DISC ASSEMBLIES FOR BRAKES

Abstract: A disc assembly (1) for a brake has a rotatable disc member (2) mounted on a rotatable hub (3), with a coupling device (4) providing a driving engagement between the disc member (2) and the hub (3). Opposed faces (9, 10) of the disc member (2) and the hub (3) are of complementary non-­ circular outline, for example, octagonal, so that on failure of the coupling device (4) a driving engagement is provided between the disc member (2) and the hub (3). The coupling device (4) may comprise spring roll-pins (12), located in recesses (11) in the opposed faces (9, 10) of the disc member (2) and the hub (3).

Description: DISC ASSEMBLIES FOR BRAKES This invention relates to disc assemblies for brakes of the kind comprising a substantially annular rotatable disc member adapted to be braked, the disc member being mounted on a rotatable hub, and coupling means providing a driving engagement between the disc member and the hub so that they rotate together. According to the invention, opposed faces of the disc member and the hub are of complementary non-circular outline such that on failure of the coupling means a driving engagement is provided between the disc member and the hub. Our invention therefore contributes to the safety of the assembly, as drive can be maintained when the coupling means fails. The invention is of particular value where the coupling means comprises spring roll-pins located in conjoined recesses in the opposed faces of the disc member and the hub. In one construction the opposed faces are octagonal in outline, with the coupling means comprising spring roll-pins located at the vertices. Clearly, the faces may be of hexagonal, or indeed any convenient lion- circular outliile. The disc assembly is conveniently incorporated in a transmission brake, with the disc member braked by friction pads actuated by any suitable actuating means. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a side view, partly in section, of a transmission disc brake incorporating a disc assembly according to our invention; and Figure 2 shows the brake as viewed from the left in Figure 1. The transmission disc brake shown in the drawings has a disc assembly 1, which comprises a substantially annular rotatable disc member 2 mounted on a rotatable hub 3 which forms part of a vehicle transmission. Coupling means 4 provide a driving. engagement between the disc member 2 and the hub .3sQ that they rotate together. The disc member 2 has a flange S extending radially inwardly, by which. the disc member 2 is coupled to the hub 3. The hub#' is .f,qrmed in three axial parts, 6, 7 and 8, and, as shown in Figure 2,. the outer peripheral face 9 of the intermediate part 7 is of octagonal outline. The inner peripheral face 10 of the flange 5, is also of octagonal outline and surrounds the intermediate hub part 7 so that the faces 9, 10 are opposed. A small clearance is provided between the faces 9, 10. The flange S and hub part 7 are provided with eight conjoined part-cylindrical axial recesses 11, located at the vertices of the octagonal shape, and each recess 11 receives a spring roll-pin 12. These pins 12 form the coupling means 4, and are under radial compression to centre the disc member 2 on the hub 3 and accommodate thermal expansion of the disc member. The disc member 2 and hub part 7 are conveniently manufactured as a single casting, in which the recesses 11 are drilled, slots then being made between the recesses 11 to form the two components which are therefore supplied in matched pairs. Returning to Figure 1, the two end hub parts 6 and 8 extend radially outwards beyond the intermediate part 7 to receive bolts 13 which are inserted through the roll-pins 12 to clamp the hub parts securely together. Brake pads 14 and 15 are located on axially opposite sides of the disc member 2 for operation by actuator means 16, in this case a convential mechanism of the type in which the brake is held inoperative by hydraulic pressure acting against an actuating spring. In use, the pins 12 couple the disc member 2 to the hub 3, providing a driving engagement. If the spring pins 12 should fail the opposed faces 9, 10 of the flange 5 and the hub part 7 will come into engagement, and provide a driving engagement between the disc member 2 and the hub 3. Another possible advantage of the described arrangement is that during normal heavy braking the faces 9, 10 could come into engagement after a small angular movement, to relieve the spring pins 12 and bolts 13 of excessive stress. The opposed faces 9, 10 of the disc member and the hub could be hexagonal or of other non-circular shapes arranged to provide the necessary driving engagement.

Claims: CLAIMS 1. A disc assembly for a brake of the kind comprising a substantially annular rotatable disc member (2) adapted to be braked, the disc member (2) being mounted on a rotatable hub (3), and coupling means (4) providing a driving engagement between the disc member (2) and the hub (3) so that they rotate together, characterised in that opposed faces (9, 10) of the disc member .(2) and the hub (3) are of complementary non-circular outline, such that on failure of the coupling means (4) a driving engagement is. provided between the disc member (2) and the hub (3). 2. A disc assembly according to claim 1, characterised in that the coupling means (4) comprises spring roll-pins (12) located in conjoined recesses (11) in the opposed faces (9, 10) of the disc member (2) and the hub (3). 3. A disc assembly according to claim 1 or claim 2, qharacterised in that the opposed faces (9, 10) are octagonal in outline, with the coupling means (4) comprising spring roll-pins (12) located at the vertices. 4. A disc assembly according to any preceding claim, characterised in that . it is incorporated in a transmission brake, with the disc member (2) braked by friction pads (1d, 15) actuated by. actuating means (16).

Inventors: OTTEWELL, GERALD ALLAN
Applicants: LUCAS INDUSTRIES PUBLIC LIMITED COMPANY
Application year: 1983
Main classification: F16D65
IPC codes: B60T1, F16D65