in fig7 and 8 according to fig7 and 8 the frontal jointed bar 7 instead of a deflecting arm comprises a toothed wheel segment 8 whose center point coincides with the rotation point of the bar 7 a toothed rod 15 engages in the toothed wheel segment 8 and is connected with the distal end of a push rod 14 u2032 the push rod 14 u2032 can be configured as a single piece with the toothed rod 15 the push rod 14 u2032 runs through an insulation 10 in the proximal insulating plane 5 a crosswise motion does not occur in this embodiment and therefore the push rod 14 u2032 is not required to have flexibility in this area to improve insulation from steam during autoclaving according to the fourth embodiment of the invention illustrated in fig9 and 10 an additional bellows 6 u2032 u2033 can be applied by means of a push rod 14 u2033 on the proximal insulating plane 5 it is sealed off insulated from steam with a covering plate 21 on whose underside the push rod 14 u2033 rests and on whose upper side a short toothed rod 20 is fastened in this variant as well the push rod 14 u2033 does not need the same flexibility as the push rod of the first embodiment because here no crossways deflection is expected in addition no additional insulation is required in the proximal insulating plane 5 because the bellows 6 u2032 u2033 ensures sufficient insulation a fifth embodiment of the invention is illustrated in fig1 and 12 the actuated front jointed bar 7 here as.