Disc brake assembly with parking brake mechanism

Claim 1

A disc brake assembly equipped with a parking brake mechanism, said disc brake assembly including a caliper member having a cylinder body and a reaction portion straddling a portion of a rotary brake disc, and a piston axially slidably disposed in a fluid-tight manner within a cylindrical bore of said cylinder body to be actuated by hydraulic fluid under pressure supplied into said cylinder body, said parking brake mechanism comprising: a cam shaft rotatably mounted within a lateral bore formed in a bottom wall of said cylinder body and being formed with a cam groove; a plunger axially slidably disposed in a fluid-tight manner within an axial bore formed in the bottom wall of said cylinder body coaxially with said cylindrical bore and having an outer end opposed to said cam groove and a cylindrical inner end portion formed with an annular tapered surface and a pair of radial slots; a toggle having one end engaged with said cam groove and another end engaged with the outer end of said plunger; a support plate fixed in place within said cylindrical bore and having an intermediate portion axially slidably engaged with the radial slots of said plunger to restrict rotation of said plunger; a spring interposed between said plunger and said support plate to bias said plunger toward said cam shaft; an adjusting bolt threaded into a nut portion integral with said piston and having a head portion engageable at its center with said support plate and at its outer periphery with the annular tapered surface of said plunger for frictional engagement therewith; a retainer member arranged in surrounding relationship with the head portion of said adjusting bolt and fixed to said support plate; and a thrust bearing coupled with the head portion of said adjusting bolt and resiliently retained by a support portion of said retainer member to permit rotation of said adjusting bolt.