US2931319A - Welded bolster construction - Google Patents

Description

April 5, 1960 J. E. CANDLIN, JR

WELDED BOLSTER CONSTRUCTION 2 Sheets-Sheet 1 Filed March 30. 1953 Inventor Aftorney l r M IIIIIIIIIIIIIIIIIIIIIII'II I James E. Candlin Jr.

April 5, 1960 J. E. CANDLIN, JR

WELDED BOLSTER CONSTRUCTION v 2 Sheets-Sheet 2 Filed March 30. 1953 Fan-=2 95 5 5: 2..

Inventor JamcsE. Candli c771 Attorney nited States Patent WELDED BOLSTER CONSTRUCTION James E. Candlin, Jr., Hammond, Ind., assignor to Pullman-Standard Car Manufacturing Company, Chicago, Ill., a corporation of Delaware Application March 30, 1953, Serial No. 345,657

2 Claims. (Cl. 105-414) The present invention relates to a welded body bolster construction in which possibility of failure is minimized, and more particularly to such a construction which aifords relief of stresses on certain critical weld portions and provides for plastic deformation at non-critical bolster portions under extreme load conditions.

In the two embodiments of the invention illustrated, there is formed in each case a welded body bolster having a diaphragm provided by a pair of aligned webs spaced to receive a center sill therebetween with top and bottom cover plates welded to their upper and lower edges. The webs have keyhole-shaped slots opening at their upper inner corners defining with the adjacent web edges tongues on and around which extend the welds between each web and top plate and between the web and center sill, and which are kept substantially free of vertical load stresses in the webs by means of the slots. The top and bottom plates are tapered from the center sill to the side 'sills, and their rear edges at the inner ends are faired or curved in the direction of the midpoint of the center sill adjacent their connections thereto, directing horizontal load stresses in the plates away from the adjacent weld ends. In one of the illustrated forms, the opposed halves of the top and bottom plates abut the center sill, and in the other form they abut each other at the center line of the center sill. Relatively long side sill reinforcements are provided for connection of the bolster ends to the side sills. Railway car bolsters are subjected to several types of stresses, sometimes acting in different directions at once, and therefore must be constructed to withstand compression, tension, and torsion shear, and bending forces. Furthermore, many of the forces acting on a bolster may change very suddenly and abruptly, varying between zero or a low value and a maximum or peak almost instantaneously, especially in the case of stresses resulting from buifing or like impacts on the center sill, which are transmitted to the bolster through its connection to the center sill. Lateral deflection of the center and side sills occurs in the operation of the car and causes deflection of the bolster longitudinally, and with the vertical loads on the bolster results in the imposition of stresses of great magnitude on the junction of the bolster web or diaphragm with the center sill at each side of the latter, and particularly at the corners or angles defined between the center sill sides and the top plates, so that the upper inner corner portions of the bolster webs are subjected to rather violent disruptive forces. Bolster failure occurs most frequently at the center sill connection, and particularly in the area adjacent the top of the center sill. The most critical portion of a railway car bolster is at the connection to the center sill, and the next most critical is at the side sill connections. The bolster of this invention has great strength and rigidity at such connections to obviate failure or permanent deformation at the critical portions, and provides relatively less rigid intermediate portions which are non-critical and at which plastic deformation occurs to increase the energy absorption of the bolster. The effect of the keyhole slots in directing stresses away from the portions of welds adjacent each other at the junctures of the webs and top plates with the center sill reduces the strains on such weld portions and thus greatly lessens the chances of rupture of the welds and failure of the bolster.

It is an object of the invention to provide a welded body bolster having means for relieving critical weld portions of load stresses so as to minimize the possibility of failure.

Another object is the provision of a welded web type bolster in which the web is so formed as substantially to prevent vertical load stresses on those portions of the welds between the web and top plate and between the web and center sill located adjacent each other.

Another object is the provision of a welded body bolster with a web having a stress-directing aperture at a corner portion adjacent the top plate and center sill to direct stresses in the web away from the welds between the parts at the corner.

A further object is the provision of a welded body bolster constructed to provide critical portions of great strength to resist failure and relatively flexible non-critical portions for plastic deformation, to increase energy absorption and reduce possibility of failure.

It is also an object of the invention to provide a method of relieving a portion of a web of a welded bolster construction of stresses due to imposition of a load on the web so as to minimize strains on the welds joining the Web to other parts.

It is another object of the invention to provide means for relieving stresses in portions of welds in bolsters or other welded structures.

