Hydraulic linear actuators operate with pressurized hydraulic fluid, which is typically oil. Their basic design dates back hundreds of years and is especially useful for rugged applications requiring high force, high power per unit weight and volume, mechanical stiffness, and high dynamic response.

Fremont, CA: Linear actuators are classified into four types: mechanical/electromechanical, hydraulic, pneumatic, and piezoelectric.

Mechanical or electromechanical linear actuators:

Hydraulic Linear Actuators

Hydraulic linear actuators operate with pressurized hydraulic fluid, which is typically oil. Their basic design dates back hundreds of years and is especially useful for rugged applications requiring high force, high power per unit weight and volume, mechanical stiffness, and high dynamic response. Hydraulic linear actuators can operate at 500 PSI or higher and provide far more precise control than pneumatic systems. They are commonly found in precision control systems and heavy-duty machine tools used in marine, engineering vehicles, and aerospace applications. Noise, heat, leakage issues (when not properly maintained), and the need for additional equipment such as release valves, motors, fluid reservoirs, and pumps, as well as additional equipment to reduce noise and heat, are all disadvantages.

Pneumatic Linear Actuators

Pressurized air or gas is used in pneumatic linear actuators. Their basic design is also hundreds of years old, but they are usually powered by an electric compressor in modern times. They are used in applications that require 100 PSI or less or when high speeds ranging from a couple of inches per second to over 60 inches per second are required. Switches, sensors, air compressors, dentistry, pumps, mining, nail guns, mail tubes, door closers, and countless other industrial applications are examples of applications.

Linear Actuators

Typically, mechanical linear actuators or electromechanical linear actuators convert rotary motion to linear motion. The difference between mechanical and electromechanical linear actuators is whether they are powered by an internal or external source, such as a motor or by hand. The screw, in which rotating the nut moves the screw shaft in a straight line; the wheel and axle, in which spinning a wheel produce linear motion along a belt, cable, chain, or rack; and the cam, in which an eccentrically shaped wheel is rotated to produce linear motion, is the most common mechanisms.