US2426963A - Journal structure - Google Patents

Description

Sept. 2, 1947. F. s. BALL E'rm.

JOURNAL STRUCTURE Filed Dec. 27, 1944 6 SheetsfShet 1 Sept 2f 1947- F. s.'BAL| ET AL. 2,426,963

JOURNAL STRUCTURE Filed nec; 27, 1944 6 sheets-sheet 2 sept. 2, 1947'.

F. 5.1BALL ET AL JOURNAL STRUCTURE Filed Dec. 27, 1944 6 Sheets-Sheet 3 Sept. 2; 1,947.

F. s. BALL ETAL 2,426,963

JOURNAL STRUCTURE Filed Dec. 27, 1944 6 Shees-Sheet 4 x 5 m if N N v I y al I 3) ,N l N N Iliff/1111 ?atented epti 29 ld? .YURN STRUCTE Frederick S. Ball, Per wt sar llagren, and

Haakon Styri, Philadelphia, Pa., assignors to S K El industries, Ene., Philadelphia, Pa., .a

corporation ci Delaware Application December 27, 1951i, Serial No. 569,990

(Cl. 3ds- 130) Claims. i

This invention relates to improvements in journal structures of the type employing anti-friction bearings, and a principal object of .the invention is to improve the load-carrying capacity and durability of journals of this type.

To this general end, an object of the invention is to provide an improved journal structure of the stated type affording a more favorable load distribution in the anti-friction bearing and avoiding areas of 4high stress arising from concentration of load in localized areas of the bearing.

More specifically, an object of the invention is to provide a, novel design of housing for journal structures of the stated type through the medium of which the loads imposed upon the bearing may be more uniformly distributed over a relatively extended area of the said bearing.

In the attached drawings:

Figure 1 is a transverse sectional view of a portion of a railway journal constructed in accordance with the invention;

Figure 2 is a sectionon the line 22, Figure 1; Figures 3 and 4 are views corresponding respectively to Figures 1 and 2 and illustrating a modlcation within the scope of the invention;

Figures 5 and 6 are corresponding views illusvtrating another modification;

Figures 7 and 8 are views of the same character illustrating still another modification within the scope of the invention,

Figures 9, 10, 11, and 12 are diagrammatic sectional views of loaded bearings illustrating the principle of the invention, and

Figure 13 is a fragmentary transverse sectional view of a journal structure illustrating a modification within the scope of the invention.

Preliminary consideration of established facts concerning stresses and load distribution in antifriction bearings, will clarify this invention and the manner in which it operates to increase fatigue life and consequently the capacity of bearings made in accordance with the invention. In this specification the term anti-friction bearing means one having rolling elements between the races as distinguished from plain bearings which lack such elements. The principles herein described and disclosed apply to all annular antifriction bearings whether containing balls or other type of roller. We will use the term roller" to cover any such rolling element.

Figure 9 shows in cross section a roller bearing having seven rollers in the loaded half of the Y the inner race is tightly pressed, and thence to bearing designated respectively a, b, c, d, e, f, and

g. The load comes upon the bearing vertically downward and, through the outer race contacts,

rconstituted by the wheel and rail.

, upon the various rollers which pass it through the inner race contacts to the inner race. From the latter, the load passes to the axle, upon which a support which, in the case of the herein described railroad journal structure for example, is Since the vertical reaction at the rail must equal the vertical load on the bearing, the effect of load on any of the intermediate bearing or housing parts will be the same, whether the load originates as a pressure upon the housing supported by the axle, or whether it originates in a shaft and is supported by the housing. Hereinafter, we shall describe the eect of'various loads applied on the housing but wish it understood that the invention embraces the situation of reversed loading.

In railway journal bearing applications, the load rests upon the housing which in turn is supported by the bearing. Load applied at the center of the housing, hereafter given the more usual name of box, will divide among the rollers in the manner explained by Stribeck in 1900. A translation of. Stribecks work was presented by Henry Hess to the American Society of Mechanical Engineers and appears in volume 29 of their translations for 1967. According to the principles set forth in this treatise, each roller within' the loaded half of the bearing will bear a portion of the total load, such portion depending upon the position of the roller in relation to the direction of loading and upon the number of rollers contained in the bearing. Thus, if the rollers fit without looseness or tightness in the unloaded bearing and if the outer race possesses suilcient rigidity to move downward the same amount at al1 points due to elastic distortion of the bearing parts at the points of contact, the roller in the top position directly under the load (the roller d in Figure 9) will carry a predominant fraction of the total bearing load. In the radial direction the other rollers will carry lesser loads decreasing rapidly in intensity from the vertical to the horizontal position, as indicated by arrows drawn to scale, in Figure 9.

