Patent GB-721323-A (GB)
Title: Disc type brakes for vehicles
IPC: F16D55/28
Filed: 1952-06-21
Abstract: 721,323. Disc brakes. DUNLOP RUBBER CO., Ltd., and BUTLER, H. J. May 28, 1953 [June 21, 1952]. No. 15695/52. Class 103 (1). In a vehicle disc brake comprising a rotatable and axially movable annular disc, a non-rotatable housing straddling the outer periphery of the disc, a pressure plate slidably associated with the housing and carrying a pad of friction material, a pad of friction material associated with the housing and engageable with the other face of the disc, fluid pressure means is associated with the pressure plate for forcing the friction pads and disc together in frictional engagement and alternative mechanical means is also associated with the pressure plate for effecting this engagement. In the embodiment shown, a disc 10 is slidably mounted for axial movement only on splines 11 on a rotatable shaft 12. Two non-rotatable U- shaped housings 14 straddle the outer periphery of the disc at diametrically opposed points and a pressure plate 33 is slidably mounted in one limb of each housing for movement perpendicular to the face of the disc. A pad of friction material 34 is secured to each pressure plate for engagement with one face 18 of the disc 10 and another pad of friction material 35 is associated with the other limb 15 of each housing for engagement with the other face 20 of the disc. Each housing 14 has associated with it a combined fluid pressure and mechanically operated brake applying mechanism which is spaced away from the main body of the housing to prevent overheating of the fluid by the heat generated on brake application. Each housing 14 has two parallel strengthening ribs 21 which merge into a substantially cylindrical part 22; each connected by tie bars 24 which pass one each side of the driving shaft 12 and serve to hold the assembly rigidly together and prevent distortion when the brake is applied. Each cylindrical part 22 has formed in it a piston and cylinder mechanism by which each pressure plate 33 is applied. Fluid pressure is supplied from a normal master-cylinder system, via union 43, into the annular recess 41 provided in the crown of each piston 29. This forces a plunger 30 in each housing 14 against a part-spherical abutment 32 on the pressure plate 33 and moves the friction pad 34 into engagement with the face 18 of the disc 10, face 20 of which is subsequently moved into engagement with the friction pad 35 secured to a similar pressure plate 36 arranged opposite the pressure plate 33 and having a partspherical abutment 37 engaging a hollow partspherical seating in the limb 15. Fig. 3, a section through 3, 3 of Fig. 1, shows details of both the fluid pressure and mechanical actuating means. The operating lever 69 is actuated to rotate the eccentric recess 68 to cause a friction pad wear adjusting screw 58 to be moved outwardly with respect to the housing 14 so that the screw 58 pivots a cranked lever 52 about its fulcrum pin 54 to cause its end 51 to move towards the disc 10 and engages the plunger 30 to force the friction. pads into frictional engagement with the disc. Means are described whereby'the lever mechanism to the plungers 30 are individually adjustable with respect to the operating member to which they are connected through an equalizing device for obtaining balanced application of the two pressure plates to the disc. The Provisional Specification refers to Specification 631,877.