GB1401020A - Break actuators - Google Patents

Abstract

1401020 Spring applied compressed air released brake units CLAYTON DEWANDRE CO Ltd 31 Dec 1973 [29 Dec 1972] 60028/72 Heading F2F A brake actuator comprises a movable wall 4 urged by a spring 12 towards the output end of a housing 1 but normally held in a retracted position by compressed air introduced into the housing 1 via a supply port 17, and a service piston 9 displaceable by pressure in a service chamber 8 and being connected with an axial thrust rod 14 extending through a hollow axial extension 5 of the movable wall 4, a nut 15 being displaceable axially but non-rotatably within said hollow extension 5 and having screw-threaded connection with the thrust rod 14 so that by rotation of the rod 14 the nut 15 is traversed along the latter to release the brake after an emergency spring application. As shown, the service piston 9 is displaceable within a cylindrical shell 7 which defines the service chamber 8 the shell 7 being located at the inner side of a removable end cover 6. The end cover 6 embodies a service brake line plug connection 10. The housing 1 is provided with a series of dimples 21 to provide an inwardly facing shoulder 21a. A split ring plate 20 holding the end cover 6 in position is held by the spring- loading on the cover 6 in abutment with shoulder 21a, the end cover 6 having a shoulder 6a which prevents radial inward displacement of the ring plate 20 until the end cover 6 has been displaced inwards. A gaiter 22 is provided with a series of slits 23 coincident with a ring of apertures 24 in housing 1 whereby the gaiter 22 excludes dust from the unit but allows it to breathe. The rod 4 is connected with a brake wedge or with brake actuating linkage through means which permit rotation of the rod 4, and the nut 15 is of hexagonal or other non-circular form with the bore of the extension 5 being correspondingly formed. To release the brake after spring application when no supply of compressed air is available, the service brake line and the connection 10 are removed and the piston 9 and rod 14 are rotated to advance the nut 15 until the movable wall 4 which abuts the nut 15 at a shoulder 16 is moved sufficiently. Spring rings 18 or equivalent stops limit the travel of the nut 15. To facilitate rotation the piston 9 may have a hexagonal central boss 19 to receive a tool.