A-further object is the provision of a method of relieving stresses in portions of welds in bolsters or other welded structures.

Other and further objects, advantages, and features of the invention will be apparent to those skilled from the following description, taken with the accompanying drawings, in which:

Fig. 1 is a plan view of the major portion of one form of a bolster of this invention, with parts broken away and in section;

Fig. 2 is a vertical sectional view of the bolster taken as indicated by the line 22 of Fig. 1;

Fig. 3 is an enlarged vertical sectional view of a portion of the bolster, taken substantially as shown by the line 3-3 of Fig. 2;

Fig. 4 is a view similar to Fig. 1, but showing a somewhat diiferent form of the bolster;

Fig. 5 is a vertical sectional view of the bolster shown in Fig. 4, taken substantially as indicated by the line 55 thereof; and

Fig. 6 is an enlarged fragmentary detail view of a portion of the bolster as shown in Fig. 5.

Referring first to Figs. 1 to 3 of the drawings, there is shown a railway car center sill 10 of common inverted channel form, provided by two Z members welded together, with outwardly directed flanges 11 at the open bottom thereof. A side sill 12 in the form of an angle member is disposed outwardly of each side of the center sill and parallel thereto, with a horizontal flange 13 extending inwardly. Suitable floor stringers 14 extending longitudinally of the car between the side sills and center sill are also provided. The bolster 15, of which only somewhat more than half is illustrated because it is symmetrical about the longitudinal axis of the car, comprises a diaphragm extending transversely of the center sill provided by a pair of aligned webs 16 each of which is welded at its inner end to one side of the center sill and at its outer end to the web of a relatively long side sill connection or reinforcement 17 of channel form. The

reinforcement 17 is disposed with its flanges extending inwardly above and below the web end, the upper flange acetate lying under and being riveted or otherwise secured to the horizontal flange 13 of the side sill. Welded to the upper edge of each web 16 is a top cover plate 18 extending between the center sill and the side sill reinforcement 17 to which it is welded at its inner and outer ends respectively. Each of the top plates is substantially flush with the upper surface of the center sill, which is in the same plane as the side sill flange 13, the web and plate being suitably formed to have the outer end portion of the plate 18 extend under the upper flange of the rein forcement 17. The stringers 14 have their ends connected to the top plates, their upper surfaces being flush with the top plates except that the end portions may be offset downwardly for welded securement to the plates as shown. The top plates are of tapered form, their edges converging outwardly of the center sill. rear edge, that is the edge directed toward the center of the car, formed on a sweeping curve adjacent the inner end of the plate so as to fair into the center sill, as indicated at 19 in Fig. 1. This sweep or fairing 19 avoids the raising or concentration of stress due to horizontal load on the bolster which results from an abrupt angular relation of the plate edge with the center sill, tending to direct stress flow away from the end of the weld between the top plate and center sill. The inboard or rear side of the bolster is given a conformation such as to sustain the tensile stresses imposed thereon by impacts on the adjacent end of the center sill. The curved edge portion also provides for a relatively long or extended weld connection between the plate and center sill parallel to the direction of draft and buff stresses which minimizes the effect of incipient notches which may be present therein and adds strength to the connection of the bolster to the center sill. A pair of bottom cover plates 20 generally similar to the top plates are welded to the lower edges of the webs 16, each bottom plate having its inner end welded to the edge of one of the bottom flanges of the center sill and its outer end welded to the side sill reinforcement 17. Each of the bottom plates has a fairing 21 similar to the fairings 19 of the top plates. To allow for variation or roughness in the center sill flanges, the bottom plates are made slightly longer than necessary to extend from the reinforcements 17 to the flanges. and the flanges 11 are cut away at their edges as may be required to accommodate the plates, as shown by way of example at 22. when the bolster is assembled with the center sill. The forward or outboard edges of the top and bottom plates may be faired like the rear edges, if desired. but the fairing is not as important in this case, since the main stresses on the outboard sides of the bolsters are compressive, resulting from impacts on the adjacent center sill end, and tensile stresses due to im acts on the opposite or remote end of the center sill are weaker than those on the corresponding side of the bolster adjacent the struck end.

