2. Hydraulic Directional Control Valve
The direction of hydraulic fluid flow is controlled by a directional control valve. A directional control valve broadly consists of four parts. Namely, these are the valve body, valve spool, actuator, and spring. The valve spool get shifted with respect to the valve body which opens or closes valve ports for controlling fluid flow. The actuator provides power for shifting the spool and the spring pushes the spool back to its normal position. Look at the representation of a typical two position two way valve:
Tips for reading directional control valve symbol:
1. The number of boxes shown in the valve symbol is the number of positions for the valve. In the above symbol two square boxes are there so it is a two position valve.
2. Number of ports tells how many pipes can be connected to the valve.
3. Actuator always pushes and never pulls the spool.
4. The box, which is away from the actuator, is the neutral or normal position of the valve. This way the above shown valve is normally closed valve.