GB894821A - Improvements in or relating to brakes - Google Patents

Abstract

894,821. Disc brakes. JOHNSON, E. W. June 6, 1958 [March 6, 1957; March 25, 1957; Jan. 27, 1958; March 3, 1958], Nos. 7475/57, 9750/57, 2663/58 and 6752/58. Class 103 (1). A brake system comprises a non- rotatable braking member mechanically urged against a rotatable member'and moved away from the rotatable member by pressure means including piston means and a booster between an operator actuated control member and the piston means. Friction pads 19, 20 are applied to a disc 11 by sets of Belville washers 18 housed in cups 17 screwed into bores 15 in opposite limbs of a fixed bridge 14, the brake being released by fluid pressure supplied via connection 28 to chambers 26 to move annular pistons 21 away from the disc 11, the pistons 21, 22 being attached to pads 19, 20 by a screwthreaded stud 23, the chambers 26 being primed through a connection 27. The pressure in each chamber 26 normally at a maximum is developed primarily in a master cylinder or a pump, pressure from which acts on a piston 32 in a booster 29 secured to the bridge 14, the piston 32 forcing a stem 34, Fig. 2, into a chamber 35 connected to chambers 26 to create a high pressure, the master cylinder including a plunger spring biased to expel fluid from the master cylinder to the booster 29, pressure from the master cylinder or a pump being relieved for brake application. On wearing of the friction pads 20, the pistons 21 will be forced further into chamber 26 on brake application and the excess fluid in chamber 26 is expelled via a bore 37 and ports 38 in stub 24 (not shown) into the booster 29 when the piston 32 is raised and escapes through port 36 for lubrication purposes. In a modification in Fig. 3, one of the pads 20a is fixed to a bridge arm by support 19a and stud 41 and the bridge is mounted for limited axial movement by attaching its long arm to a fixed member by two pairs of links 43, one pair on each side of the bridge arm. The links 43 may be extended in one direction to frictionally engage a pad, of nylon for example, on the bridge to restrict freedom of movement of the bridge. In a further embodiment, Figs. 8 to 9 (not shown), a pneumatically operated booster is common to both actuators and the pads are applied to the disc by arms pivoted intermediate their lengths to the bridge. A hand lever may be used by a by-pass circuit between the booster and brake, the brake pedal being only inoperative when the hand lever is in the brake release position. In the first Provisional Specification six washer-containing cups are used, arranged in three opposed pairs, each set of three cups being connected to a pad-carrying segmental member, these members being connected together by pins located externally of the disc, each member being slidably mounted on two studs extending from the bridge arms. A system employing a pump and having electromagnet control is also described. Reference has been directed by the Comptroller to Specification 815,375.