Dynamometers, also known as dynos, are meters that are used to measure mechanical force to determine the output power or horsepower of a motor or an engine. In mimicking anticipated real-life situations, dynamometers enable the engine to operate for long durations at peak levels without getting a vehicle in motion. There are two types of dynamometers, loading and inertia. The loading dynamometer measures power at a constant speed, while the inertia dynamometer measures power in an accelerating vehicle. The automotive industry extensively uses dynamometers to develop and test commercial and race vehicle engines. However, dynamometers are also used to test various types of engines that are used for industrial applications.
An engine's crankshaft end is combined with the dynamometer through a drive shaft and couplings, in an engine/dynamometer simulation. The dynamometer can deliver a braking force while the engine is in operation, as well as measure the engine speed and torque. The braking force on a test device can be applied through a variety of ways via AC & DC and water-brake and eddy-current dynamometers. A DC dynamometer is trunnion-mounted, while an AC motor is powered by alternating current.
A water-brake dynamometer incorporates a bladed rotor that generates a greater braking force, based upon a higher level of water rotating inside the dynamometer housing. Eddy-current dynamometers produce brakes based upon the eddy currents created in a revolving metallic disk seeped in a magnetic field. Today dynamometers are computer-controlled, allowing operators to select speed ranges for measuring engine torque.
When using this device you should also have a good computerized data acquisition system to record the data that is put out by the dynamometer. Hand held dynamometers are relatively inexpensive. When searching for a good one you should try to find one that samples at least 100Hz (samples per second), however 200Hz is better as it will give you a more accurate reading. Try to stay away from dynamometers that read less than 100Hz, as you will usually get inexact readings. If you want to get the most accurate results from the meter you will have to properly understand how to use it. If you don’t use it properly you will get incorrect readings.