US2869689A

US2869689A - Railroad brake shoes

Info

Publication number: US2869689A
Application number: US603402A
Authority: US
Inventors: Rosser L Wilson
Original assignee: American Brake Shoe Co
Current assignee: American Brake Shoe Co
Priority date: 1956-08-10
Filing date: 1956-08-10
Publication date: 1959-01-20
Anticipated expiration: 1976-01-20

Description

Jan. 20, 1959 R. L. WILSON RAILROAD BRAKE SHOES 2 Sheets-Sheet 1 Filed Aug. 10, 1956 27 FIG. 2

INVENTO R. ROSSER L. WILSON ATTORNEYS Jan. 20, 1959 R. L. WILSON RAILROAD BRAKE SHOES Filed Aug 10, 1956 FIG. 6

FIG. 7

ROSSER L. WILS AT TO R N EYS United States Patent RAILROAD BRAKE SHOES Rosser L. Wilson, Mahwall, N. J., assignor to American Brake Shoe Com an New York N. Y. a tion of Delaware p y, corpora This invention relates to a new and improved brake shoe for use in a railway braking system and is particularly concerned with a new and improved metal backing structure for a composition type brake shoe.

The brake shoe which has long been standard in the railroad industry comprises a cast iron body having a substantial thickness and having a braking surface which 18 curved to correspond in general to the curvature of a railroad car or locomotive wheel. The back, of the cast iron brake shoe may include a supporting plate or strip formed from rolled steel around which the brake shoe body is cast; this supporting member reinforces the cast lIOIl body and, to a certain extent, serves to hold it together in the event that the brake shoe body is fractured.

during service. Another type of brake shoe which has been suggested for use on railway cars and locomotives comprises a composition body supported on a steel backing plate which is in some respects similar to the support member of the cast iron type of shoe. In the composition brake shoe, the support lugs and other elements for mounting the brake shoe upon a brake head are formed as a part of or are mounted upon the supporting back, whereas in the cast iron shoe construction the mounting lugs, toe guides and the like are frequently cast as a part of the brake shoe body.

There are several distinctive differences between cast iron and composition type brake shoes. For example, the composition type shoe provides substantially higher retarding force per unit braking area, since it achieves a substantially higher coeflicient of friction than may be ob tained with a cast iron shoe. In general, it may be stated that cast iron shoes are low-friction high-pressure devices, whereas composition shoes are high-friction low-pressure devices. Accordingly, the composition shoe may be employed at substantially lower operating pressures than the cast iron shoe. The composition type shoe, however, as known in the prior art, has exhibited several disadvantages which have precluded general adoption for railroad service. One particularly important difficulty mitigating against general use of composition type shoes in railway systems has been the tendency of the composition body to break under severe operating conditions and to separate from the metal back structure under even mild braking conditions. To a certain extent, this disadvantage may be attributed to the difference in thermal coefficients of expansion of the composition body and the metal back structure; in addition, the brake' shoe body may be stressed beyond the breaking point or may be separated from its metal back due to forces tending to flex the brake shoe which are frequently encountered in railroad service. Moreover, the relatively severe vibrational forces encountered in railway service and the substantial shock to the brake shoe occurring upon initial application of the brakes may tend to detach the composition body from the metal back and/ or to fracture the shoe body.

It is an object of the invention, therefore, to overcome 'or substantially minimize the above noted disadvantages of previously known composition type railroad brake 2,869,689 Patented Jan. 20, 1959 ice shoes by resort to a specially constructed back for th composition shoe.

A further object of the invention is a new and improved back structure for a railroad brake shoe of the composition type which. provides inherently better resistance to fiexural forces and shock than previously known constructions without requiring separate and additional reinforcing members.

A corollary object of the invention is a new and improved brake shoe of the composition type including a back structure which provides maximum adherence to and interlocking with the composition body of the shoe.

It is an important object of the invention to provide a new and improved back structure for a composition type railroad brake shoe which is substantially stronger than conventional composition brake shoe backs but which is inherently economical to manufacture.

