Abstract: A method for monitoring the short-circuiting switching device of a three-phase motor (3) for driving vehicles, which is fed from a DC voltage source (1) via a controlled converter (2), wherein the short-circuiting switching device (5) actuated by a control logic (6) is connected to the inputs of the motor, and the motor currents and/or motor voltages are measured, and a predetermined test pattern, which is different from the voltage/current profiles during operation, is generated with the aid of the controlled converter (2) during a test phase and is supplied to the motor (3), the short-circuiting switching device is actuated for the activation thereof, the current and/or voltage profile is detected during the test phase by opening and closing of short-circuiting contacts and, on the basis of the current and/or voltage distribution in the individual motor phases, the correct open-ing/closing of the short-circuiting contacts is detected and evaluated.

Abstract: The test head manipulator comprises two bearings coupled to a frame. A lead screw is rotatably disposed between the two bearings. A non-translation mechanism is also provided to prevent the lead screw from translating along its longitudinal axis. A lead nut is threaded onto the lead screw, but is prevented from rotating about the longitudinal axis by a non-rotation mechanism. A carriage configured to couple with an electronic test head is coupled to the lead nut by means of a system of cables and pulleys. Therefore, when the lead screw is rotated, the lead nut translates along the longitudinal axis, moving the cables and translating the carriage and test head along a vertical path. The lead screw and nut are non-backdrivable to lock the carriage in position.