US3000330A - Car truck - Google Patents

Description

J. A. SHAFER Sept. 19, 1961 CAR TRUCK 2 Sheets-Sheet 1 Filed June 9, 1960 INVENTCR.

Sept. 19, 1961 J. A. SHAFER 3,000,330

CAR TRUCK Filed June 9, 1960 2 Sheets-Sheet 2 PRIOR ART FRAME IN VEN TOR.

United States Patent 3,000,330 CAR TRUCK James A. Shafer, East Cleveland, Ohio, assignor to National Malleable and Steel Castings Company, Cleveland, Ohio, a corporation of Ohio Filed June 9, 1960, Ser. No. 35,863 4 Claims. (Cl. 105206) This invention relates to side frames for railway car trucks and the like, and more particularly to the class of side frame which is of the truss type. The subject matter disclosed herein is partially disclosed in copending application, Serial No. 678,578, filed August 16, 1957, now abandoned.

In the usual form of railway truck, a pair of transversely spaced and longitudinally extending side frame members are supported on their outer ends on wheel and axle assemblies and a transversely extending bolster is supported adjacent its outer ends on the side frames, through some suitable resilient medium, such as coil springs. The structure of the side frames is generally of a so-called truss design and comprises a lower tension member and upper compression member disposed between journal-receiving boxes. members and form therebetween a bolster-receiving opening. A portion of the tension member is used as a beam extending between the columns and forms a spring seat for the bolster supporting springs for transmitting a load from the bolster to the side frame structure. This spring supporting portion of the tension member is therefore subjected to bending action which, because of the rigid connections between the columns, tension and compression members of the truss structure, induces bending in these members also, and thus tends to rearrange the true truss alignment and causes bending stresses to be added to the direct stresses. These bending stresses are particularly detrimental to, and find their greatest effect in, the diagonally extending portions of the tension member of the frame structure which connect between the column portions and the journal-receiving portions of the frame.

In addition, in certain types of side frames and in particular those types which are adapted for use with separable journal boxes, such as roller bearings, as opposed to integrally formed boxes, the points of support of the side frame on the axles through the journal boxes are not at the true junctures of the tension and compression members, but are in reality on extending cantilever portions which are adapted to provide a practical seat for the journal boxes. Because of this cantilever action at the junctures of the tension and compression members, further bending stresses are set up in the frame structure, thus aggravating the flexure of the frame, especially in the diagonally extending portions of the tension member of the structure.

In conventional constructions, the diagonal portions of the tension member are channel or U-shaped in vertical cross-section and may be either of normal upright or inverted U-shape throughout their length, depending upon the preference of the manufacturer. Many railroad men prefer the inverted U-shape since this prevents the collection of dirt and other debris in the member during operation. However, the inverted U-shaped diagonal portion is subject to a disadvantage in that two cores are necessary during casting, thereby increasing time and cost of manufacture.

Hence, an important object of the present invention is to provide a novel construction for the diagonal portions of the tension members of the side frame which eifectively resists the bending stresses applied thereto, without the necessity of materially increasing the weight of the frame.

Spaced columns connect said Ancillary to the foregoing object, it is desired to make use of but one core within the tension member during the casting of the side frame while, at the same time, accomplishing the advantageous feature of preventing the collection of dirt and debris by the member during operation.

A further important object is to provide a truss type side frame for a car truck which embodies a novel tension member construction to eifectively reduce bending stresses in the other members of the frame.

Another object is to provide a novel side frame tension member which is characterized by simplicity of construction, economy of manufacture, and which retains all the advantages of conventional constructions while eliminating their objectionable features.

Briefly, the invention resides in a truss type side frame for a car truck in which each of the diagonal portions of the tension member, disposed between the generally centrally located columns of the frame and the journalreceiving box portions on the outer ends of the frame, comprises a lower section of inverted U-shaped configuration, a middle section of box-like configuration and an upper section of normal upright U-shaped configuration, all of said sections being disposed in series, progressing from the lower or inner end of the diagonal portion of the tension member to the upper or outer end thereof.

