US3195477A

US3195477A - Conveyance construction

Info

Publication number: US3195477A
Application number: US143088A
Authority: US
Inventors: Bobby L Jones; Charles R Gray
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1961-10-05
Filing date: 1961-10-05
Publication date: 1965-07-20
Anticipated expiration: 1982-07-20

Description

J y 1965 a. JONES ETAL CONVEYANCE CONSTRUCTION Filed Oct- 5, 1961 INVENTORS CHARLES R. GRAY ATTORNEYS BOBBY L. JONES United States Patent ration of Delaware Filed Get. 5, 1961, Ser. No. 143,088 12 Claims. (Cl. 105-422) The present invention relates generally to freight carrying conveyances and more particularly to the structure of the flooring of such conveyances.

For many years, in freight conveyances such as railway rolling stock, all-steel freight cars of the open top variety had been used provided with floors comprised of steel plates fastened together. These gondola cars, as they are called, were fairly satisfactory for the transportation of freight of a loose nature such as coal, grain, iron ore, pig iron, or steel scrap or the like. Loose freight could simply be dumped into the car and transported without securement of any kind, the steel floor providing underlying support for the freight and nothing more.

However, for those types of lading which needed to be immobilized with respect to the freight car for satisfactory transportation and those which needed floating or restrained connection with the car, wooden freight car floors had long been the only practical solution in both open top and box cars. In order to immobilize freight or to set it up in floating relation to such Wooden flooring of freight cars, various blocking arrangements were used. Heavy wooden blocking was placed in a position on the car floor where it would abut against the proper part of the lading and this heavy blocking was nailed in this position to the wooden floor with heavy nails. When the freight reached its destination, the blocking was ripped up in order to remove the freight from the car.

The old steel plate floors, which obviously could not be used in connection with blocking, had fairly long life. On the other hand, wood car floors did not. The impact forces of loading and unloading using heavy clamshell buckets and magnets in open top cars and the fork trucks used for loading and unloading box cars soon ruined the wooden flooring. Moreover, Wooden flooring continuously used for blocking freight deteriorated rapidly due to weakening by the numerous nail holes.

Thus, the railroads were obliged to buy two kinds of cars, steel floor and wood floor. But this initial double expense was not the only disadvantage, as the steel cars and wood cars often ran empty. For example, in the steel industry, pig iron and scrap steel came into the plants in the old steel bottom cars and the finished prodnot packaged to prevent damage in transportation went out in wooden bot-tom cars. Most of the time the wooden bottom cars came in empty and the steel bottom cars went out empty because neither type of car alone could handle both types of freight.

In an effort to provide a single all-purpose, stronger freight car flooring, it was proposed quite some time ago to provide steel flooring having inserts comprising wooden nailing strips, as in US. Patent Nos. 986,422 of 1911 and 2,056,137 of 1936, in the hope of combining the strength of steel with the nailability of wood. However, in spite of the great additional expense involved, this solution has not been satisfactory because the nail holes were concentrated in the inserted strips with the result that the wood broke up and deteriorated very rapidly. Furthermore, all attempted combinations of wood and steel have resulted in inordinate steel corrosion, possibly because the wood retains moisture and holds it in contact with steel surfaces.

In recent years, an all-metal flooring has been devel oped which is strong and has good nailing properties.

This flooring is described in US. Patent No. 2,667,243 and comprises metal structural members arranged sideby-side to form the flooring of a freight conveyance. These structural members as illustrated in that patent have reinforcing webs along their opposite sides and one web is provided with a male corrugation while the other web is provided with a complementary female corrugation. When the structural members are arranged side-byside, the male and female corrugated members are in opposed spaced apart relationship to define therebetween a sinuous groove into which nails can be driven and gripped.

This recent metal flooring has been a vast improvement over any freight car flooring known theretofore. Nevertheless, it has been susceptible to various improvements to strengthen it and render it cheaper and easier to manufacture, and the present invention embodies several such improvements.

Accordingly, it is an object of the present invention to provide a conveyance flooring adapted to receive and retain nails, having improved strength characteristics under static or shock loads applied normal to the plane of the freight-engaging surface of the flooring.

Another object of the present invention is the provision of flooring for freight conveyances, adapted to receive and retain nails, which has high strength per unit of cross-sectional area, thereby to enable the use of lighter and less expensive flooring than in the past.

The invention also contemplates the provision of flooring for freight conveyances which is better adapted to distribute vertical loads imposed thereon, thereby to reduce the maximum unit stresses imposed on the flooring and to make possible the use of lighter and less expensive flooring.

