Disc brakes for vehicles

A disc brake comprising first and second friction pad assemblies for engagement with opposite faces of a rotatable disc, a relatively stationary carrier member, actuating means for urging said first friction pad assembly directly into engagement with a first face of said disc, a clamping member straddling a portion of the periphery of said disc, said clamping member comprising first and second pressure plates which are chordal to said disc and are located on opposite sides thereof with said first pressure plate located adjacent to said first friction pad assembly, said second pressure plate acting on said second friction pad assembly, and circumferentially spaced draw-bars which interconnect said pressure plates at the outermost ends thereof and determine the axial spacing between said pressure plates, the reaction of said actuating means acting indirectly on said second friction pad assembly through said second pressure plate such that said second friction pad assembly is applied to a second face of said disc opposite said first face, at least one of said draw-bars having first and second opposite ends of which said first end includes a threaded portion and one of said pressure plates has a clearance bore through which said threaded portion is passed, and a pair of axially spaced inner and outer nuts are both axially adjustably screwed onto said threaded portion on opposite sides of said one pressure plate and between which said one pressure plate is clamped, wherein said first end of said draw-bar has an end portion, a groove is defined in said draw-bar between said screw-threaded portion and said end portion, said outer nut incorporates an internal groove, and a releasable coupling is provided between said first end of said draw-bar and said outer nut, said coupling comprising an abutment member releasably retained in said groove in said outer nut and engaged within said groove in said draw-bar.