The webs 16 are located substantially in the plane of the vertical neutral axis of the bolster so that they bear only a minor proportion of any horizontal load to which the bolster is subjected. Between the two halves of the bolster. within the center sill, is a center filler comprising a base plate 23 to which is welded a tubular center pin retainer 24. A side brace 25 in the form of a plate substantially closing the interior of the center sill and having a cutout in its lower portion to accommodate the center pin retainer is disposed in alignment with the webs 16 and over the retainer, and welded to the interior surfaces of the center sill and to the base plate 23 and retainer 24. angular form are disposed parallel to the sides of the center sill, on opposite sides of the side brace and in alignment with each other, and are welded to the base plate, side brace, and retainer, portions of their inner edges being cut away to accommodate the retainer. The

Each has its A pair of end braces 26 of generally tricenter filler reinforces the center sill and bolster, the side brace 25 forming in effect a connecting extension of the bolster webs 16. The base plate 23 extends longitudinally of the center sill a distance corresponding to the length of the inner end edge of the top plates 18, and is arranged with its forward edge in the same vertical plane as the junctions of the forward edges of the top and bottom plates with the center sill, as shown in Fig. 1. The rear edge of the base plate is cut away on a substantially semi-circular curve so as to fair into the center sill on each side. Below the center filler base plate 23 extends a sole plate 27, which is of sufficient size to extend beneath the center sill flanges 11, to which it is welded. Both the base plate and the sole plate are apertured for the reception of a suitable center pin, not shown. A body center plate 28 of any desired type is disposed on the lower face of the sole plate 27, and secured by rivets or the like to the sole plate and the center sill flanges. At an intermediate portion of each bottom plate 29 is a body side bearing 29 formed of a suitably shaped plate secured to the bottom plate below a stiffener 30 formed by a pair of flat plates on opposite sides of the bolster web 15 in alignment with each other transversely of the web each extending between the top and bottom plates and welded to these plates and to the web. The stiffener plates have their corners adjacent the webs cut away to accommodate the welds between the web and the plates 18 and 20.

At its upper inner corner, that is, the corner defined between its upper and inner edges, each web 16 is provided with a slot 31 of a generally bulbous or keyhole shape having a smooth generally curvilinear contour eliminating possible stress-concentrating angles or notches. The slot is best shown in Fig. 6 inconnecton with the other form of the bolster. The slot has a relatively narrow open outer end which separates the ends of the upper and inner web edges, and a relatively large closed inner end shown as of arcuate conformation the outer edge portions curving reversely from the arcuate edge porton to the respective web edges. With the upper edge and inner end edge of the web, the slot 31 defines a pair of relatively narrow web portions or tongues 32 and 33, the tongue 32 extending alongthe upper web edge and the tongue 33 along the inner end edge of the web. Each tongue has an inner side edge defined by a part of the closed end of the slot, more or less parallel to its outer side edge, which is defined by the web edge along which the tongue extends, and a convexly curved outer end edge connecting the side edges. The outer ends of the tongues are spaced apart by the open outer end of the slot 31, so as to permit the welds 34 on opposite faces of the web 16 between the web and the top plate 18 and the welds 35 between the Web and the center sill to be joned or continue uninterruptedly around the cnds of the tongues 32 and 33 respectively, as will be clear from Fig. 3. This construction also permits the weld 36 along the lower face of the top plate between the top plate and the center sill to continue uninterruptedly the full length of the connection between the plate and sill.

While such continuity of the welds is advantageous from the standpoint of weld strength, it is secondary to the man purpose of the slot, which is to divert or direct stresses occasioned in the web away from the corner of the web, or more precisely from the tongues 32 and 33, more or less as indicated by the direction arrows in Fig. 6, so that the tongues and particularly the end portions thereof are substantially relieved of such stresses. The weld portions on the tongues thus are maintained substantially free of stress, the slot 31 contributing to a reduct'on of the stress level at the critical center sill connection to very greatly reduce the possibility of failure of the welds and fracture of the bolster parts. The slot need not have the particular shape or contour illustrated, and may be a closed slot or hole insteadof an open slot so long as it is of such shape and so located as to provide a substantially unstressed portion or portions on whichthe weld connections between the parts extend. p

