阅读说明：本技术 鼓式制动蹄以及用于更换鼓式制动蹄的装置和方法 (Drum brake shoe and device and method for replacing a drum brake shoe ) 是由 肯·皮特 于 2020-03-31 设计创作，主要内容包括：本公开涉及重型车辆鼓式制动器,特别地,涉及一种制动蹄,以及一种用于更换鼓式制动蹄的装置和方法。在一个方面,制动蹄包括：支撑制动衬片的衬片台,和从所述衬片台延伸的至少一个腹板,所述腹板包括延伸穿过所述腹板的弹簧附接孔口,所述制动蹄还包括延伸穿过所述衬片台和所述制动衬片的接入孔口,其中所述接入孔口的中心线与所述附接孔口的中心线相交或至少接近相交。因此,提供了一种鼓式制动蹄,其适于容易地接入与其接合的复位弹簧的端部。(The present disclosure relates to heavy vehicle drum brakes, and in particular, to a brake shoe, and an apparatus and method for replacing a drum brake shoe. In one aspect, a brake shoe comprises: a pad table supporting a brake pad, and at least one web extending from the pad table, the web including a spring attachment aperture extending through the web, the brake shoe further including an access aperture extending through the pad table and the brake pad, wherein a centerline of the access aperture intersects or at least nearly intersects a centerline of the attachment aperture. Thus, a drum brake shoe is provided which is adapted to easily access the end of a return spring engaged therewith.)

1. A brake shoe comprising: a pad table supporting a brake pad, and at least one web extending from the pad table, the web including a spring attachment aperture extending through the web, the brake shoe further including an access aperture extending through the pad table and the brake pad, wherein a centerline of the access aperture intersects or at least nearly intersects a centerline of the attachment aperture.

2. The brake shoe of claim 1 wherein said spring attachment aperture is adapted to receive a pin or bolt engaged with a spring.

3. A brake shoe according to any one of the preceding claims wherein said brake shoe includes a pair of webs.

4. The brake shoe of claim 3 wherein said webs are generally parallel.

5. A brake shoe according to claim 3 or 4 wherein said access aperture is located between said webs.

6. The brake shoe of any one of claims 3 to 5 wherein both said webs include a spring attachment aperture.

7. The brake shoe of claim 6 wherein said spring attachment apertures in each said web are longitudinally coaxial.

8. A brake shoe according to any one of the preceding claims wherein the access aperture extends generally perpendicular to the or each spring attachment aperture.

9. A brake shoe according to any one of claims 3 to 8 wherein both said webs include a mount for actuating a follower of a cam.

10. The brake shoe of claim 9 wherein said actuation cam is an S-cam.

11. The brake shoe of any preceding claim wherein said brake shoe includes a brake shoe guide extending from at least one web of said brake shoe.

12. A brake shoe according to claim 11 wherein said one web is an outboard web in use.

13. The brake shoe of any preceding claim wherein said brake shoe is a heavy vehicle brake shoe.

14. A brake shoe comprising: a pad table supporting a brake pad, and at least one web extending from the pad table, the web including a spring attachment aperture extending through the web, the brake shoe further including an access aperture extending through the pad table and the brake pad, wherein the access aperture extends in a direction toward the attachment aperture.

15. A tool for use with a drum brake shoe according to any one of the preceding claims for engaging and disengaging a return spring with said drum brake shoe, said tool comprising a lever element and a tie down element depending from said lever element.

16. The tool of claim 14, wherein the tethering element comprises a ring.

17. A tool according to claim 14 or 15, wherein the tethering element is formed by a cable or a tie wrap.

18. A method of using a tool according to any one of claims 15 to 17 to disengage the return spring from the brake shoe, the method comprising the steps of: passing the tie down element through the access aperture in the brake shoe and engaging an end of the return spring with the tie down element, and then using the lever element as a lever to extend the return spring to disengage the return spring from the brake shoe.

