US3038755A - Railway wheel - Google Patents

Description

H. C. KEYSOR RAILWAY WHEEL June 12, 1962 2 Sheets-Sheet 1 Filed June 6, 1960 June lz, 1962 Filed June 6, 1960 WJ-Ze H. c. KEYSOR 3,038,755

RAILWAY WHEEL 2 Sheets-Sheet 2 United States Patent 3,038,755 RAILWAY WHEEL Harold C. Keysor, La Grange, Ill., assignor to Amsted Industries Incorporated, Chicago, 111., a corporation of New Jersey Filed June 6, 1960, Ser. No. 35,106 11 Claims. (Cl. 295-21) This invention relates to wheels for railway cars and particularly to cast steel wheels therefor.

This is a continuation-in-part of my copending application, Serial No. 778,530, filed December 5, 1958, titled Railway Wheel and now abandoned.

For many years, a considerable amount of time, effort and money has been expended in attempting to produce, economically, a wheel for railway cars which would consistently have long service life without the danger of abrupt failure. Although various types of wheels have been developed, each with variations in plate and rim thickness and in contour, all of them have been basically identical in theory of design. All of these prior art Wheels are subject, to a greater or lesser extent, to stress cracks in the plate portion of the Wheel in the areas adjacent the hub and the rim.

It has been found that the stress cracks in the plate portion of the Wheel are caused primarily by repeated brake applications during which large amounts of heat are generated by the frictional contact of the brake shoes on the wheel rim. The temperature rise in the wheel rim causes it to expand in a radial direction and this expansion creates highly concentrated stress patterns in the plate portion of the Wheel. These high-stress areas are likely to develop cracks which continually expand with repeated brake applications. The ultimate result when this occurs is early wheel failure.

It is further noted that upon repeated service of the wheel, the wheel treads become worn and grooved, and the wheel itself becomes out-of-round. Without proper wheel treads, the wheel loses its utility. However, if the treads could be refinished after the above defects occur the life and utility of the wheel would be extended. Consequently, my invention is particularly applicable to double wear or multiple-wear wheel tread rim construction.

An object, therefore, of the present invention is to provide a railway car wheel which is inherently resistant to stress cracks, particularly when subject to repeated brake applications in service, and which therefore has a greatly increased fatigue life expectancy.

A correlary object is to provide a railway car wheel which is inherently resistant to stress cracks, and which therefore has a greatly increased fatigue life in service; and to provide the wheel with sufficient rim volume to accommodate refinishing of worn tread surfaces, and which therefore has a greatly increased wear life in service.

These and other objects and advantages of the invention will become apparent from the following description and accompanying drawing wherein:

FIGURE 1 is a fragmentary central vertical sectional view of a railway car wheel embodying the features of the invention,

FIGURE 2 is a fragmentary central vertical sectional view of a railway car wheel having an alternate embodiment of the rim construction used in my invention.

Referring to FIGURE 1, it is seen that the wheel comprises a hub portion 10 having centrally thereof a transverse bore 12 arranged to receive in conventional manner one end of an axle (not shown). Formed integrally with the hub 10 and extending generally radially thereof is a plate portion indicated generally at 14. A rim 16 is peripherally formed at the radially outer edge of the plate 14 and comprises a tread surface 18 and a flange 20 ex- 3,038,755 Patented June 12, 1962 "ice tending radially outward of the tread surface 18 on the inboard side of the wheel. It will be noted that the rim i6 is axially offset from the hub 10 toward the outboard side of the wheel in a conventional manner.

According to the present invention the plate 14 is preferably arcuate in cross-sectional contour and the center line 30 of the plate is preferably tangent to a line 31 lying in a plane positioned midway between the inboard and outboard surfaces of the hub and normal to the axis of rotation of the wheel, the point of tangency preferably lying within the hub itself as at 32.

The radius of the center line 30 is of such a length that the latter also passes through a point 34 which is preferably located at approximately the center of gravity of the rim 16. This point, however, may vary somewhat from the center of gravity of the rim in order to obtain a properly balanced design. The inboard and outboard walls of plate portion 14, designated 36 and 3S, respectively, are formed of arcs concentric with the center line 30. Fillets 40, 42, 44 and 4-6 merge the plate 14 with the hub 10 and rim 16. The fillets are formed with a gradually changing radius of curvature and in the preferred form are parabolic curves. The term parabolic, as used herein, covers curves which are exact parabolas, as mathematically defined, and also any other curve having the general characteristics of a parabola, but having a different and perhaps more complicated equation, due to its method of formation. The reason for utilizing this fillet form is that tests have shown that stresses are magnified in areas of abrupt changes of radius of curvature. This condition is most severe where a curved section is tangent to a straight line section but is also prevalent at the tangency points of successive arcs having different radii. For this reason, elimination of high stress areas can not be accomplished by joining the plate with the hub and rim by arcs of large radii. However, it has been ascertained that, because of rapidly increasing plate thickness in the area adjacent the hub, the final sweep of the fillet into the hub may be in the form of a circular arc. It has been noted further that, during a brake application, the plate portion in the areas of fillets 46 and 4-0, being in tension, are the most critical, whereas the plate portions in the areas of fillets 44 and 42, being in compression, are less critic-a1. Obviously, then, an improved wheel, as compared to those of prior art designs, could be obtained by providing parabolic fillets at 46 and 40 only, or con ceiv'ably at 46 only. The preferred wheel, however, would be provided with the four parabolic fillets 40, 42, 44 and 46.

