When a machine uses hydraulic fluid, for that fluid to work right, it has to circulate properly throughout the motors and the actuator and, when it is finished circulating, the fluid has to go back into the hydraulic fluid reservoir. That reservoir then cleans, filters, and re-pumps that fluid to the motor and actuator again, thus continuing the cycle.
This hydraulic fluid circle is called a circuit. Three of these circuits are available to use, all of which use hydraulic valves, or a control valve to control the fluid. However, the most common is an open centers circuit system. These systems are hydraulic pumps that pump continuously and push the fluid to the control valve through its center that is open and into a tank. In other words, when the control valve is centered properly it allows the fluid to return to the tank, but if it is instead actuated, and then the fluid runs to and from the tank through the actuator instead.
Without the hydraulic valves, this open circuit system would never work, and the pressure would get so high in the pump that the pump could explode. Keep in mind that a hydraulic pump and system is a specialized piece of equipment and if you are not trained to use it, you should not try otherwise you might get badly hurt.
If you are looking for information about the hydraulic pump process, or need training on how to use one, then Business.com can help. Offering valuable informational resources, anyone can find a hydraulic pump and the valves that make the pumps work right, as well as classes on how to use them. Check out the links to the left to read more information about these valves and classes.