from the representation of fig2 that disposed at the end of head sleeve 12 surrounding the breakout link 13 is a breakout control pin 20 adapted to engage in a breakout control slot 21 formed in the breakout link 13 the breakout control slot 21 has a circumferentially extending front section 22 disposed directly at the end of breakout link 13 directed toward rivet holding head 11 and an also circumferentially extending back section 23 which is offset away from rivet holding head 11 with respect to front section 22 extending between front section 22 and back section 23 is an obliquely extending breakout slanted section 24 it can also be seen from fig2 that the bearing part 15 surrounding feed shaft rod 14 houses a drive gear 25 which is non rotatably connected to feed shaft rod 14 and is coupled to the drive unit 10 not visible in the representation of fig2 in order to drive the feed shaft rod 14 to rotate also attached to bearing part 15 are connecting rods 26 27 provided for displaceable engagement with feed link shells 28 29 that form the feed link 16 at its opposite end from the breakout link 13 feed shaft rod 14 comprises a feed bearing ring 30 and a set control link 31 which are also non rotatably connected to fed shaft rod 14 the feed bearing ring 30 carries a feed control pin 32 that protrudes.