Working principle of Dynamometer and its types

Introduction

What is a dynamometer? What does a dynamometer measure? For what purpose it is used for? What is its working principle?

A dynamometer can be defined as a device used for measuring force, speed, power, and torque.

For example to find out the moment of force or speed of an engine we can use Dyno. By acting as variable load it absorbs the power generated by the engine.
A dynamometer is basically a type of brake which calculates frictional resistance. With this value of frictional resistance, we can further calculate transmitted torque and power.

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Types of Dynamometer

The two main types of dyno are,

Absorption dynamometer 

In this type, the energy measured is absorbed by electrical or frictional resistance. While measurement, the work is done in this type by the prime mover is converted into heat.

Absorption dynamometers are further classified into prony brake and rope brake.

The continuous conversion of power into heat can raise the temperature of the system. Therefore, coolant is used. It helps to cool down the flywheel of the engine.

Transmission Dynamometer

In this type, unlike the above, energy is not wasted in friction. It utilizes other parts which can measure torque. It uses useful load which is getting transmitted by the shaft or prime mover.

Transmission dyno is further divided into the epicyclic train, belt transmission, and torsion dynamometer.

Let us discuss some of the other versions of dyno which are commonly used by industries.

Dillon dynamometer

W.C.Dillon invented Dillon dyno over 70 years ago. It is an instrument that finds the tension in attached shackles. It has an accuracy of 0.5% of full-scale capacity.

The device cannot be subjected to shock loads as it cannot withstand it.

Chassis dynamometer

The chassis dyno is also called as a rolling road. It composed of the roll set, the absorption unit, and the torque indication system. It uses roll for measurement purpose.

Chassis dyno may have one or two rolls. The diameter of the roll varies according to the application.

The working principle of chassis dyno: First the vehicle is driven onto the chassis dyno and then it undergoes various tests by the operator or inspector. 

The test checks various parameters which are important for the vehicle to work smoothly.