GB1293210A - Improvements in and relating to disc brakes - Google Patents

Abstract

1293210 Motor-cycle disc brakes; brake covers; cooling T C MARTIN 12 Aug 1970 [12 Aug 1969 4 Aug 1970] 38909/70 Index B7C 26 C61B C63B A disc brake and wheel assembly comprises an annular part supported on and rotatable with respect to a fixed axle, a disc part attached to the annular part and having at least one surface or part surface intended for engagement by a brake pad, structure for supporting a brake pad actuator in a fixed position relative to the axle, and at least one face plate coaxial with the annular part and extending radially at least as far as the outer periphery of the engagement surface or part surface of the disc part. As shown, applied to a motor cycle front wheel, located between fork members, 2, 3, Fig. 3, a brake shoe 40 is located at each side of a web 22 forming part of the hub 7 of the wheel. Each shoe co-operates with an annular steel disc 31 secured by pins in a recess in the side of the web. Each shoe 40 is applied by two hydraulic piston-and-cylinder devices 50, Fig.4, wherein each piston includes a resilient seal element 86, a metal portion 90 and a flexible resilient diaphragm 91 secured by a screw 98. The piston is assisted by a compression spring 88, and is sealed at its outer end by an annular web 94, located at one edge between diaphragm 91 and metal portion 90, and at the other edge between the face of the cylinder block and the outwardly flared lip 96 of a steel sleeve 82 lining the cylinder cavity. The backing plate 100 of shoe 40 is secured to two pins 110 each guided in a cavity 112 in the brake cylinder block and provided with an adjusting screw 114. The screw may be tightened or loosened to take account of wear of brake lining 101, and is retained in adjusted position by insertion, through a hole 119 in it, of a cotter pin 121 co-operating with a slot 120 in the brake cylinder block as the shoe is advanced and retracted. A single return spring 131 is provided. Each brake cylinder block is integral with a face plate 60, Fig. 3, the face plate having a peripherallip 65 for co-operation with a shoulder 66 on a flange 24 or 25 of the hub 7, the hub flanges having holes 15 for attachment of wheel spokes. Each face plate 60 thus prevents ingress of grease and the like to the brake parts, but lip 65 is omitted from the plate along part of the lower edge to leave a space 147 through which water, dirt and the like may fall. At its centre each face plate is secured between a bearing 9 or 10 and a washer 62 around fixed axle 5, and in the region of the cylinder block each face plate is locked to fork member 2 or 3 by a bracket 68, Figs. 3 and 4, forming shoe restraining means and having ridges 71 co-operating with grooves 69 in the face plate. For cooling purposes, each face plate is provided with a pair of mainfolds 140, Fig. 3, each formed as an arcuate segment having an outer wall 141 and an arcuate perforated plate 145 through which air may pass into the region between the two face plates 60. Also, ribs 12 are provided on the periphery of hub 7. In Figs.9 to 11 (not shown) a single cylinder and piston, but two brake return springs, are provided, the piston in this case having the diaphragm 91 omitted. Instead, web 94 is extended radially inwards to seal around a rod secured at one end to the brake shoe and engaging, at the other end, the piston. In a modification of this arrangement Fig.12, (not shown), the guide pins 110 are located respectively above and below the cylinder. As applied to the motor cycle rear wheel, 303, located between forks 301, Fig.18, steel discs 320, 321 are provided on the two sides, respectively, of web 304 for co-operation with braking assemblies 322 to 324 similar to those shown in Fig.3. Locking brackets 325 for the face plates are again provided, keyways 328 permitting tightening of the drive chain without necessitating disengagement of bracket and plate. Drive sprocket 312 is secured to a support 308, in turn secured to the hub 303 around shoulders 307 of ribs 306, the support 308 having sliding contact at 315 with the curtailed face plate or housing 314 on that side of the wheel. In Fig. 19 (not shown), a piston-and-cylinder device and co-operating steel disc and provided on the left hand side only of web 304, plate or housing 314 is omitted, and support 308 is radially extended to co-operate directly with the adjacent spoke flange of the hub. In Figs. 17 and 21 a face plate 360 is provided on one side only because at the other side protection is afforded by annular part 362 of the wheel hub. Also the hydraulic unit 350 includes a support structure 253 attached to one leg 301 of the rear fork. Cooling slots 397A, Fig.17 are provided in disc part 375.