WO1989005925A1

WO1989005925A1 - Split disc for disc brake rotor

Info

Publication number: WO1989005925A1
Application number: PCT/GB1988/001128
Authority: WO
Inventors: Peter Dennis
Original assignee: Urban Transportation Development Corp Ltd
Current assignee: Urban Transportation Development Corp Ltd
Priority date: 1987-12-18
Filing date: 1988-12-16
Publication date: 1989-06-29
Anticipated expiration: 1990-06-18
Also published as: AU2924589A

Abstract

A split brake rotor (24) assembly for a disc brake comprises a pair of semicircular segments (42, 44) that are joined along abutting radial edges (46). Each edge has an undercut channel (48) formed in the radial edge and receives an I-shaped key (54) to bridge the two edges and support the segment along the radial edge. The key (54) is tapered to inhibit radial movement.

Description

SPLIT DISC FOR DISC BRAKE ROTOR The present invention relates to disc assemblies for brake rotors.

Disc brakes are widely used in all transportation industries on an efficient and effective means of braking vehicles. It is, however, frequently necessary to remove the rotor of a disc brake for servicing. Where the rotors are mounted outboard of the hub or wheel assembly, their removal does not cause particular design problems. However, in many applications the disc rotor will be mounted inboard of the wheel and/or hub assembly, which necessitates a major overhaul in order to remove the rotor.

To overcome this problem it has been proposed to manufacture the rotor as two segments that can be assembled about an axle to form the rotor. This then permits the rotor to be split and removed without removing the whole axle assembly. This arrangement is known as a split disc. A number of techniques for forming such discs are shown in the prior art. One technique utilised by a number of earlier proposals is to bolt, the segments of a disc to one another by means of a bolt that extends across a chord of the disc. Such proposals are shown in U.S. Patent 1,272,081; U.S. Patent 4,120,386 and an equivalent structure shown in U.S. Patent 4,004,661. The difficulty with utilising such arrangements is that the thickness, i.e. the spacing between oppositely facing brake surfaces, has to be relatively large to. accommodate the bolted structures and allow access for assembly and disassembly. An alternative concept is disclosed in U.S. Patents 2,610,719 and 3,904,000, where a bridging piece is utilised on the circumference of the disc to interconnect a pair of segments. However, with this arrangement, the bridging pieces must be located radially outward of the swept area of the disc pad so that the overall dimensions of the disc are increased.

A number of proposals for use with clutches have suggested the use of complementary formations which allow the segments of the clutch to be locked together, such as is shown in 4,449,621 and 4,512,540. However, these proposals are utilised in a clutch environment where a discontinuous friction surface is utilised as, for example, in the U.S. Patent 4,512,450 to Babcock, so that the Joint line between segments is not as critical as in the brake rotor. Moreover, the loads are uniformly distributed about the surface at all times so that the service requirements are significantly different from that of a disc brake rotor.

A similar arrangement is shown in U.S. Patent 4,199,044 to permit a two-segment disc rotor float relative to the carrier. For this purpose a dumb-bell shaped link is utilised to interconnect the two segments but axial support for these segments is provided by the backing structure, in this case the wheel hub. U.S. Patent 2,869,688 to Busch discloses a railway disc brake in which the segments are interconnected through a tongue and groove joint, as shown in Figure 9 of that patent. In the Busch arrangement, support is provided between adjacent discs along the entire radial length of the disc but no provision is made for distributing the circumferential loads between adjacent discs.

it is therefore an object of the present invention to provide a disc rotor that obviates or mitigates the above disadvantages.

In accordance with the invention there is provided a disc assembly for a brake rotor comprising a plurality of segments arranged edge to edge to define a disc with each segment having a pair of oppositely directed braking surfaces and a pair of radial surfaces extending between said braking surfaces, a radial extending formation formed on each of said radial surfaces and a bridging member engaged with and extending between opposed formations of adjacent segments to interconnect said segments along said radial surfaces.

By providing the formations that extend along each radial edge it is possible to support the edges of adjacent segments along their entire length with the bridging member being able to transfer circumferential loads to the rotor.

Preferably, each of the formations is a channel having undercut edges so that a single line of abutment is provided between adjacent segments. This minimizes the surface irregularities on the braking surface of the rotor.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which

Figure 1 is a front elevation of a wheel set of a rail vehicle having a disc brake mounted thereon;

Figure 2 is a section on the line 2-2 of Figure 1, having portions of the rotor shown broken away;

Figure 3 is a section on the line 3-3 of Figure 2; Figure 4 is a view in the direction of arrow 4 on Figure 3; and Figure 5 is a view in the direction of arrow 5 in Figure 3.