In Figs. 4 to 6 there is illustrated a bolster 38 differing in some respects from the bolster 15, the differences relating primarily to the disposition and securement of the top and bottom plates relative to the center sill. Parts of thebolster 38 of Figs. 4 to 6 are identified by the same reference numerals as substantially identical parts of the first-described bolster 15. A center sill 10 is provided as before described, between the side sills 12 and reinforcements 39, which latter differ from the side sill reinforcements 17 of Figs. 1 to 3 in being angle members instead of channels. Each reinforcement is welded by the edge of a vertically disposed flange to the inwardly directed horizontal flange 13 of one of the side sills 12, with its other flange extending horizontally and inwardly. The webs 16 forming the bolster diaphragm are secured at their inner ends to the sides and bottom flanges 11 of the center sill 10 by the welds 35, substantially as in the other form of the invention, and at their outer'ends are welded to the vertical flanges of the reinforcements 39. The webs are of course aligned transversely of the sills, but in this case their upper edges are at the level of the top of the center sill and straight throughout their extent so that the top plates may be perfectly flat and extend over the center sill and under the side sills. The side brace is welded within the center sill, in alignment with the webs 16, and to a center filler base plate 40 which is similar to the plate 23 previously disclosed but does not have the arcuate cutout in the rear edge. The base plate 40 is welded to the inner surfaces of the center sill sides to extend flush with the lower faces of the flanges 11, and the center pin retainer 24 and end braces 26 are d'sposed and welded in the same way as in the first form of the bolster. Top cover plates 41 are welded to the upper edges of the webs 16, and extend from the reinforcements 39 over the center sill to meet at the center line thereof. The top plates are similar to the top plates 18 in having the edges converging from the center sill outwardly and having the rear edges adjacent the inner meeting ends thereof curving back in smooth sweeps as shown at 42, but are longer than plates 18 and are not bent downwardly at their outer ends. A weld 43 secures the inner ends of the top plates 41 to each other and to the top of the center sill 10. The top plates in this instance do not extend flush with the upper surfaces of the side sill flanges 13, but have their outer ends lying against the lower faces thereof and welded or otherwise suitably secured to the flanges. Floor stringers 14 are provided in the usual manner, as described in connection with the bolster 15, but except for their connections are disposed at a higher level than the upper surface of the top plates 41, since they extend in the plane of the horizontal flanges 13 of the side sills 12. Bottom plates 44 are welded to the lower edges of the webs 16, extending from the longitudinal center plane of the center sill 10 beneath the plate 40 to the reinforcements 39, to which their outer ends are welded. As evident from Fig. 5, the bottom plates extend horizontally under the center sill and are bent upwardly at a slight angle adjacent the outer edges of the flanges 11, and are bent to the horizontal adjacent the reinforcements 39. The inner ends of the bottom plates 44 are welded to each other and to the center filler base plate 40 as indicated at 45, and are thus secured to the center sill, though not directly welded thereto. The top and bottom plates are advantageously formed of the same shape and dimensions in the flat, the bottom plates tapering and having the smooth rearward sweeps 42 of their rear edges adjacent their inner ends as in the case of the top plates 41. As with the top and bottom plates 18 and 20, the forward or outboard edges of the plates 41 and 44 may be curved in the same manner as their rear edges.

Body side bearings 29 and stiffeners 30 are formed and secured on the bolster 38 substantially as in the bolster 15. The sole plate 27 is not employed in the bolster 38, since it is substantially replaced by the inner end portions of the plates 44 extending under the center sill 10. The body center bearing plate 28 is disposed against the lower surface provided by the bottom plates 44, and is secured by rivets to the bottom plates, the center sill flanges 11, and the tiller base plate 40, the bottom plate thus being additionally connected to the sill. The keyhole slots 31 are provided in the upper inner corners of the webs 16 just as in the case of the bolster 15, defining the tongues 32 and 33, as will be evident from Fig. 5, and as shown more clearly in Fig. 6. It is to be noted, however, that in the bolster 38 there are no welds 36 between the top plates and the sides of the center sill, as in the bolster 15, since the top plates do not abut the center sill but overlie it, and are welded thereto only at its center line. The welds 34 between the top plates and webs and the welds 35 between the center sill and webs extend continuously through the apertures. and along and around the tongues, just as in the bolster 15. The effect and advantages of the slots 31 in decreasing the likelihood of failure of the bolster, and thus effectively increasing its strength and resistance to fracture and deformation, are substantially the same as described in connection with the other form of the bolster. There is, however, an additional advantage provided by the slots 31 in the bolster 38. Because the top plates 41 are not rigid with the center sill at its sides, horizontal impact forces acting on the bolster through the center sill tend to cause a temporary buckling or upward flexing of the top plates adjacent the sides of the center sill 10, which in the absence of the slots 31 might exert such a disrupting force on the welds 34 at the center sill as to cause failure of the welds at the ends, and thereby also tend to disrupt the ends of the welds 35 at the upper inner corners of the Webs 16, it being remembered that in the absence of the slots the welds would extend into and terminate at the angle defined by the surfaces of the center sill and top plate. By reason of the slots 31, however, a relatively flexible portion of each web 16 is provided adjacent the area of upward flexing of the respective top plate, namely, the tongue 32. This tongue, by reason of its relatively small cross section and vertical dimension,

moves sufficiently with the flexing of the top plate so to ease the disruptive strain on the weld 34 as to prevent failure of the Weld adjacent the slot. At the same time, the fact that the weld 35 does not extend to the top plate by reason of its following the surfaces of the tongue 33 precludes any stressing thereof by such buckling or flexing of the top plate, so that this weld also is safeguarded against failure.

