US3698677A

US3698677A - Pallet for moving and securing cargo

Info

Publication number: US3698677A
Application number: US4882A
Authority: US
Inventors: Robert Looker
Original assignee: Satco Inc
Current assignee: Satco Inc
Priority date: 1970-01-22
Filing date: 1970-01-22
Publication date: 1972-10-17
Anticipated expiration: 1989-10-17
Also published as: CA919603A; JPS5411580B1; FR2077261B1; DE2056501A1; GB1335445A; FR2077261A1

Abstract

A pallet to support cargo items for movement over ball mats and roller trays is relatively thin and of light weight and of sufficient resilient flexibility to bend and bow out of its plane to accommodate itself to relatively high points of a supporting structure without permanent deformation. The invention teaches new constructions of pallet sockets for engagement by cargo anchoring fittings. Some forms of the pallet are reversible for use with either of its faces uppermost.

Description

United States Patent Looker [54] PALLET FOR MOVING AND SECURING CARGO [72] Inventor: Robert Looker, Santa Monica, Calif.

[73] Assignee: Satco Inc., El Segundo, Calif.

[22] Filed: Jan. 22, 1970 [21] Appl. No.: 4,882

[52] U.S. Cl ..248/346, 108/55, 248/361 R [51] Int. Cl. ..B65d 19/38 [58] Field of Search.248/36l R, 361 A, 346; 108/57,

[451 Oct. 17,1972.

3,422,508 1/1969 I-liguchi ..248/361 X 3,428,002 2/1969 Mclntire ..108/57 3,429,536 2/1969 Petry ..248/346 3,452,958 7/1969 Hambleton ..248/361 3,509,832 5/1970 Daisley ..108/51 FOREIGN PATENTS OR APPLICATIONS 522,589 6/1940 Great Britain ..52/624 Primary Examiner-Chance11or E. Harris Attorney-Smyth, Roston & Pavitt [57] ABSTRACT A pallet to support cargo items for movement over ball mats and roller trays is relatively thin and of light weight and of sufficient resilient flexibility to bend and I bow out of its plane to accommodate itself to relatively high points of a supporting structure without permanent deformation, The invention teaches new constructions of pallet sockets for engagement by cargo anchoring fittings. Some forms of the pallet are reversible for use with either of its faces uppermost.

13 Claims, 39 Drawing Figures V mg\\\\\\\\\\\Z\\\\\\\\\\\\\\ 7 PATENTEDnm 17 1972 3.698.677

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PALLET FOR MOVING AND SECURING CARGO BACKGROUND OF THE INVENTION This invention relates to a base structure to serve as a pallet or to serve as the bottom of a container for moving cargo into and out of the cargo space of a vehicle such as an aircraft and may be either in the form of -a flat pallet for anchorage of cargo thereto of a flat base or a cargo container.

It is common practice to provide a cargo space with rotatable elements in the form of balls or in the form of rollers to define a support plane and to facilitate movement of cargo items along the support plane. For example, the Davidson U.S. Pat. No. 3,262,588 discloses a structure for the floor area of a cargo space of an air craftwherein ball mats define an entrance area opposite the side door of the cargo space of an aircraft and rollers are incorporated in so-called roller trays that extend longitudinally of the aircraft in both directions from the entrance area. The balls of the ball mats are universely rotatable about their centers to define a support plane along which palletized or containerized cargo may be moved in all directions with minimum frictional resistance and the rollers of the roller trays are freely rotatable to define support planes along which cargo may be moved with minimum frictional resistance.

The heretofore prevalent type of pallet or container base for moving cargo into and out of such a cargo space comprises a relatively rigid laminated panel which may be of a thickness of three-fourths inch and is usually 88 inches wide and 125 inches in length. One common panel of this type is of high pressure laminated plywood construction bonded with the melamine with top and bottom phenolic high pressure laminate skins of approximately one-tenth inch thickness. Another such panel of sandwich construction bonded with epoxy or phenolic resin has an end grain balsa wood core with top and bottom skins of aluminum alloy of a thickness of approximately one-sixteenth inch. Laminated panels of these types have a weight in the range of 200 250 pounds and may cost approximately $360.00 each.

Unfortunately, such a conventional panel of this type usually has a service life of only one to two years and only rarely under ideal conditions may have a service life as long as 2 or 3 years. Not only is the first cost high and the service life relatively short, but also there is the disadvantage of high maintenance cost. Daily inspections for air worthiness are in order and if a pallet is found to be damaged it is not easily repaired. Damaged pallets must be transported to a repair location with consequent transportation costs as well as loss of the service of the pallet during the repair period.

