Abstract: The invention relates to the dry run-high pressure stage of a multistage piston compressor with a piston designed as a tappet (2) guided in the high pressure cylinder (1) and sealed against the compression space of the cylinder (1) by means of self-lubricating sealing elements (3) forming an annular gap together with the working surface, whereby the latter is formed by a material suitable for dry run. According to the invention, the sealing elements having a height conforming at least to their diameter are embodied in the form of at least two cylindrical sealing elements (3), which are loosely placed one on top of the other in the cylinder (1) on the free end of the tappet (2), provided with working surface guides at least in part areas, and have chamfers (6) on the face side.

Abstract: A gripping element for a sports shoe comprises a body portion of plastic material and a ceramic insert which is embedded into the body portion and which provides the ground-engaging surface of the element. The ceramic insert is surrounded over a part of its length by a metal sleeve which is also embedded into the body portion of the element. At least on its outside peripheral surface around which the metal sleeve extends, the ceramic insert has surface configurations such as annular ribs and/or grooves to provide a positive connection to the plastic material therearound, with a layer of plastic material between the ceramic insert and the metal sleeve.

Abstract: A gripping stud for sports shoes comprises a stud body and a ceramic insert connected to the stud body thereby to form the ground-engaging surface thereof. The stud body comprises a central metal portion and a base portion disposed therearound while the ceramic insert connected to the lower end of the metal portion is of a flat lens-like configuration, with curved top and bottom sides. Alternatively the ceramic insert comprises a plurality of juxtaposed balls embedded in a stud body at the ground-engaging surface of the stud.