Referring now to Figure 1, a wheel set generally indicated at 10 and suitable for use on a railroad truck, comprises an axle 12 and a pair of wheels 14. The axle is rotably mounted in bearings 16 attached to frame members 18 of the truck. A brake disc assembly 20 is mounted on the axle between the frame members 18. The brake disc assembly 20 is seen in more detail in Figure 2 and comprises a mounting boss 22 secured to the axle 12 and having a rotor 24 secured through bolts 26 to an end face 28 of the boss 22. The rotor 24 includes a dished web 30 extending radially outwardly from the boss 22 and terminating in a pair of annular, oppositely directed braking surfaces 32, 34. Ventilation slots 36 are provided between the braking surfaces 32, 34 to assist in dissipation of heat generated during braking.

A caliper 38 of conventional design is supported on a frame member of the vehicle and has a pair of brake shoes 40 engaging with each of the surfaces 32, 34 in a conventional manner.

As can best be seen in Figure 3, the disc 24 is formed from a pair of segments 42, 44 of identical shape. Each of the segments 42, 44 is delimited by a pair of radial edges 46 extending between the braking surfaces 32, 34. An undercut channel 48 is formed in each of the radial edges 46. The channel 48 is formed by a pair of opposed side walls 50 that terminate in an enlarged head portion 52. The channels 48 extend across the radial edge 46 delimiting the braking surface to the dished web 30. As may be seen from Figure 4, with each of the segments 42, 44 installed on the hub 22, the channels 48 of adjacent radial edges 46 define a generally I-shaped recess that extends across the full width of the braking surfaces 34, 32. The enlarged heads 52 of each of the channels 48 converge toward one another in the radially outward direction so that the aperture formed between the two channels 48 tapers in a radial direction. To secure the segments 42, 44 of the disc to one another, a key 54 is inserted into the aperture formed by the channels 48. The key 54 is of substantially complementary shape to the aperture formed by the channels 48 and is inserted from the radially inward edge of the braking surfaces toward the radially outer edge. The undercut nature of the channels 48 ensures that circumferential forces are transmitted between the two segments and also ensures that the edges are supported along their entire length.

The tapered form of the aperture inhibits radially outward movement of the key 54 but for extra security a fastener in the form of a plate 56 is located in a depression 58 formed in the circumferential edge of the rotor 24. The plate 56 is secured by a pair of bolts 62 that extend radially into the body of the disc rotor. The bolts 62 may be secured by means of a conventional wire lock to prevent release of the bolts. It will be apparent that assembly of the disc rotor 24 can readily be accomplished by bolting the segments 42, 44 to the bushing 22 and subsequently inserting the key 54 into the respective channels 48 to bridge the two segments. Similarly, disassembly of the rotor is readily accomplished by simply forcing the key out in a radially inward direction and removing the bolts 26 to allow disassembly of the rotor without necessitating removal of the whole wheelset.

Claims

We claim :

1. A disc assembly for a brake rotor comprising a plurality of segments arranged edge to edge to define an annular disc with inner and outer with each segment having a pair of oppositely directed braking surfaces and a pair of radially extending surfaces connecting said braking surfaces, a formation formed on each of said radial surfaces and extending along said surface between said edges and a bridging member engaged with and extending between opposed formations of adjacent segments to interconnect said segments along said radial surfaces.

2. A disc according to claim 1 including fastening means to prevent radial movement of said bridging member.

3. A disc assembly according to claim 1 wherein the formation on each radial edge is similar.

4. A disc assembly according to claim 3 wherein each of said one formations is formed in sectors and is a channel having an undercut side wall, said bridging member being substantially complementary in shape to the aperture formed between abutting radial surfaces.

5. A disc assembly according to claim 4 wherein fastening means are provided to inhibit radial movement of said bridging member.

6. A disc assembly according to claim 5 wherein said fastening means are disposed on the circumference of said disc.

7. A disc assembly according to claim 6 wherein said fastening means are located in a depression formed between said braking surfaces on the circumference of said disc.

8. A disc assembly according to claim 7 wherein said fastening means is a bar disposed on a chord of said disc and secured at opposite ends by releasable fasteners.

9. A disc assembly according to claim 4 wherein opposed end walls of said channels converge in a radially outward direction and said bridging member tapers along its length.

10. A disc assembly according to claim 9 wherein said fastening means are located in a depression formed between said braking surfaces on the circumference of said disc.

11. A disc assembly according to claim 10 wherein said fastening means is a bar disposed on a chord of said disc and secured at opposite ends by releasable fasteners.