Abstract: A device is provided for guiding a workpiece or tool during the machining of toric or spherical surfaces. The device includes an axially movable spindle sleeve disposed on the grinding or polishing machine and having first and second ends. A seating chuck has support for supporting one of a lens and a tool. A connecting means is provided for fitting the chuck concentrically to the first end of the spindle support. The connecting means includes a bell-shaped flange. A ball joint connects the support means to connecting means. A roller bellows is non-resilient in the circumferential direction and connects the support means to the bell-shaped flange. The roller bellows is arranged to form a joint chamber for sealing the space in which the ball joint is situated. A pressure fluid line is connected to the joint chamber. A pressure fluid cylinder-piston assembly is disposed coaxially with the spindle sleeve and the spindle sleeve being movable with the piston.

Abstract: A pneumatic impact tool wherein a two-stage piston is reciprocable in the two-stage chamber of a cylinder. The tool which is to penetrate into a bone is mounted in the front portion of the cylinder and the piston strikes against such front portion in response to admission of compressed air against its rear end face. A relatively small annular shoulder of the piston faces forwardly and is continuously acted upon by compressed air. When the piston approaches or reaches the end of its forward stroke and rebounds from the front end portion of the cylinder, it seals the source of compressed air from its rear end face so that the action of compressed air upon the shoulder suffices to propel the piston rearwardly against the rear end portion of the cylinder at which time the piston reestablishes a path for the flow of compressed air against its rear end face so that it is propelled forwardly against the front end portion of the cylinder.