 30% of the load induced pressure but check the valve manufacturer recommendations. Full clockwise setting is 200 psi (14 bar). Select your pilot ratio. Pilot ratio 5 to 1 Pilot ratio 2.5 to 1 Pilot pressure required for opening Pilot ratio 0 50 100 150 200 250 Instability results from rapid changes in the load pressure. Matching this selective pilot ratio to particular equipment sometimes corrects the problem. The pilot area divided by the relief area equals the pilot ratio. 3:1 pilot ratio, standard capacity counterbalance valve L C ap city: 30 gpm (120 /min.) For explanation we will use the 3:1 ratio. counterbalance, valve. Low pilot Ratio requires a high pilot ratio pressure in order to lower the load, but it permits a more precise and smooth control of the motion. Tagged counterbalance valves, eaton, pilot ratios, Your email address will not be published. 2) inside the valve. This site uses Akismet to reduce spam. Pilot assist at port 3 lowers the effective setting of the relief valve at a rate determined by the pilot ratio. 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