US3891825A

US3891825A - Lined brake shoes

Info

Publication number: US3891825A
Application number: US419661A
Authority: US
Inventors: Gethyn James Pritchard
Original assignee: Girling Ltd
Current assignee: Girling Ltd
Priority date: 1972-11-28
Filing date: 1973-11-28
Publication date: 1975-06-24
Anticipated expiration: 1992-06-24
Also published as: JPS4995088A; FR2215114A5; DE2359304A1; GB1416719A

Abstract

An apparatus for bonding by heat a layer of friction material to the convex surface of an arcuate platform of a brake shoe having a web extending from the opposed concave surface of the platform, comprises arrangements for locating the shoe in the apparatus and for holding the friction material against the platform. Two electrical heating elements are disposed one on each side of the web and each element has a heating portion which follows the contour of the web and extends along the whole length of the web and a pair of cold tail portions received in a recess in the apparatus and extending away from the platform. The heating portion of each element conveniently takes the form of two radially spaced apart runs joined at one pair of adjacent ends.

Description

United States Patent l 1 1 25 Pritchard June 24, 1975 LINED BRAKE SHOES [75] Inventor: Gethyn James Pritchard, m 'f Truhe Birmingham England Asszsmm Exammerl lv D. He rkamp I Attorney. Agenl, or Fzrm-Scrivener Parker Scrivener [73] Assignee: Girling Limited, Birmingham, d Cl k England [22 Filed: Nov. 28. 1973 [571 ABSTRACT An 21 aratus for bondin b heat a la er of friction [211 App. 4l966l matei i l to the convex sfi'fage of an ar uate platform of a brake shoe having a web extending from the op- [30] Foreign Application Priority Data posed concave surface of the platform, comprises ar- 28 I972 United Kingdom H 549551172 rangements for locating the shoe in the apparatus and for holding the friction material against the platform. [52] US. Cl. 219/243; 2l9/254; 219/255; O electrical heating elements are disposed one on 219/25q each side of the web and each element has a heating [51 Int. Cl. H05!) 3/02 Portion which follows the conwur of the Web and [58] Field of Search 219/254v 255, 259 tends along the whole length of the web and a pair of 156/499! 583 cold tail portions received in a recess in the apparatus and extending away from the platform. The heating [56] References Cited portion of each element conveniently takes the form UNITED STATES PATENTS of two radially spaced apart runs joined at one pair of adjacent ends. 2l489t496 ll/l949 OBrien 219/243 X 2.662.960 12/1953 Williams 219/243 x 5 l 4 ing Fig r s PAT JU 2 ENTED N 4 I975 SHEET 3.891.825

LINED BRAKE SHOES This invention relates to lined brake shoes and in particular to an improved bonding apparatus for the manufacture of lined brake shoes.

As is known in this art, a brake shoe has a platform of arcuate form with a web extending from its inner concave surface, the friction material being generally preformed to the shape of the outer convex platform surface, but of short arcuate length. It is known to secure the friction material to the shoe to provide a lined shoe by bonding the material to the shoe under heat and for this purpose it has previously been proposed to use two pairs of individual heating elements one pair being disposed in each side of the web and the elements of each pair being radially spaced apart. With the need under modern conditions to bond quickly, it has been found however, that the shoe was not heated uniformly and that either one end portion of the lining was not adequately bonded to the shoe or that the central portion of the lining though bonded to the shoe was partly burned and its frictional operating characteristics unacceptably reduced. The electrical heating elements have heating portions and tail portions, the connections of the tail portions with the supply being safely located within the heating apparatus. Thus the tail portions of the resistor wire within the insulating surround which joins the heating portion to the supply connection has heretofore had to lie along-side part of the shoe web; that part of the web is therefore less-well heated, as is the adjacent platform area, resulting in unreliable and possibly un-safe bonding with large reject quantities.

According to one feature of the present invention there is provided an apparatus for bonding a layer of friction material to the arcuate platform of a brake shoe having a web extending from the concave surface of the platform, said apparatus comprising shoe locating means locating the brake shoe, retaining means for holding a layer of friction material against the platform of the shoe, and a pair of electrical heating elements disposed one on each side of the web of the shoe and each having a heating portion and at least one tail portion connected thereto, wherein the heating portions extend adjacent the web of the shoe along the whole length of the web.

According to another feature of the invention, there is provided an apparatus for bonding a layer of friction material to the convex surface of an arcuate platform of a brake shoe having a web extending from the concave surface of the platform, said apparatus comprising an arcuate recess for receiving the shoe web, locating means for locating the shoe with the web within the recess, retaining means for holding the friction material against the convex surface of the platform, a pair of electrical heating elements disposed one on each side of the recess for heating the shoe web received therein, each heating element having a heating portion and a pair of tail portions, wherein each heating element comprises two radially spaced apart, arcuate runs conforming generally to the arcuate profile of the recess, one pair of adjacent ends of said runs being integrally interconnected by a loop portion and the other, free pair of ends being turned inwardly away from the platform, and wherein the heating portion of each element extends in each run along the whole length of the web.

The shoe web may be either single-walled or double walled. An apparatus in accordance with the invention for bonding a layer of friction material to the platform of a brake shoe, will be described by way of example, with reference to the accompanying drawings in which:

FIG. I is an end elevation of the apparatus,

FIG. 2 is a part section on line II-II of FIG. 1 and FIG. 3 is a pre-formed heating element forming part of the apparatus, and

FIG. 4 is a section showing the disposition of the heating element of FIG. 3 within a heat portion of the apparatus. As seen in FIG. I, the apparatus comprises a support for the shoe consisting of a heat portion 1 connected to a base portion 2.

