CWBG-LHN - Vented counterbalance valve, T-21A

Vented counterbalance valves with pilot assist are meant to control an overrunning load. The check valve allows free flow from the directional valve (port 2) to the load (port 1) while a direct-acting, pilot-assisted relie valve controls flow from port 1 to port 2. Pilot assist at port 3 lowers the effective setting of the relief valve at a rate determined by the pilot ratio. Back pressure at port 2 does not affect the valve setting because the spring chamber references the vent (port 4).

Technical Features

• Counterbalance valves should be set at least 1.3 times the maximum load induced pressure.


• Turn adjustment clockwise to decrease setting and release load.


• Full clockwise setting is 0 psi (0 bar).


• Free-flow check capacity (port 2 to port 1) is equivalent to the CAC* and CWC* models but the piloted-open flow capacity (port 1 to port 2) is reduced. See performance curve.


• All 4-port counterbalance and pilot-to-open check cartridges are physically interchangeable (i.e. same flow path, same cavity for a given frame size), however, the model CWBG has a reduced overall length, allowing for easier packaging.


• Reseat exceeds 85% of set pressure when the valve is standard set. Settings lower than the standard set pressure may result in lower reseat percentages.


• Sun counterbalance cartridges can be installed directly into a cavity machined in an actuator housing for added protection and improved stiffness in the circuit.


• This valve has positive seals between all ports.


• With vented valves, a lower pilot ratio may be required to achieve machine stability compared to non-vented valves.


• Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.