GB2119878A

GB2119878A - Disc brakes

Info

Publication number: GB2119878A
Application number: GB08309997A
Authority: GB
Inventors: Gerald Allan Ottewell
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1982-04-27
Filing date: 1983-04-13
Publication date: 1983-11-23
Also published as: GB8309997D0; GB2119878B

Abstract

A disc (1) for a rail vehicle disc brake is adapted to be mounted on a hub (3) by a compliant mounting (16). The disc comprises two components 6, 7 of arcuate outline of which adjacent ends are held together by a connecting link (23) (Figure 1), which may be of generally H-outline, and a gap (17) is left between the two adjacent ends to allow for thermal expansion. <IMAGE>

Description

SPECIFICATION Disc brakes This invention relates to vehicle disc brakes, particularly, but by no means exclusively, for railway vehicles.

A familiar problem with disc brakes is that the dimensions of the disc can change due to the cyclic heating and cooling which it undergoes in use. This can result in undesirable stresses in the disc, which may lead to cracking and eventual failure.

British patent No. 1 506151 proposes to alleviate the problem by providing the disc with a specified form of compliant mounting. Whilst there is no doubt that this gives a significant improvement it has now been found that the problem can be alleviated still further.

According to our invention a disc for a vehicle disc brake is adapted for mounting on a hub by means of a compliant mounting, and the disc comprises at least two components of arcuate outline of which adjacent ends are held together by connecting means, a gap being left between the said adjacent ends to allowforthermal expansion.

The adjacent ends of the arcuate components are preferably resiliently biassed apart by spring means to ensure that a predetermined circumferential relationship is maintained between the disc components. In a particularly preferred embodiment, the spring means comprise spring roll pins located in generally radial recesses in adjacent faces of the disc components. The pins may thus additionally serve to locate the disc components axially relative to each other, thus keeping the opposed outer faces, which define the braking faces, flush.

Each of the arcuate components may comprise a pair of plates held in a rigid spaced apart relationship by cooling fins, in which case the adjacent ends of the plates are preferably provided with inturned radial abutments, and the connecting means comprises a connecting link which is received between the abutments and has parts which are located behind the abutments to hold the disc brake components together. The link may conveniently comprise a tie of generally H-outline.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa plan of part of an edge of a disc for a rail vehicle; and Figure 2 is a section on line 2-2 of Figure 1.

The disc 1 illustrated in the drawings is of annular outline having a central opening 2 to receive a hub 3.

The disc 1 has a pair of opposed external braking faces 4 and 5 with which a pair of friction brake pads (not shown) are engageable when the brake is applied.

The disc comprises two arcuate components 6 and 7, each in the form of a one-piece casting and each comprising a pair of plates 8,9 and 10, 11 held in a spaced relationship by radial cooling fins 12 with the outer faces, constituting the braking faces 4, 5, lying in spaced parallel planes.

The inner peripheral edge of the disc 1 is provided with angularly spaced radial projections 13 which extend radially inwards towards the hub 3, leaving a clearance between the projections and the hub. The projections have part-cylindrical recesses 14 in registes with corresponding recesses 15 in the hub 3 to receive spring roll pins 16. The roll pins 16 are under radial compression so that they centre the disc on the hub 3 and form a compliant mounting.

The adjacent ends of the two components 6,7 are separated by radial gaps 17, only one of which is shown in the drawings.

As can be seen from Figure 1, the adjacent ends of the plates 8,9 and 10, 11 are provided with facing, inturned radial abutments 20 and 21 respectively, which receive between their opposed ends, with clearance, the cross-piece 22 of a tie constituted by a connecting link 23 of generally H-outline. The arms 24 of the link 23 are seated behind the abutments 20 and 21, so that the link 23 holds the two components 6,7 of the disc together against an outwardly directed radial bias of the roll pins 16 and, in use, against centrifugal force.

The opposed end faces of each pair of plates 8, 9 and 10, 11 are provided with pairs of spaced registering, radially extending, part-cylindrical recesses 26 (only one pair of which are shown in the drawings) to receive further spring roll pins 27.

These pins are under compression and positively locate the two components 6 and 7 relative to each other, thus keeping the braking faces 4 and 5 flush.

In order to retain the roll pins 27 and the link 23 in place, the radially inner and outer ends of the abutments 20,21, are respectively provided with recesses 30 and 31 in which respective retainer plates 32 and 33 are received. These plates 32 and 33 are clamped against faces at the bases of the recesses by bolts 34 which pass through the roll pins 27 with clearance.

Thermal-induced changes in the dimensions of the disc are taken up by the gaps between the projections 13 and the hub 3 and byte gaps 17, with the result that stresses in the disc are for all practical purposes eliminated.

Although the presence of the roll-pins 27, or some other means of biassing apart the components 6 and 7, is highly desirable they could conceivably be dispensed with altogether, in which case the provision of some alternative means of axially locating the components 6 and 7 relative to each other is recommended. This could be achieved by making the link 23 a location fit between the abutments 20 and 21 or by adapting the retainer plates 32 and 33 to locate the sections axially and positively. For example, the retainer plates 32 and 33 could be bolted to both components, the plates 32 and 33 being provided with circumferentially slotted bolt holes to permit circumferential movement between the disc components 6 and 7 to take place.

Instead of an H-shaped link, the disc components 6 and 7 could be joined by a bolt passing through holes in the adjacent ends of the disc sections. They could also be joined by a bar coupled to each disc component 6,7 by a spring roll pin which is preferably disposed radially.

Claims

1. A disc for a vehicle disc brake adapted for mounting on a hub by means of a compliant mounting, the disc comprising at least two components of arcuate outline of which adjacent ends are held together by connecting means, a gap being left between the said adjacent ends to allow for thermal expansion.

2. A disc as claimed in claim 1, in which ths adjacent ends of the arcuate components are resiliently biassed apart by spring means to ensure that a predetermined circumferential relationship is maintained between the disc components.

3. A disc as claimed in claim 2, in which the spring means comprise at least one spring roll pin located in generally radial, complementary, recesses in adjacent faces of the two disc components.

4. A disc as claimed in claim 2, in which the spring means comprise two spring roll pins received in pairs of radial, complementary, recesses in adjacent faces of the two components.

5. A disc as claimed in claim 4, in which bolts projecting through the roll pins act to clamp retaining plates against radially spaced inner and outer faces of the two components in order to retain the roll pins and the connecting means against movement relative to the components in a radial direction.

6. A disc as claimed in any preceding claim in which the connection means comprise ties which extend circumferentially and interconnect adjacent ends of the components.

7. A disc as claimed in any preceding claim in which each arcuate component comprises a pair of plates held in a rigid spaced apart relationship by cooling fins, and the adjacent ends of the plates are provided with inturned radial abutments, the connecting means comprising a connecting link which is received between the abutments and has parts which are located behind the abutments to hold the disc brake components together.

8. A disc as claimed in claim 7, in which the link comprises a tie of generally H-outline.

9. A disc for a vehicle disc brake substantially as described herein with reference to and as illustrated in the accompanying drawings.

New claims or amendments to claims filed on 20 July 1983 Superseded claims 1 and 2 New or amended claims: Claims 3-9 renumbered as 2-8 and appendances corrected

1. A disc for a vehicle disc brake adapted for mounting on a hub by means of a compliant mounting, the disc comprising at least two components or arcuate outline of which adjacent ends are held together by connecting means, a gap being left between the said adjacent ends to allow for thermal expansion, and the adjacent ends of the arcuate components are resiliently biassed apart by spring means to ensure that a predetermined circumferential relationship is maintained between the disc components.