In most applications of anti-friction bearings, the inner race rotates and is pressed onto the shaft, while the outer race remains stationary and fits into the housing with a clearance of several thousandths of an inch. The rollers also fit with slight play between the races 4when unloaded. The outer race therefore is subject to bending and, in fact, receives stiffening support from Athe housing only to the extent .that it is brought into engagement therewith by bending out-of- 3 round. Such looseness and bending will affect the loading on the individual rollers and will the load for the rollers c, d, and e to carry. Loading of the outer race at the center will tend therefore to increase the maximum oi the higher roller loads and to decrease the minimum of the lower loads. Conversely application of the load on the outer race in the regions of rollers a and b, and

f and g will tend to bend the outer race inwardly toward these elements and thereby force them to increase their individual radial and vertical components. This will relieve the rollers e, f, and y of a portion of the total bearing load and thus reduce the maximum of the higher loading values and increase the minimum of the lower values.

Testing of thousands of anti-friction bearings has disclosed denite relationship between loading and endurance and has shown that life, measured in hours expected at given speeds, is inversely 4proportional to a power of the load. l

Mathematically expressed life=1/load". The exponent n has values of 3 or more. This relationship naturally applies as specically to the individual roller loads as to the whole bearing unit. Evidently even small reductions of the individual loads will materially lengthen bearing life, or conversely, increase bearing capacity at the same speed, changes in the maximumand high loads having the greatest effect by far. Though the increase in the low loads offsets to some extent the beneficial effect of decreasing the high loads, the invention makes possible an adjustment between these opposite effects which will produce a highly favorable increase in bearing endurance.

This invention accomplishes application of the loadupon the outboardiregions of the outer race by interposing a load-distributing saddle between the truck frame and the box. The saddle, receiving the load from the frame at its center, applies it in two equal parts on seats in the outboard region of the box.' To make this spreading of the 'load more eiective, the portion of the box' directly over the bearing has' a cross section thin enough to wrap as much as practicable around the outer race, yetthick enough to avoid weakness of structure. l

The four diagrams of the same anti-friction bearing shown in Figs. 9 to 12 of the drawings illustrate distribution of loading among the several rollers under various conditions, the arrows indicating by their'length the relative amount of load on each and its relation to the total load on the bearing. Action denotes the load imposed by the box upon the outer race, while reaction denotes the support given by the axle to the inner race. Action must equal reaction Fig. 9 shows the distribution when the box wall is thick enough to provide complete rigidity to the outer race which fits into it without clearance. The rollers also fit in the unloaded bearing without play or pressure between races. Though not a standard practice mounting. it is a possible arrangement and is the condition used as the basis of the mathematical solution of individual roller loads.

Figure 10 shows a reasonable estimate of changes from Figure 9 when the mounting con- 4 forms with standard practice by making the bore of the housing a few thousandths of an inch larger than the outer race to provide clearance for easy installation and by providing slight original play between rollers and races. This clearance is exaggerated for clarity. Here the outer race, receivlng no support from the housing wall in the regions of rollers a, b, f, and y, will spread away from them, thus relieving them of some of their load. This will throw more load on rollers c, d,

and e which will cause them to iiatten more than formerly, at their contacts with the two races and thus permit the outer race to bend downwardly out-of-round to the point of establishing equilibrium. In this case the race is shown to bend to the larger circle of the housing from roller position c to roller position e. It may bend far enough to clear rollers a and g entirely as indicated. Looseness of roller fltwill make this clearance more likely to occur. In Figure 11, where the load is imposed at two points, the race conforms from b to f; and in Figure 12 the race wraps so completely around the complement of rollers that every one of those in the loaded region will bear nearly equal loads.

