Linear Actuators

Hydraulic linear actuators are basically used to convert hydraulic power into linear mechanical force or motion. Although the actuator itself produces linear motion, a variety of mechanical linkages and devices may be attached to the actuators for producing a final output which is rotary, semi-rotary, or a combination of linear and rotary. Levers and linkages may also be attached to achieve force multiplication or force reduction, as well as an increase or reduction of motion speed. A variety of refinements, additions, and options can be added to this basic actuator.

Generation of linear thrust force is very simple: fluid under pressure, when delivered to one end of the actuator, acts against the piston area. The piston with the attached piston rod starts to move in linear direction as long as the reaction force is smaller. The developed force is used to move a load, which may be attached either to the piston rod or to the actuator housing. The distance through which the piston travels is known as the stroke. Linear displacement may be controlled by alternately pressurizing or de-pressurizing the sides of the piston.

A common example of a manually operated hydraulic actuator is a hydraulic car jack. Typically though, the term "hydraulic actuator" refers to a device controlled by a hydraulic pump.