Abstract: A measuring apparatus for accurately measuring the alteration of a liquid quantity, especially the quantity of oil in an internal combustion engine, in a reservoir containing said liquid, especially the oil pan of the internal combustion engine, comprises a measuring chamber which is separate from the reservoir and communicated thereto via a liquid compensator conduit. The liquid compensator conduit and the measuring chamber are heated to a constant temperature by heater. A level sensor for measuring the propagation of a sonic signal is disposed within the measuring chamber above the liquid level. Any temperature variations in the measuring chamber above the liquid level are detected by a gas thermometer and are utilized in an evaluator unit for correcting the measured level signal.

Abstract: A device for measuring the wear of a radioactively marked machine component by sensing the presence of radioactive wear fragments in a lubricant has a flow-through chamber; an inlet for tangentially introducing the lubricant into the flow-through chamber; a radiation detector at least partially surrounded by the flow-through chamber; and an outlet for removing the lubricant from the flow-through chamber. The device further includes an outer hollow cylinder having a closed radial end face; an inner hollow cylinder having a closed radial end face and an outer diameter which is smaller than the inner diameter of the outer hollow cylinder. The inner hollow cylinder is supported coaxially within the outer hollow cylinder and the space between the two cylinders constitutes the flow-through chamber. The cylinders are supported in a substantially horizontal orientation.