One cause of damage to a conventional pallet is impacts by falling cargo items. If a heavy cargo item is dropped on a pallet at a point where the pallet is supported from below by an unyielding structure, the pallet is subjected to a severe blow across its thickness that results in at least a permanent dent or fracture in one or both of its skins. If the point of impact by a falling cargo item is between two underlying spaced supports, for example, spaced rollers of a roller tray, the pallet structure is subjected to concentrated high magnitude bending stress in a small area. Since the pallet structure is not resilient it is not capable of dissipating the energy and the result is local damage the skin being displaced inwardly and thus dented if not cut, and the core of the panel often delaminating from the skin. Another cause of damage occurs when a heavily loaded panel is moved over an uneven support surface, for example a support surface having a high point extending above the normal support plane. Such a high point may be an upwardly displaced roller or ball element protruding above the surrounding support plane and is often a broken rotary element. Since the pallet is inherently relatively rigid the result is high unit loading at the high point, the load that is carried by a large area of the panel being concentrated at the high point. The greater the rigidity of the panel the higher the stresses imposed on the bottom skin and the consequent greater likelihood of deformation and or rupture of the skin.

Another cause of damage to ,a conventional pallet is found in the stresses involved in transferring a loaded pallet from one support plane to an adjacent support plane at a lower level. The transition of the loaded pallet from the higher plane to the lower subjects the pallet to severe bending stresses that tend to deform the aluminum skin balsa wood core with a permanent set. While being conveyed over irregular conveying surfaces the bottom skin deforms into small grooves as the pallet is conveyed over the projections. After having been so conveyed many times the bottom skin grooves take on the appearance of irregular corrugations. When such pallet is then conveyed from a higher to a lower conveying surface bending stresses are induced into the panel putting the top skin in compression and the bottom skin in tension. The tensile stresses induced upon the bottom skin cause the grooves or corrugations to straighten effectively lengthening the bottom skin and causing the pallet to take a concave bowed shape, often in magnitude such as to keep the pallet from fitting under the fixed height floor locks in the vehicle.

Additionally, if there is local delamination of the skin from the core, such delamination spreads easily to adjoining areas from the stresses induced on both top and bottom skins as the pallet is conveyed from a higher conveying surface to a lower conveying surface. After a relatively short service period the panel usually becomes bowed and delaminated in small areas with the under surface badly cracked and with the top surface caved in at various points.

The object of the present invention is not only to circumvent these various causes for the shortened service life of a panel but also to provide a panel of substantially less first cost and substantially less weight as well as to substantially eliminate maintenance costs.

SUMMARY OF THE INVENTION One reason for the described construction of a conventional panel is that the panel is intended to be sufficiently rigid to carry a heavy cargo when the panel is carried by a lift fork. It has also been assumed heretofore that a panel must be of relatively heavy and rigid construction to cooperate with cargo captivating means such as a cargo net. A conventional cargo net has a number of strong Dacron or Nylon webs running in the fore and aft direction and in a crash condition the cargo net is exceedingly highly stressed. To transmit this stress to the floor structure of the aircraft, T- shaped locking devices are commonly used which overhang marginal portions of a panel and in certain cargo systems have arms that pass through rings on the ends of the webs of a cargo net;

The present invention arises from a newly arrived conclusion that making the pallet sufficiently rigid for cooperation with a lift fork and also making the pallet of heavy enough construction to carry peak crash loads is actually wasteful and substantial savings may be made by designing such a pallet primarily for moving cargo items into and out of the cargo space of an aircraft and for effective anchorage in the aircraft. Carrying out this concept sacrifices the capability of the pallet to carry a load on a lift fork but only moderately reduces the capability of the pallet for carrying peak crash loads. What is given up turns out to be a small price for the surprising economies achieved by extending the service life of a pallet as well as by drastically reducing the cost of maintenance of the pallet.