Other features and advantages of the invention will be apparent from the following description taken in conjunction with the drawings, wherein:

FIG. 1 is a partially sectioned side elevational View of one-half of a side frame embodying the invention, it being understood that the other half is identical in construction with the half illustrated.

FIGS. 2, 3 and 4 are sectional views taken generally along lines 22, 33, and 44, respectively, of FIG. 1.

FIGS. 5 and 6 are fragmentary auxiliary views taken, respectively, along lines 55 and 66 of FIG. 1, looking in the direction of the arrows.

FIG. 7 is a partially sectioned side elevation of onehalf of a prior art side frame illustrating the neutral axes of a tension member and a compression member intersecting therewith.

FIG. 8 is a partially sectioned side elevation of onehalf of the side frame of the invention shown in FIG. 1 illustrating the neutral axes of its intersecting tension and compression members.

FIG. 9 is a diagram of the neutral axes of FIG. 7 superimposed upon those of FIG. 8.

FIG. 10 is a neutral axis diagram of an entire prior art side frame of FIG. 7 illustrating the shifting of the neutral axes upon loading of the frame.

FIG. 11 is a neutral axes diagram of an entire side frame in accordance with FIG. 8 illustrating the effect of loading upon the neutral axes.

Referring to the drawings, and in particular to FIG. 1, there is shown approximately one-half of a car truck side frame 8 of the truss type (it being understood that the other half is identical in construction) comprising an upper compression member 10, a lower tension member 12, and a generally centrally located vertical column 14 joining the tension and compression members. The upper end of column 14 is recessed as at 14a to form a widened top portion for bolster-receiving opening 16 in the frame. The bolster (not shown) is adapted to extend into opening 16 and be supported in the usual manner on springs (not shown) resting on the horizontal spring seat portion 18 of the tension member. Portion 18 is thus substantially the equivalent of a beam arrangement of the restrained type and is of box-like configuration in transverse section. The top wall of portion 18 is widened on each side thereof to accommodate the aforementioned bolster-supporting springs. Upstanding flanges 19 at the outer edges of the spring seat serve to strengthen the latter and also to aid in retaining the bolster supporting spring in proper position. Each column 14 also comprises an inwardly facing pocket 20 which is adapted to receive a friction wedge member (not shown) for frictionally controlling bolster movements in a manner well-known to those skilled in the art.

Tension and compression members 10 and 12 merge at their ends and are provided, in the embodiment shown, with integral journal box 20 for receiving the conventional journal of an associated wheel and axle assembly (not shown). In this connection, it will be understood that the journal boxes may be either formed integrally with the frame ends or can be formed separately therefrom and adapted to be received between pedestal-like jaws formed on the frame ends, as is well-known to those skilled in the art. As discussed above, the type of side frame which is adapted for use with separable journal boxes is subjected to greater bending stresses than the integral journal box type of frame, due to the cantilever action of the journal box mountings of the former. The mergence of compression and tension members 10 and 12 in combination with column 14 define window opening 22 in the frame.

Referring to FIGS. 1 and 11, it will be seen that the members of the improved frame are integrated by fixed joints at intersections or junctures of the neutral axes of the members at A, B, C, and D. In FIG. 11, A and B represent the axes junctures of the diagonal portions 26 of the tension member with the spring seat 18 and the columns 14. C and D represent axes junctures of the diagonal portions 26 of the tension member with the journal-receiving portions '20 and the compression member 10. Because of the massive construction of the frame joints at the axes junctures, the joints tend to rotate about such junctures during loading of the frame with consequent deflection and development of secondary stresses in the member adjacent each joint. The deflection of the members of two different frames in response to such loading is illustrated in a qualitative manner in FIGS. 10 and 11.