The specific parabolic curve used for each fillet will, of course, vary with the particular size and style of the cast wheel to which it is applied. Therefore, the particular method of defining the parabolic fillet 46 may be given as illustrative of the manner of forming the fillets for any desired wheel.

The first step in constructing the fillet is to select certain points, designated 48 and 50 on the hub and plate, respectively, as the desired terminal points for the fillet. Preferably, the length of the fillet along the plate is greater than the length of the fillet along the hub or the rim. Next, the distanw between the point 48 and a point 52 is divided into, for example, two or more equal spaces. In the disclosed embodiment ten spaces are utilized. It will be understood that the point 52 is approximately at the theoretical point of intersection of the hub and the plate surface are 38. The above divisions are designated on the drawing by the letters a through 1'. Similarly, the distance between points 50 and 52 is divided into ten equal spaces or, if a more sweeping fillet is desired, into ten spaces which increase progressively preferably by a given increment. These divisions may be designated by the letters It through s. The point a is then connected by a straight line to the point 56; point b is connected by a straight line to the point s, and so through sequential points, until the point i has been connected to point k. A fillet curve is then constructed which is tangent to the hub and to the plate and also to each of the straight lines connecting the designated points. This curve is parabolic in form and, more important to the present invention, has a continuously changing radius of curvature. Each of the other fillets 4t 42 and 44 are constructed in a similar manner.

It has been found that a wheel having an arcuate plate which is connected to the hub and rim by fillets having a gradually changing radius of curvature, not only is substantially less subject to shock fatigue and stress cracks, but also is comparatively stronger than prior art wheels. Because of these improved physical characteristics, it has been found possible to appreciably decrease the weight of the wheel and still derive longer service life and safer performance than is obtainable with prior art wheels.

It may be noted with reference to FIGURE 2 that rim 16 alternately may be made with a thickened substantially rectangularly shaped cross section having a flanged portion 20 at the inner edge thereof. To ensure adequate rim volume, the radial thickness of the rim at the outer portion thereof is originally made not less than twice the radial projection of flange 2 9 from wheel tread 18. After prolonged service, the wheel tread wears to a contour similar to line 60 of FIGURE 2. However, at this time the wheel and axle assembly may be disassembled from the car truck and the wheel treads thereon may be refinished to the contour 62. It may be noted that the newly contoured rim is yet of ample thickness to pass Association of American Railroads specifications (see AAR Manual of Standards and Recommended Practice, section G).

It is thus seen that my invention utilizes the inherently longer wheel life (fatigue-wise) of parabolic fillet construction. It may further be seen that my invention is specifically adaptable to multiple-wear and double wear rim tread construction to accommodate longer wheel life (wear-wise) in addition to the added fatigue life of the railway car wheel.

I claim:

1. In a cast steel railway wheel, a hub having an axial bore; a rim concentric with said bore; a plate extending substantially radially from said hub toward said rim, said plate being substantially arcuate in crosssection and having a center line intersecting said hub generally centrally thereof and intersecting said rim at approximately the center of gravity thereof; and fillets merging said plate into said hub and rim, said fillets being parabolic in form and extending for a greater distance along said plate than along said hub and said rim.

2. A cast steel railway wheel according to claim 1, wherein said rim comprises a wheel tread and a flange extending radially therefrom, and wherein, said rim is substantially twice as thick at its outer portion as the radial projection of the flange therefrom.

3. In a cast steel railway wheel, a hub; a rim concentric therewith; an arcuate plate having a center line intersecting said hub approximately centrally thereof and intersecting said rim at approximately the center of gravity thereof; and parabolic fillets connecting said plate to said hub and to said rim, said fillets having greater length along the arcuate plate than along the hub and the rim.

4. In a cast steel railway wheel, a hub and a rim concentric therewith; an arcuate plate having a center line intersecting said hub approximately centrally thereof and intersecting said rim at approximately the center of gravity thereof; and parabolic fillets merging said plate into said hub and said rim.

5. A cast steel railway wheel according to claim 4, wherein said rim has a wheel tread and a radially projecting flange, and wherein said wheel tread is substantially thicker than the radial projection of the flange.

6. In a cast steel railway wheel, a hub and rim; an arcuately formed plate extending generally radially from said hub toward said rim; and parabolic fillets connecting said plate with said hub and said rim.

7. In a cast steel railway Wheel, a hub and rim; a substantially arcuate plate interconnecting said hub and rim and having fillets at the points of juncture therewith, each of said fillets having a continuously changing radius of curvature.

8. A cast steel railway wheel according to claim 7, wherein said rim has a wheel tread and a flange extending radially therefrom, and wherein said wheel tread is of sufficient radial thickness to accommodate refinishing thereof, and to provide a new flange.

9. In a cast steel railway wheel, a hub; a rim concentrio therewith; a plate extending generally radially between said hub and rim; and fillets merging said plate into said hub and rim, each of said fillets being formed in a curve having a continuously changing radius of curvature.

10. In a railway car wheel, a hub and rim; a plate portion extending generally radially from said hub toward said rim; and parabolic fillets connecting said plate with said hub and said rim.

11. In a railway car wheel according to claim 10, wherein said rim comprises a wheel tread and a flange extending radially therefrom, and wherein the ratio of the radial thickness of said rim to the radial projection of the flange from the wheel tread is not less than two.

References Cited in the file of this patent UNITED STATES PATENTS

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