which contains the equipment and is indicated by a chain dotted outline in the quiescent state illustrated in the figure in which both motor m and load l are stationary the electromagnet s of the actuator 45 is supplied with current via the auxiliary switch d 2 and via the auxiliary switch c 1 which has closed after a time interval which is considered as having already elapsed the safety switch s 1 is therefore open and the rod 30 of the slide block 27 does not lock the key 22 with the result that the door p can be opened opening of the safety switch s 1 and of the startup switch d 1 prevent the supply of current to the coil cb of the contactor device k when the door is opened withdrawal of the key 22 confirms by mechanical means 11 rotary member 11 of fig1 and 2 the open state of the safety switch s 1 and the motor m cannot be restarted even in the event of a power supply failure or any other fault condition in the electromagnet s when the door is reclosed the key 22 displaces the mechanical component 11 in the direction j but the slideblock 27 remains in the downwardly displaced position since it is acted upon by the the electromagnet s still supplied with current an action exerted on the startup push button d established closure of the startup switch d 1 interrupts the supply of current to the coil s by opening the auxiliary switch d 2 the electromagnet s therefore releases the.