With reference to Figures 1 and 2 of the drawings, which show a conventional form of railway journal structure, the anti-friction roller bearing, which in this instance comprises an outer race ring l, an inner race ring 2 and rollers 3, is housed within a box I, this box being mounted in conventional manner in a frame 5 indicated in broken lines in Figure 1. The journal 6 of axle-1 receives the inner race 2 of the bearing and the load is applied to the axle by way of the box 4 and through the medium in the present instance of an equalizer 8 which seats upon the housing. In so far as described above, the structure is conventional.

In accordance with the present invention, a saddle 9 is interposed between the equalizer 8 and the box 4. The equalizer 8 seats centrally at the top of said saddle and in the present instance in vertical alignment with the axis of the journal 6, and the saddle in turn seats upon the housing 4 at two points l l, i l located toward the opposite sides of the box 4, and of the said axis, and preferably in uniformly spaced relation with respect to the latter. In this manner the load applied to the box 4 is divided into two components at opposite ends respectively of that portion I2 of the box which extends around -the upper portion of the outer race l of the bearing. This portion l2 of the housing is designed to ilex under load so that it tends in eiect to wrap around the outer race and to thereby distribute the load with a high degree of uniformity over a substantial peripherallarea of the said race at the upper part of the bearing.

The aforedescribed design is conducive to a highly favorable distribution of load on the rolling elements of the bearing, and lessons the localized bending out-of-round of the outer race, which is responsible for the relatively rapid fatigue that results in shorter life of bearings in journal structures of conventional form. Whereas in the prior greatly reduced, and the load is more uniformly distributed and over a relatively large number of the rolling elements. The practical load capacity and durability of the bearing is thereby greatly increased.

The invention also makes possible the successful use of relatively inexpensive materials having lower strength and hardness characteristics than y have previously been found practicable. Since the elongation -and hence bending of a material is inversely proportional to the elastic modulus, those materials which have the lower moduli will tend under any given load to wrap around the outer race over a longer area than those having the higher moduli.

Materials of low modulus of elasticity will bend away from the outboard regions of the outer race, more than those of higher modulus and will therefore tend to concentrate the load more in the center. The saddle loading heren described tends to correct this Weakness, and will act more effectively with these materials than with iron or steel. The lighter materials such as aluminum and its alloys, being softer than 4iron or steel, will tend to suffer from peening in the areas where the equalizer bars or other loading devices rest upon the housing. This is caused by the pounding of wheels over rail joints, cross overs and other track irregularities. This invention divides the load on the box into two equal parts which minimizes peening to a degree suiiicient to make their use practical. Thus the weight saving advantages of light materials is realized.

In Figures 3 and 4 we have illustrated a modication of the structure shown in Figures 1 and 2. In this instance the saddle 9 of the previously described embodiment is formed as an integral part of the journal box. Thus the box is provided with a section I2a corresponding to the flexible strap portion I2 of the previous embodiment and the equalizer is seated in this instance directly upon an upper portion 9a of the box which corresponds to the saddle 9 previously described except that in this instance it becomes an integral part of the box structure. It will assembly, form seats for the shoulders I 3| 3. In this case the load is applied tothe bearing solely through the flexible strap I4 which effects a highly favorable distribution of the load over substantially the entire upper half of the bearing.

In the journal structure illustrated in Figures '7 and 8 the load is applied directly to the housi-ng .at two points lli-I8 at opposite sides of the journal axis and at opposite ends of an intermediate iexible strap portion I1 of the box. l In order to reduce wear between the box and the frame at the points of load application, suitable metallic wear plates I8l I8 are provided between the frame I9 and the box 4.

The two plates will wear substantially equally and such wear will not change thecharacter of loading on the box. In the present method of loading over a central area, wear will be greater at the ledges of that area than at the center thereof, which will tend to increase concentration of loading at the center rather than to spread it over a. wider area.

In its functional aspects this embodiment is of the same nature as those previously described.

With reference to Fig. 13, the embodiment of the invention therein illustrated corresponds to the embodiment of Fig. 1 with the exception that (using the same reference numerals as in Fig. 1

to identify the corresponding parts) the seats II, II on the housing t which receive the respective legs of the saddle '9, are disposed at an angle tothe horizontal for the purpose of imposing the thrust of the saddle on the housing in directions favorable to the desired wrapping action in the exible portion I2 and to the desirable uniform distribution of pressure upon the rolling elements 3 of the bearing. In the present instance the planes in which the seats I I are formed are substantially radial to the axis of the journal 6; and the angle of these planes to the horizontal is approximately 45. These positional relations may vary without departure from the invention.