In accordance with the invention, the lower section X of each of diagonal portions 26 of the tension member is made of inverted-U or channel shape in transverse cross-section and comprises a top web or plate 28 and side webs 30 depending from web 28. The bottom ends 32 of side walls 30 curve inwardly and are spaced from one another, as shown, to form elongated opening 34 in the bottom of diagonal portion 26 of tension member 12. At the upper and lower ends of opening 34, end portions 32 merge in arcuate relationship, as at 35 (FIG. to form transversely extending strengthening web portions 36 and 37. The lower ends of top web 28 curves upwardly, as at 38, and eventually merges with the underside of longitudinally sloping wall 40 which partially defines the aforementioned friction wedge-receiving pocket 20 in column 41. The side web portions 30 of section X merge with the side webs 41 of column 14 and the side webs 43 of spring seat portion 18 to form a comparatively rigid juncture of substantial strength between ten-, sion member 12 and column member 14.- The upper or strengthening web portion 42 disposed above the aforementioned transverse web portion 36. Thus, in effect,

the middle section Z of diagonal portion 26 0f the tension member is of a closed configuration in vertical crosssection with the side webs 30 of the member merging with upper and lower web portions 36 and 42 to form a boxlike contour (FIG. 3). V

The upper section Y of each of portions 26 of tension member 12 is of normal upright U-shaped configuration in transverse cross-section and comprises a bottom web 44 which at its lower or inner end merges with and forms a continuation of transverse web portion 36, and at its upper. or outer end,curves outwardly tomerge with the side wall 46 of the journal box 20. Side webs 30 of diagonal portion 26 project upwardly from web 44 and at their upper ends 47 curve inwardly to define elongated top opening 48 in portion 26. At the lower end of opening 48, ends 47 merge in 'arcuate relationship, as at 49, with the aforementioned upper transverse web portion 42 of middle section Z. At the upper end of section Y, ends 47 of side webs 30 merge with and form continuations of the inwardly curved ends 50 of side webs 52 of compression member 10 of the frame. Opening 49 also curves upwardly and terminates at cross-tie 51 in compression member 10. It will be noted that the juncture of compression and tension members 10 and 12 with the journal box 20 is of a rigid and comparatively extensive nature.

The middle section Z of diagonal portion 26 of the tension member, which comprises the aforementioned box or enclosed configuration in vertical cross-section insures that portion 26 of the tension member will be adequately rigid in the transition area from upward to downward flexure (assuming a direction toward the outer ends of the frame) due to the bending stresses. Section Z also provides a region in which the neutral axis of the diagonal member is located centrally of its cross-section. In the embodiment shown, the length of central section Z of diagonal portion 26 is less than half the length of either lower section X or upper section Y.

It will be apparent, then, that as bending stresses occur in the frame structure the lower inverted-U section X will effectively resist the upward bending stresses, the upper section Y of normal upright U-shaped configuration will effectively resist the downward bending stresses, and the middle box-like section Z will provide rigid resistance in the transition area of the bending stresses from an upward to a downward nature (assuming a direction outwardly toward the ends of the frame).

A particularly advantageous feature of the invention when compared with prior art side frame construction, is the realignment of the neutral axis of the tension member 12 achieved. Graphic comparison is made in FIGS. 9, 10, and 11 wherein FIG. 9 illustrates a prior art side frame SP and the neutral axes 61 and 62 of its compression member 10 and tension member 121, respectively. As shown, axes 61 and 62 intersect each other at a common intersection M with a vertical loading plane 63 containing the horizontal axis of rotation 66 of a wheel axle received by the frame. The tension member 12P has a solid lower web 64 and open top resulting in a generally uniform transverse U-shaped cross-section (resembling that illustrated in FIG. 4) causing its neutral axis to be parallel to a geometric longitudinal axis 65. The term neutral axis is used herein in its usual sense, i.e., as the line of no stress of a beam subjected to bending. The side frame SP is illustrated as identical with side frame 8 of FIG. 10 in structure, dimension, and proportions except for differences in upper and lower web lengths in the respective tension members 12 and 12P.

The structural details of the tension member 12 of the side frame 8 of FIG. 10 are described earlier herein with respect to FIGS. 1 to 6. The compression member 10 of the illustrated prior art construction and member of the improved side frame 8 are identical and hence have a similar neutral axis 61. The tension members 12P and 12 of the prior art frame and the improved frame, respectively, have identical longitudinal axes 65 because the overall dimensions of these tension members are identical. Hence, in lateral silhouette, frames SP and 8 are identical.

