The tests are for noise
under load and over the speed range, accelerating and de-accelerating.
This means the front end is driven by the rig and the rear end
restricted for acceleration, thus loading the transfer box.
The reverse procedure is used for de-acceleration. This is the
original manufacturers test rig and these graphs accompany every
transfer box supplied by Dorfbrunnen as a mark of the final
Quality of the workmanship.