Patent GB-1378362-A (GB)
Title: Mechanically-operated disc brake
IPC: F16D55/00
Filed: 1973-03-07
Abstract: 1378362 Mechanically-applied spot-type disc brakes SOC ANON FRANCAISE DU FERODO 7 March 1973 [10 March 1972 8 Aug 1972] 11150/73 Addition to 1240920 Heading F2E A mechanically-applied spot-type disc brake of the kind comprising a disc 10, Fig. 1, fixed to the member to be braked, one brake shoe 13A or 13B arranged on each side of the disc and slidably mounted in a housing 12A or 12B in a  fixed support 11, an operating lever 33, Fig. 3, co-operating with one of the shoes, 13A, by a cam surface 35 and a "transfer member" or caliper 18 on which the lever 33 is pivoted at 32 and, which is movable to transmit braking action to the second shoe 13B, the caliper being also pivotally mounted relative to the fixed support 11 against spring action 26, Fig. 3, is characterized in that the pivotal axis of the caliper is substantially diametral relative to the disc 10, and the axis of the lever pivot 32 is parallel to the said pivotal axis. In operation, when cable 40 is pulled in the direction 45, Fig. 3, cam surface 35 first slides on shoe 13A, so shoe 13A is applied to the disc 10 and caliper 18 is moved bodily to the right to apply shoe 13B, and thereafter the cam surface rolls without slipping on shoe 13A, so caliper 18 is forced to pivot counter-clockwise, e.g. about the point of contact of screw 36 with shoe 13B, the right hand end of caliper 18 moving slightly upwards, in the sense of Fig. 3, against the action of torsion element 27A of spring 26, Fig. 2. The spacing of bead 30, Fig. 2, on caliper 18 from the adjacent edge of slot 19 in fixed support 11, permits this pivoting. Spring 26 is retained by pins 25A, 25B, on fixed support 11 and retains caliper 18 by arms 29A, 29B. Each shoe is held against the top of its housing by a spring blade 14A or 14B.  In Fig. 7 two calipers 18<SP>1</SP>, 18<SP>11</SP>, are pivoted to a common cross-member 50, and each has pivoted to it a lever, cable 40 being secured to lever 33<SP>1</SP> and sheath 42 being secured to lever 33<SP>11</SP> (instead of to a fixed part as in Fig. 3). In operation, spring 53 first yields as the cam surfaces on the levers slide on shoe 13A, and in the second stage the cam surfaces roll on the shoe 13A, causing the stronger spring 52 to yield and the calipers to pivot about the cross-member 50. A holding blade 54 retains the calipers. In Figs. 11, 12, one caliper 121 is provided as in Fig. 1, and the inner face of its right-hand limb is provided with a pivotal edge 133 and a slot 134 for engagement with a grooved shaft 141 extending through lever 137 and a flat end 138 on the lever, respectively. The slot 134 and end 138 provide a rest position for the lever, while edge 133 and shaft groove 140 provide the pivot. A restoring and retaining torsion spring 145 is provided. Retention and pivoting of the  caliper 121 are similar to those of Figs. 1 to 3, but in this case each brake shoe, e.g. 117A has lateral feet 118 held against the upper edges of slots 119 by spring blade 120A. In Fig. 17 the lever arrangement is similar to Figs. 11, 12; the caliper 121 is retained and controlled by tension springs 162A, 162B. The plane of lever movement in accordance with the invention is chordal, instead of radial as in the parent Specification 1,240,920 which facilitates installation, especially on a steered vehicle wheel. (For Figures see next page.)