According to the invention, however, the upper and lower web structure of the tension member 12 resulting from 1) inverted-U cross section of the lower portion (FIG. 2), (2) box section at the middle (FIG. 3) and (3) upright-U cross section of the upper portion, aligns the neutral axis 67 at a less steep inclination than that of the geometric horizontal axis 65 of the same member 12. As the axis 65 occurs also in the prior art tension member, the neutral axis 67 of the improved tension member is similarly angularly displaced with respect to the neutral axis 62 of the prior art tension member as shown in FIG. 11 wherein the axes of both frames are superimposed.

Obvious in FIG 11 is the spacing of the intersection N of the improved side frame outwardly from the intersection M with respect to a vertical center plane 70 of the side framesby a distance 71. Further shown is that the vertical loading axis 63 intersects the neutral axis 67 of the improved tension member at a point 0 located inwardly toward the central plane 70 from point N at the intersection of the axis 67 with the compression member axis 61.

The most important advantage of changing the neutral axis of the tension member from that of the prior art axis 62 to that of neutral axis 77 and the associated shifting of the intersection of the tension and compression members outwardly is the substantial reduction of the secondary bending stresses of the various members of the frame achieved. FIGS. and 11 are neutral axes diagrams of the side frames in FIGS. 7 and 8, respectively, and are exemplary of loading conditions to which such side frames may be subjected. The deflections of the neutral axes in each case are, of course, greatly exaggerated for clarity of illustration of the principle of operation involved.

In FIGS. 10 and 11, the unloaded position of the axes is illustrated in dotted lines; the full lines of each figure represent the neutral axes of the loaded frame. In each case the frame as a whole is bowed downwardly at the middle as any simply supported beam will be when it is loaded at the middle and supported at the ends. As a basic observation, the beam will deflect downwardly at the center with shortening by compression taking place along its upper side and stretching by tension taking place along its underside.

Considering now the axes diagram of the conventional frame in FIG. 10, the frame is acted upon by three external forces, -i.e., the main supporting forces 75 and 76 at axes intersections D and C and the loading force 84 applied centrally along the axis of the springseat extending between axes intersections B and A. Two basic force components contribute to the moments 80 and 81 acting about intersections D and C, respectively, to deflect the neutral axes 61 of the compression members and the neutral axes 62 of the tension members downwardly. One component of each moment 80 and 81 is generated as the compression member is deflected downwardly through sagging of the beam as a whole under loading. The other component is generated from the stress and deflection developed in the spring seat of the frame by the main load 84. This load rotates the fixed joints defining intersections B and A. Such rotation is transmitted by the frame columns to the fixed joints at intersections E and F, and thence to the joints at intersections D and C.

FIG. 11 illustrates the neutral axes of the improved frame 10 in dotted line at the unloaded condition and in full line when subjected to the load 84, and supported at points 0 by forces 75 and 76 acting in vertical planes 63 having the same spacing as in the prior art frame of FIG. 10. Moments acting about the various intersections of the axes generated as discussed immediately above are illustrated in dotted line arrows about respective joints in both figures. The arcuate full line arrows represent countermoments about the various joints introduced into the frame through practice of the present invention.

Strong countermoments 86 and 87 are generated about axes intersections D and C, respectively, through application of the main supporting forces 75 and 76 at points 0 inwardly from intersections D and C toward the vertical plane 70. The countermoments 86 and 87 eliminate to a substantial extent the downward curvature of the neutral axes in respective diagonal portions characteristic of the conventional tension member as illustrated in FIG. 10.

In FIG. 11, this curvature is illustrated as practically removed. As intersections D and C comprise relatively fixed portions of the adjacent tension and compression members, any rotation thereof by a countermoment results in removal of downward deflection of the portions of the compression member between D and E, and F and C. The fixed intersections at E and F are in turn subjected to countermoments 88 and 89, respectively. Rotation of the joints at E and F produces in turn a countermoment at the joints defining intersections B and A, respectively. Transmission of the countermoments at the various joints as just described tends, in each case, to reduce the secondary bending stresses occurring in all members of the frame and, hence, the transverse deflection thereof. The countermoments generated in the frame from D to E to B and concurrently from C to F to A when considered as to their net effect on joints at B and A are apparently greatly preponderate relatively to countermoments 91 and 92 generated about joints B and A, respectively, directly from joints D and C, respec tively, to the interconnecting tension members.