The webs 16 in the bolster 38 are stepped or coped to accommodate the center sill flanges 11, and have slots or notches 46 opening from their lower edges at the stepped portions to avoid dimculty in fitting the webs to the flange edges. The notches 46 are of sufiicient width to bridge over the edges of the flanges regardless of roughness or width variations of the flanges, and of sufficient depth or height to extend above the upper surfaces of the flanges. The upper ends of the notches are formed on a smooth curve between the notch sides, so that stressraising angles are avoided. The notches permit the welds 35 between the webs and center sill to extend uninterruptedly along both sides of the webs through the notches and at their lower ends in the same way as they continue through the slots 31 at their upper ends, and similarly the welds between the webs and the bottom plates 44 may be continuous through the notches. The notches 46, however, do not function like the slots 31 to minimize or relieve stresses, since as will be obvious from Fig. 4 they do not appreciably prevent stresses in the webs 16 from acting on the angle or corner portions defined between the notches and the lower web edges. The notches remote bolster.

do provide for a certain degree of yielding upon relative vertical movement as between the bottom plates and the center sill, such yielding tending to prevent excessive strains on the weld portions adjacent the notches resulting from such movement.

As with the bolster 15, the webs 16 of the bolster 33 are disposed substantially at the vertical neutral axis of the bolster, so as to be subjected to a minimum of horizontal load, while providing the necessary strength for vertical loads. The shape of the top and bottom plates and the connections to the center and side si is provide for the greatest strength and rigidity at the center and ends of the bolster, the most critical portions, to resist horizontal forces and allows deformation under extreme impact to occur at intermediate non-critical portions, as in the case of the bolster 15. The connections of the top and bottom plates to the center sill by welds in the vertical midplane thereof largely eliminate the possibility of bolster failure at the center sill because longitudinal forces acting on the center sill as the result of butting impacts or the like are transmitted to the bolster at the widest part thereof through long welds extending parallel to the direction of such forces.

The taper of the top and bottom cover plates is so calculated as to provide for substantial uniformity of stress along the bolster, or in other words to give in conjunction with the webs a section modulus conforming to the normal loads on the bolster. The long side sill reinforcements 17 or 39 at the ends of the bolster give strength and rigidity sufficient to withstand the shear stresses resulting from horizontal impact forces on the center sill and therefore more than sufficient to resist bending under such forces. The construction largely prevents failure at the bolster end connections, which are also critical portions of the bolster, although not to the same extent as the center'sill connections. At the same time, the strength of the bolster at the center and side sills results in the parts of the bolster intermediate these critical portions having relatively less rigidity, these intermediate parts or portions being relatively non-critical. It is at these less rigid and non-critical portions that plastic deformation of the bolster occurs because of the relative flexibility, preventing more serious damage to or actual failure of the bolster, and permitting absorption of energy in excess of the elastic limit.

The disposition of the diaphragm webs in the plane of the vertical neutral axis 'of the bolster results in 'sub stantial reduction of theproportion' of horizontal load carried by the webs. The consequent largely unstressed condition under horizontal load of the welds between the webs and the center sill contributes to the resistance to failure of the center sill connection of the bolster, and in conjunction with the reduction of stress on these welds under vertical load afforded by the slots 31 practically eliminates the web connections to the center sill as a source of bolster failure.

The bolster of this invention is relatively more flexible than bolsters of conventional construction, and while it has just as desirable strength and energy absorption characteristics as such bolsters, it provides for a more uniform distribution of impact forces throughout the underframe and thus further minimizes failure possibilities. Draft or bufiing stresses on one end of the center sill are transmitted by the center sill to the bolster adjacent that end and also to the bolster at the remote end, and the bolsters in turn"transmitunabsorbed stress through the side sills to the bo'dyframing. With bolsters of the conventional type, their great rigidity results in a major proportion 'of the longitudinal stress in the center sill under "draft or buff being imposed on and transmitted by the bolster adjacent the center sill end at which the stress originates,'a'nd only a'srnall part is carried to the Thus's'onieportions of the car struc ture are subjecte d'to greater'or more concentrated stresses thanothe'rs,andpossibilitybf failure is'enhariced or i makes necessary the use of more or stronger material. The use of bolsters of this invention results in a more even division of the longitudinal forces in the center sill as between the two bolsters, so that a more even and uniform distribution of stresses over the car structure is achieved. The exact proportion of stresses transmitted to and by the several members depends upon various factors, including the type of lading and its manner of securement, if any, but the distribution in any case is more favorable with the disclosed bolster than with conventional ype bolsters.