Yet another object of the present invention is the provision of freight conveyance flooring having improved antiskid properties.

Finally, it is an object of the present invention to provide freight conveyance flooring which will be easy and inexpensive to manufacture and install and rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a fragmentary perspective view of the interior of a lower corrner of conveyance construction according to the present invention as embodied, for example, in a railway freight car;

FIGURE 2 is an enlarged fragmentary prospective view of a portion of the flooring of FIGURE 1;

FIGURE 3 is an enlarged transverse cross-sectional view of a flooring member according to the embodiment of the present invention that is shown in FIGURES 1 and 2; and

FIGURE 4 is view similar to FIGURE 3 but showing another embodiment of the present invention.

Although the present invention is illustrated and will hereinafter be described in connection with railway rolling stock it will be appreciated that it is susceptible of embodiment in conveyances of other types, such as motor trucks, ships, airplanes and the like. Furthermore, although the illustrated embodiment indicates the use of an integral hotor cold-rolled sheet metal structural member defining the outer surfaces of a major portion of the flooring member of the invention, this metallic member can also be in the form of an extrusion or can be built up of component parts.

Referring now to the drawing in greater detail, there is shown in FIGURES 1-3 a first embodiment of the present invention, in the form of railway rolling stock comprising a conventional freight car of open top or box-car type hav- 7 I eraser? ,The' hearing carried by this conveying supporting struci 'ture'comprises a plurality of long,fnarrow, contiguous metallicstructural members 13 arranged side-by side and extending across the car transversely of the length of the car and supportedon framemembers 7. In order to pro.-

vide a floor to withstand the hard usage, to which it'Wlll be subjected in a freight conveyance such as a freight car,

the structural members 13 are preferably comprisedof steel, and have at least most'of their width comprised each of a panel 15 having fiat horizontal coplanarside portions 17 one on either side of and extending longitudinallysubstant ially full length of each panel 15. Between each pair of side portions 17 is a depressed central portion 19 of panel 15, each depressed central portion 19 havingapair of generally flat side portions 21 and a flat horizontal bottom portion .23. Each side portion 21 isjoined along its upper edge to the'inner edge of a horizontal-side portion 17 by means of a rounded fillet-25, and is joined along its lower edge to an outer edge of bottom portion 23 by a fillet 27. Depressed central portion 19 is upwardly open arid is filled level with its top with a hardened plasti'cmaterial 2s. V

The sides of each metallic structural member 13 are comprised by'flat webs 31 that extend generally away from the conveying supporting structure and are perpendicular to the common plane of side portions 17 of panel 15.

Webs 31 terminate downward each in an'in'wardly directed horizontal flange 33 extending substantially full length of the flooring member but terminating short of depressed;

central portion 19 of panel 15. Flanges 33 are coplanar with each other and with bottom portion 23., Webs 31 are joined along their upper edges to the outer edges of panel 15, that is, to the outer edge of the associated side portion 17, by means of rounded fillets '35; and webs 31 are joined to the outer edges of flanges 33, by means of rounded fillets 37. Preferably, structural members 13 are formed'by cold forming or hot rolling, in which case fillets 25, 2'7, 35 and 37 have -as small radii as is consisten't with keeping the" 1 of the flooring" members.

' gauge of the sheet metal of the flooring member, the

'29 Within depressed central portion 19. On the other hand, howevcr,'the greater the divergence of side portions 21 from each other, the greater will be their width and hence the greater will be their Weight. Moreover, the greater the divergence of side portions21from each other, the greaterwill be the width and hence the weight of bottom portion 23 and also the volume and hence the weight of hardened plastic material -29. Therefore, in an effort to decrease the Weight of the metallic structural members 13, it is desirable to make side portions 17 as wide as possible ,and side portions21'as-hearlyupright as possible. Ac-

cordingly, it has been found that the preferred angular disposition of side portions 21is thus about 80 from the horizontal with a manufacturing tolerance of about 2 either way from any selected angle. a The preferred width of side portions 17, however, is subject to variation depending on the other dimensions In general, the heavier the wider can bethe side portions 17. On the "other hand,