The head portion 1 comprises a central part 4 sandwiched between a pair of intermediate parts 5 and end parts 6. Central part 4 and each intermediate part 5 have aligned recesses forming radially spaced arcuate channels, 7,7a whilst co-operating intermediate parts 5 and end parts 6 have correspondingly aligned recesses forming radially spaced

arcuate channels

8,8a. Between channels 7,7a and channels 8,80 each intermediate part 5 has an actuate recess for receiving the web 10 of shoe 11, the platform 12 of which is to be lined with a layer of friction material 13. The web 10 may have a single wall as illustrated or a double wall.

Locating means are provided for positioning the shoe on the support and, as best seen if FIG. 2, comprise pivoted abutments 14 having first abutment portions I40 for engaging the side edges of the shoe platform to locate the shoe axially on the heat portion 1, clamping portions 14b which clamp the shoe platforms against the head, and second abutment portions Me which engage the side edges of the friction material 13 to centralize it axially of the platform. Preferably the pivoted abutments are protruded at the ends of the shoe and are shouldered to locate and acruately centre the layer of friction material relative to the head portion Retention means in the form of a metal strap I7 connected to a travelling platform below base portion 2 holds friction material 13 against the shoe platform 12 during bonding, the platform being moved upon completion of a bonding operation at one intermediate part to an operational position at the other intermediate part.

One or more end abutments, not shown, are provided to locate the shoe relative to head portion 1. Preferably these end abutments are adjustable so that the apparatus can accept shoes having different configurations.

The pivoted abutment l4 and the end abutments cooperate to centralise the lining in the head portion 1 whilst permitting offset location of the shoe, whereby to obtain the correct relative arcuate disposition of lining to shoe for the particular brake requirement.

Channels 7,7a are interconnected at their terminal portions to receive a heating element 15 (FIG. 3)

channels

8,8a are similarly inter-connected to receive a second heating element 15. Each heating element 15 has has its tail portions I6 within a recess 19 formed between head portion 1 and base portion 2. Thus, the tail portions 16, which are cooler than the heating portion 18 of the element, are not aligned with that part of heat portion 1, receiving the shoe web. The element has two radially spaced apart runs 15a 15b joined at one pair of adjacent ends, the other, free ends being turned inwardly away from the platform 12. The two runs 15a 15b permit uniform heating of that part of the head portion 1 aligned therewith and thus of the shoe web and its associated platform.

3 An advantage of using a single element 15 of the form described is that failure of the element results in a large measurable temperature drop, permitting the apparatus to be stopped automatically. With the previous proposal using independent elements in each of 5

channels

7,7a,8,8a failure of one of the elements was not readily detected by means responsive to temperature drop, and bonding could continue notwithstanding unacceptable temperature gradients resulting in poor bonding.

lt will be appreciated that a tail portion of each of the elements could be joined together. Alternatively, the heating portion of one element could be directly joined to that of the other element to provide a unitary structure having only two tail portions, one at each end of the structure.

I claim:

1. An apparatus for bonding a layer of friction material to a brake shoe including an arcuate platform having a convex surface for receiving said layer of friction material and an opposed concave surface and a web ex tending from said concave surface of said platform, said apparatus comprising shoe support means, means for positioning said shoe on said support means comprising a plurality of abutment members each having a clamping portion arranged to clamp said shoe platform against said support means and an abutment portion for locating said layer of friction material on said platform, retaining means for holding said layer of friction material against said convex surface of said shoe platform, and a pair of electrical heating elements disposed one on each side of said web of the shoe, each heating element having a heating portion and at least one tail portion connected thereto, wherein said heating portions extend adjacent said web of said shoe along the whole length of said web.

2. An apparatus according to claim 1 wherein each of said abutment members includes another abutment portion for locating said shoe on said support.

3. An apparatus according to claim 2, wherein said abutment members are adjustable to receive shoes having different configurations.

4. An apparatus according to claim 1 wherein said support means includes an arcuate recess for receiving said shoe web and wherein each heating element has a pair of tail portions and comprises two radially spaced apart, arcuate runs conforming generally to the arcuate profile of said recess, one pair of adjacent ends of said runs being integrally interconnected by a loop portion and the other, free pair of ends being turned inwardly away from the platform, and wherein said heating portion of each said element extends in each run along the whole length of said web.

5. An apparatus according to claim 4 including means defining a further recess within said apparatus wherein said tail portions of said heating elements are received within said further recess in said apparatus.

Claims

1. An apparatus for bonding a layer of friction material to a brake shoe including an arcuate platform having a convex surface for receiving said layer of friction material and an opposed concave surface and a web extending from said concave surface of said platform, said apparatus comprising shoe support means, means for positioning said shoe on said support means comprising a plurality of abutment members each having a clamping portion arranged to clamp said shoe platform against said support means and an abutment portion for locating said layer of friction material on said platform, retaining means for holding said layer of friction material against said convex surface of said shoe platform, and a pair of electrical heating elements disposed one on each side of said web of the shoe, each heating element having a heating portion and at least one tail portion connected thereto, wherein said heating portions extend adjacent said web of said shoe along the whole length of said web.