Hydraulic Actuator Design and Operation

Hydraulic and Pneumatic Knowledge

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Hydraulic Actuator Design and Operation

Pneumatic actuators are normally used to control processes requiring quick and accurate response, as they do not require a large amount of motive force. However, when a large amount of force is required to operate a valve (for example, the main steam system valves), hydraulic actuators are normally used. Although hydraulic actuators come in many designs, piston types are most common.

A typical piston-type hydraulic actuator is shown in the illustration below. It consists of a cylinder, piston, spring, hydraulic supply and return line, and stem. The piston slides vertically inside the cylinder and separates the c y l i n d e r i n t o two chambers. The upper chamber contains the spring and the lower chamber contains hydraulic oil.

Hydraulic Actuator Section View

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