US1563728A - Shell for composition brake shoes - Google Patents

Description

M. R. DE FRANCE SHELL FOR COMPOSITION BRAKE SHOES Filed July as, 1925 2 Sheets-Sheet 1 Murre R. De Trance WM awm his af'farnlq Dec. 1 1925 M. R. DE FRANCE SHELL FOR COMPOSITION BRAKE SHOES Filed Jul 23, 1925 2 sheetssheet 2 FIG. 3

FIG. 5

FIG. 5

l2 IN VENTOR' M urreII R. De Trance 129 mm, wnm

25 points where protection and binding. are

Patented Dec. 1, 1925.

UNITED STATES MURBELL R. DE FRANCE, OF BELLEVUE, PENNSYLVANIA.

SHELL FOR COMPOSITION BRAKE SHOES.

Application filed July 23, 1925.

i To all whom it may concern:

Be it known that I, MURRELL R. DE FRANCE, a citizen of the United States, residing at Bellevue, in the county of Allegheny and State of Pennsylvania, have in- *-*1 vented a new and useful Improvement in a Shell for Composition Brake Shoes, of which the following is a specification.

This invention relates to a pressed steel brake shoe shell for use as a container for frictional composition toprovide a complete pressed steel shell for use with a composition filler of frictional material. These features are as follows: A shell for a composition filler which is pressed from a blank which may be easily formed, a blank which may be pressed to form the containing shell patents, among without tearing the metal at any point, a shell which is strong at the areas subjected to greatest stress, a shell which protects and holds together the composition filler at the most needed, a shell which presents a relatively small area of metal to the Wheel to which the brake shoe is applied during wearing away of the shoe and throughout the entire useful life thereof.

The desirability of one or more of such features is fully explained in various prior which are the patent to De France No. 1,114,343, dated October 20,1914, the patent to De France No. 1,303,173, dated May 6, 1919, the patent to Pettis No. 1,503,514, dated August 5, 1924, and the a plication to De France Serial No. 743,93 filed Oct. 16, 1924.

In the accompanying drawings Figure 1 is a plan view of a blank in condition to be pressed into the brake shoe shell of the present invention; Figure 2 is a cross section View thereof on the line 22 Figure 1, showing in dotted lines the position assumed by the metal alongthe edges of the blank in forming the sides of the shell; Figure 3 is a side elevation of the completed brake shoe with the composition filler of frictional material in the shell, Figure 4 is a bottom plan view of the shell without the composition filler therein; Figure 5 isa .cross sectional view on the line 5-5 Figure 3; Figure 6 is an end elevation of the brake shoe; Figure 7 is a fragmentary elevation of a portion Serial No. 45,551.

of one side of the brake shoe shell, showing the shell in unused or very slightly used condition; Figure 8 is a bottom plan View of the shell portion shown in Figure 7, showingthe distribution of the metal which comes into contact with the tread of a wheel; Figure 9 is a fragmentary elevation of a portion of one side of the brake shoe shell, showing the shell partially worn down; and Figure 10 is a bottom plan view of the shell portion shown in Figure9, illustrating the distribution of the metal which comes into contact with the tread of a wheel.

Ill the drawings the reference numeral 1 designates generally the blank from which the brake shoe shell of the present invention is pressed. This blank is rolled to provide a central longitudinally extending portion of relatively great thickness, and side portions 3 tapering outwardly to the edges of the blank. The central portion 2 of the p blank becomes eventually.the back and ends of the shell; and the side portions 3 of the blank become the sides of the shell, while praviding some metal which goes into the en s.

The blank is then punched into the form in;

shown in Figure 1. By this punching opera tion the central portion 2 of the blank is provided with slots 4 for the attachment of a lug to engage the brake shoe hanger, and with slots 5 for the atttachment of the end lugs of the brake shoe. The side portions 3 of the blank are also punched so that they form a plurality of strips or tabs 6,

with intervening apertures 7 which extend 7 completely to the edge of the blank.

The apertures 7, punched from the side portions of the blank, are of greatest. width adjacent'the central portion of the blank and decrease in width gradually toward the edge of the blank. strips 6 are of least width adjacent the central portion of the blank, and increase in width gradually toward the edge of the blank.

correspondinglythe v In the pressing operation, the sidesand ends are folded down so that the central portion 2 of the blank becomes the back 9 and ends 10 of the brake shoe shell, while the side portions 3 of the blank become the sides 11 of the brake shoe shell. During this pressing operation a certain amount of metal from the side portions of the blank flows into the end portions 10 of the shell.

In order to accommodate this surplus metal, 1,;

" reticulated sides, as heretoforedesigned, a

relatively} great loss has been suffered 'due to pulling or tearing the sides of the shell from the back during the pressing operation. lVith this dorm, however, the relatively great amountof metal along the line of the fold, and at-the base of the side strips 6, prevents su'ch tearing and pulling away.

