US3513950A - Brake shoe including expanded metal reinforcing member - Google Patents

Description

y 26, 1970 E. RATCLIFFE ETAL 3,513,950

BRAKE SHOE INCLUDING EXPANDED METAL REINFORCING MEMBER Filed June 28, 1968 INVENTOR. EDWARD RATC Ll FFE W5 LLlAM MCRAWFORD ATT'Y United States Patent Office 3,513,950 Patented May 26, 1970 3,513,950 BRAKE SHOE INCLUDING EXPANDED METAL REINFORCING MEMBER Edward Ratcliffe and William N. Crawford, Mont St.

Hilaire, Quebec, Canada, assignors to AMSTED Industries Incorporated, Chicago, 11]., a corporation of Delaware Filed June 28, 1968, Ser. No. 740,968 Int. Cl. F16d 69/04 US. Cl. 188-250 1 Claim ABSTRACT OF THE DISCLOSURE In a molded composition brake shoe having a composition body and a back supporting member, an expanded metal strip is welded to the supporting back member and acts as a mechanical bond between the composition and said supporting member.

This patent relates generally to railway brake shoes and nlalore particularly to an improved back structure for said s oes.

Molded composition body brake shoes have become widely used in recent years in the railroad industry. These hoes consist of friction compounds in an organic binder molded to a pressed steel backing plate so that the braking surface of the shoe body corresponds to the curvature of a railway car or locomotive wheel. The steel backing plates are intended to lend strength and rigidity to the brake shoe body. Support lugs and other elements utilized to mount the shoe upon a brake head are usually formed as part of or comprise separate steel elements mounted on the metal supporting back.

Although it has been shown through years of testing and use that the composition shoes have excellent wearing and braking characteristics, they still possess some disadvantages. Among these, a principal one has been the tendency of the composition body to separate from the metal back or support structure under certain braking conditions. This problem may, in part, be attributed to the difference in the thermal coefficient of expansion between the composition material and the metal backing structure. Further causes of the separation are due to the unusual flexual and impact forces, and the severe vibrations that are imparted to the shoes and their parts under railroad operating conditions.

In an attempt to solve these problems, various types of shoe construction and means for securing the composition material to the metal backing plate have been tried only to meet with failure or limited success. The separate or combined use of various chemical bonding agents and anchor elements punched out at distributed locations on the back plate support member to engage the composition material have both been tried. Chemical bonding has generally been found to be unsatisfactory under prolonged use and/or adverse temperature conditions. The punched out anchor elements have been somewhat more successful but tend to weaken the back structure. Undesirable localized flexibility and vibration resulting in composition separation around and transverse to the apertures also occur in the apertured back plate member.

In an effort to strengthen these apertured back plates and reduce flexibility, various means of reinforcement have been tried, e.g., a second reinforcing strip secured to the back plate, and longitudinal flanges aflixed to the edges of the back plate. Although these methods have strengthened the overall back structure, undesirable localized flexibility and vibration still existed resulting in poor bonding between the back plate and composition material. Also,

the added steps in manufacturing the shoe has a further undesirable economic effect. It is, therefore, an object of this invention to provide an improved, inexpensive method of adhering the composition friction material to pressed steel brake shoe backs in order to reduce composition material separation from the metal back structure.

It is a further object of this invention to provide an improved composition brake shoe which will withstand adverse conditions and temperature variations without composition material separation from the supporting back member.

Another object of this invention is to provide a mechanical bond between the backing structure of the brake shoe and the composition body.

The foregoing and other objects and advantages of the invention will become apparent from the following description and accompanying drawings wherein:

'FIG. 1 is a side elevational view, partly in section, of a composition-type railroad brake shoe embodying features of this invention;

FIG. 2 is a top plan View, partly in section, of the brake shoe illustrated in FIG. 1;

FIG. 3 is an enlarged, detailed sectional view taken on line 3-3 of FIG. 1; and

FIG. 4 is an enlarged, detailed sectional view taken on line 4-4 of FIG. 2.

Describing the invention in detail and referring to the drawings, FIG. 1 illustrates a railroad brake shoe having a molded composition body 6 mounted upon a backing structure generally indicated at 8. The composition body 6 has a predetermined length, width, and thickness and a predetermined curvature along its length corresponding to the curvature of the railroad car or locomotive Wheel (not shown) with which it is to be employed.

