well as by a ring 25 secured atop the hollow spindle 20 on the end facing away from the pneumatic motor 4 the driver 22 has clutch coupling jaws 26 fig5 which mesh with the front face clutch coupling jaws 27 of a clutch component 28 of the separating clutch 23 it likewise is seated atop the hollow spindle 20 axially adjustable and torqued to it clutch component 28 is held in tension by a compression spring 29 fig2 in the direction of its clutch position compression spring 29 surrounds compression spring 24 for the driver 22 with a space in between the hollow spindle 20 is equipped with at least one stop member or buffer 30 which extends into an impression 31 of clutch component 28 and runs axially the operation model shows the stop member using balls located in the radial transit drill holes 32 of the hollow spindle 20 the stop members 30 are secured against dislocation through the transit drill holes 32 radially to the outside by clutch component 28 and radially to the inside by the switching ram 5 additional stop members 30 of this kind can be used around the circumference of the hollow spindle and the clutch component as needed similarly the bushing shaped driver 22 has axial impressions on the interior which mesh with pieces of the clutch 34 these are best designed with the use of balls which also mesh with the impressions 35 of the hollow spindle 20 in order to transfer the torque with certainty from the hollow spindle 20 to the driver 22 it is best to provide in each case two balls 34 in the impressions 33 35 axially adjacent moreover the hollow spindle 20 is further equipped with additional radial transit drill.