19. A method of using the tool of any one of claims 15 to 17 to engage the return spring with the brake shoe, the method comprising the steps of: passing the tie down element through the access aperture in the brake shoe and engaging an end of the return spring with the tie down element, and then using the lever element as a lever to extend the return spring to engage the return spring with the brake shoe.

20. A tool for use with a drum brake shoe according to any one of claims 1 to 14 for engaging and disengaging a return spring with said drum brake shoe, said tool comprising a lever element and a hook element, said hook element comprising a lever portion and a hook portion extending from said lever, wherein said lever of said hook element is pivotally connected to said lever element at or near an end thereof remote from said hook portion.

21. The tool of claim 20, wherein the hook element is pivotally connected to the lever element at a point closer to one end of the lever element than the other end.

22. A method of using the tool of claim 20 or 21 to disengage the return spring from the brake shoe, the method comprising the steps of: passing the hook element through the access aperture in the brake shoe and engaging the end of the return spring with the hook portion, and then using the lever element as a lever to extend the return spring to disengage the return spring from the brake shoe.

23. A method of using the tool of claim 20 or 21 to engage the return spring with the brake shoe, the method comprising the steps of: passing the hook element through the access aperture in the brake shoe and engaging the end of the return spring with the hook portion, and then using the lever element as a lever to extend the return spring to engage the return spring with the brake shoe.

Technical Field

The present disclosure relates to heavy vehicle drum brakes. In a particular form, the present disclosure relates to a brake shoe, and an apparatus and method for replacing a drum brake shoe.

Background

Compressed air brake systems are commonly used in heavy vehicles such as trucks, particularly those having one or more trailers that must be coupled to a brake system. Reasons for this include the fact that: the air brake circuit on the trailer can be easily and safely attached and the supply of air is not limited so that the system never runs out of its operating fluid.

Drum brakes are commonly used on trucks and trailers because they are considered more durable than disc brakes, so that fewer lining replacements are required in a given period. Also, due to greater economies of scale, replacement parts for drums are generally cheaper.

Drum brakes in compressed air brake systems are typically of the cam follower type. That is, at least one end of each brake shoe includes a cam follower (roller) that follows a generally "S" shaped cam that is attached to a shaft that is rotationally driven via a pneumatic brake booster that is located externally of the wheel.

One or more return springs bridge (i.e., extend between) a pair of brake shoes inside the drum of a typical drum brake assembly and perform the dual function of: the brake shoes are returned to their rest state when the brake pedal is released and contact of the cam follower with the S-cam is maintained.

When the brake shoes and/or return springs are replaced and/or the drum brake assembly is serviced, the or each spring must be removed to release the brake shoes and then reassembled upon reassembly. Disassembly involves overcoming the bias of the spring so that each end of the spring can be unhooked from the bolt extending between the webs of one of the brake shoes, and reassembly involves reversing the process by hooking the spring ends over the bolts. These tasks are made difficult by the strength of the spring and the limited access provided to the ends of the spring nested between the two webs of each of the two brake shoes. Thus, the hub needs to be removed to facilitate adequate access to perform these tasks, but disassembly and reassembly of the hub is time consuming and therefore expensive, and can defeat the warranty of parts such as the wheel bearings.

It is with this background and the problems and difficulties associated therewith that the present invention has been developed.

Certain objects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the invention is disclosed.

Disclosure of Invention

According to a first aspect, there is provided a drum brake shoe adapted to provide access to an end of a return spring engaged therewith.

According to another aspect, a tool for use with the drum brake shoe described above is provided for disengaging a return spring from the drum brake shoe.

According to yet another aspect, a method of using the tool described above to disengage a return spring from a brake shoe is provided.

According to yet another aspect, a method of using the tool described above to engage a return spring with a brake shoe is provided.

In one configuration, the brake shoe comprises: a lining table supporting a brake lining, and at least one web extending from the lining table, the web including a spring attachment aperture extending through the web, the brake shoe further including an access aperture extending through the lining table and the brake lining, wherein a centerline of the access aperture intersects or at least nearly intersects a centerline of the attachment aperture.

