Abstract: A test bench for testing a drive train of a test vehicle from an internal combustion engine up to drive shafts for wheels includes an electronic function element or computer simulating moments of inertia, spring stiffnesses, and damping masses. The electronic function element or computer simulates the wheels and a vehicle acceleration process, with the exception of actually present vehicle components. At least two mutually independent moment-regulated electric load machines serve as a transmission element between the electronic function element or computer and the test bench having the test vehicle. The load machines are flanged directly to the drive shafts of the drive train to be tested.

Abstract: Test stands for automotive vehicles at the present are required in most cases to permit dynamic tests wherein an essential criterion consists of the simulation of the actual vehicle inertia moment, in order to obtain a realistic acceleration behavior. The test stand normally has a constant inertia moment. A process and a circuit layout is proposed for the simulation of vehicle inertia moments, whereby the test stand and the test specimen represent a n-mass oscillator, the masses of which are elastically joined together. By means of electronic functional elements (24, 25, 27, 32, 33, and 34), an m number of further masses are imitated electronically so that the regulation technical structure corresponds to the differential equation system of a (n+m) mass system. An air gap moment controlled electric machine is used as the transmission element (34) between the electric functional elements (24, 25, 27, 32, 33, and 34) and the mechanical masses. By setting the time constants (T.sub.Kfz, T.sub.