Electrical brake lining wear indicator

Claim 1

An indicator for indicating a predetermined amount of wear of a brake lining comprising: a brake lining support member adapted for assembly in a brake mechanism to be supported thereby, said brake lining being mechanically fastened to said brake lining support member by a plurality of bolts, said brake lining adapted to frictionally engage a rotating member associated with said brake mechanism, an electrical contact resiliently disposed on said brake lining support member and insulated therefrom by a shouldered resilient insulating bushing, said electrical contact comprising a threaded bolt attached to said brake lining support member and held thereon by a threaded nut, said insulating bushing completely surrounding said threaded bolt and extending through said support member to insulate said threaded bolt from said brake lining support member, a resilient annular insulating washer surrounding said bolt and disposed between said brake lining support member and said nut to further insulate said nut and bolt combination from said brake lining support member, said nut capturing an electrical connector on said bolt to electrically connect it thereto, said electrical connector electrically connected to an insulated wire member, said brake lining support member being a brake shoe comprising a brake shoe table supported by and attached to a brake shoe web and said rotating member being a brake drum, said brake lining being provided in two, separate longitudinal segments on said brake shoe table and said threaded bolt having a head disposed within a groove formed in a longitudinal end of each of said lining segments and within an opening separating said two segments of said lining midway from the end of said table, the threaded shank of said bolt being disposed in an aperture in said brake shoe table offset on said table from an intersection of said brake shoe table and said brake shoe web, said head of said threaded bolt having a cylindrical head portion which engages the groove in each of said lining segments and acts as said electrical contact, said threaded bolt being of brass and which material is a softer material than said drum and of a greater height than the bolt heads of the bolts that mechanically fasten said brake linings to said brake shoe table and said insulating bushing being provided with an annular shoulder seated directly on said brake shoe table and disposed adjacent to said head portion to insulate said portion from said brake shoe table, said insulating washer disposed on the side of said brake shoe table opposite said annular shoulder, said resilient insulating bushing and said annular insulating washer maintaining said threaded bolt and said nut in spaced relation from said brake shoe table and said threaded bolt and nut assembly floating with respect to said brake shoe table to accommodate rotating irregularities in alignment between said drum and said brake shoe table.