Device for driving a conveyor according a pattern of unequal separate steps

Device for intermittently moving an output shaft, said device comprising a said output shaft, a continuously driven input means, at least first and second alternately activated movement transfer devices connected to said input means for, when activated, driving the output shaft over predetermined movement steps, the length of the movement step provided by said first movement transfer device, differing from that of the movement step provided by said second movement transfer device, at least one of said movement transfer devices including a cam and a cam follower for providing the predetermined movement step, at least one controllable clutch disposed between the continuously driven input means and said first movement transfer device, at least one further controllable clutch disposed between the continuously driven input means and the second movement transfer device, and clutch control means for activating one of said controllable clutches or the other such that the movement transfer device associated with the activated clutch drives said output shaft, said clutch control means including step regulating means for declutching the controllable clutch activated thereby after a predetermined movement step.