What Is A Dynamometer?

A dynamometer is a machine used to measure torque and rotational speed from which power produced by a motor can be measured.

The main components of a dynamometer are:

  • Base – Provides a stable platform where all components are mounted.
  • Pedestals – Provides support and transfers static and rotational forces to the base.
  • Collection Box – Collects the coolant discharged from the dynamometer after usage.
  • Rotor (Shaft) – The rotating element that is turned by the unit being tested.
  • Stator (Housing) – Encases and supports the rotor. Also assists in cooling.
  • Lubrication System (Pump, Tubing etc.) – Provides lubrication and cooling for rotor bearing assemblies.
  • Load Cell – Provides a calibrated output that is usually measured as torque.

Principles of Operation
There are many types and variations of dynamometers currently in use, but generally a dynamometer works as follows. A drive motor (the unit to be tested) is physically connected to the dynamometer rotor shaft using adaptors. A flow of coolant then begins to run thru passages inside of the dynamometer to absorb heat that will be generated from the “braking” action of the dynamometer. The drive motor begins to rotate, and in turn rotates the dynamometer rotor shaft. When the drive motor and rotor shaft reach the desired speed a “brake” is applied to the rotating shaft housed inside the dynamometer. Application of the “brake” creates a counter rotational force causing the load cell to deflect. The movement of the load cell is measured and is converted to torque. The drive motor power output is then calculated by using the following formula:

HP – Horsepower
Torque – Usually measured in pound-feet (lbf•ft).
RPM – Revolutions Per Minute
5252 – Constant

dynamometer parts description