A counterbalance, or load-holding, valve is a mechanism typically located near the actuator that uses hydraulic pressure to keep a load from moving . Generally, these valves have three related functions: support, control and safety.
What is the purpose of a counterbalance valve?
Counterbalance valves play an integral role in the important task of safely controlling an actuator which may be holding a load or a person in the air. They help manage pressure created by impacts and loads to help stabilize loads, avoid equipment damage, and cope with hose failure and more.
What is the difference between a counterbalance valve and a brake valve?
The counterbalance valve and brake valve have similar symbols (Fig. 3.26). The single difference is that the brake valve has a remote pilot line in addition to an upstream pilot line . As with the sequence and pressure-reducing valves, a check valve is built in to allow free flow in the reverse direction.
What kind of valve is a counterbalance valve?
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.
Is a counterbalance valve normally open?
Sequence valves and counterbalance valves are normally closed — like relief valves and unloading valves — but they usually allow bi-directional flow, so they need a bypass check valve in their bodies.
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.
What is the function of unloading valve?
Unloading valves are typically used in high-low circuits . The circuit is sometimes referred to as a fast approach, slow feed circuit. The unloading valve is put to good use in a system where a high flow volume is needed at a lower pressure, and then later a low flow volume is required with a higher pressure.
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).
What is the other name for the plug valve Mcq?
What is the other name for the plug valve? Explanation: Plug valve is also called as slim valve and is used for on/ off control but with little pressure drop.
Is a pressure reducing valve normally open or closed?
The most practical components for maintaining secondary, lower pressure in a hydraulic system are pressure-reducing valves. Pressure-reducing valves are normally open, 2-way valves that close when subjected to sufficient downstream pressure.
What is a poppet type valve?
A poppet valve consists of an orifice that is opened and closed by raising and lowering a sealing surface onto the orifice . It usually has an internal spring that holds the valve in the closed position. When the spring force is overcome, the sealing surface lifts off the orifice and the valve opens.
What is the difference between pressure relief valve and pressure reducing valve?
It closes normally and opens only when the system pressure exceeds the setting of the pressure relief valve, by releasing pressurized oil to the lower pressure side or tank. Whereas on the other hand, the pressure reducing valve limits the pressure for the system to less than the maximum pressure .
What are the types of check valves?
Most common types of Check valves are swing, lift (piston and ball), butterfly, stop and tilting-disk .
At what pressure should a counterbalance valve be set?
Pressure should be approximately 700 to 750 psi . Any time the cylinder loading changes, repeat the above process. Resetting the counterbalance valve keeps the cylinder from running away and reduces energy loss with a lighter load.
Is connected between pump and tank?
Deenergizing the solenoid on the solenoid-operated relief valve connects pump flow to tank and the hydraulic motor coasts to a stop. ... A normally open solenoid-operated relief valve lets flow from the pressure-compensated pump go to tank until the electric drive motor is up to speed.
Which type of valve allows fluid to escape back into a tank when the maximum setting is reached?
Relief valves . Pressure safety or relief valves are designed to allow escape of water or heat transfer fluid from the system when the maximum working pressure of the system is reached. In this way, the system is protected from high pressure. This valve incorporates a spring, which keeps the valve closed.
