Abstract: To correct the loading moment due to the test bench related frictional losses in the simulation of masses on stationary test benches, a correction circuit (10) is connected to a weather detection device (13) which detects the air pressure (P), humidity (&phgr;) and temperature (T), and calculates the air density (&rgr;) which is transmitted to the correction circuit (10). A loss characteristic function stored in the correction circuit defines the total frictional losses of the test bench, including mechanical friction losses and aerodynamic friction losses which are dependent on the velocity, the weight loading and the air density for a particular test. From the actual existing air density (&rgr;) and/or the actual weight loading of the roller bearings (G), the correction circuit (10) calculates the air frictional losses and the bearing loading losses, which are then combined with the nominal rated rotational moment so that the loading moment is corrected to the extent of the losses.

Abstract: The invention relates to a method and an apparatus for the mass simulation of vehicle masses on a stationary roller test stand, wherein the simulation mass (msim) is determined from the test stand mass (mP) and from the mass (mRad h?) of the non-driven rotatable vehicle parts that are determined by measuring techniques, as well as from the mass (mRad h?) of the driven rotatable vehicle parts that are determined by measuring techniques, and with the aid of the translatory vehicle mass (mF), in an evaluating device (10) of the test stand.

Abstract: A torque moment is simulated in a rotary testing stand for test samples by providing a feed-back closed loop control circuit for controlling a torque moment generator. The feed-back control circuit generates a feed-back control signal by differentiating an angular velocity signal derived from a torque applying shaft and passing the differentiated signal through a proportional time element that has a controllable, variable time constant. Both the differentiating circuit and the time circuit are preferably controlled by a difference signal that represents a difference between the inertia moment of the test sample and the inertia moment of the testing stand. The output signal of the time circuit is compared in a comparator with an actual torque signal. The output of the comparator provides a rated or reference torque signal that is then used for adjusting the output of the torque generator to produce the required simulated torque load.