in end of each end piece of the conductor tracks 32 34 there is an enlargement a depression extending in the plug in direction which corresponds to depression 19 or 20 of the electrically conductive elements 13 14 for the sake of clarity it is not indicated in fig3 this depression is exactly associated with the forked area of the electrically conductive elements so that the fork prongs can be expanded elastically providing a good mechanical and electrically conductive contact the other leg 23 or 24 which is remote from the motor is inserted in a slot 35 or 36 fig1 and 3 and retained in this slot by clamping it with depression 25 or 26 the slot having an angular form according to fig3 so that the whole electrically conductive element 13 or 14 with the exception of the free end of leg 16 or 17 is entirely accommodated in the base member 15 made of plastic material and is therefore stored safely from an electrical point of view each slot 35 and 36 is crossed by another slot 37 or 38 fig1 furthermore each slot accommodates an end piece of a conductor track the open slot 27 or 28 of the leg 23 or 24 remote from the motor is in alignment with the slot 37 or 38 so that the end pieces of the conductor tracks can be pushed through in the direction of arrow 39 when the adapter 5 is mounted in practice however the adapter 5 with the electric motor 2 will be slipped onto the end pieces of the conductor tracks 33.