In actual practice, the S-shaped deflection characteristic of each diagonal portion of the tension member in the convention frame, and any substantial upward convex deflection, is found to be absent in the tension members of a frame loaded according to FIG. 11. The theoretical explanation for this result is not completely known at this time. Deflections of this nature are difficult to observe visually in an actual frame but may be readily ascertained by known instrumentation. The above result has been fully established by direct visual observation of the reaction to loading of wooden models comprising joint-blocks and rods extending therebetween having section moduli in proportion to respective members of the frame which they represent.

The improvement in loading capacity of car frames resulting from the present invention was indeed unexpected when considered in relation to the small amount of modification of the conventional frames. Under actual testing, conventional side frames usually fail under a test load of about 5% to 10% above the minimum ultimate load required by the Association of American Railroads (A.A.R.). In most cases, the failure occurs by rupture of a diagonal portion of the tension member. Side frames for journals of 6% inches in diameter and 12 inches in length incorporating the improved tension member described herein but of otherwise conventional design, failed at an ultimate load of 868,000 to 894,000 pounds. This is approximately 16 to 20 percent above the minimum ultimate load of 750,000 pounds required by the A.A.R. for side frames of this size, thereby indicating substantial increase in strength of the diagonal portions of the tension member. Such improvement borders on the phenomenal in view of the mere redistribution of metal within the diagonal portions of the tension member without an increase in weight.

The terms and expressions which have been employed are used as terms of description and not of limitation and there is no intention of excluding such equivalents of the invention described, or of the portions thereof, as fall within the purview of the claims.

What is claimed is:

1. In a railway truck side frame, the combination of a lower tension member and an upper compression member merging at the outer ends thereof with journal-receiving portions; spaced columns extending between and rigidly attached to said members intermediate said j ournalreceiving portions; said tension member comprising a generally horizontal load-supporting portion disposed between said columns and diagonally-extending portions joining said columns and said journal-receiving portions; each of said diagonal portions having a geometric longi- 7 tudinal axis and a neutral axis in intersecting less steeply inclined relation with the longitudinal axis; said compression member having a neutral axis extending in opposite directions outwardly from the columns to intersect first with said geometric axes and then further outwardly with the neutral axes of said tension members.

2. In a railway truck side frame, the combination of a lower tension member and an upper compression member merging at the outer ends thereof with journal-receiving portions adapted for receiving wheel axles with the axes of rotation thereof contained in two spaced vertical planes of said frame; spaced columns extending between and rigidly attached to said members intermediate said journal-receiving portions; said tension member comprising a generally horizontal load-supporting portion disposed between said columns and diagonally extending portions joining said columns and said journal-receiving portions; said compression member having a neutral axis extending through said planes; each ofsaid diagonal portions having a geometric longitudinal axis, and a neutral axis in crossed and less steeply inclined relation with said longitudinal axis intersecting said axis of the compression member outwardly from said column beyond said planes.

3. In a railway truck side frame, the combination of a lower tension member and an upper compression member merging at the outer ends thereof with journal-receiving portions, spaced columns extending between and rigidly attached to said members intermediate said journalreceiving portions; said tension member comprising a generally horizontal load-supporting portion disposed between said columns and diagonally extending portions joining said columns and said journal-receiving portions; each of said diagonal portions comprising, in vertical cross section, a lower section of inverted U-shape configuration; a middle section of box-like configuration, and an upper section of normal upright U-shape configuration occurring along a longitudinal geometric axis and disposing the neutral axis thereof in crossed, less steeply inclined relation with the longitudinal axis.

4. The side frame of claim 3 wherein: said journalreceiving portions are arranged With respect to axes of rotation for wheel axles received therein occurring in two spaced parallel planes, said planes being spaced at a distance centered within a greater distance separating the intersections of the neutral axis of the compression member with the neutral axes of said diagonal portions.

References Cited in the file of this patent UNITED STATES PATENTS 1,745,847 Floyd Feb. 4, 1930 1,962,442 Hedgcock June 12, 1934 2,097,579 Symington Nov. 2, 1937

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