will be the weight of the structuralmember. For railway rolling stock, fol-example, suitable over-all dimen sions for the metallic structural members for purposes of illustration could be taken as 7% inches in width and 1 inches'in height, with the sheet metal of 12 gauge. (0.105 inch); For 12-gauge metal, the preferred width of side'portions 17is about) inches. Notice, there fore; thatthe width of side portions 17yis a little greater than the height of webs 31, andthat the tops of side portions 21 are spaced from webs 31a distance greater than the height of webs 31, but the bottoms of sideportions 21 are-spaced from webs 31 a distance less than the heightofwebs 31, Notice also that the combined width of both side portions 17 is onlyslightlygreater than the 'distance between them, so: that considering the slight overlap of hardened plastic material about fillets 25,

side portions 17;.1 In other words, the area of hardened plasticmaterial exposed tolthe load borne by the flooring is about the same'as the area of the metal of side pormetal in satisfactory condition during the forming opera;

tion. Where the metal is extruded, however, the external corners of the fillets may be made as close to 90 as is,

desired, bearing in mind that fillets 35 have a nail-guiding function when rounded, as will be explainedin greater de-' portion 23 is of a width greater than'the distance between side portion 17, and hardened plastic material 29 within depressed central portion 19 is of a width at its bottom greater than its width at the top. This cross-sectional configuration of depressed central portion 19 is'di-ctate-d by several factors. In the first place, it is desirable to make side portions 17 as wide as possible, thereby to reduce the size of depressed central portion 19 and lighten the structure by reducing the quantity of hardened plastic material 29 therein. side portions 17 is limited by their strength, for when they that Webs 31 extend full height at hardened plastic material to a minimum.

On the other hand, however, thewidth of are excessively wide they tend to dish under heavyjloads.

In the second place, it is desirable to incline side portions 21 as shown, in order to lock thehardened plastic material r The exposed surfaces of side portionslfl and hardened plastic material}? are horizontal and coplanar, and the umplanar surfaces or the plurality of structural .members 13 are in turn coplanar andlhorizontal and are arranged at a uniform level to provide a uniplanar freighte'ngagingface 39 of the floor. construction as a whole,

this-face 39 being directed away from the conveying supporting structure andexposed'to the interior of the freight conveyance. i Another embodiment era flooring member accordmg to the present invention is shown in cross section in FIGURE 4. As mentioned above, it is desirable to,

keep the weight of the flooring members to a minimum, and one way toxdo this is to reduce the weight of the Accordingly, li'llhe embodiment ofrFIGURE 4,.the weight of hardened plastic material 2 9 is reduced by providing voids therein, these voids being produced by first inserting in depressed central portion 19" a filler in the form of a voidplate 41 extending substantially full length of the flooringmember and having a plurality of arches or corrugations therein-such that voids will be produced beneath the plate, 41 when depressed central portion 19' carrying plate 41' is-filled with hardened plastic'material 29. Plate. 41- need only'be of the lightest gauge metal, for example, 29 -gauge sheet steel (0.0141 inch).

The flooring is integrated with the conveying supporting structure by means of welds 43 by which atleast some of the webs 31 or flanges 33 adjacent fillets 35 are secured toframemembers7, or by other suitable fastening procedures. The flooring is thus secured to the supporting structure of the conveyance with the opposed flat surfaces of webs 31 of adjacent structural members 13 parallel to each other and vertical and spaced apart about A of an inch. When the car floor is built up of single structural members, each member may be attached in this or similar manner to the car frame. Where the car floor is built up from panels which in turn are formed of a plurality of preassembled structural members, not all of the structural members have to be welded to the car frame.

Between opposed webs 31 is a body of solid elastic deformable material 45 of an elasticity such that nails may be driven therein and may displace material 45 laterally, but such that when the nails are withdrawn, the material 45 will recover substantially its original position, save for the presence of a rupture along what was formerly the axis of the nail. It is not necessary that material 45 be self-sealing in the sense that the rupture left by the nail completely heals; on the other hand, preferably, the hole left by the nail should be substantially reoccupied by material 45 upon withdrawal of the nails. Suitable materials are woven fiber belting impregnated with rubber, as shown for example in the drawing in FIGURE 2, or other fibrous material impregnated with rubber or rubbery plastic, or, in general, a solid elastic deformable material, preferably in the form of an impregnant or binder for a woven or random filament fibrous filler and reinforcing material. Suitable materials, their physical form and arrangement, the spacing between adjacent webs 31, the manner of bonding material 45 to the webs, and various other aspects of the structure related to elastic deformable material 45 are discussed in greater detail in copending application Serial No. 74,398, filed December 7, 1960, to which reference is had for a more complete disclosure of this feature so as to avoid the inclusion of unnecessary disclosure in the present application. Another form of nail-gripping structure which may be used in the flooring of the present invention is that disclosed in copending application Serial No. 109,750, filed May 12, 1961. Still another form of nail-gripping structure suitable for use in the present invention is shown in the above-mentioned US. Patent No. 2,667,243 in the form of complementarily corrugated adjacent webs, in lieu of fiat webs with solid elastic deformable material between them. In this last embodiment, the corrugations of the webs grip the nail by deforming it between them.

