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Categories : Hydraulic valves
3 spool valve is a device used to control hydraulic systems. 3 spool hydraulic valves are very wide used from automotive power-steering systems to constructions machines like cranes, loaders, diggers. 3 spool hydraulic valve can manage the flow of hydraulic fluid from a hydraulic pump to an actuator. It can be open or closed, blocking of the route the fluid takes.
The build of 3 spool hydraulic valve is simple. It is a sealed case with cylinder inside. It has sockets to attach hoses, one from the pump and second for more hydraulic devices like for example actuator. Fluid under pressure can flow into 3 spool hydraulic valve from the pump into the hydraulic devices, or drain out of them back into a hydraulic storage tank. A controller moves the valve back and forward in its case to slide the spools into different positions. The 3 spool valve consists of lands and grooves. The lands block oil flow but the grooves allow oil to flow around the spools and through the valve body. The position of the spool will only allow the hydraulic fluid to flow in one direction to perform a specific task.
3 spool hydraulic valves can be divided to couple groups like: directional valves, check valves, drain valves and shut-off valves.
3 spool hydraulic valves may be direct-operated or pilot-operated. A direct-operated 3 spool valve is either electrically controlled with solenoids, mechanically (for example manually) controlled with levers or rollers, or controlled with. Whether a 3 spool valve hydraulic is direct- or pilot-operated depends on the actuating force needed to move the spool. This is dependent on the nominal size of the directional spool valve (flow).
Manually operated valves work with simple levers or paddles where the operator applies force to operate the valve. Spring force is sometimes used to recover the position of valve.
Electrically operated directional control valves make use of electromechanical solenoids for sliding of the spool. Because simple application of electrical power provides control, these valves are used extensively. However, electrical solenoids cannot generate large forces unless supplied with large amounts of electrical power. Heat generation poses a threat to extended use of these valves when energized over time. Many have a limited duty cycle. This makes their direct acting use commonly limited to low actuating forces.
Often, a low power solenoid valve is used to operate a small hydraulic valve (called the pilot) that starts a flow of fluid that drives a larger hydraulic valve that requires more force.