What does a counterbalance valve do in hydraulics?
Counterbalance valves are used in hydraulic systems working with an overriding (run-away) or suspended load. They are designed to create backpressure at the return line of the actuator to prevent losing control over the load. The following illustration shows a counterbalance valve schematic.
What is the purpose of counterbalance valve?
The basic function of a counterbalance valve is to control a load, by providing a restriction through a differential area. They also help prevent cavitation when controlling an overrunning load. Load control is achieved when enough pressure is present at the work port of the valve to overcome the spring setting.
How do you set a counterbalance valve?
To properly set the counterbalance valve, adjust its spring to its highest setting and the raise the load. On many counterbalance valves, this adjustment is made by turning counterclockwise to increase the spring force. Next, very slowly turn the adjustment in the opposite direction.
At what pressure should a counterbalance valve be set?
approximately 100 to 150 psi
Set the counterbalance approximately 100 to 150 psi higher than the load-induced pressure. Normal procedure for setting a counterbalance valve is to turn the adjusting screw to its highest pressure before raising the cylinder.
How does counterbalance work?
A counterbalance is a weight or force that balances or offsets another as when two objects of equal weight, power, or influence are acting in opposition to each other. The objects are then said to be in counterbalance.
How do you test a counterbalance valve?
First the valve is set to just crack open at the desired setting. The pressure is dropped to zero and then brought up to 85% of the setting. The valve is then piloted open and allowed to reseat.
How do you calculate pilot pressure on a counterbalance valve?
For example, in a valve with a 3:1 pilot ratio, set for 3000 psi with a load of 2000 psi, the pilot pressure required to open the relief valve is 333 psi—i.e., (3000 psi – 2000 psi)/3 = 333 psi pilot pressure. To calculate the pressure required to lower a load, use the following equations.
What is pilot ratio counterbalance valve?
Therefore, the vast majority of counterbalance applications are satisfied with a 3:1 pilot ratio. Higher ratios will be more efficient (reduce heat generation) but at the cost of stability and smooth motion control. This is why 10:1 pilot ratio valves, generally, should be avoided.
What kind of valve is a counterbalance valve?
Counterbalance Valves Parker counterbalance valves are screw-in type cartridge valves that control the pressure at an actuator controlling its motion. Uses include controlling over-running loads in cylinders and motors.
How is load holding capacity achieved in a counterbalance valve?
The load holding capacity is achieved by allowing free flow into the cylinder/actuator and by blocking the reverse flow until a pilot pressure inversely proportional to the load is applied. In short, the counterbalance valve permits flow in one direction and block the flow opposite to it.
What is the pressure of a Parker counterbalance valve?
Parker’s CB series counterbalance valve controls the actuator movement with overrunning loads. Manifold Mounted Motor Control Valve capable of pressures up to 210 bar (3000 psi) and flows up to 56 lpm (15 gpm).
Who is the industry leader in counterbalance solutions?
As the industry leader in counterbalance solutions, Sun Hydraulics offers more than 150 standard counterbalance models in a range of capacities, pilot ratios and configurations.