Thus, the invention is directed to a back structure for use in a railroad brake shoe of the type comprising a molded composition body supported upon a metal back which is adapted to be mounted upon a brake head, the brake shoe body having a predetermined length, width, and thickness and having a predetermined curvature along its length. The term composition as used throughout this specification and, in the appended claims is defined as meaning a comminuted friction material in a heat resistant organic binder such as a rubber, a resin, or a rubber-resin mixture. A back structure constructed in accordance with the invention comprises a metal support member, preferably of rolled steel, having a length, width, and curvature approximately corresponding to the length, width, and curvature of the composition body. A plurality of intersecting diagonal ribs are formed integrally with the metal support member, preferably in the rolling operation; these ribs project from the concave surface of the. support member and serve to interlock. the composition body with the support member. The height of the interlocking ribs is made substantially smaller than the thickness of the composition body of the brake shoe. In

addition, a plurality of individual metal projections are affixed to and extend from the support member to provide additional interlocking between the support member and the composition body, the height of these projections also being substantially smaller than the thickness of the composition body. Preferably, these individual metal projections are formed by punching out individual portions of the support member. The invention is applicable to railway brake shoes intended for use on locomotive driver templated applying these principles. Other embodiments of the invention embodying the same or equivalnet principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the'ap pended claims.

In the drawings:

Fig. 1 is an elevational view, partly in cross section, of a railway car brake shoe constructed .in accordance with one embodiment of the invention;

Fig. 2 is a plan view of the railway car brake shoe illustrated in Fig. 1;

Fig. 3 is a bottom view of the metal back structure of the brake shoe of Fig. 1;

Fig. 4 is a cross-sectional view taken along line 44 in Fig. 1;

Fig. 5 is a detail sectional view taken along line '5'5" in Fig. 2;

Fig. 6 .is an elevation view, partly in cross section, ofa driver shoe constructed in accordance with the invention;v

Fig. 7 is a plan view of the driver shoe of Fig. .6;

Fig. 8 is a bottom view showing the metal back structure of the brake shoe of Fig. 6; and

Fig. 9 is a cross sectional view taken .along line 99 in Fig. 6.

The brake shoe 20 illustrated in Fig. 1 comprises a metal support member 21 utilized to support a molded composition braking body 22. Support member 21 is preferably fabricated from either hot-rolled or cold-rolled steel, hot-rolled steel usually being preferred. Composition body 22 may be molded from any composition material suitable for railway braking service, depending to some extent uponthe type ofcar or locomotive to which the brake shoe is to be applied. A preferred type of composition material, which exhibits superior characteristics with respect to heat and shock resistance and which afiords a favorable ratio of wet to dry coefi'icients of friction, is described and claimed in the copending application of R. E. Spokes et al., Serial No. 491,510, filed March 1, 1955, and assigned to the same assignee as the present invention. This preferred type of composition comprises a comminuted friction material, selected from the .sillimanite and related aluminum silicates, distributed in a heat-stable rubber binder; additional friction material in theform of cast iron particles may also be included.

Composition body 22 may be provided with two or more vents 23 in the braking surface thereof to assist in'uniform curing-of the composition throughout its thickness and to aid in difiusion of heat during braking service. .As indicated in the drawing, composition body 22 has a predetermined length and width and a substantial thickness and has a predetermined curvature along its length .to conform with the curvature of the wheel to which it is applied during braking service. Support member 21, in general, corresponds approximately in length, width, and curvature to the composition body, although exact dimensional correspondence is not essential and minor variations may be effected without substantially affecting the invention.

A pair of longitudinal flanges or

projections

24 and 25 extend from the edges of support member 21 into clamping engagement with composition body 22, as best illustrated in Fig. 4. The height of

flanges

24 and 25 should be made relatively small as compared with the thickness of composition body 22in order to avoid the possibility that the metal flanges will be brought into contact with the wheel to which the brake shoe is applied after the .brakeshoe has seen substantialservice. Otherwise, .thefianges may tend to score the wheel or toleave metal deposits thereon, since the temperatures reached during braking service are frequently high enough to partially melt the metal back structure and weld it to the wheel if the two come in contact with each other.

