Patent GB-1238601-A (GB)
IPC: F16D55/227
Filed: 1969-10-23
Abstract: 1,238,601. Spot-type disc brakes; slack adjusters. BENDIX CORP. 23 Oct., 1969 [31 Oct., 1968], No. 51944/69. Heading F2E. The caliper housing 34, Fig. 2, straddling the disc 12 of a disc brake, is mounted for sliding movement of a predetermined amount relative to two pins 74, Figs. 1 and 4, each pin 74 being itself mounted for sliding movement, in certain circumstances, relative to an arm 30 or 32, Fig. 1, of a torque-taking member 10 located on the inboard side of the disc 12. The torquetaking member is secured to a fixed spindle 24. The " predetermined amount" above referred to is represented by spacings A<SP>1</SP>B<SP>1</SP> and A<SP>1</SP>C<SP>1</SP>, Fig. 4, provided between the ends of a pin 74 and the effectively-closed ends of the bores 84 in which the pin-ends slide. Any normal lateral disc displacement during non-braking conditions will move the housing 34 transversely with respect to the disc faces, taking up space A<SP>1</SP>B<SP>1</SP> or A<SP>1</SP>C<SP>1</SP> on each pin. This movement takes place freely. On normal brake application, the reaction movement of housing 34 (upwards in Fig. 4) brought about by admission of brake fluid at 56, to chamber 52, Fig. 2, is relative to the pins 74, and is sufficient to take up some or all of space A<SP>1</SP>C<SP>1</SP>, Fig. 4. If lining 66 becomes sufficiently worn for space A<SP>1</SP>C<SP>1</SP> to be exceeded, the housing 34 engages the appropriate ends of pins 74 and moves them transversely relative to arm 30 or 32 as the case may be, this movement being resisted by sliding contact with leaf springs 92, 96, Fig. 1, described below. This movement is an automatic wear-compensating movement. Pin 74 on the right of Fig. 1 is held in groove 88 of arm 30 of torque-taking member 10 by leaf spring 92 secured at 94 to member 10. Owing to manufacturing tolerances the pin 74 on the left is held away from the base of groove 90 of arm 32 by an amount C<SP>1</SP>D<SP>1</SP>. Pin 74 on the left is held up by leaf spring 96, secured at 98 to member 10, and shown with its free end broken away: the free end turns inwards horizontally and supports pin 74 above the end of groove 90 by an amount E<SP>1</SP>F<SP>1</SP> owing to manufacturing tolerances. With reference to friction element 68 on the right of Fig. 2, the diameter of piston 44 and bore 46, and the dimensions of seal 48 and bore 50 are so chosen that on normal brake application the piston 44 in being forced to the left merely stresses seal 48 without sliding within it. On release of fluid pressure, seal 48 recovers its shape, moving piston 44 to the right to its former position. If lining 72 of friction element 68 becomes worn, piston 44 slides in seal 48 during brake application until the wear distance has been automatically compensated for. On pressure release, recovery of seal 48 moves piston 44 to the right slightly. A rubber boot 54, Fig. 2, seals the open end of cylinder bore 46, and seals 100, Fig. 4, are provided in grooves 102 to prevent entry of dirt. Friction element 58, Fig. 2, is removably attached to the radial portion 38 of housing 34 by inserting integral projections 60 into openings 62.