A directional control valve is one of the most critical parts of the hydraulic machinery and pneumatic machinery as well. They permit fluid to flow into various paths from one or more sources. It usually has a spool that is located inside a cylinder; this spool is either mechanically or electrically controlled. The movement of the spool restrains the fluid and controls the flow.
The spool that is located in the valve has lands and grooves; the lands block the oil flow through the valve body. The grooves, on the other hand, let the oil or gas to flow around the spool and through the valve body.
Now there are two essential positions of the directional control valve; they are the normal position where the valve returns on the removal of actuating force and the other is a working position that is created when power is applied on the valve.
The directional control valve can be categorized according to:
- The number of ports
- The number of positions
- Actuating methods
For example, A 5/2 directional control valve will have five ports and two spool positions. Ports help liquid to flow through them. There are mainly four ports P-pump, t-tank or oil sump, A&B flow of liquid to the inlet and outlet of the tank.
A Number of Positions:
The standard and working positions which a valve spool can take, there are various types like two position, three positions, and proportional valve.
Manual, spring, electrical, pneumatic and hydraulic.
These valves work with easy levers or paddles where the operator applies force to operate the valve. The spring force can sometimes be used to improve the position of the pipe. There are still some manual valves that use a lever or an external pneumatic or hydraulic signal to return the spool.
This directional control valve functions at quite high pressures than the pneumatic equivalent. They must be tough, and the precision should be of high quality and strength materials.
This directional control valve is widely used in the hydraulics industry. These valves use electro mechanical solenoids for the spool slide. This is because a straightforward application of power provides control and that is why the pipes are used extensively. Although, solenoids that are powered with electricity can’t generate large forces unless they are supplied with vast amounts of electricity. Heat generation can pose as a threat if extended to these valves for an extended period. A low powered solenoid valve is used to operate a small hydraulic valve that is called the pilot, it starts the flow of the fluid and allows a larger hydraulic valve that will require more force.