In one configuration, the brake shoe comprises: a lining table supporting a brake lining, and at least one web extending from the lining table, the web including a spring attachment aperture extending through the web, the brake shoe further including an access aperture extending through the lining table and the brake lining, wherein the access aperture extends in a direction toward the attachment aperture.

In one configuration, the spring attachment aperture is adapted to receive a pin or bolt that engages the spring.

In one configuration, the brake shoe includes a pair of webs.

In one configuration, the webs are generally parallel.

In one configuration, the access aperture is located between the webs.

In one configuration, both webs include spring attachment apertures.

In one configuration, the spring attachment apertures in each web are longitudinally coaxial. This allows the spring or bolt to pass through the aperture and extend between the webs.

In one configuration, the access aperture extends generally perpendicular to the or each spring attachment aperture.

In one configuration, both webs include a mount for a follower of an actuation cam.

In one configuration, the actuation cam is an S-cam.

In one configuration, the brake shoe includes a brake shoe guide extending from at least one web of the brake shoe.

In one configuration, the brake shoe guide is of the type disclosed in WO 2018/094441.

In one configuration, one web is, in use, an outboard web.

In one configuration, the brake shoe is a heavy vehicle brake shoe.

In one configuration, the tool includes a lever element and a tethering element attached to the lever element.

In one configuration, the tie down element comprises a ring.

In one configuration, the tie down element is formed by a cable or tie wrap.

In one configuration, the method comprises the steps of: the tie-down element is passed through an access aperture in the brake shoe and engages the end of the return spring with the tie-down element, and then the lever element is used as a lever to stretch the return spring to engage or disengage the return spring from the brake shoe (as desired).

In one configuration, in the alternative, the tool comprises a lever element and a hook element comprising a stem portion and a hook portion extending from the stem, wherein the stem of the hook element is pivotally connected to the lever element at or near an end thereof remote from the hook portion.

In one configuration, the hook element is pivotally connected to the lever element at a point closer to one end of the lever element than the other end.

In one configuration, the method comprises the steps of: the hook element is passed through an access aperture in the brake shoe and engages the end of the return spring with the hook portion, and then the lever element is used as a lever to stretch the return spring to engage or disengage the return spring from the brake shoe (as desired).

The following provides a detailed description of one or more embodiments of the invention and provides the accompanying drawings that illustrate, by way of example, the principles of the invention. While the invention will be described in conjunction with such embodiments, it will be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention.

The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.

Drawings

Embodiments of the disclosure will be discussed with reference to the accompanying drawings, in which:

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

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

FIG. 3 is a top view of the brake shoe of FIG. 1;

FIG. 4 is a bottom view of the brake shoe of FIG. 1;

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 brake shoes as shown in FIG. 1, and FIG. 5 further illustrates a tool for engaging the return spring.

FIG. 6 is a top view of the arrangement shown in FIG. 5;

FIG. 7 is an end view of the arrangement shown in FIG. 5; and

fig. 8 is a sectional view taken along a-a of fig. 6.

In the description below, like reference characters designate identical or corresponding parts throughout the several views.

Detailed Description

Referring now to fig. 1, there is shown a brake shoe 1 comprising a lining table 2 having a working surface to which a brake lining 4 is attached and a backing surface to which a pair of parallel, spaced apart webs 6 are attached.

Each web 6 of the brake shoe 1 includes one of a pair of mutually aligned anchor pin holes 8 via which the brake shoe 1 can be pivotally attached to a fixed bracket associated with the axle assembly. Each web 6 also includes, at the end remote from the anchor pin holes 8, one of a pair of mutually aligned generally U-shaped cam follower mounts 10 for mounting the opposite ends of the cam followers in the configuration of rollers retained therein by retaining clips (not shown).

Each web 6 of the brake shoe 1 includes spring attachment apertures 12 extending through the web and which are longitudinally coaxial.

