The Five Main Types Of Dynamometers

Dynamometers are diagnostic tools that are designed to measure the output, in terms of power and torque, of an engine or a drive system. As such, all dynamometers can be broadly categorized into engine or chassis dynamometers, which like their name suggests, measure the power output of an engine and the power output of a chassis or drive shaft system respectively. While dynamometers are most commonly used to refine engine output in vehicles, they can also be used in mining systems and other industrial applications to see if there is a difference between output by the engine and output by the driveshaft, and make technological or engineering refinements as needed to improve productivity. Understanding the various types of dynamometers available on the market can help you choose the one that best fits your needs.

Powder Dynamometers

Powder dynamometers make use of a magnetic powder within the dynamometer's rotor, which then bond together to create resistance to the engine's output. While they work very well at measuring the torque output of an engine, but have issues dealing with high RPM engines, as they are unable to cool off very quickly. They are best used for engines designed solely for towing and not high speeds.

Hysteresis Dynamometers

Hysteresis dynamometers make use of two opposite magnets, which slow down a metal rotor that is moving between them. Like powder dynamometers, they work very well for measuring torque, but do not have the same issues with heat, as they can cool down fairly easily. This allows hysteresis dynamometers to be used with engines that are running at a higher RPM than powder dynamometers can. However, this does come at a price: hysteresis dynamometers are more expensive than their powder counterparts.

Fan Brake Dynamometers

Fan brake dynamometers power a fan with the engine being measured. Torque can be adjusted by increasing resistance to the fan itself, or by changing the amount of air that passes through the fan. These types of dynamometers are extremely affordable, but are only able to measure the power output of smaller engines, as they can only absorb a limited amount of torque without becoming damaged.

Eddy Current Dynamometers

Eddy current dynamometers, also referred to as ECs, are the most common type of dynamometer available on the market, and for good reason. A metal core moves through magnetic fields, which provides resistance for the engine. They are effectively cooled using either air or water. The draw of eddy current dynamometers is that they can are controlled through computers, and can be accurately adjusted very easily. Additionally, because they are so well cooled and do not produce a great deal of heat, they are able to measure the output of engines both large and small - depending on the size of the dynamometer and the model, of course.

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