| 摘要 |
The invention relates to an apparatus for selectively driving an element which is displaceable in a straight line with a reciprocating movement, the drive being effected under the control of an electromagnetic control device (12) and a movable intermediate arm which is driven by a drive device with a periodic movement and can be controlled selectively by the control device in order to be brought into contact with the element to be driven and to transmit its movement thereto. In this apparatus, the support device (9) of the electromagnetic control device (12) is driven by the drive device (5, 6, 8) and is arranged in such a way that the electromagnetic device (12) is also excited with a periodic movement with the same period as the movement of the intermediate arm (13), the support device (9) also being arranged in such a way that the intermediate arm (13) is brought essentially into contact with the electromagnetic device (12) at a given moment in each period of the movement without being in contact with the element (1), a synchronising device (20, 23) in this apparatus bringing about or interrupting the excitation of the electromagnetic device (12) solely at this given moment in a movement period. <IMAGE> |
