A chassis dynamometer is used to simulate on-road driving 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 enables the assessment of "real world" emissions in a controlled environment. This allows for a more accurate assessment of the benefits of new fuels and vehicle technologies, and is essential for assessing the performance of heavy hybrid trucks and buses.
The ReFUEL Laboratory is one of the few facilities in the United States with a chassis dynamometer that operates with laboratory-grade emissions analysis equipment. The dynamometer is supported by 72 data acquisition channels along with fuel metering and combustion analysis subsystems. It can test medium- and heavy-duty vehicles—from small trucks and delivery vans to full-size buses and Class 8 tractors—with a focus on vehicle performance and emissions.
The chassis dynamometer features the following capabilities:
- Inertial simulation range: 8,000 – 80,000 lb (vehicle classes 3–8)
- Grade simulation and optional dynamometer-assisted braking
- Hydraulic hitch loading system
- Tandem axle, 40 in. rolls
- Range of adjustable rolls: 42 – 56 in.
- Range of vehicle wheel base: 89 – 293 in.
- Programmable driver's aid for enhanced test repeatability.
To learn more about NREL chassis dynamometer testing projects, visit the Data and Resources page.