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A dual mode drum brake assembly includes a backing plate, a brake drum, and first and second brake shoes supported on the backing plate and movable into frictional engagement with the brake drum. The drum brake assembly further includes a service brake mechanism for selectively moving the brake shoe

A dual mode drum brake assembly includes a backing plate, a brake drum, and first and second brake shoes supported on the backing plate and movable into frictional engagement with the brake drum. The drum brake assembly further includes a service brake mechanism for selectively moving the brake shoes into frictional engagement with the brake drum, and a rotation preventing abutment secured relative to the backing plate and disposed between and engageable with the brake shoes. A pivot lever is pivotally supported relative to the first brake shoe and is operatively coupled to exert an outward force on the first brake shoe when the parking and emergency brake is actuated. A first strut is disposed adjacent the hydraulic actuator and includes one end coupled to the second brake shoe and opposite end coupled to one end of the pivot lever. A second strut is disposed adjacent the rotation preventing abutment and includes one end coupled to the second brake shoe and an opposite end coupled to an opposite end of the pivot lever. The drum brake assembly further includes an actuation cable having an end portion supported in a generally perpendicular relationship relative to the backing plate, and a parking and emergency brake actuating means carried by the brake assembly and coupled to the actuation cable for mechanically actuating the pivot lever to urge the first brake shoe outwardly into engagement with the brake drum and thereby initiate duo-servo actuation of the parking and emergency brake through one of the first and second struts.

대표청구항 ▼

[ What is claimed is:] [1.] An operating mechanism adapted for use in a drum brake assembly having a pair of brake shoes supported relative a backing plate and selectively moveable into frictional engagement with a brake drum comprising:a composite strut adapted to be supported relative to the brake

[ What is claimed is:] [1.] An operating mechanism adapted for use in a drum brake assembly having a pair of brake shoes supported relative a backing plate and selectively moveable into frictional engagement with a brake drum comprising:a composite strut adapted to be supported relative to the brake shoes, said composite strut having a long dimension and a short dimension and including an upper link and a lower link, said upper and lower links including slotted opposed ends adapted to receive respective portions of the brake shoes, said upper link includes a first aperture formed therein and said lower link includes a second aperture formed therein which is concentric with said first aperture, said upper and lower links of said composite strut including sections which are spaced apart from one another to define a composite strut cavity;an actuating lever having a long dimension and a short dimension and pivotally supported relative to said composite strut, said long dimension of said actuating lever disposed substantially within the confines of said composite strut cavity and said long dimension of said actuating lever extending in the same direction as said long dimension of said composite strut, said actuating lever including a third aperture formed therein wherein said actuating lever is a composite actuating lever comprised of an upper link and a lower link adjacent ends of which are joined at one end and define an actuating lever cavity therebetween at an opposite end thereof to accomodate said actuation cable;a fastener extending through said first, second and third apertures to pivotally support said actuating lever relative to said composite strut; andan actuation cable having an end portion operatively connected to said actuating lever in a generally perpendicular relationship relative to the backing plate.