GB1324659A - Brakes - Google Patents

Abstract

1324659 Full-face disc brakes; shoe removal; external drum brakes; cooling H KLAUE 15 Sept 1970 [2 Dec 1969 27 Dec 1969 (2)] 43915/70 Heading F2E In a brake assembly where pairs of segmental brake shoes are disposed in an annular gap between two rotatable circular members and the shoes of each pair are moved in opposite directions to cause them to contact the respective braking surfaces of the adjacent circular members to effect braking, the shoes are removable from, or insertable into the annular gap in the radial direction without dismantling the brake assembly. In the first embodiment, Figs. 3, 4 and 7, the circular members are the sides of a U-section annular brake "housing" 27, Fig. 3, secured at 26 to the hub 24 of the wheel 25 of a heavy duty vehicle for rotation therewith. Two sets each of four brake shoes are provided, the four shoes 30, Fig. 4, being engageable with the annular brake surface 27a, Fig. 3, and the other four being engageable with surface 27b. The shoes are applied by relative circumferential displacement of actuator rings 31 1 , 31 2 , by pneumatic cylinder 29, Fig. 7, via rod 29, pivoted arm 35, tappets 34 1 , 34 2 , and thrust members 33 1 , 33 2 ; each ring has ramps co-operating with balls 32 or rollers located between the rings. Preferably between each actuator ring, and the adjacent set of shoes, an outer ball race e.g. 37 2 , balls e.g. 39 and an inner race e.g. 40 2 are provided. The shoes are guided for axial movement but prevented from circumferential movement, during operation, by the provision of shoulders on them, Fig. 4, for co-operation with flanges 28 1 to 28 4 associated with a fixed bracket 28, Fig. 3, in the shape of a four-arm spider. The flanges are hinged as shown in Fig. 3 to permit the shoes 30 to be removed radially outwards. Pull-off springs 41, Fig. 3, are provided. Cooling ribs 27c are provided on the brake "housing" 27. In the second embodiment, Figs. 9, 10, 12, each set of shoes consists of two shoes only, e.g. 43, Fig. 10. Here the shoes are applied by the relative axial separation of two overlapping L- section rings 50, 51, Fig. 9, to the space between which hydraulic fluid is admitted at 48. A further ring 52 1 , or 53 1 is interposed between the actuating ring 50, or 51 and the adjacent pair of brake shoes. Pull-off springs 54 are again provided. To prevent circumferential shoe movement, a fixed bracket 42 provided by the wheel axle housing cover has opposite flanges 42 1 , 42 2 , Fig. 10, with which shoulders on the brake shoes engage. To permit shoe removal, two arms 44, circumferentially midway between flanges 42 1 , 42 2 , may be unscrewed from bracket lugs 42 3 , Fig. 9. Preferably the arms 44 are resilient to reduce rattle or chatter. This embodiment is intended for a lighter (private) vehicle having hub 46 driven by rotary axle 47. For cooling, ribs 45 4 and apertures 45 1 are provided respectively on and in the rotary brake "housing" 45. Cooling air paths are shown by arrows 62 to 66. An independent mechanical drum brake operable e.g. by a hand brake lever is provided in association with this embodiment. It comprises an arcuate shoe 55, Figs. 9 and 12, engageable with an annular rim 45a of housing 45. The shoe is pivoted at 55a, Fig. 12, and applied by a roller 56 eccentrically mounted on a pivoted arm 57 pulled counter-clockwise by a cable against the force of a pull-off spring 58. Figs. 13 to 20 (not shown) which do not have the drum brake feature, but have toggle-andlink mechanism for alternative mechanical actuation of ball-and-ramp actuating rings, are substantially identical with Figs. 1 to 8 of Specification 1,255,450. In the variation shown in Figs. 21 and 22, a single hydraulically-operated piston 192 partly rotates actuating-ring 190, which acts on one pair of shoes by cooperation with the other actuating ring 189 and balls 196 located between the rings in ring ramps; actuating-ring 189, however, is axially-slidable only, and bears directly on the other pair of shoes. Two rows of ball-bearings 194, 193, and an axially-slidable thrust-ring 195 are interposed between actuating ring 190 and the adjacent pair of brake shoes. The respective pairs of shoes are joined by shackles 197, 198 respectively, which are removable for shoe-withdrawal.