dynamometer

A dynamometer is a device used to measure the force, torque, or power output of a rotating machine such as an engine, motor, or generator. It converts the mechanical power into a measurable quantity, typically by applying a controllable load to the shaft and recording the resulting torque and rotational speed. Dynamometers are essential in design, development, testing, and performance verification across automotive, industrial, and research settings.

There are several fundamental types. Absorption (brake) dynamometers dissipate the test power as heat through braking mechanisms such as hydraulic, fluid–friction, or eddy current brakes. Inertia (or flywheel) dynamometers measure power by observing the response of a known inertial load to controlled acceleration or deceleration, sometimes using a torque sensor and a speed signal to compute power. Hybrid systems combine elements of both methods. In automotive applications, engine dynamometers test the engine at a stand, while chassis dynamometers measure power at the wheels.

Measurements typically include torque (τ), rotational speed (ω), and derived power (P = τ·ω). Additional data such as speed, temperature, airflow, and fuel flow may be recorded to determine efficiency and emissions. Instruments include torque transducers, speed sensors, and data acquisition systems.

Applications span motor and engine development, performance testing, efficiency assessments, and quality control. Proper calibration, cooling for high-load tests, and adherence to standards are important for accurate and repeatable results. The dynamometer remains a central tool for quantifying how a machine converts energy into useful work.