Dynamometers are machines used to measure the torque and power of rotating devices like engines and motors. There are different types including electrical, hydraulic, and mechanical dynamometers. A dynamometer consists of an absorption unit with a rotor that is coupled to the device under test. It allows the device to rotate while applying a braking torque through various means to measure its performance characteristics.

3. Need?
Dynamometers is a machine or instrument
which is used to measure torque and
power of an engine, motor, turbine, or
other rotating device
Used in stress and deflection analysis
Determining the performance
characteristics of machines

4. Types of Dynanometers
Electrical
Generator Type
Eddy current
Hydraulic –Water Brake
Mechanical
Prony Brake
Rope Brake

8. A dynamometer consists of an absorption (or
absorber/driver) unit, and usually includes a
means for measuring torque and rotational
speed. An absorption unit consists of some
type of rotor in a housing. The rotor is coupled
to the engine or other equipment under test
and is free to rotate at whatever speed is
required for the test. Some means is provided
to develop a braking torque between
dynamometer's rotor and housing. The means
for developing torque can be frictional,
hydraulic, electromagnetic etc. according to
the type of absorption/driver unit.

9. One means for measuring torque is to mount
the dynamometer housing so that it is free to
turn except that it is restrained by a torque
arm. The housing can be made free to rotate by
using trunnions connected to each end of the
housing to support the dyno in pedestal
mounted trunnion bearings. The torque arm is
connected to the dyno housing and a weighing
scales is positioned so that it measures the
force exerted by the dyno housing in
attempting to rotate. The torque is the force
indicated by the scales multiplied by the length
of the torque arm measured from the center of
the dynamometer.

15. Hydraulic dynamometer:
The Hydraulic Dynamometer is essentially a compact servo-
hydraulic test rig packaged with an integral power supply and control
system.
The Hydraulic Dynamometer can test at a range of strokes and
velocities that are determined by the flow output of the servo valve. The
maximum load is determined by the size of the actuator and the
maximum value of the load cell.

18. Eddy current
When a current carrying conducting material
moves through a magnetic field voltage is
generated, which results in current.
If the conductor is a part of circuit then current
will flow through circuit. But if it is isolated than
voltage is still induced & local currents may flow
in a short circuited path within the bar itself.
These current are called eddy eddy currents,
dissipated in the form of heat.

19. Electric Generator
BP= VI/(Generator Efficiency)

20. Electric Generator

22. Chassis dynamometer
A chassis dynamometer measures power from the
engine through the wheels. The vehicle is parked on
rollers which the car then turns and the output is
measured. These dynos can be fixed or portable.
Because of frictional and mechanical losses in the
various drivetrain components, the measured
horsepower is generally 15-20 percent less than the
brake horsepower measured at the crankshaft or
flywheel on an engine dynamometer.[1]

24. Measurement of Indicated power
Morse test