The back 9' of the brake shoe shell, being formed of the thick central portion) of the blank,is of'relatively great thickness and strength. It is thusenab'led to resist the forces tending tofpull theshoe apart in use after the body has-become worn thin.

When the brake shoe shell, designated generally by the reference numeral 14,'has

jacent'the lower edges of the sides, thefillilngcomp'ositlon hardening 1n the apertures been pressed :to form; the filling block '15 o f-a' suitable frictional composition, inplastic-condition, is pressed thereinto. 'As'the side apertures 7 occupy eacha "relatively great area, no more-pressure is necesaryto force the-composition through them than need be exerted in pressing the filling'composition into a shell having sides of acon- 'tinuous extent ofmateria'l. All varieties of composition which may be used are so composed that after being pressed into the brake shoe shell they "harden upon baking or'mere exposure to the air.

As thewidth of the apertures is least adcauses them to form an anchorage for the entire block of filling compositionequal'to that secured by the provision ofreticu'lated or perforated sides. Since the greatest 'area embraced by the aperturesis adjacent the back of the shell, their form also-:contributes to the rapid andperfect drying and hardening of the composition. This is the case In actual use ofthe brake shoe, the only portions of the sides'll'which are subjected to stress are the areas adjacent the ends and. closeto the back ofthe brake shoe. At such areas there is a turning moment, due to the engagement of the brake shoewith' the-wheel to which it is applied, which tends in some degree to pull the brake shoe apart. Asa special precaution in meeting this tendency,

the apertures -16,=which"are adjacent the ends of the shell are made of lesser extent than the other apertures 7 in the sides. This provides a greater-extent of metal at these general areas 17 on the sides of the shell. Durlng'lrandllng of the brake shoe prior to its mounting for use, and even after such mounting, the composition filler of the brake shoe is susceptible to chipping or cracking due to blows received by the lower edges of =the filling block. In I this I connection it should be noted that the widest portions of the sidestripsG ofthe shell lie alongthese edges and serve to adequately protect the same during handlingand whi'le the depth of tlre brake shoe remains sufficient to render probable the reception of blows along the edges of the shoe.

lt is a well lmownfact that injury to the tread of a wheelto which a brake shoe is applied results from the presentationof-a relatively "great 'area of the hardmetal of the brake shoeshell to the 'tread of the wheel. It is therefore desirableto avoid the presentation of an excessive area-of such metal, *while retaining'the other characteristics which are desirable in a'brake shoe shell.

Ithasbeen previouslyn'oted that the portions 3of-the blank from which'the shell is pressed are tapered outwardly toward the side-edges of-the blank. This naturally resultsin theproduction of a shellwhich has sides taperin downwardly toward their lower edges. he thickness ofthe metal of the side strips 6 is thus greatest-where their width is least, andis least where their width is greatest;

By proportioning the width of the strips 6 at any point along'theirvertical extent'with the thickness of the strips-at such point, the

area of metal in contact with the tread of a wheel array he maintained constant-at 'all -'t1mes duringthe 'usefulhfe of the brake shoe. In computing su'ch proportion, re-

gardshou'ld of course be -given to the effect produced by nnposmg the necessary arcuate form on'the shell during the;pressing' operbrake shoe shell. By comparing theefl'ec- 'tive areas 18 of the strips as shown in Figure i8'with the effective areas 19 of" the strips asshown inFigure 10, it is found that the sum of the areaslS, and the sum of the "areas 19 is approximately equal. "This is true at any stage of wear during the effective life of'the brake shoe.

It will be readily understood that "the brake shoe shell illustrated and described herein 'presents an unusual combination of the qualities found most desirable in an arhole of such nature.

What I claim is:

1. A brake shoe shell for use with a filling of frictional composition formed with integral back end and side Walls, the side walls of the shell comprising a plurality of strips with intervening apertures, said strips being so proportioned that the total areas of metal presented by the strips of one side is approximately equal at any point along the vertical extent of the shell as the brake shoe wears away in use.

2. A brake shoe shell for use with a filling of frictional composition formed with integral back end and side walls, the back wall being of relatively great thickness, and the side walls comprising a plurality of strips tapering in thickness from the back downwardly to the edges of the sides and having their width tapering upwardly to the back of the shell with interveningapertures between strips.

3. A brake shoe shell for use with a filling of frictional composition formed with integral back end and side walls, the back wall being of relatively great thickness, and the side walls comprising a plurality of strips tapering in thickness from the back downwardly to the edges of the sides and having their width tapering upwardly to the back of the shell with intervening apertures between strips, said strips being so proportioned that the total area of metal presented by one side is approximately equal at any point along the vertical extent of the shell as the brake shoe wears away in use.

In witness whereof, I hereunto set my hand.

MURRELL R. DE FRANCE.

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