Working of Direction Control Valves
Let us discuss the working of 3-way 4-port, spring-loaded, solenoid operated direction control valve. The valve has the above name because:
3-way: the hydraulic fluid can make three different paths through the valve.
4-port: every valve unit has four ports, two of which are hydraulic oil inlet and two are hydraulic oil outlets.
Solenoid-operated and spring-loaded: Each unit of the valve is activated by the signal from the solenoid and when the solenoid de-energizes, the spring force which is acting against the solenoid force, brings back the control valve in its initial position.
After the pressurized oil passes through the direction control valve, it reaches the hydraulic cylinder or hydraulic motor, where it uses its pressure energy and does work. The pressure is lost in performing the required work of either lifting, rotating etc. Thus the oil losses pressure and drains back into the reservoir. Any leakage in the pipelines or any other hydraulic machinery, the return oil to the reservoir volume is reduced and thus results in decrease in the reservoir tank level.
In my next article, we will discuss on the hydraulic starting arrangements for emergency generator and life boat/rescue boat.