Abstract: A piston sealing arrangement particularly for pistons used in railway brake cylinders, comprising a flexible piston seal and a multi-function ring in the form of a separate wear band. The wear band is allocated on the pressure side of the piston seal to minimize radial motion of the sealing ring if the piston rocks.In FIG. 1 is shown a pneumatic brake cylinder 10 in which is located a piston 11. Piston 11 has an external flange 14 which backs a piston seal 15. Located on the pressure side of the piston seal 15 is a wear band 16 which is located very close to the piston seal 15 on the pressure side. The rubber piston seal 15, has a sealing lip 18 in contact with the inner wall of the cylinder 10.The wear band is chamfered at 19 so that the portion 20 of the wear band closest to the sealing ring 15 is the part of the wear band that actually contacts the inner wall of the cylinder.

Abstract: Scraper rings are known which are mounted in the back plate of a hydraulic cylinder to scrape a hydraulic piston rod. Known scrapers are not very suitable for applications where the piston rod is liable to movement and vibration e.g. in pneumatic pistons and cylinders. The present invention provides a shaft scraper ring arrangement in which the scraper ring is so supported so as to be movable, to a limited extent, in a plane transverse to the shaft or rod which is to be scraped. Cylinder 1 contains a piston 2 and a back plate 3. Supported centrally in the back plate 3 is a housing 4 which supports a plate 5 carrying a rod scraper 5a. Piston 2 is supported by a piston rod 2a which is scraped by the rod scraper. A seal 10 located on the rod scraper plate 5 bears against the rod 2a. Rod scraper plate 5 has limited freedom for movement in a plane transverse to the rod 2a. The plate 5 is loosely carried by the housing 4 being located between two felt oil retaining annular rings 8.