How do you select 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?
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.
What is pilot ratio in counterbalance valve?
However, the pilot ratio is one of the most important features when selecting a counterbalance valve. Defined, a pilot ratio is the ratio of pilot area to differential area. This means the higher the ratio, the less amount of pressure needed to assist the valve and unseat the poppet.
How do you calculate pilot ratio?
The pilot area divided by the relief area equals the pilot ratio. Reverse flow from port 1 to port 2 is blocked by the check valve until a pilot pressure is sensed at port 3 (pilot) that is inversely proportional to the load pressure at port 1 (load).
How do counterbalance valves work?
Counterbalance valves are hydraulic devices that function using this basic principle: fluid can freely flow through a check valve into the actuator, and reverse flow will be blocked using a relief valve until a pre-set pressure is reached that is set based on the system pressure and load capability.
What do p and t mean in hydraulics?
On hydraulic valves, the P stands for pump (high-pressure input) and the T stands for tank (low-pressure return to reservoir).
Which type of pressure control valve is suitable for overrunning type of load?
Many directional control circuits for high pressure hydraulic systems utilize check valves of the poppet type for controlling the flow of fluid to and from a hydraulic motor. Poppet type check valves provide positive blockage of fluid flow when closed to a greater degree than, for example, conventional spool valves.
What is pilot ratio hydraulics?
The pilot ratio is the ratio of the pilot piston area to the check poppet seat area, e.g. in a 3:1 pilot ratio valve, the pilot piston area is 3 times the check poppet seat area.
What is a hydraulic counterbalance valve?
How does counterbalance work?
How to calculate pilot pressure of a counterbalance valve?
So, if for example cylinder’a Area ratio CR = 1.64, min pilot pressure to open counterbalance valve is: Let discovery the system where the counterbalance valve on the rod end of the cylinder with a load retracting the cylinder cap: For this system the formula of min. pilot pressure is:
How does a check valve and counterbalance valve work?
The check valve lets fluid flow into rod-end port to raise the load. Referring to Fig. 1, when no pressure is applied to the cap end of a cylinder, the counterbalance valve maintains fluid pressure in the rod-end volume. The two pilot lines shown act on different surface areas inside the counterbalance valve.
How does a hydraulic counterbalance valve work in MATLAB?
If a directional valve (not shown in the picture) is shifted into position that lowers the load, then the fluid from the rod chamber of the cylinder can exit only if pressure at port P (pilot pressure) and port L (load pressure) create enough force to overcome the spring force and open the valve. In statics, the valve is described with the equation
What are the ports of a hydraulic counterbalance valve?
Connections L and B are hydraulic conserving ports associated with the load and backpressure ports of the valve. The hydraulic conserving port P is associated with the pilot port. The block positive direction is from port L to port B. Positive pressure at port P opens the valve.