Patent GB-1073829-A (GB)
Title: Disc brakes
IPC: F16D65/46
Filed: 1965-08-06
Abstract: 1,073,829. Disc brakes. RECHERCHES ETUDES PRODUCTION R.E.P. Aug. 6, 1965 [Aug. 7, 1964; May 14, 1965], No.. 33822/65. Heading F2E. A disc brake of the floating caliper type has its pads applied by screw--and-nut mechanism wherein balls run in complementary helical grooves in the co-operating portions of the screw 3 and nut 2 to transmit the applying force therebetween. Nut 2 is located against rotation in a recess of the floating housing 1 by a peg 8, and is secured by a threaded ring which also limits withdrawal of the screw 2, a wear-compensating screw 13 being threadedly engaged in a bore of screw 2 and co-operating with a pushrod 14 to enable the clearances between pads 6 and the disc 7 to be adjusted to the required value when screw 2 is in its withdrawn position. In the embodiment of Fig. 1 the screw 13 is manually adjustable and is fitted with a locknut 15. Rotation of the screw 3 to apply the brake is effected by a cable 5 engaged around a pulley 4 secured to the screw 3. A helical spring 9 acting as a torsion spring releases the brake. Two floating calipers (20), (Fig. 2, not shown), having screw-and-nut applying means as above may be disposed at diametrically opposite points with respect to the disc (7) and operated by a single cable (22) which is looped around a sheave (23), attached to a pedaloperated cable (24), and connected at its ends to the two pulleys (4). In a second embodiment (Figs. 3-6, not shown), the pulley 4 is replaced by a lever (46), the two levers (46) of a pair of diametrically oppositely disposed calipers being operated by a pair of hydraulic cylinders (47) .mounted on a common pivot and having associated release springs (60). Alternative manual operation is provided by a cable (59) operating between a pair of further levers (58) engageable with the levers (46) by abutment, so as to provide for independent power operation. A pair of such cables (71), (Fig. 7, not shown) may be connected via a balance beam (71) and booster cylinder (72) to a pedal (73). The wear-compensating screw (13) is in this case operated automatically via a drive-shaft (54) which is driven unidirectionally from the screw (3) via a one-way clutch comprising balls (51) and springs (53) (Fig. 4, not shown) and with which is associated device comprising two pegs (55), (56) (Fig. 5, not shown), secured to the caliper housing which are engaged by one end of a spring (57) arranged to be self-tightening in the brake-release direction. The drive shaft (54) thus follows the nut in the brake-applying direction, spring (57) slipping on the shaft after contacting peg (56), but can only return through a limited angle, equivalent to the normal pad clearance, so that the remaining return movement of screw (3) is effected with screw (13) stationary, whereby a key (50) rotates the push-rod (14) to unscrew it slightly. Figs. 8-11 (not shown) disclose a slightly simplified version of the embodiment of Figs. 3-6, in which the caliper housing has an integral yoke (116) pivoted on a spindle (115) which is secured to a plate (109) bolted to axle housing (107). Plate (109) also carries spindles (111) on which the backing plates (112) of a pair of pads are mounted for sliding movement towards and away from an annular disc (7) carried by a support (103) which is secured, together with a wheel disc (101), to a hub (106). The arrangement of nut (2) and screw (3) is similar to that of the previous embodiment but the automatic wear-adjustment device includes a friction peg (140) inserted in a groove in the adjuster screw (13) to restrain relative movement between it and the push-rod (14). No separate drive-shaft is provided for the screw (13), and the pegs (55), (56) are carried by a bracket (146) secured to the yoke (116). The brake is applied either by a cylinder (162) carried by the yoke and acting on the face (160) of a lever (150) secured to the screw (3), or by a cable (155) acting between bracket (159) on the yoke and a ball-and-socket connection (153), (156) with the lever (150).