The pallet construction taught by the present invention comprises essentially a rectangular panel that is relatively thin and is resiliently flexible but, nevertheless, when anchored to the floor of an aircraft by conventional locks has sufficient strength and rigidity to retain the cargo thereon under normal accelerations and decelerations even including survivable crashes. In some embodiments of the invention, the pallet is thickened along its four sides to, in effect, incorporate a rectangular protecting and reinforcing frame that is capable of transmitting stresses of substantial magnitude across the panel. Even when the panel incorporates such a reinforcement frame, the major portion of the area of the panel is flexible where flexibility is required for the panel to accommodate itself to any support structure on which it may be placed. Severe unit stressing by a high point of the underlying support structure is avoided by the capability of the panel to flex at the high point and thus accommodate itself to the irregularities of the support structure by distributing a substantial portion of the load to adjacent regions of the support structure.

If falling cargo makes a severe impact at a point 7 where the thin panel is rigidly supported from below, the thin solid sheet material of the panel is capable of withstanding the impact force across its thickness with only insignificant deformation. If the impact of falling cargo occurs between points where the thin panel is supported from below, the example midway between two underlying rollers, the panel tends merely to flexresiliently to absorb the load without permanent deformation or set.

If the panel is used to move a load across a juncture between two support structures with an abrupt change in level at the juncture, the panel assumes a curved configuration for transition from one plane to the other without being flexed beyond its elastic limit. The thickened rectangular frame portion is a compromise between the high degree of flexibility required in the central area of the panel and the higher strength required at the marginal regions of the panel, the compromise permitting the frame portion to bend liberally without taking a permanent set.

The whole panel may be made of metal such as aluminum alloy or of equivalent material such as plastic reinforced by embedded glass fibers and may be a onepiece body. The weight of the panel is minimized either by making the major central portion of the panel thinner than the margins of the panel or by recessing the material in the major central area without reducing the overall thickness in the central area. In both cases the major central portion of the panel has a ratio of mass to unit plan area substantially lower than the ratio of mass to unit plan area of the marginal portions of the panel around its four sides.

Some embodiments of the invention have the impo'rtant feature of being reversible for use with either face of the panel uppermost. inevitably some of the downward impacts to which a panel of the invention is subjected deforms the panel out of its normal plane. It has been found, however, that reversing a battered panel of the new construction results in subsequent downward impacts to restore the configuration of the panel. Thus a reversible panel will outlast a non-reversible panel.

With reference to the sockets in a panel for engagement by cargo-retaining fittings, one embodiment of the invention employs a socket in the form of a sheet metal stamping that is riveted to the panel so that the panel is not locally weakened by the socket. Other embodiments of the invention have sockets in the form of recesses in the panel material and still others have sockets in the form of apertures in the panel material. The recesses and apertures may be reinforced by metal plates to avoid locally weakening of the panel or even to add local strength to the panel. The invention also teaches that a reversible panel may be provided with sockets for use with either face of the panel uppermost.

- The features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to be regarded as merely illustrative:

FIG. I is a fragmentary plan view of one embodiment of the invention in which the central area is perforated without reduction in thickness;

FIG. 2 is an enlarged fragmentary section along the line 2 Q 2 ofFIG. 1;

FIG. 3 is a view similar to FIG. 1 showing a panel which has blind bores in its central area;

FIG. 4 is an enlarged fragmentary section along the line 4 4 of FIG. 3;

FIG. 5 is a view similar to FIG. 1 showing a panel which is lightened in its central area by numerous recesses;

FIG. 6 is an enlarged fragmentary cross section along the line 6 6 of FIG. 5;

FIG. 7 is a view similar to FIG. 1 illustrating a panel that is lightened by internal voids in its central area;

FIG. 8 is an enlarged transverse section along the lines 8 8 of FIG. 7;

FIG. 9 is an enlarged section along the line 9 9 of FIG. 8;

FIG. 10 is a fragmentary plan view of a panel which comprises simply a sheet of uniform thickness made of aluminum or of reinforced plastic material;

FIG. 11 is a plan view of a panel having a frame portion along its four sides surrounding a thinner major central portion;

FIG. 12 is an enlarged fragmentary section taken along the line 12 l2 ofFIG. ll;

FIG. 13 is a sectional view similar to FIG. 12 illustrating another embodiment of the invention;

FIGS. 14, 15 and 16 are views similar to FIGS. 12

and 13 illustrating additional embodiments of the invention;

FIG. 17 is a plan view of a fragment of a panel showing how the panel may be reinforced at each of its four corners;

FIG. 18 is an enlarged section along the line 18 18 of FIG. 17;

FIG. 19 is a viewsimilar to FIG. 18 illustrating another form of corner reinforcement;