Flanges

24 and 25 serve to bind the composition body andmetal back structure of the brake shoe to each other and also add to the rigidity of the backstructure.

Support member 21 and composition body 22 .arealso interlocked with each other by means of a plurality of individual metal projections aflixed to and extending from support member 21 into the composition body. These individual metal anchors are most conveniently and economically formed by punching out individuaLportions 26of support member 21 to form the desired anchor elements. As in the case of the longitudinal :flanges, the efiectiveheight of projectionsZfi should be ;made sub st;antially smaller than the thickness of compositionbody Moreover, individual portions of support element 21

adjacent flanges

24 and 25 may be punched out and portions of composition body 22 may be molded into the resultingapertures 27 to provide further anchor points he Figs. 1 and 2.

ber 21, as illustrated in Fig. 3. preferably formed in support member 21 by rolling in tween support member 21 and composition body 22. This construction, with the multiple interlocking between composition body 22 and support member 21, as thus far described, is essentially similar to that described and claimed in the copending application of E. Ellsworth Caton et al., Serial No. 603,405, filed concurrently herewith and assigned to the same assignee as the present invention.

Although the metal back structure described in the aforementioned Caton et al. application is extremely advantageous as compared with previously known composition brake shoe structures and is very well suited for many types of railroad service, it may frequently be desirable to provide a substantially stronger back structure for the more severe operating conditions encountered in some railway systems, One construction which effectively achieves this objective is described and claimed in my copending application, Serial No. 603,403, filed concurrently herewith and assigned to the same assignee as the present invention. In the construction described in that application, a separate metal reinforcing member is employed to strengthen the brake shoeagainst fiexure and to afford sOme degree of additional interlocking between the support member and the composition body. In the present invention, these same objectives re achieved by an entirely different structure comprising a plurality of intersecting diagonal ribs 28 projecting from the under or concave surface 29 of support mem Diagonal ribs 28 are the early stages of fabrication of the metal support member and thus constitute an integral part of the support member. As in the case of anchorprojections 26 and

flanges

24 and 25 the effective height of ribs 28 should be made substantially smaller than the thickness of comp sition body 22 in order to prevent metalto-metal contact between support member '21 and the wheel to which the brake shoe is applied. Interlocking ribs 28 provide a multiplicity of additional interlocking elements which add substantially to the effective adherence between composition body 22 and support member 21. In addition, the diagonal ribs make the support member much stiffer than would otherwise be the case and thus provide a marked increase in the ability of the brake shoe to resist deformation from ilexural and other forces encountered during service. Moreover, it should be noted that, in the ribbed structure of the invention, a substantially greater number of anchorage points such as those provided by projection elements 26 and apertures 27 may be provided without unduly weakeningsupport member 21, thereby further improving the adherence of composition body 22 to the support member.

7 In accordance with conventional practice, brake shoe 20 may be provided with a center attaching lug 30 preferably formed as a separate steel member and clinched into apertures in support member 21, as indicated in The centerlug30 is provided with the usual keyway and is adapted to be mounted on abrake head in conventional manner. The brakeshoe may also be provided with a plurality of end stops 31, 32, 33, and

34 in accordance with conventional practice; preferably, the end stops are fQ i ed as integral parts of support member 21 and comprising punched or otherwise bent sections of the support member extending above its convex surface 37. Brake shoe 2!) may also be provided with a pair of toe guides35 and 36 at the opposite ends thereof; in the illustrated construction, the toe guides comprise integral lugs formed as apartof supporhrnem- .ber 21 in the same manner as the .brakeshoeandstops.

It should 'beunderstoodthatthe rnountingarr ngement to be mounted; in this connection, attention is directed to application Serial No. 606,868, filed August 29, 1956, and to application Serial No. 606,869, filed August 29, 1956; both of these applications, which are assigned to the same assignee as the present invention, describe stantial improvement in the performance characteristics 7 of railway car brake shoes in that it affords a much more rigid back structure for the brake shoe and at the same time provides markedly better adherence between the metal backing structure and the composition brake body. The qualities of rigidity and superior adherence between the parts of the brake shoe afforded by the inventive construction, however, are even more important in locomotives, since the shocks, vibrational forces, and other disturbing factors present in all railway service are usually most prevalent at the driver wheels. Thus, the advantages afforded by the invention are even more important in a driver brake shoe of the type illustrated in Figs. 6-9.

