Spring applied parking brake actuator having a collet style slack adjuster

摘要

A brake actuator (10) for use on passenger transit railway vehicles. The actuator includes a housing containing a service piston (14) and a parking brake piston (16). The service piston is connected to an inner hollow stem (20) having a forward conical surface (40) disposed to engage a conical surface (38) of a collet (36) provided on a threaded rod located within the stem. The parking brake piston has a hollow outer sleeve (21) surrounding the hollow stem, while a coil spring (28) is located about the outer sleeve for applying a braking force when fluid pressure is removed from a housing containing the parking brake piston. The spring expands against a locking ring (34) located on a forward sleeve (22) secured to an intermediate sleeve (42) that engages the hollow stem. This causes forward movement of the outer sleeve and forward movement of the conical portion of the hollow stem into engagement with the conical portion of the conical surface of the collet. This, in turn, moves the threaded rod (26) to engage brake applying components of a transit vehicle. <IMAGE>