The invention therefore provides a greatly improved welded body bolster construction in which possibility of failure is greatly minimized by reduction of stress level at critical portions, as well as a method of relieving vertical load stresses in the bolster web. The invention, however, is not limited to incorporation in bolsters having but a single diaphragm for the advantages of the slots 31, for example, may be even greater in the case of bolsters with a plurality of diaphragms than in bolsters such as disclosed. In fact, the invention in certain aspects at least is advantageously applicable to welded structures of the general type or relationship of parts represented by the bolsters.

What is claimed is:

1. A railroad car underframe construction including a bolster subject to stresses resulting from the combination of static and impact loads applied to the car structure in vertical and horizontal directions, said loads being transmitted to the bolster through the underframe resulting in a concentration of high tension stresses in the upper portion of the bolster, said bolster including a web having at its inner end a pair of adjacent rightangularly related edges and having an open slot of generally keyhole configuration extending diagonally into the web corner portion adjacent said edges, said slot having a closed inner end of smooth curvilinear contourand cooperating with said edges to define a pair of tongues each extending along one of said edges, a center sill having a plate surface substantially perpendicular to and extending transversely of the web and connected to one of said edges by a continuous weld provided along both sides and across the end of the tongue extending along said one edge, and a top cover plate member substantially perpendicular to and extending transversely of the web and connected to the other of said edges by a continuous weld provided along both sides and across the end of the other of said tongues, whereby stresses in the web are directed away from the tongues by the inner end of the slot to substantially relieve the weld connections thereon of such stresses, the said top cover plate in the area of the said open slot being flexible with respect to the center sill thereby permitting relative movement of the top cover plate and the center sill without disruptive strain on the welds.

2. A railroad car underframe construction including a longitudinal center sill member, a pair of longitudinal side sill members disposed outwardly from the center sill, one on each side, a bolster member extending from each side of the center sill to the respective side sills "and having a top cover plate member secured by welding to said center sill and side sill members, said bolster member being subject to stresses resulting from the combination of static andimpact loads applied to the'car structure in vertical andhorizontal directions, said loads being transmitted to the bolster memberthrough the said center sill and side sill membersresulting ina concentration of high tension stresses inthe upper portion of theboister adjacent to thecenter sill, said bolster member including "a web having at its inner end a pair of adjacent rightangularly related edges and having anopen slot of generally keyhole configuration extending diagonally into the web corner portion adjacent said edges, said slot havin g' a elose'd inner 'e'ndof smooth curvilinear contour and co-operating with said edges to define a pair of tongues each extending along one of said edges, said center sill having a plate surface substantially perpendicular to and extending transversely of the web and connected to one of said edges by a continuous weld provided along both sides and across the end of the tongue extending along said one edge, and said bolster topcover plate being substantially perpendicular to and extending transversely of the web and connected to the other of said edges by a continuous weld provided along both sides and across the end of the other of said tongues, whereby stresses in the web are directed away from the tongues by the inner end of the slot to substantially relieve the weld connections thereon of such stresses, the said bolster top cover plate in the area of the said open slot being flexible with respect to the center sill thereby permitting relative movement of the top cover plate and the center sill without disruptive strain on the welds.

References Cited in the file of this patent UNITED STATES PATENTS 840,797 Ostrander Jan. 8, 1907 10 2,146,333 Deming Feb. 7, 1939 2,242,727 Meyer May 20, 1941 2,247,273 Blomberg June 24, 1941 2,382,584 Scheyer Aug. 14, 1945 FOREIGN PATENTS 723,623 Germany Aug. 7, 1942 OTHER REFERENCES 15 number 11, November 1946, pages 1091-1108. Pages 1095, 1102 and 1103 relied on.

Article entitled: New Factors to be Considered in the Design and Welding of Ships, by Milton Forman, in the Journal of the American Welding Society, vol. 27,

20 No. 9, September 1948, pp. 672-674.

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