An evaluation apparatus for the transmission of mechanical motion used in a system for mutually locking power switches. The apparatus has a first input slide with a coupling member, which can be detachably installed as a driver for an output slide. A guide is provided on a carrier for a second input slide, arranged as a mirror image to the first input slide in relation to the output slide. The evaluation apparatus operates as an AND element when the output slide is equipped with a roller, and the output slide operates optionally as an AND or an OR element when the input slide is provided with one or more additional coupling members.