Abstract: An S-cam assembly (33) is disclosed for expanding internal shoe brakes of the type comprising a pair of pivotally mounted brake shoes (17) located within a brake drum (11), each brake shoe carrying a cam follower (31). The assembly comprises an S-cam member (35) comprising a pair of substantially identical working portions (37), each working portion defining a working surface (39) and defining a nominal lift circle having a diameter D1. Each working portion includes a ramp member (43) pivotable about a pin (47) from a retracted position (FIG. 2) in which a ramp surface (51) is disposed within the nominal lift circle. Each ramp member has an extended position (FIG. 5) in which the ramp surface is disposed outward of the nominal lift circle and in engagement with the adjacent cam follower (31) and defining a larger lift circle having a diameter D2. The substantially increased reserve lift is accomplished without increasing the minimum installation diameter of the S-cam assembly.

Abstract: A brake shoe guide member (50) is provided that is adapted to be firmly secured to the brake spider (38) and which features a pair of spaced-apart guide surfaces (56, 56) on one side of the brake shoe web (16) and an opposed guide surface (58) on an opposite side of web (16) intermediate surfaces (56, 56) such that web (16) is held in substantial parallel alignment with spider (38) by guide surfaces (56, 56 and 58) as web (16) moves therebetween when the brake shoe moves between the retracted and expanded positions.

Abstract: An "H" shaped retainer (60) is provided for retaining trunnions (42) of a brake cam follower roller (18) in open-sided bearing surfaces (20) at the end of spaced-apart webs (34) extending from a brake shoe (8). Retainer (60) features a bridging portion (26) adapted to be disposed intermediate webs (34) and has resilient arms (28) at opposite ends that respectively extend towards and around trunnions (42) and thence towards and past portions (26) and thence outwardly to releasably engage and releasably secure fastener (60) to webs (34) in which, in a preferred embodiment, the ends of the arms are shaped into helical coils (30) that are adapted to extend into openings (44) through each web (34).

Abstract: A multi-member, variable configuration template (100) is provided as an aid for determining acceptable brake assembly mounting variables for an air operated, cam actuated brake assembly to be mounted on a vehicle of known configuration. The template comprises a first member (102) corresponding to the brake spider, a second member (104) corresponding to the air chamber mounting bracket, a third member (106) corresponding to the air chamber and a fourth member (108) corresponding to the slack adjuster. The second and fourth members are pivotably connected to the first member about a point (110) corresponding to the axis of the brake actuating cam, the third member is slidably mounted on the second member and the third member is removably connectable to the fourth member at a series of points on the fourth member. Various arrays (112, 116, 120 and 124) are provided to determine the brake assembly mounting variables corresponding to a particular template configuration.