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How Do Directional Control Valves Affect Oil Flow? 08## August 2019

A directional control valve is an essential component of a hydraulic system. It moves from a fully open to a fully closed position very quickly, triggering rapid acceleration and deceleration of fluid.

In a hydraulic system, oil flow can be managed with the following directional control valve types:

• Spool Type
• Cartridge Type
• Pilot-Operated Check Valves
• Diverter type

 

Simple Directional control valves tend to be of the diverter type and are often used to control the movement of hydraulic cylinders, oil entering one port and being sent on an either or basis via two other ports or together with a tank port to both ends of a double acting cylinder to extend or retract it.

The more sophisticated spool types have three positions and, depending upon the specification of the spool, it will be neutral in the central position and then the two service ports will either be pressurized or open to tank in the two other positions.

These are mainly used to control cylinders with, but have the advantage over diverters of being easier to operate under pressure and can be used to operate multiple cylinders and/or motors as well as other actuators from the same block of spools. Some manual spool valves will sometimes have a fourth position which is described as a float and is effectively the two service ports linked so that the attached hydraulic cylinder will move in and out as the load on it dictates (e.g. on a grading blade).

A pilot-operated check valve will allow oil to move freely in one direction, but it will move only in the opposite direction when a pilot pressure is applied to lift the check off its seat to let the blocked fluid to pass through. The cartridge type directional control valves operate in a similar manner to the other types, but the valve mechanism is contained within a cartridge so it can, for example, be combined with other sorts of cartridge valves within the same block.

Order a directional valve, hydraulic oil pump, or any other part for your hydraulic system today or call White House Products, Ltd for assistance with product selection or hydraulic troubleshooting.

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