Table of Contents

Piston Motor | Types , Diagram , Working , Advantages

Introduction to Piston Motor :

Piston motors are positive displacement motors which can develop an output torque at the shaft by allowing pressurised fluid to act on the pistons.
The piston motors can be either fixed or variable-displacement devices.
They are suitable for low speed, high torque traction applications such as earth-moving machinery, agricultural tractors, railway locomotive and other industrial applications.
The piston motors are the most efficient and can operate at the highest speeds and pressures, when compared to gear and vane type motors.

Types :

Piston motors are classified into the following types:

1. According to the piston of the cylinder block and the drive shaft, piston motors are classified as follows:

Axial piston motors.
Radial piston motors.

2. According to the basis of displacement, piston motors are classified as follows:

Fixed-displacement piston motors.
Variable-displacement piston motors.

Axial Type Piston Motors

Construction and Operation:

The operation of an axial type piston motor is essentially the same as that of an axial piston pump except for the direction of flow .
The pressurised liquid introduced through the motor inlet forces the piston assembly against the thrust cam or swash/wobble plate. The angular application of this force causes the plate to rotate and this rotation is transmitted by the shaft. The displacement can be varied by changing the angle of the thrust cam.

Radial Type Piston Motors

Construction and Operation : The operation of a radial type piston is also essentially the same as that of an radial piston pump except for the direction of flow . Fluid enters the piston chamber through a central eccentric cam. The piston is forced radially outward against the thrust ring, thereby producing a force tangent to the piston chamber. The resulting torque causes the shaft to rotate.