The metal support member 8 has a length and width approximately equal to the corresponding length and width of the composition body 6 and has essentially the same longitudinal curvature.

Means for aflixing the brake shoe to a brake head (not shown) are illustrated in FIGS. 1 through 3. Toe stops 10 and 12 formed at opposite ends of the metal support member 8 and intermediate the sides extend above the convex surface 14 of the plate 8. These stops 10 and 12, as illustrated, are integral with the back plate 8 and may be formed by punching or other suitable manufacturing techniques. It should be noted that other toe stops may be added or all toe stops may be completely omitted depending upon the shoes interconnection with a brake head. The stops 10 and 12 may also be welded to the back plate 8.

A center attaching lug 16, which may also be utilized to mount the brake shoe upon a brake head (not shown), includes a central longitudinal slot 18 for receiving a mounting key (not shown) in the usual manner, this keyway 18 is best shown in FIG. 3. The lug 16 is located on the convex surface 14 of the back plate 8 intermediate the ends of said plate. Opposed legs 20 and 22 on lug 16 are bent at their lower extremity relative to the convex surface 14 and are secured to said surface 14 as by welding. The opposed legs 20 and 22 may also project through suitable apertures (not shown) in plate 8 and be cinched at their lower extremities or may be formed as a unit with the back plate 8. It should be noted though, that it is preferable to maintain the back plate 8 of the brake shw free from all apertures.

A mesh type strip or sheet 24, shown in FIG. 2 as expanded metal, has a length, width and curvature corresponding to that of the back plate 8. The expanded metal 24 is secured to the concaved surface of the back plate 8 by welding or other equivalent means at various distributed locations. Said expanded metal 24 may also project upwardly into the toe stops 10 and 12 as shown in FIG. 1. The mesh 24 is intended as a mechanical bond between the composition body 6 and the metal support 8, whereby the composition is secured to and interlocked with the interstices 26 of the mesh 24. It should be noted that by welding the expanded metal 24 to the back plate 8 the initial flexibility and strength of the back support is not reduced. The mesh 24 may also consist of a plurality of sections secured at distributed locations.

According to this invention, the brake shoe may be manufactured in the following way. The metal backing structure 8, toe stops 10 and 12, and center lug 16 are first fabricated as a completed unit having a predetermined length, Width and longitudinal curvature corresponding to that of the desired .brake shoe body 6. The

expanded metal 24, having a width, length and curvature,

approximately that of the support member 8 is then welded, brazed or soldered to the concaved surface of the metal support 8 at distributed locations, e.g., four spaced rows of three welds each. The metal backing structure is then placed in a suitable brake shoe mold. A composition material, composed of a friction compound in an organic binder, is placed in the mold and under pressure fills the expanded metal in such amanner as to avoid any air pockets or discontinuities in the composition material and forming a composition body 6 of a predetermined width, length, thickness and longitudinal curvature. The composition is then curved, as by heat, forming a completed brake shoe.

It is to be understood that the foregoing description and the accompanying drawings have been given only by way of illustration and example. It is also to be understood that changes in form of the elements, rearrangement of parts, and substitution of equivalent elements, which will be obvious to those skilled in the art, are contemplated as within the scope of this invention.

What is claimed is:

1. A railroad brake shoe comprising: a metal back structure having a predetermined length, width, thickness and longitudinal curvature forming opposed concave and convex surfaces; expanded metal intermittently fused to the concave surface of said structure, and in face to face engagement with said concave surface, said expanded metal having members angularly positioned relative to the metal back structure and having a predetermined length and width, and a curvature approximately equal to the curvature of said back structure; and a composition brake body embedded in said expanded metal and having a length, width and curvature approximately equal to said back structure and a thickness substantially greater than said back structure.

References Cited UNITED STATES PATENTS 1,470,475 10/ 1923 Pettis 188-254 1,907,635 5/1933 Winters 188254 1,947,894 2/1934 Whitworth l88251 X 2,869,689 l/ 1959 Wilson 188--25l 2,911,074 11/1959 Fraula et a1. 188251 GEORGE E. A. HALVOSA, Primary Examiner

Images