FIG. 20 is a plan view of a socket of the panel in the form of an aperture through the panel with the aperture reinforced by a pair of metal plates;

FIG. 21 is a sectional view along the angular line 21 21 ofFlG. 20;

FIGS. 22, 23 and 24 are views similar to FIG. 21 illustrating other forms of a reinforced panel socket;

FIG. 25 is a fragmentary plan view of a socket in the form of an aperture through the material of a panel;

FIG. 26 is a transverse section along the line 26 26 of FIG. 25;

FIG. 27 is a plan view of a portion of a reversible panel having two sets of sockets therein for use respectively at the two faces of the panel;

FIG. 28 is a section along the line 28 28 of FIG. 27;

FIG. '29 is a section along the line 29 29 of FIG. 27;

FIG. 30 is a fragmentary plan view of a panel showing another form of sockets for use with either face of the panel uppermost;

FIG. 31 is a section along the line 31 31 of FIG.

' FIG. 32 is a section along the line 32 32 of FIG. 30; FIG. 33 is a plan view of a socket that is in the form of a sheet metal stamping that is attached to the panel;

FIG. 34 is a section along the angular line 34 34 of FIG. 33;

FIG. 35 is a plan view of still another embodiment of a panel;

FIG. 36 is an enlarged fragment of FIGS. 35;

FIG. 37 is a fragmentary section taken along the line 37 37 ofFIG. 35;

FIG. 38 is a fragmentary section taken along the line 38 38 ofFlG. 35; and

FIG. 39 is a section similar to FIG. 37 showing a modification of the panel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION In the embodiment of the invention illustrated by FIGS. 1 and 2, the panel, which may, for example be 88 inches wide and 125 inches long, is essentially a plate of suitable material of uniform thickness with a solid marginal portion 40 along its four sides surrounding a major central area that is reduced in weight by numerous apertures or perforations in the form of bores 42. The panel may be made of any suitable material, for example an aluminum alloy or a suitable plastic material, which plastic material may be reinforced by embedded glass fibers. The purpose of perforating the large central area is to reduce the weight of the central area by reducing the ratio of the mass to unit plan area of the central portion below the ratio of mass to unit plan area of the marginal portion 40. The advantage of perforating the panel for this purpose is that the perforations reduce the mass and, therefore, the weight of the large central area without correspondingly reducing the resistance of the panel to flexure. Thus an aluminum panel of this construction may" be relatively thin, for example of a thickness'in the range of 0.150 inch 0.375 inch to strike a desirable compromise between rigidityand flexibility without undue sacrifice of flexibility in the major central area.

The panel shown in FIG. 3 is a similar plate of suitable material having a solid marginal portion 44 along its four sides but in this instance the major central area of the plate is provided with numerous blind. bores 45 which extend into the plate from opposite faces of the plate. The blind bores serve the same purpose as the perforations 42 in FIG. 1.

FIGS. 5 and 6 illustrate an embodiment of the invention in which the panel is a similar plate of a selected thickness. The panel has a solid marginal portion 46 along its four sides with the ratio of mass to unit surface area of the major central portion of the plate reduced by numerous shallow recesses 48 in the opposite faces of the plate.

It is to be noted that the panels shown in FIGS. 1 6 are of one-piece construction and therefore may be aptly termed monolithic panels.

FIGS. 7, 8 and 9 show the construction of a panel having a solid marginal portion 50 extending along its four sides with the major central area of the panel reduced in weight by voids inside the material of the panel. In the construction shown the panel comprises two bonded or welded or otherwise attached

laminations

52 and 54 of aluminum or other suitable material with recesses or grooves in one of the laminations at the inner face between the two laminations to provide the voids for reducing the ratio of mass to unit plan area. FIG. 8 shows parallel grooves 55 in the inner face of the lamination 52 and FIG. 9 shows similar parallel grooves 55 in the inner surface of the lamination 54, the two sets of grooves being perpendicular to eachother to provide a pattern of intersecting voids that is indicated by broken lines in FIG. 7.

FIG. 10 shows how a panel to serve the purpose of the invention may comprise simply a single plate 56 of suitable material such as aluminum or reinforced plastic, the ratio of mass to unit plan area being uniform over the whole plate.

