Chassis dynamometers may be fixed or portable units. The horsepower measured by a chassis dynamometer is often 15% to 20% lower than results from an engine dynamometer, as friction and losses occur through various drivetrain components such as the gearbox or transmission.
As a result, the measurements provided by chassis dynamometers are often less accurate and repeatable than those of engine dynamometers. Despite their inefficiencies compared to other dynamometers, recent developments in chassis dynamometer technology have overcome, to some extent, the primary inherent deficiencies of chassis dynamometers.
The expression of this is a reduction of measurement inefficiency and, therefore, inaccuracy. Chassis dynamometers are used for a number of testing purposes. For instance, semi-truck owners and owner-operators may use chassis dynamometer services to troubleshoot potential problems with their engines.
Chassis dynamometers are just one dynamometer variety. Dynamometers are also known as dynomometers, dynometers or simply dynos. While their most widespread use may be in the context of engine performance measurement, a dynamometer can be any utility that measures force exertion.
For example, a device that measures the force exerted by the grip of a human hand can be considered a dynamometer. Dynamometers are used for different reasons, and these reasons depend largely on the context in which the subject of measurement is used.
A casual motorist has little use of a chassis dynamometer outside of the context of vehicle diagnostic tests and repairs, and chassis dynamometric tests in that context are almost always performed by professionals at repair shops. Hobbyists may own small chassis dynamometers; such devices can be stationary or portable.
Performance vehicles, like race cars and off-road vehicles, can be better maintained when subject to regular testing. Chassis dynamometers may be employed for this purpose. When chassis dynamometers are not suitable for a given application, other kinds of motor testing tools often can be used.
Use of these tools should always be left to professionals, as unsecured vehicles could pose a danger to surrounding people and objects. Care should always be taken in the use of all vehicle dynamometer varieties.