Types of Dynamometers

Introduction of dynamomter which is mention below:
Absorption dynamometer
Prony brake dynamometer
Rope brake dynamometer
Transmission dynamometer
Belt transmission dynamometer
Epicyclic dynamometer
Torsion dynamometer

1. Subject :Theory Of Machine (2151902)
Topic : Types of Dynamometer
GANDHINAGAR INSTITUTE OF
TECHNOLOGY(012)

2. Content
Introduction
Classification of Dynamometer
Types of Absorption Dynamometer
Types of Transmission Dynamometer
GTU Question

3. Introduction
Dynamometer is a device which is used to measure the frictional
resistance. By knowing frictional resistance we can determine
torque transmitted and hence the power of engine.
Dynamometer can be used either to measure force, torque or
power.

4. Types of dynamometers
1)Absorption dynamometer
Prony brake dynamometer
Rope brake dynamometer
2) Transmission dynamometer
Belt transmission dynamometer
Epicyclic dynamometer
Torsion dynamometer

5. Absorption dynamometers
This dynamometers measure and absorb the power output of the engine to which
they are coupled, the power absorbed is usually dissipated as heat by some means.
Examples such dynamometers are:
1.Prony brake dynamometer
2.Rope brake dynamometer
3.Hydraulic dynamometer

6. Prony Brake Dynamometer
It works on the principle of converting power into heat by dry friction. In
this method of measuring horsepower is to attempt to stop the engine by
means of a brake on the flywheel and measure the weight which an arm
attached to the brake will support, as it tries to rotate with the flywheel.
In Prony Brake Dynamometer , when the Brake is to be put in operation ,
the long end of the lever is loaded with suitable weights W and the nuts
are tightened until the engine shaft runs at a constant speed and the lever
is in Horizontal Position. Under these conditions , the moment due to the
weight W must balance the moment of the Frictional Resistance between
the Blocks and Pulleys .

8. Rope Brake Dynamometer
It consists of a number of turns of rope wound around the rotating drum attached to
the output shaft. One side of rope is connected to a spring balance and the other to a
loading device.
The power is absorbed in friction between the rope and the drum. The drum
therefore require cooling.
Rope brake is cheap and easily constructed.
It isnotvery accurate because of changes in the friction coefficient of the rope
with temperature

9. The upper end of the ropes is attached to a
spring balance while the lower end is kept
in position by applying a dead weight. In
order to prevent the slipping ofthe ropes
over the flywheel, wooden blocks are placed
at intervals around the circumference of the
flywheel. . During operation of the brake, the
prime mover is made to run at constant
speed.

10. Transmission Dynamometers
In these dynamometers, the energy is used for doing work. The power developed by
the prime mover is transmitted through the dynamometers to some other machine
where the power is suitably measured.
This type of dynamometer can be classified as follows:
1.Belt Transmission Dynamometer
2.Epicyclic Train Dynamometer
3.Torsion Dynamometer

11. Belt Transmission Dynamometer
A belt transmission dynamometer consists of driving pulley, rigidly fixed to the shaft
of the prime mover. There is another driven pulley mounted on another shaft, to
which the power from pulley is transmitted.
The pulleys are connected by means of a continuous belt passing round the two loose
pulleys, which are mounted on the lever. The lever carries a dead weight at the one
end, and a balancing weight is attached at the other end.

13. Epicyclic Train Dynamometer :
Epicyclic train dynamometer which measures power while it is being transmitted
from driving to the driven shaft.
It consist of simple epicyclic gear train.
The pinion is free to rotate on a pin fixed to the lever arm.
The lever is pivoted about common axis of the driving and driven shaft.
When the dynamometer is in operation, two tangential forces acts at the end of
pinion.

15. Torsion Dynamometer
 When power is transmitted along a shaft, the driving end twists
through a small angle relative to the driven end.
 Torque transmitted is directly proportional to the angle of twist.
 Therefore, a torsion dynamometer works on the principle of angle of
twist.
A torsion dynamometer is used to measure large power developed
by a turbine or marine engines. A large number of torsion
dynamometers are used to measure the angle of twist.

16. Bevis-Gibson flash light torsion dynamometer

17. GTU Question
Q.3 (a) Explain working of epicyclic train dynamometer. 03
Epicyclic train dynamometer which measures power while it is being
transmitted from driving to the driven shaft.
It consist of simple epicyclic gear train.
The pinion is free to rotate on a pin fixed to the lever arm.
The lever is pivoted about common axis of the driving and driven shaft.
When the dynamometer is in operation, two tangential forces acts at the
end of pinion.