We claim: i

1. In a journal structure, a plurality of rolling elements arranged in annular series and constituting components of an anti-friction bearing for be apparent that the functional characteristics j the case of this invention, however, the box hasl downwardly facingshoulders Iii-I3 one on each side of the box and at opposite sides of the axis of the bearing. The box is supported on the outer race I of the anti-friction bearing through the medium of a flexible metallic band or strap I4 which extends over the top of the race I and is secured at each end to a bar I5 which, in

said journal, a housing, and means for loading said -housing at spaced points of initial concentration on vopposite sides respectively of a plane containing the axis of the journal, said housing having a strap portion extending around the outside of said series of elements from one of said points of initial concentration to the other for applying the load to the bearing, and said strap portion being of minimal thickness as compared with the other portions of the housing interposed between the load and the bearing and being ilexible under said load so as to distribute'the load over the relatively extended portion of the bearing embraced by the strap portion.

2. In a journal structure, an anti-friction bearing for said journal, and a housing for said bearing, and means for loading the housing in spaced areas of initial load concentration on opposite sides respectively of a plane containing the axis of the journal, said housing having a strap portion extending around the outside of said bearing and from one of said areas of initial concentration to the other for'applying the load to the bearing, and said strap portion being of minimal thickness as compared with the other portions of the housing interposed between the load and the bearing and being flexible under said load so as to distribute the load over the relatively extended 7 portion of the bearing embraced by the strap portion.

3. In a journal structure, a housing, an antifriction bearing having an outer race ring mounted in -the housing and an inner race ring for reception of said journal, said housing having areas of initial load concentration at opposite sides respectively of a plane containing the axis of the journal and having a strap portion extending around the outside of said outer race and from one of said areas to the other for applying the load to the bearing, and said strap portion being of minimal thickness as compared with the other portions of the housing interposed between the load and the bearing and being flexible under said load so as to distribute the load over the relatively extended portion of the bearing embraced by the strap portion.

4. In a journal structure, an anti-frictionvbearing having 'inner and outer race rings, a housing having a flexible wall portion engaging and extending around the said outer race, a seat at each end oi said iiexible wall portion, and means including a substantially rigid load-transmitting structure supported on said seats for loading the housing so as to Wrap said ilexible portion around ring. a seat on said housing at each end of said the outer race and to thereby distribute the load over the contiguous portions of said bearing;

5. In a journal structure including an antifriction bearing for said journal, a housing having a exible strap portion seating against and conforming to the peripheral surface of said bearing, and means for loading the housing in areas at opposite ends respectively of said strap portion, said strap portion being of minimal thickness as compared with the other portions of the housing interposed between the load and the bearing and being ilexible under said load so as to distribute the load over the relatively extended portion of the bearing embraced by the strap.

6. In a journal structure, an anti-friction bearing having inner and outer cylindrical race rings, a housing having a exible wall portion engageable with andextending around the outside of said outer race ring, said wall portion embracing less than half of the circumference of said outer radial to the axis of the journal, and meansfor loading the housing at said seats and in directions substantially normal to the planes of the latter.

'7. In a journal structure, an anti-friction bearing having inner and outer race rings, a housing having a exible wali portion engaging and extending around the said outer race, a seat at each end of said flexible wall portion in a plane substantially radial to the axis of said bearing, and a substantially rigid structure supported on said seats and constituting a means for transmit ting load to the housing of sufficient magnitude to cause exure of said Wall portion around the outer race in a manner tending to distribute the load with uniformity over the contiguous portions of the bearing.

8. In a journal structure, an anti-friction bearing having inner and outer race rings, a housing having a exible wall portion engaging and extending around approximately one-quarter of the circumference of said outer' race, a seat at each end of said ilexible Wall portion in a plane substantially radial to the axis of said bearing, and a structure supported on said seats in wedging relationthereto and constituting a means for transmitting load to the housing of sufcient magnitude to cause flexure of said wall portion around the outer race in a manner tending to distribute the load with uniformity over the contiguous portions of the bearing.

FREDERICK S. BALL. l PER GUNNAR PALIvGREN.

HAAKON STYRI.

- REFERENCES CITED The following references are of record in the ile of this patent:

UNITED STATES PATENTS

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