TABLE OF CONTENTS After reading this chapter, the student will be able to:
Differentiate between hydraulic pumps and motors
Understand and describe the design and construction of various motors used in hydraulics
Explain the operation of the various hydraulic motors of the likes of gear, vane and piston motors and also evaluate their performance by determining their mechanical, volumetric and overall efficiencies
Select and size motors for hydraulic applications
Understand the performance parameters of hydraulics motors.
Hydraulic motors are classified as rotary actuators. But strictly speaking, the term Rotary actuator is reserved for a particular type of unit whose rotation is limited to less than 360 . Hydraulic motors are used to transmit fluid power through linear or rotary motion. They resemble pumps very closely in construction. However, as already understood, pumps perform the function of adding energy to a hydraulic system for transmission to some remote point, while motors do precisely the opposite. They extract energy from a fluid and convert it to a mechanical output to perform useful work. To put it more simply, instead of pushing on the fluid as the pump does, the fluid pushes on the internal surface area of the motor, developing torque. Since both the inlet and outlet ports in a motor may be pressurized, most hydraulic motors are externally drained.
Hydraulic motors can be of limited rotation or continuous rotation type. Limited rotation motors are called oscillation fluid motors as they produce a reciprocating motion. Continuous rotation motors (hydraulic motors) as...
