Hydraulic Actuators

This chapter considers the output device of the hydraulic control system. This device, which the authors call the actuator, is the mechanism that is responsible for delivering force and motion to the external load system of a given application. The chapter considers two actuator types: linear actuators and rotary actuators. It discusses the performance characteristics of linear actuators. These characteristics include a consideration of the actuator efficiency and the quasi-steady operation and function of the actuator. Four hydraulic actuators are used to operate a car lift that is used within an auto mechanic garage. The chapter also discusses the performance characteristics of rotary actuators. The efficiency equations for the rotary actuator (hydraulic motor) are similar to those of the hydraulic pump and the discussion of pump efficiency measurement is also applicable to the efficiency measurement of the hydraulic motor.