A hydraulic overcentre valve is used in holding loads and controlling motions in an impressive way. The main areas of use of an overcentre valve have been discussed here to tell you the importance of the component.
Uses of Overcentre Valves
- Holding Load– the load movement is restricted by an overcentre valve when the directional vale position is neutral. This prevents leakage in an excellent way.
- Controlling Load– when the pump runs the actuator treads to run ahead due to the energy induced by load, it is prevented by the overcentre valve. Thus, loss in control with cavitation can be avoided.
- Load Safety– when an overcentre valve is fitted on or inside a cylinder, then the load movement can be kept in control. Hose failure of cylinders while in the boom usage is critical to avoid injuries to people and damages to properties. This is ensured with the use of this component.
The relief setting for the valve has to be done based on some common idea of adjustment. The relief pressure may vary when the load changes suddenly. There is a calculation of pilot pressure needed to open the valve, and this is calculated on the formula of valve setting minus the load pressure or pilot ratio.
How the Overcentre Valves Works
Their working revolves around balancing the load. This can be explained with a reverse pendulum example. If you imagine a cylinder attached to a reverse pendulum, and swaying the pendulum from one extremity to another, then the cylinder would be doing this against the gravity. Thus, the pendulum is controlled by the load driving pump.
Now when the pendulum starts descending being away from its centre of gravity, then the balance in load is disturbed. The pendulum automatically tries moving faster than it’s allowed by the cylinder. As a result of the load, the pump is driven since the gravity and load both are from the same direction. The cylinder movement would be regulated by the overcentre valve in this case as the flow is metered out, while the load will be kept in control throughout.
As the same movement repeats again, but this time in the opposite way, another overcentre valve will be needed to balance things the opposite way. And this way the flow of the cylinder at both directions will be regulated.
Use of Dual Hydraulic Overcentre Valves
The dual overcentre valves are used in heavy earthmoving tools with the track wheels. These equipments are sent on steep slopes and accented high; thus, needing the valves. The use enables the machines to move both in front and back on the steep slopes. The valves work by balancing the load as the machine tries ascending a reverse slope, or descending a slope. But these machines need support of a parking break for the rotary actuators.
Use of Hydraulic Overcentre Valves in Winches
The use of overcentre valves is seen in winches, where loads are lifted against gravity as winches are reeled. As a result, the load is driven in by the pump. But when the load is lowered, then the gravity and load both act in the same direction. Hence the load tends to run faster downwards, and this motion needs to be balanced. Here comes the use of the overcentre valve to keep a balance by checking the flow off the hydraulic motor.
In this way, there are several uses of the load balancing hydraulic overcentre valves, and you have to get the best quality for your machinery, so that quality stays uncompromised with utmost safety.