The directional control valve performs three functions:
- Stop fluid flow
- Allow fluid flow
- Change the direction of fluid flow
The three functions operate together in the form of a combination. The easiest directional control valve is the two-way valve. This valve has two features, that is, it either stops the flow or allows the flow. A water faucet is the perfect example of a two-way valve. The water faucet allows a flow or prevents the flow with manual control.
A single acting cylinder needs a steady supply to and exhaust from its port to operate; now, this will require a three-way valve. A three-way valve allows the liquid to flow to an actuator in one position and this exhausts the fluid from it in the additional position. Some of the three-way valves include a third position that stops the flow at all the ports.
A double acting actuator needs a four-way valve. This variant of the valve produces pressure and exhausts the two ports interdependently. A three position, four-way valve stops an actuator, or it can allow it to float. The four-way function is a common type of directional control valve for both air and hydraulic circuits. The three position, four-way valve is way more common in hydraulic circuits.
The five-way valve is found mostly in air circuits; it performs the same functions as its 4-way counterpart. The only difference being the extra tank, also known as, the exhaust port. Some suppliers also call the five-way valves the five ported four ways. All the spool valves consist of five ports; however, the hydraulic valves have connected exhaust ports internally that go into a conventional outlet. This is because the fluid must return to the tank. Hence it is convenient when you combine the dual tank ports to a single return port.
When it comes to the air valves, the atmosphere is the tank, so exhaust piping is usually not that important. When you use two exhaust ports, the dual exhausts used for speed control mufflers or as double pressure inlets make this configuration versatile.
The directional control valve is one of the critical parts of the hydraulic machinery and pneumatic machinery too. It permits 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 spindle 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 slots, 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.