In any event, it is important to note that either the nailing slot is filled with a material that substantially completely recovers when a nail is withdrawn, as in the case of the straight web embodiments of the present invention and of application Serial No. 74,398, or else the nail but not the web is deformed, as in the case of the corrugated web embodiment of the above-mentioned U.S. Patent No. 2,667,243. In this Way, the nailing slot can be subjected to repeated driving and pulling of nails, time after time, without itself undergoing any substantial change.

A mastic material, not shown, may be used to close the slots above elastic material 45 to form a smoother floor, but with or without such mastic filler, the floor can be considered uniplanar for all practical purposes.

Bridged welds 47 at widely spaced locations on the freight conveying surface of the flooring at the top of the nailing slots integrate the structural members 9 across the nailing slots between adjacent webs 31, thereby to prevent the webs 31 from pulling away from each other.

The manner of use of the novel flooring according to the present invention is also indicated in FIGURE 2, in which a piece of timber 49 is shown secured to the metallic floor by means of a nail 51 passing through timber 49 and into the nailing slot between webs 31. The timber in turn serves as a stop to prevent certain classes of freight from shifting about in the car. From the illustrated manner of securing timber 49 in place, with a nail 51 passing through its midportion, it will be evident that the provision of a nailing slot wider than the nail is additionally valuable as providing a sufiiciently large target to reduce the chances of missing the nailing slot when the point of the nail emerges from the blind underside of the timber. The chances of missing the slot are also reduced by the rounded configuration of fillets 35, which help guide poorly aimed nails into the slot.

Flooring members according to the present invent-ion may be made in any of a variety of ways. Apart from the metal-forming operations described above, the plastic material may be inserted in depressed central portion 19 either in fluid or in solid state. For example, the upwardly opening central portion 19 may be filled with material 29 in a plastic or semiplastic condition, Whereupon material 29 is then allowed to harden and the flooring member is complete; or plastic material 29 may be precast, having such dimensions and shape that it can readily be placed in the central portion 19 and securely anchored in place by means of a grout material com patible with the plastic material 29; after hardening, the grout and the precast plastic material would be bonded together in a monolithic mass.

Plastic material 29 can take any of a variety of forms. It is important to note, however, that the material 29 will be chosen more from a standpoint of its light weight and load-distributing properties than from a standpoint of its structural strength. This is because material 29 does not function primarily to strengthen the flooring members in the manner of a rigid beam. Instead, the principal function of the material 29 is to distribute loads more uniformly to the metallic channel members which encase material 29. To perform this function, material 29 must be exposed on its upper surface to the concentrated loads imposed for example by the wheels of fork lift trucks and the like. The strength of the flooring members is essentially the strength of the metal portions of the members; but by distributing the load more uniformly over the metallic portions of the flooring members, material 29 makes it possible to reduce the over-all strength, and hence the weight and cost, of the metallic members. Thus, although material 29 would apparently seem to add to the weight of the flooring members, the upwardly open depressed central portion 19 may be designed so that the reduction in the quantity of metal made possible by the use of material 29 is greater than the weight of the material 29 used. Accordingly, a net reduction in the weight of the flooring members can be achieved by the practice of the present invention.

Inasmuch as material 29 acts as a load-distributing pad rather than as a rigid beam, it also follows that material 29 need not be rigid. Indeed, it is to be expected that in some forms material 29 will to some extent break up or become rearranged in use, and this breaking up or rearrangement of the material is largely unobjectionable so long as the material is not thereby displaced from central portions 19. It is necessary, of course, that freight-engaging face 39 be maintained substantially flat, and therefore material 29 should not be substantially compactible, nor should it be readily displaceable. Various cements and asphalt-bonded compositions are suitable for the present invention, it being most desirable, however, that they incorporate a light-weight filler or aggregate rather than sand or stone. Indeed, the various materials used for road-surfacing compositions are quite suitable for the present invention, when modified by the inclusion of light-weight fillers rather than the customary heavy fillers and, where desired, by the addition of latex or the like. A number of plastic flooring compositions are also suitable for use in the present invention, such as foamed magnesia cements. As the plastic filler materials of the present invention are continuously in contact by volume of expanded shale of the type known as Haydite and in the size known as sand size? This particu lar composition, however, is given only by way of ex ample, there being a multitude of other suitable compositions. a

It is important to note that in addition to minimizing the over-all weight of the flooring members and at the 7 same time increasing their strength by distributing the loads imposed thereon, material 29 serves as an antiskid composition that improves the traction of wheeled lift trucks when loading and unloading freight in the conveyance. Accordingly, it is an important feature of the present'invention that the upper surface of material 29 in an unloaded conveyance be exposed.

