Modern dynamometers test benches offer the front and rear axle mechanical linkage. This mechanical linkage is provided through different mechanical solutions (e.g. electric, cardans, belts).
Often, the aforementioned solutions also offer the possibility of being disconnected, to allow user working with independent axes; this could be an advantage when working on older vehicles, thanks to a more favorable testing environment.
Mechanical synchronization: we mean that front and rear axes rollers spin exactly and at the same speed.
Is this important for today’s cars?
The answer is simple: YES
Many modern cars, thanks to electronics and high frequency control systems, monitor the speed of individual wheels.
Working on a test bench NOT mechanically synchronized, perceiving deviations in the different rotation speeds, the traction control system will intervene, cutting the power supplied by the engine (thus falsifying the tests results).
In many cars of the latest generation, deactivating the traction control system from the control panel, it will be only partially induced: some functions may make it impossible to correctly test the power on chassis dynamometers (E.g. presence of gyroscopes in the passenger compartment or other feedback tools and).
Working with test benches without connected axes, it is very often necessary to activate the hidden functions in the vehicle software, commonly known as ‘dyno mode’.
In particular with new vehicles these instructions are not easy to find, thus entailing time to search for the right solution to use (e.g. different vehicle software versions)
Visit also the MAIN CONCEPTS page