| 摘要 |
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. The plane about which the wear band rocks passes through the portion 20 and this is closely adjacent the lip 18 which is the point of contact of the sealing ring with the cylinder. The wear band has a small scraper lip 23 projecting towards the sealing ring 15. Between the wear band and the sealing ring is a grease retaining cavity 24. This cavity is partially formed by an annular recess in the face of the piston seal 15 and partially by the shape of the rear face of the wear band 16.
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