Piston Motor | Types , Diagram , Working , Advantages

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.

Read More : What is Hydraulic Motor or Rotary Actuator | Types , ApplicationOpens in a new tab.

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.

swash plate piston motor
swash plate piston motor

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.

radial piston motor
radial piston motor

Advantages of Piston Motors

  • The piston motors exhibit very high volumetric efficiencies.
  • They produce very high torque.
  • They are capable of working at very high pressures and speeds.
  • They are available in both fixed and variable type displacement units.

Disadvantages of Piston Motors

  • The cost per horse power is relatively high.
  • The power-to-weight ratio of piston motors are comparatively less as that of gear and vane motors.


The piston motors are available at pressure ratings upto 350 bars, with rated capacities upto 30 Lps and at operating speeds of 12,000 rpm,

More Resources /articles
Fluid Mechanics - Notes , articles , Interview Que. & Ans
Latest seminar topic index - Report ,PPT Download
Mechanical Subjectwise Basic Concept Notes ,Articles
New Mechanical Projects 2020 ( All Projects Post Index List )


Sachin Thorat

Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Recent Posts