National Renewable Energy Laboratory

ReFUEL Laboratory

Chassis Dynamometer

A chassis dynamometer is used to simulate driving on a road inside a laboratory under controlled conditions. The vehicle is driven on rolls, while a dynamometer simulates the inertia of the vehicle as well as the drag and friction on the vehicle (known as "road load" in the vehicle testing community).

Because an entire vehicle is tested instead of just an engine, and a driver controls the vehicle instead of a computer, the use of a chassis dynamometer allows the assessment of "real world" emissions. This allows a better assessment of the benefits of new fuels and vehicle technologies, and is absolutely essential to assessing the performance of heavy hybrid trucks and buses.

Vehicle testing is more complex than engine testing and is not as standardized. Therefore, the results can be more variable and it is not yet known if results from one lab will agree with the results from another. The ReFUEL Lab is actively leading projects to compare results from different labs around the nation (a "Round Robin" test program) and to establish standardized test procedures, especially for heavy hybrid vehicles.

Chassis Dynamometer Capabilities:

• Inertial simulation range: 8000 — 80,000 lb (vehicle classes 3–8)
• Grade simulation
• Dynamometer assisted braking
• Hydraulic hitch loading system
• Tandem axle, 40in. rolls
• Programmable driver's aid

To learn more about chassis dynamometer testing, visit the Data and Resources page.