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, the access aperture 14 comprises a circular aperture, although other aperture shapes may be employed to allow access (discussed below) if desired. The centerline of the access aperture 14 intersects the centerline of the attachment aperture 12. That is, the access aperture 14 extends in a direction towards the attachment aperture 12.

Referring now to fig. 5-8, 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 is shown.

The drum brake assembly comprises the aforementioned fixed bracket (not shown) on which a pair of arcuate brake shoes 1 are pivotally mounted in an oppositely directed arrangement to be enclosed in and co-operate with the cylindrical inner surface of a rotatably mounted drum brake to which the vehicle wheel assembly is attached.

The drum brake assembly will also include a shaft extending from a pneumatic brake booster (not shown, but typically attached to the axle housing of the wheel) into the drum brake where it terminates in an S-shaped actuation cam (hereinafter S-cam) 110 that interferes with a cam follower 120.

The return spring 140 bridges (i.e., extends between) a pair of brake shoes 1 within the drum and performs a dual function: when the brake pedal is released, the brake shoe 1 is returned to its rest state and contact of the cam follower 120 with the S-cam 110 is maintained. The exemplary return spring 140 includes a hook 142 at each end thereof.

In use, when the brake pedal of the vehicle is pushed, compressed air is supplied to the pneumatic brake booster which will rotate the S-cam via the push rod, slack adjuster (i.e. lever-not shown) and then via the shaft, thereby driving the brake shoes 1 outwards into contact with the drum brakes.

As discussed in the background, when replacing a brake shoe 1 and/or servicing a drum brake assembly, the spring 140 must be removed to release the brake shoe 1. This involves overcoming the bias of the spring 140 so that the hook 142 at each end of the spring 140 can be unhooked from the bolts 150 extending between the webs 6 of one brake shoe 1.

A tool 200 for a brake shoe 1 is disclosed.

The tool 200 includes a lever element 210 and a tethering element 220. In the illustrated embodiment, tethering element 220 comprises a cable or tie-wrap forming a loop that loops around lever element 210.

In use, the tie-down element 220 passes through the access aperture 14 in the brake shoe 1 to engage (by looping around the hook 142) the end of the return spring 140. The lever element 210 can then act as a lever to stretch the return spring 140 to disengage it from the bolt 150 and thus from the brake shoe 1.

When the drum brake assembly is reassembled, the tie-down element 220 passes through the access aperture 14 in the brake shoe 1 to engage (by looping around the hook 142) the end of the return spring 140. The lever element 210 may then act as a lever to tension the return spring 140 to engage it with the bolt 150 and thus with the brake shoe 1.

Advantageously, it can be seen how the brake shoes disclosed herein allow external access to the ends of the return springs that engage or are to be engaged with the brake shoes. As a result, disengagement, removal and assembly of the return spring becomes significantly easier and faster, and can be achieved without removing the hub.

Further, in the case of smaller drum brake assemblies (such as those used on light duty load trailers), further advantages may be realized, further reducing access for maintenance.

Still other advantages are realized because the present invention makes brakes employing more robust return springs easier to maintain, the return springs themselves being advantageous because they improve brake operation and reduce wear of components (such as surface flattening of rollers).

Throughout this specification and the claims which follow, unless the context requires otherwise, the words "comprise" and variations such as "comprises" and "comprising" will be understood to imply the inclusion of a stated feature or group of features but not the exclusion of any other feature or group of features.

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

Those skilled in the art will appreciate that the use of the present invention is not limited to the specific applications described. The present invention is also not limited to the preferred embodiments thereof with respect to the specific elements and/or features described or depicted herein. It will be understood that the invention is not limited to the embodiment(s) 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.

It is noted that the following claims are only provisional claims and are provided as examples of possible claims and are not intended to limit the scope of what may be claimed in any future patent application based on the present application. Features may be added to or deleted from the following example claims in order to further define or redefine the invention.