GB1161203A - Improvements in Disc Brakes. - Google Patents

Abstract

1,161,203. Disc brakes. GIRLING Ltd. 23 Aug., 1966 [3 Sept., 1965; 10 March, 1966], Nos. 37710/65 and 10519/66. Heading F2E. In a spot-type disc brake of the kind having inner and outer pistons working in a common bore in a stationary member at one side of the disc and acting respectively on a directlyoperated pad, engageable with the same side of the disc, and a yoke, which surrounds the stationary member and a portion of the disc and applies another pad to the opposite side of the disc, there is provided between the pistons an automatic wear adjusting assembly through which a mechanical actuator acts on the inner piston, the assembly being arranged to adjust automatically during hydraulic application of the brake after wear of the pads has taken place. In one embodiment, Fig. 1 the assembly comprises a stem 12 on inner piston 11 and an intermediate sleeve 17 in screw-threaded engagement with one another, rotation of the sleeve to effect adjustment being obtained by a pawl 21 formed on a pawl carrier 22 and engaging a ratchet wheel 19 formed on the sleeve, the pawl carrier being pivoted at 23 and being actuated by the engagement of an associated lug (26, Fig. 2, not shown) with the outer end of the sleeve. The sleeve is initially in abutment with an outer piston formed of a main portion 14 and an end cap 15. Inner piston 11 acts on a directlyoperated pad while the outer piston acts on a yoke (45, Fig. 3, not shown). The mechanical actuator is a lever-operated cam 27 journalled in the end cap 15 and acting on the sleeve 17. When the brake is applied hydraulically by the admission of fluid at 16 the stem 12 is drawn through a sealed aperture in the outer piston so that the sleeve is moved towards a lug (26, Fig. 2, not shown) on the pawl carrier 22 to operate the pawl for rotating the sleeve, either during application or release of the brake, should adjustment be necessary. In the embodiment of Fig. 3, a friction type adjuster is used comprising a ring (34) which is locked against a stem (33) secured to the inner piston (31) during mechanical application by a cam (43), acting via a dolly (44) and a member (41) having an inclined forward face, but is able to slide along the stem in either direction during hydraulic separation of the pistons (31, 39) so that its position after braking is adjusted to compensate for wear. In the embodiment of Fig. 4, the adjuster is of the type comprising a sleeve 73 and an intermediate member 74 having co-operating conical friction surfaces 76 which are urged together when the intermediate member is moved by a cam 84 and dolly 85 to apply the brake mechanically but which are maintained out of engagement by a spring 77 during hydraulic separation of the pistons 71, 75, there being screw-threaded connection between the sleeve 73 and a stem 72, secured to the inner piston 71, which is of sufficiently coarse pitch to enable the sleeve to be rotated by the thrust applied to it by the intermediate member acting via a thrust ball race 81, thus automatically adjusting its position along the stem 72. A heavy compression spring 82 is arranged between the member 74 and the piston 75. In the modifications of Figs. 5 and 6 (not shown) a similar adjusting mechanism is used but one of the co-operating conical surfaces is provided by the inner piston in each case, the other conical surface being provided on the sleeve in the case of Fig. 5 and on an enlarged portion of the stem in the case of Fig. 6.