The driver brake shoe 40 shown in Figs. 6-9 is in many respects quite similar to brake shoe of Figs. 1-5 and comprises a composition body 41 supported upon a metal back structure 42. As indicated in Fig. 6, brake shoe body 41 has a predetermined length and a predetermined longitudinal curvature; support member 42 is of approximately the same length and has a curvature generally coring section 41A of substantially rectangular cross-sectional configuration and having a predetermined thickness; a

second or flange-engaging portion 41B extends from one side of tread-engaging section 41Aand is arched or curved to fit the flange of a driver wheel (not shown). Flange-engaging section 41B of the composition body is not of uniform configuration throughout its length; rather as, indicated in Figs. 6 and 9, the central portion of the flange-engaging section is relieved so that it does not contact the wheel flange when the brake shoe is first placed in service. This discontinuous or sectional flange structure is conventionally employed to prevent chattering of the driver brake shoe during the initial or wear-in period of service.

Support member 42 also comprises two sections, a tread section 42A which generally conforms to the configuration of tread-engaging section 41A of the composition body, and a flange section 423 which extends from one side of tread section 42A and is curved to conform, in general, to the configuration of flange-engaging section 413 of the brake shoe body.

Sections

42A and 42B of support member 42 are preferably formed from a single sheet of rolled steel to provide the strongest possible back structure. As in the embodiment of Figs. l5, composition body 41 may be fabricated from any composition material suitable for railway brake service, preferably that described in the aforementioned Spokes et al. application.

Both tread section 42A and flange section 42B of support member 42 are preferably provided with a plurality of individual metal projections 46 which extend a relatively short distance into composition body 41 to interlock support member 42 to the composition 'body; as in the previously described embodiment, the height of these anchor projections should be made substantially smaller than the thickness of the composition body into which they extend in order to prevent metal-to-metal contact between the brake shoe and the wheel. As indicated in Figs. 7 and 9, anchor projections 46 are preferably formed by punching out individual areas in support member 42., The brake shoe may also be provided with the usual center attaching lug 47 comprising a separate steel member clinched into apertures provided therefor in support member 42, as shown in Fig. 7, and provided with the usual keyway. A pair of end stops 48 and 49 may be formed at the opposite ends of support member 42 by suitably bending the support member upwardly from is convex surface in order to afford a means for preventing longitudinal motion of the brake shoe with respect to a brake head upon which it is mounted.

As in the previously described embodiment, and in accordance with the invention, a plurality of intersecting diagonal ribs 50 are formed integrally with support member 42 on the under or concave surface SI-thereof; di agonal ribs 50 project fro-m the concave surface of the brake shoe into interlocking engagement with composition body 41. The height of ribs 50 should be made substantially smaller than the thickness of the composition body at any given point to avoid scoring of the wheel surface and to prevent welding of the brake shoe to the wheel. In the preferred construction illustrated, the diagonal ribs are not confined to flange section 42A of the brake shoe support member, but extend into flange section 428 in order to interlock both portions of the support member with the corresponding sections of the composition body and to provide the desired rigidity and stiffness in the flange section as well as the tread section of the brake shoe. Ribs 50 thus serve to strengthen the entire brake shoe backing structure and at the same time to afford substantially improved interlocking between the complete composition body and the metal support element. As in the embodiment of Figs. 1-5, ribs 50 are preferably formed by rolling of steel support member 42 before the metal is punched and otherwise shaped to form the support member. Because ,of the added strength and rigidity provided by ribbed support member 42, a relatively large number of individual metal anchors 46 may be formed in the support member without weakening it, thus permitting the achievement of substantially improved adherence between the support member and the composition body without sacrificing essential strength characteristics.

Hence, while I have illustrated and described the preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall Within the purview of the following claims.

