energized in the manner described to thereby simultaneously prevent stop members 23n 1 and 23n 1 from being likewise displaced to their stop positions and to hold the next adjacent stop members in their passive position with an increased force it would also be conceivable to dimension and arrange the solenoids in such a manner that the acceleration impulse applied to any given stop member is only sufficient for overcoming the holding force between the associated permanent magnet and one of the two abutment stops when two or more solenoids cooperate with one another in an arrangement of this type the next adjacent stop members would remain in their passive positions irrespective of their oppositely directed polarity when they have the magnetic force of only one solenoid applied thereto in a further possible modification core 21 may be used to act as the abutment stop defining the passive position in cooperation with the magnetic force of the respective permanent magnet in which case the outer abutment stops 25n could be omitted the actuation of each stop member is accomplished by the cooperation of a plurality of solenoids as a result of which the load acting on each solenoid remains rather low permitting the volume of the solenoids to be correspondingly reduced the bistable mounting arrangement of each stop member results in the advantage that.