Theory of chassis dynamometers

Principles of the braked chassis dynamometer (equipped with eddy current brake and load cell)

The power and torque detection point of Bapro dynamometers is in the crankshaft. Detection is carried out on a complete vehicle and under normal operating conditions.

With braking bench testing (controlled), a more precise and representative measurement of the actual power of the vehicle being tested is obtained as a result of the eddy current brake.
It is a much more accurate test than those guaranteed by traditional test benches, such as ‘inertial’ ones.
Chassis dynamometers are, above all, distinguished by the option of setting the “ramp time” (usually never less than 15 seconds), or performing it in “points” for a given range of revolutions/time, in order to obtain more reliable results, adapting to any type of power or torque.
These measurements must usually consider different dispersions of the transmitted energy in order to accelerate to the actual power to the crankshaft (link to the FAQ section on power to the wheels or power to the crankshaft). These dispersions have different origins, just think of all the surfaces in contact with the engine (bearings and bushings) that enable rotation, the gear system (with continuous /automatic variation), transmission oil (if applicable) and end transmission, as well as from the tyres.

The main principles for correct operation (and guarantee of measurement precision) of the eddy current chassis dynamometer have different factors which, when carefully controlled, enable:

  • the lowest overall inertial mass (which enables better power acceleration precision to the crankshaft)
  • no vibrations (that can affect readings and communication between test bench and output signals)
  • maximum wheel/roller grip (slippage and micro-slippage would not enable correct reading of the vehicle’s power)
  • no uncontrolled resistance (which could affect the overall inertial mass, thereby distorting data)

Compliance with these requirements, integral development of products and their optimisation, the sole use of high quality components and specifications, and attention to detail have always been the guiding principles at Bapro.

Decades of collaboration with large companies in the automotive industry, such as Magneti Marelli, Ducati and Maserati, have allowed us to develop specific skills in their research and development departments.
Today, this results in the quality and reliability of our products, which are constantly updated to meet demands in a rapidly developing market.