(a) Actuators: A device which converts fluid, power into mechanical power is known as actuator.
• An actuator transforms the output of a controller into a controlling action! Motion.
• It produces physical changes such as linear or angular displacement.
• Examples Solenoids, electric motors, hydraulic cylinder, pneumatic cylinders and motors.
(b) Classification of actuators: Actuators are available in various forms to suit the particular requirement of process control. It can be classified into three main categories:
1. Pneumatic actuators
2. Hydraulic actuators
3. Electrical actuators.
(c) Piston actuators is also known as cylinder actuators
1. Torque capability is high.
2. Can work at high temperature.
3. Compact and light weight.
4. Fast speed.
I Necessity of positioner for throttling
2. Cost is high.
3. Require high pressure.
Applications: Piston actuators are used to perform the works like linear movement of jigs, fixtures, raw material feeding etc.