Disc brake shoe assembly

Abstract

A disc brake shoe in which a relatively thin gage, low-cost metal backing plate has bonded to one face a friction brake lining and is formed on the opposite face with a plurality of straps that are adapted to engage corresponding recesses formed in a complementary thick gage metal backing plate to interlock the respective backing plates into a unitary brake shoe assembly which can be easily disassembled to permit change-out of a worn brake shoe by simply substituting a newly lined, low cost backing plate for the existing backing plate having worn lining without the need to re-claim the backing plate for re-use.

I claim: 
     
       1. A disc brake shoe assembly comprising: (a) separate primary and secondary metal backing plates;   (b) a block of brake lining material bonded to one face of said secondary backing plate, said primary backing plate having one face with which the face opposite said one face of said secondary backing plate is engaged in an assembled condition of said primary and secondary backing plates, wherein said secondary backing plate is interposed between said primary backing plate and said block of brake lining material, the thickness of said secondary backing plate being less than the thickness of said primary backing plate;   and   (c) interconnecting means for releasably locking said primary and secondary backing plates against relative movement in response to a tangential force acting on one of said backing plates in said assembled condition thereof comprising:   (i) a plurality of elongated radial slots all being formed in said one face of said primary backing plate, each said slot having a planar base recessed from said one face of said primary backing plate and elongated parallel sides perpendicular to said one face of said primary backing plate; and   (ii) a plurality of elongated radial straps all projecting from said opposite face of said secondary backing plate, each said strap having a planar head upraised from said opposite face and elongated parallel sides perpendicular to said opposite face, said plurality of straps having a configuration complementary to said plurality of slots and being engageable therewith such that the respective elongated sides therebetween are contiguous in said assembled condition, said primary and secondary backing plates in said assembled condition having free relative movement in a direction parallel to said perpendicular sides of said slots and said recesses in the absence of a tangential force on said primary and secondary backing plates to accommodate disassembly thereof.   
     
     
       2. A disc brake shoe assembly as recited in said claim 1, wherein the minimum depth of said plurality of slots is at least as great as the maximum height said plurality of straps are upraised from said opposite face of said secondary backing plate to assure said face-to-face contact between said one face of said primary backing plate and said opposite face of said secondary backing plate. 
     
     
       3. A disc brake shoe assembly as recited in claim 2, wherein said plurality of straps are formed integral with said secondary backing plate. 
     
     
       4. A disc brake shoe assembly as recited in claim 2, wherein each one of said plurality of straps comprises a displaced section of said secondary backing plate. 
     
     
       5. A disc brake shoe assembly as recited in claim 1, wherein said primary backing plate is an arcuate segment having at least one lug projecting from the outer periphery thereof, said at least one lug lying in the plane of said primary backing plate and having an opening therethrough. 
     
     
       6. A disc brake shoe assembly as recited in claim 5, wherein said at least one lug is the same thickness as said primary backing plate. 
     
     
       7. A disc brake shoe assembly as recited in claim 6, wherein said secondary backing plate is an arcuate segment having at least one lug projecting from an outer periphery thereof, said at least one lug lying in a plane of said secondary backing plate and having an opening therethrough. 
     
     
       8. A disc brake shoe assembly as recited in claim 7, wherein said at least one lug of said secondary backing plate is the same thickness as said secondary backing plate between said one and said opposite faces thereof. 
     
     
       9. A disc brake shoe assembly as recited in claim 8, wherein said opening in said at least one lug of said primary backing plate is coaxial with said opening in said at least one lug of said secondary backing plate. .Iadd. 
     
     
       10.  A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, and having an interconnecting means for releasably locking the primary and secondary backing plates against relative movement in response to a tangential force acting on one of said backing plates in such assembly, said disposable secondary backing plate comprising; (a) a thickness less than the thickness of such primary backing plate,   (b) a block of brake lining material bonded to a first face of said secondary backing plate, and   (c) a plurality of elongated radial straps projecting from a second face of said secondary backing plate, said elongated radial straps having a configuration adapted to mate with and engage a plurality of complementary radial slots formed in an abutting face of such primary backing plate..Iaddend..Iadd.11. A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 10, in which said plurality of elongated radial straps each have a planar head upraised from said second face of said   
     
     
        secondary backing plate..Iaddend..Iadd.12.  A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 10, in which said plurality of elongated radial straps each have elongated parallel sides perpendicular to said second face of said secondary backing plate..Iaddend..Iadd.13. A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 10, in which said plurality of elongated straps are formed integral with said secondary backing plate..Iaddend..Iadd.14. A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 10, in which said plurality of elongated straps comprise displaced sections of said secondary backing plate..Iaddend..Iadd.15. A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 10, in which said secondary backing plate is generally an arcuate segment in 
     
     
        shape..Iaddend..Iadd.16.  A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 15, in which said secondary backing plate has at least one lug projecting from an outer periphery thereof, said at least one lug adapted to mate with a lug on such primary backing plate..Iaddend..Iadd.17. A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 16, in which said at least one lug is provided with an aperture therethrough adapted to coaxially mate with an aperture through such lug on such primary backing plate..Iaddend..Iadd.18. A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 10, in which said secondary backing plate is made of sheet steel having a thickness of about 0.0897 inch..Iaddend..Iadd.19. A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 18, in which said 
     
     
        plurality of elongated straps are formed by stamping..Iaddend..Iadd.20.  A disposable secondary backing plate for use in a disc brake shoe assembly having separate primary and secondary backing plates, according to claim 19, in which said plurality of elongated straps each have a planar head upraised from said second face of said secondary backing plate by a distance of approximately 0.1103 inch..Iaddend.