I claim:

1. In a railroad brake shoe of the type comprising a composition body supported upon a metal back which is adapted to be mounted upon a brake head, said brake shoe body having a predetermined length, Width, and thickness and having a predetermined curvature along said length, a back structure comprising a metal support member having a length, width and curvature approximately corresponding to the length, width and curvature of said composition body; and a plurality of intersecting diagonal ribs formed integrally with said metal support member and projccting from the concave surface thereof for interlocking said composition body and said metal support member, the height of said ribs being substantially smaller than the thickness of said body; and a plurality of individual metal projections affixed to and extending from the concave surface of said support member to interlock said support member with said composition body, the height of said projections being substantially smaller than the thickness of said body.

2. in a railroad brake shoe of the type comprising a composition body supported upon a metal back which is adapted to be mounted upon a brake head, said brake shoe body having a predetermined length, width, and thickness and having a predetermined curvature along said length, a back structure comprising a rolled steel support member having a length, width, and curvature corresponding approximately to the length, width, and.

7 sarvatur nt a Com e i n dy; a lu l t f i er secting diagonal rihs rolled into said steel support member as an integral part thereof, projecting from the concave surface thereof for interlocking said composition body and said steel support member, the height of said ribs being substantially smaller than the thickness of said body; and a plurality of individual metal projections aflixed to and extending from the concave surface of said support member for interlocking said support member with said composition body, the height of said projections being substantially smaller than the thickness of said bo y- 3. In a railroad brake shoe of the type comprising a composition body supported upon a metal back which is adapted to be mounted upon a brake head, said brake s oe sd h v n a prede erm e l W th, and thickness and having a predetermined curvature along said length, a back structure comprising a rolled steel support member having a length, width, and curvature approximately corresponding to the length, Width, and curvature of said composition body; a plurality of intersecting diagonal ribs rolled into said steel support as an integral part thereof, projecting from the concave surface thereof for interlocking said composition body and said support member, the height of said ribs being substantially smaller than the thickness of said body; and a plurality of individual metal projections, comprising punched out portions of said steel support member, for interlocking said support member with said composition body, the height of said projections being substantially smaller than the thickness of said body.

4. In a railroad brake shoe of the type comprising a composition body supported upon a metal back which is adapted to be mounted upon a brake head, said brake shoe body havinga predetermined length, Width, and

thickness and having a predetermined curvature along said length, a back structure comprising a rolled steel support member having a length, width, and curvature corresponding approximately to the length, width, and curvature of said composition body; a plurality of intersecting diagonal ribs rolled into said steel support member as an integral part thereof, projecting from the concave surface thereof for interlocking said composition body and said steel support member, the height of said ribs being substantially smaller than the thickness of said body; a plurality of individual metal projections affixed to and e t din mt s c n a r c of d uPPQ t me ber for interlocking said support member With said cornposition body, the height of said projections being substantially smaller than the thickness of said body; and a pair of longitudinal flanges formed as an integral part of said steel support member and extending into clamping relationship with the sides of said composition body,'said flanges having a height substantially smaller than the thickness of said body.

5. In a brake shoe for a railroad driver wheel of the type comprising a composition body supported upon a metal back which is adapted to be mounted upon a brake head, said brake shoe body comprising a tread-engaging section having a predetermined length, width, and thickness and a predetermined curvature along said length and further comprising a flange-engaging section extending from one side oi said tread-engaging section and having a lateral curvature generally corresponding to the curvature of a driver wheel flange, a back structure comprising: a steel support member comprising a tread section having a'length, width, and curvature approximately corresponding to the length, width, and curvature of said tread-engaging section extending laterally from said tread section and having a lateral curvature approximately corresponding to that of said flange-engaging section of said composition body; a plurality of intersecting diagonal ribs rolled into said steel support member as an integral part thereof, projecting from the concave surfaces of said tread and flange sections of said support member tor interlocking said composition body and said support member, the height of said ribs being substantially smaller than the thickness of said body at any given point; and a plurality of individual metal projections afiixed to and extending from both said body and flange sections of said support member for interlocking said support member to the said composition b dY, the height of said projections being substantially smaller than the thickness.

References .Cited in the file of this patent UNITED STATES PATENTS Winters July 3 L934