VORRICHTUNG ZUR MESSUNG EINES MASSESTROMES

In one class of measuring devices, a rotary element, which is carried by a shaft, is driven at a constant speed of rotation and deflects the mass flow impinging axially on the rotary element radially, imparting to it in the process a tangential velocity component, is used for measuring a preferably heterogeneous mass flow. The torque dependent on the mass flow is measured at the shaft. For this purpose, a first spur gear attached to the shaft is provided, the said gear being in engagement with a second spur gear. The second spur gear is mounted in a carrier element which, for its part, is mounted to allow rotation about the axis of the shaft and is held firmly in its position by a force-sensing device. To improve the measuring sensitivity, the second spur gear has a second tooth engagement, opposite to the first spur gear, with an internally toothed gearing, which is likewise mounted to allow rotation about the axis of the shaft and is made to rotate by a driving pinion. A rotational body made to rotate in the same direction as the shaft is furthermore frictionally connected to the carrier element and/or the first spur gear. The strength of the hydrodynamic frictional engagement is adjusted so that the frictional torques of the first and second spur gear are compensated by the frictional torque of the frictional engagement.