A DRUM BRAKE SHOE AND AN APPARATUS AND METHOD FOR CHANGING SAME

Abstract

The present disclosure relates to heavy vehicle drum brakes. In a particular form, the present disclosure relates to a brake shoe configured for ease of changing thereof, and to an apparatus and method for changing drum brake shoes. In one aspect, the brake shoe comprises a lining table supporting a brake lining, and at least one web extending from the lining table, the web comprising a spring attachment aperture extending therethrough, the brake shoe further comprising an access aperture extending through the lining table and the brake lining, wherein a center line of the access aperture intersects, or is at least close to intersecting, a center line of the attachment aperture.

Claims

1. A brake shoe comprising a lining table supporting a brake lining, and at least one web extending from and along an underside of the lining table, the web comprising a return spring attachment aperture extending therethrough, the brake shoe further comprising an access aperture extending through the lining table and the brake lining, wherein a center line of the access aperture intersects, or is at least close to intersecting, a center line of the return spring attachment aperture.

2. The brake shoe of claim 1, wherein in use, the return spring attachment aperture receives a pin or bolt with which the spring is engaged.

3. The brake shoe of claim 1, wherein the brake shoe comprises a pair of webs.

4. The brake shoe of claim 3, wherein the webs are substantially parallel.

5. The brake shoe of claim 3, wherein the access aperture is located between the webs.

6. The brake shoe as of claim 3, wherein both of the webs comprise a return spring attachment aperture.

7. The brake shoe of claim 6, wherein the return spring attachment aperture in each of the webs is longitudinally coaxial with each other.

8. The brake shoe of claim 7, wherein a center line of the access aperture intersects a center line of the two return spring attachment apertures.

9. The brake shoe of claim 1, wherein the access aperture extends substantially normal to the return spring attachment aperture.

10. The brake shoe of claim 3, wherein both of the webs comprise a mount for a follower for an actuating cam.

11. The brake shoe of claim 1, wherein the brake shoe comprises a brake shoe guide extending from the at least one web thereof.

12. The brake shoe of claim 11, wherein the web with the brake shoe guide is an outboard web in use.

13. The brake shoe of claim 1, wherein the brake shoe is a heavy vehicle brake shoe.

14. A brake shoe comprising a lining table supporting a brake lining, and a pair of webs extending in parallel from and along an underside of the lining table, each of the webs comprising a return spring attachment aperture extending therethrough so that the return two spring attachment apertures are coaxial, the brake shoe further comprising an access aperture extending through the lining table and the brake lining, wherein a center line of the access aperture intersects a center line of the two return spring attachment apertures.

15. A brake shoe assembly comprising a brake shoe and a return spring attachment pin or bolt, the brake shoe comprising a lining table supporting a brake lining, and at least one web extending from and along an underside of the lining table, the web comprising a return spring attachment aperture extending therethrough in which the pin or bolt is received, the brake shoe further comprising an access aperture extending through the lining table and the brake lining, wherein the access aperture is directed at the pin or bolt.

16. A brake shoe assembly comprising a brake shoe and a return spring attachment pin or bolt, the brake shoe comprising a lining table supporting a brake lining, and a pair of webs extending in parallel from and along an underside of the lining table, each of the webs comprising a return spring attachment aperture extending therethrough in which the pin or bolt is received, the brake shoe further comprising an access aperture extending through the lining table and the brake lining, wherein the access aperture is directed at the pin or bolt.

17-25. (canceled)

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0048] Embodiments of the present disclosure will be discussed with reference to the accompanying drawings wherein:

[0049] FIG. 1 is an isometric view of a brake shoe;

[0050] FIG. 2 is a side view of the brake shoe of FIG. 1;

[0051] FIG. 3 is an upper view of the brake shoe of FIG. 1;

[0052] FIG. 4 is a lower view of the brake shoe of FIG. 1;

[0053] FIG. 5 is a side view of an arrangement including a portion of a drum brake assembly including an S-cam, a return spring and a pair of the brake shoes as illustrated in FIG. 1, and further illustrating a tool for engaging the return spring;

[0054] FIG. 6 is a top view of the arrangement illustrated in FIG. 5;

[0055] FIG. 7 is an end view of the arrangement illustrated in FIG. 5; and

[0056] FIG. 8 is a cross-sectional view taken along A-A of FIG. 6.

[0057] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DETAILED DESCRIPTION

[0058] Referring now to FIG. 1, where there is illustrated a brake shoe 1 comprising a lining table 2 having a working face and a backing face, where a brake lining 4 depends from the working face, and a pair of parallel, spaced apart webs 6 depend from the backing face so as to extend from and along this.

[0059] Each web 6 of the brake shoe 1 comprises one of a pair of mutually aligned anchor pin holes 8, via which that brake shoe 1 may be pivotally attached to a stationary carrier associated with the axle assembly. Each web 6 further comprises, at an end distal to the anchor pin holes 8, one of a pair of mutually aligned generally U-shaped cam follower mounts 10, for mounting opposite ends of a cam follower in the form of a roller retained therein by retaining clips (not illustrated).