Finally, it should be noted that oneadvantage of making central portion 19 full depth of the flooring member is that bottom portion 23 thereof can be welded to frame members 7 through holes (not shown) extending through bottom portion 23, thereby to avoid overhead welding during the assembly of :the flooring members in a freightconveyance. Another 'way of avoiding overhead welding during assembly is to preassemble a plurality of flooring members by means of members spanning a 'group of them and attached to the undersides ofthe flooring members. Three or four of these preassembled groups can then be used to provide a complete floor in a freight conveyance with a minimum of time spent working inside the conveyance. It is thus relatively easy accurately to predeter Butwhether the floormine the width of the nailing slot.

structural members being arranged at a uniform level to provide a uniplanar freight-engaging fioor surface, said depressed central portions of said panels having horizontal bottom portions in contact with the conveying supportingstructure, saidbottom portions being :wider than said exposed freight-engaging surfacesof the hardened plastic material, the structural members having webs at either side thereofxextending from said side portions of the panel downward toward'the conveying supporting structure with the depressed central portion ofthe panel disposed betwecn and spaced from the webs of each structural member, downwardly terminating portions of said webs being coplanar with the horizontal bottom portions of said depressed central portion, means including rigid.

connection between the structural members and the conve ying supporting structure integrating the floor construction and conveying supporting structure and holding the structural members in' spaced side-by-side relation in the freight car with webs of adjacent structural members,

contiguous to form a nail-receiving slot therebetween transverse to the length of the freight car, and nail-gripping meansassociated with the slot.

2i A freight conveyance having conveying supporting structure and a floor construction carried thereby vto which blocking can be nailed for preventing shifting of freight in' transit, the fioor construction comprising a plurality of elongated structural members arranged in I adjacent side-by-side relation, each structural member comprising a panel havingv a relatively narrow portion on eitherside thereof and a relatively wide depressed upwardly open central portion between said side portions and extending substantially full length'of the structural member arid filled with hardened plastic material, said,

I side portions of the panel and said hardened plastic maing members are installed singly or in groups, it is preferred thatthe plastic material not be introduced until after installation, thereby to permit thehandling and shipment of the flooring members in as lightweight a condition as possible.

From a consideration of the foregoing disclosure, it will'be obvious that all of the initially recited objects of the present invention have been achieved.

Althoughthe present invention has been described and;

illustrated in connection with preferred embodiments, it

'is to be understood that modifications and variations may.

terial having exposed coplanar freight-engaging upper surfaces which together provide a uniplanar' freight-engaging face of the structural member directed away from the conveying supporting structure, each exposed freightengaging upper surface of said side, portion being narbe resorted to without departing from the spirit of the invention, as those skilled, in this art will readily 'understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

What is claimed is:

1. Railway rolling stock comprising a freight car elongated in its direction of travel and having conveying supporting structure and a floor construction carried thereby to which blocking can be nailed for preventing shifting of freight in transit, the fioor construction comprising a plurality of elongated structural members arranged in adjacentside-by-side relation transverse to the length of the freight car, each structural member comprising a panel having a relatively narrow portion on either side thereof and a relatively wide depressed upwardly open central 'portion between said side' portions and extending substantially full length of the structural member and filled with hardened plastic, material, said side portions of the panel and said hardened plastic material having exposed coplanar freight-engaging upper surfaces which together provide a uniplanar freight-engagingface of the structural member directed away from the conveying supporting structure, each exposedfreight-engaging uppersurface of said side portion being narrower than the ex- "rower than the exposed freight-engaging surface of the hardened plastic materiaL'the freight-engaging faces of the plurality of structural members being arranged at a uniform level to provide a uniplanar freight-engaging floor surface, said depressed central, portions of said panelshaving horizontal bottom portions in contact with the conveying supporting structure, said bottom portions being wider than said exposed freight-engaging surfaces of the hardened plastic material, the structural members having webs at either side thereof extending from said side portions of the panel downward toward the conveying supporting structure with the depressed central portion of the panel disposed between and spaced fromvthe webs of each structural memben'downwardly terminating portions of said webs being coplanar with thehorizontal bottom portions of said depressed central portion, means including rigid connection between the structural members and the rconveying supporting structure integrating the floor construction and conveying supporting structure and holding the structural members in spaced side-by-side relation in the freight conveyancewith webs of adjacent structural members contiguous to form a nail-receiving slot therebetween, and nail-gripping means associated \m'th the'slot. L' i g 3. 'A freight conveyance as claimed in claim 2, said depressed central portion of the panel having flat bottom and side portions, the latter side portions being oppositely inclined from the vertical at angles of about 10.

