Patent GB-1240920-A (GB)
Title: Mechanically-operated disc-brake
IPC: F16D65/46
Filed: 1969-12-31
Abstract: 1,240,920. Spot-type disc brake operation; slack-adjusters. FRANCAISE DU FERODO S.A. 31 Dec., 1969 [31 Dec., 1968], No. 63579/69. Heading F2E. A mechanically-operated disc-brake, of the kind comprising a disc 11 rigidly fixed for rotation to the member to be braked, a fixed support 10, 15, 12, two brake-shoes 14A, 14B slidably mounted in windows 13A, 13B formed in the fixed support, an operating lever 24 cooperating with one (14A) of the shoes by a cam surface 25 and a transfer member 20 on which the lever is pivoted (e.g. at 22), and which transmits the braking action to the second shoe, is characterized in that the transfer member 20 is coupled to the fixed support 10, 15 by elastic coupling means 30 which permit a rocking movement of the transfer member 20 about an axis parallel to the pivotal axis of the operating lever on the transfer member. As shown, the transfer member 20 is constituted by a stirrup comprising two parallel endplates 21A, 21B, in the form of a U, connected together at one of their extremities by the shaft 22 on which lever 24 is mounted and at the other by a cross-member 23. The elastic means 30 for coupling the stirrup to the fixed support comprises a blade fixed at its central portion by a bolt 17 to part 15 and having one arm 31 of uniform width whose end is supported against the cross-member 23, and the other arm 32 of the same width until it emerges from between the end plates (see Fig. 2), where it terminates in a wider portion having lateral wings 33A, 33B, supported against the edges of the endplates 21A, 21B (see Fig. 3). A second elastic blade 35, of U-shape (see especially Fig. 3), is fixed by the bolt 17, and its wings are in contact with the end-plates 21A, 21B for damping vibrations of the stirrup 20. A third elastic blade 16, also fixed by the bolt 17, and also of U-shape, has the extremities 18A, 18B of its arms directed towards each other and accommodated in notches 19A (see especially Fig. 3), 19B, respectively in the edge of the windows 13A, 13B, respectively, and in contact with the brake shoes 14A, 14B respectively (see especially Fig. 2) to prevent vibration of the shoes. The cross-member 23 is provided with a stop by which it is in pivotal contact (at 28) with the associated brake shoe 14B, for a purpose to be described. Preferably the stop is a screw 27 having a convex end 28, and being adjustable for taking up wear of the brake shoes. The operating lever 24 is coupled to a cable 40 whose sheath 41 is supported by a frame 43 fixed to the support 10, and when the brake is applied by pulling of the cable 40 against the action of a return spring 45, the travel of lever 24 in direction 50 is limited by the eventual contacting together of the turns of spring 45. A stud 38 acts as a stop for lever 24 in the brakerelease position. In operation, when lever 24 is moved in direction 50, cam surface 25 first causes application of shoe 14A to the disc 11 and then, by reaction through stirrup 20, application of shoe 14B. There after, further movement of lever 24, through rolling movement of cam surface 25 on shoe 14A, causes stirrup 20 to pivot about the contact zone 28 of screw 27 and shoe 14B in a counter-clockwise direction (Fig. 2) against the force of blade 30. When tractive force on cable 40 is relieved, lever 24 is return by spring 45, and stirrup 20 by spring 45 and blade 30. The fixed support 10 alone absorbs braking torque, while stirrup 20 absorbs braking force. To change the brake shoes, bolt 17 is removed to permit removal of stirrup 20 and gain access to the shoes.