[0060] Each web 6 of the brake shoe 1 comprises a return spring attachment aperture 12 extending therethrough, and these are longitudinally coaxial. In use, these return spring attachment apertures 12 receive a pin or bolt 150 therethrough so that this pin or bolt 150 bridges the webs 6.

[0061] The brake shoe 1 further comprises an access aperture 14 extending through the lining table 2 and the brake lining 4. In the illustrated embodiment, this access aperture 14 comprises a circular hole, but other aperture shapes may be employed as necessary to permit access. A center line of the access aperture 14 intersects a center line of the return spring attachment apertures 12. That is to say, the access aperture 14 extends in a direction toward the attachment aperture 12.

[0062] In the case of the illustrated embodiment, the brake shoe 1 further comprises a brake shoe guide 16 extending from what will, in use, be an outboard web thereof. This brake shoe guide 16 is of the type disclosed in WO2018/094441. It extends lengthwise from this outboard web so as to make it longer than the other web, so that the guide 16 extends in front of, and in sliding contact with, an outboard face of an actuating cam 100. In use, the guide 16 prevents brake shoe misalignment in brake drums of heavy vehicles.

[0063] Referring now to FIGS. 5 through 8, there is shown a portion of a typical drum brake assembly from a compressed air brake system of a heavy vehicle such as a semi-trailer prime mover or trailer.

[0064] The drum brake assembly comprises the aforementioned stationary carrier (not illustrated) upon which a pair of the arcuate brake shoes 1 are pivotally mounted in an oppositely directed arrangement, for enclosure within and cooperation with a cylindrical internal surface of a rotatably mounted brake drum (not illustrated), with respect to which a wheel assembly of the vehicle is attached.

[0065] The drum brake assembly will further comprise a shaft extending from an air-powered brake booster (not illustrated, but typically depending from an axle housing for the wheels) into the brake drum, where it terminates at an S-shaped actuating cam (hereinafter S-cam) 110 which interposes the cam followers 120.

[0066] A return spring 140 bridges (i.e., extends between) and is secured with respect to each of the pair of brake shoes 1 inside of the drum, and performs the dual functions of returning the brake shoes 1 to their resting condition when the brake pedal is released, and maintaining the cam followers 120 in contact with the S-cam 110. A typical return spring 140 comprises a hook 142 at each end thereof, which is hooked around one of the bolts 150 extending through the return spring attachment apertures 12 and thus between the webs 6 of each of the pair of brake shoes 1.

[0067] In use, when the brake pedal of the vehicle is pushed, compressed air is supplied to the air-powered brake booster, which rotates the S-cam 110 via a push rod, a slack adjuster (i.e., a lever—not shown) and then the shaft, driving the brake shoes 1 outward into contact with the drum brake.

[0068] As discussed in the background, when the brake shoes 1 are changed and/or the drum brake assembly is serviced, the return spring 140 must be removed in order to release the brake shoes 1. This involves overcoming the bias of the spring 140 so that the hook 142 at each end of the spring 140 may be unhooked from a bolt 150 extending between the webs 6 of one of the brake shoes 1.

[0069] Referring now to FIGS. 5 and 6, a tool 200 for use with the brake shoe 1 is illustrated.

[0070] The tool 200 comprises a lever element 210, and a tether element 220 depending from the lever element 210. In the illustrated embodiment, the tether element 220 comprises a cable or zip tie formed into a loop which is passed around the lever element 210 and secured in position with respect to the lever element 210.

[0071] In use, the tether element 220 is passed through the access aperture 14 in the brake shoe 1 so as to engage (by looping around the hook 142) an end of the return spring 140. The lever element 210 can then be used as a lever to stretch the return spring 140 to disengage this from the bolt 150 and thus with respect to the brake shoe 1.

[0072] When the drum brake assembly is reassembled, the tether element 220 is passed through the access aperture 14 in the brake shoe 1 so as to engage (by looping around the hook 142) an end of the return spring 140. The lever element 210 can then be used as a lever to stretch the return spring 140 to engage this with the bolt 150 and thus with respect to the brake shoe 1.

[0073] Advantageously, the brake shoe 1 can be used as a substitute for a conventional brake shoe without need for modification or replacement of existing brake hardware.

[0074] Moreover, the brake shoe disclosed herein permits external access to an end of a return spring engaged with respect thereto, or to be engaged with respect thereto. As a result, disengagement, removal, and fitment of the return springs is made significantly easier and quicker, and can be achieved without removal of the wheel hub or disruption of the wheel bearings. This represents a significant saving in servicing time and equipment downtime, and therefore money.

[0075] Moreover, additional advantage is realized in the case of smaller drum brake assemblies, such as those employed on low loader trailers, where access for maintenance is reduced even further.

[0076] Further advantage still is realized in that the present invention makes for ease of maintenance of brakes employing stronger return springs, which themselves are advantageous in as much as they improve brake operation, and reduce wear of components, such as flat spotting of rollers.

[0077] Throughout the specification and the claims that follow, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0078] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0079] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.

[0080] In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.