4. A freight conveyance as claimed in claim 2, said webs terminating downward in flanges disposed in a common plane parallel to said' freight-engaging face.

5. A freightconveyance as claimed inclaim 4, said flanges being coplanar with the bottom of said depressed central portion of the associatedpanel.

f 6. Freight conveyance floor construction comprising a plurality of elongated structural members, means rigidly securing the structural members together in adjacent side-by-side relation, each structural member comprising a panel having a relatively narrow horizontal portion on either side thereof and a relatively wide depressed upwardly open central portion between said side portions extending substantially full length of the structural member and having upper terminal portions defining a horizontal spacing coplanar with said side portions, said depressed upwardly open central portion having a horizontal bottom portion being wider than said horizontal spacing coplanar with said side portions, said side portions of the panel having exposed coplanar freight-engaging upper surfaces which together provide a uniplanar freight-engaging face of the structural member, each exposed freight-engaging upper surface being narrower than said horizontal spacing coplanar with said side portions, the structural member having webs at either side thereof ex tending from said side portions of the panel away from said freight-engaging face in the same direction and for about the same distance as said depressed central portion of the panel, downwardly terminating portions of said webs being coplanar with the horizontal bottom portions of said depressed upwardly open central portion, with the depressed central portion of the panel disposed between and spaced from the webs of the structural member, the webs of adjacent structural members being contiguous and having a nail-receiving slot thcrebetween, and nail-gripping means associated with the slot.

7. Freight conveyance floor construction as claimed in claim 6, said depressed central portion of the panel being filled with hardened plastic material having an exposed surface coplanar with the associated freight-engaging face of the structural member.

8. Freight conveyance floor construction comprising an elongated structural member in the form of a panel having a relatively narrow horizontal portion on either side thereof and a relatively wide depressed upwardly open central portion between said side portions extending substantially full length of the structural member and having upper terminal portions defining a horizontal spacing coplanar with said side portions, said depressed upwardly open central portion having a horizontal bottom portion being wider than said horizontal spacing coplanar with said side portions, said side portions of the panel having exposed coplanar freight-engaging upper surfaces which together provide a uniplanar freightengaging face of the structural member, each exposed freight-engaging upper surface being narrower than said horizontal spacing coplanar with said side portions, the structural member having Webs at either side thereof extending from said side portions of the panel away from said freight-engaging face in the same direction and for about the same distance as said depressed central portion of the panel, downwardly terminating portions of said webs being coplanar with the horizontal bottom portion of said depressed upwardly open central portion, with the depressed central portion of the panel disposed between and spaced from the webs of the structural member.

9. Freight conveyance floor construction as claimed in claim 8, said depressed central portion of the panel being filled with hardened plastic material having an exposed surface coplanar with the associated freight-engaging face of the structural member.

10. Freight conveyance fioor construction as claimed in claim 8, said depressed central portion of the panel having flat bottom and side portions, the latter side portions being oppositely inclined from the vertical at angles of about 10.

11. Freight conveyance floor construction as claimed in claim 8, said webs terminating away from said freightengaging face in flanges disposed in a common plane parallel to said freight-engaging face.

12. Freight conveyance floor construction as claimed in claim 11, said flanges being coplanar with the bottom of said depressed central portion of the associated panel.

References Cited by the Examiner UNITED STATES PATENTS 2,017,832 10/35 Hovey 18934 2,106,390 1/38 Crane --422 2,388,968 11/45 Hedgren 105-422 2,692,032 10/54 Peterson 105-422 2,739,543 3/56 Candlin 105-422 2,794,403 6/57 Stein 105--422 2,907,417 10/59 Doerr 105-422 2,942,701 6/60 Pope 105422 3,004,640 10/ 61 Macomber 189-34 3,132,604 5/64 Collins et al. 105422 3,132,605 5/64 Collins 105-422 LEO QUACKENBUSH, Primary Examiner.