FIGS. 11 and 12 show a panel in the form of a single plate of aluminum or plastic having a solid marginal portion 58 of selected thickness surrounding a large central portion 60 of substantially less thickness. Thus the marginal portion 58 is the equivalent of a rectangular frame of suitable thickness and the central portion 60 is a web of material of substantially lesser thickness. As shown in FIG. 12 the frame or marginal portion 58 is integral with the central portion 60, the panel being a single body of material. It is to be noted that a panel of the cross-sectional configuration indicated in FIG. 12 is symmetrical with respect to its central plane.

FIG. 13 shows how a panel similar to FIG. 11 may comprise a rectangular frame 62 united with the four sides of a thinner plate or sheet 64. It is contemplated that the frame 62 will be fabricated by interconnecting four frame members at the four corners respectively of the panel. As indicated in FIG. 13, each of the four panel members may be formed with a slot 65 opening onto its inner edge to straddle the corresponding edge of the central sheet 64, the frame member being ridigly attached to the central sheet by suitable rivets 66.

It is to be noted that the cross-sectional configuration in FIG. 13 is also symmetrical with respect to a central area. The symmetrical configuration is especially advantageous in a panel in which the frame is made of separate members because when the panel is flexed out of its plane, the resulting stresses tend to separate the rectangular frame 62 from the sheet 64, this tendency being minimized when the centroid of the frame and the sheet coincide.

FIG. I4 shows a panel which is similar in construction to the panel shown in FIG. 12 but is not symmetrical in cross-sectional configuration. The panel in FIG. 14 is a single sheet of material having a rectangular frame portion 68 surrounding a central thinner web 70. FIG. shows a panel of substantially the same crosssectional configuration as the panel in FIG. 13 but in this instance the rectangular frame 72 is joined to a central sheet 74 by suitable rivets 77. It is to be noted that the frame 72 has a V-shaped groove 75 and that the edge 76 of the sheet 74 is bevelled to fit snugly into the groove. By virtue of this construction the edge 76 of the sheet is positively interlocked with the frame 72.

Since the panels shown in FIGS. 12 and 14 are of one-piece construction they also may be aptly termed monolithic panels.

FIG. 16 illustrates a panel of cross-sectional configuration similar to the crosssectional configuration of FIG. 15. Here again the frame 78 of the panel is separate from a sheet 80 that forms the central portion of the panel and here again the frame overlaps the sheet and is attached thereto by suitable rivets 82.

FIGS. 17 and 18 show how a separate frame 84 of a panel such as shown in FIGS. 13, 15 and 16 that is connected to a central sheet 85 by suitable rivets 86 may comprise four frame members 84a which are mitered to meet at diagonal junctures 88. The adjoining ends of the panel members are interlocked by arcuate corner reinforcements 90 which preferably are made of relatively hard and tough material such as steel. As shown in FIG. 18 each corner reinforcement 90 may be formed with a slot 91 to permit the corner reinforcement to straddle a reduced edge portion of the confronting panel members 84a, the reinforcement being secured to the confronting panel by suitable rivets 92.

FIG. 19 shows how a similar corner reinforcement 90a may be formed with a flange 94 of reduced thickness that is straddled by the confronting frame members 84a, the corner reinforcement being secured by suitable rivets 92a.

The various described panels may be provided with any of the following socket constructions shown in FIGS. 20 34. In this regard a feature of the invention is the concept of providing a reversible panel which may be used with either of its faces uppermost and which is equipped with sockets accessible at both of its faces for engagement with cargo-retaining fittings.

One advantage of the panels shown in FIGS. 11 19 is that the rectangular frame portions of the panels form shoulders which tend to keep cargo items in the central areas of the panels. Such shoulders are indicated by reference numeral 95 in FIGS. 11 17.

The panel cross-sectional configurations shown in FIGS. 1 V 13 are especially suitable for reversible panels in that each of the cross-sectional configurations is symmetrical with respect to a central plane but the asymmetrical cross sections shown in FIGS. 14 16 are also suitable because the panels are relatively thin.

Socket structures that may be used for reversible panels are shown in FIGS. 20 to 32 which will now be described.

In FIGS. 20 and 21 the socket comprises an aperture 96 through the thickness of the solid marginal portion of the panel in combination with two plates 98 at the opposite entrances of the aperture, the plate being secured by suitable rivets 100 that extend through the thickness of the panel. As indicated in dotted lines in FIG. 20 the aperture 96 may be elongated to the configuratiop of a slot of suitable width and length. The socket cooperates with complementary cargo-retaining fittings in the general manner disclosed in Parker US. Pat. No. 2,688,504 and Elsner US. Pat. No. 2,743,684, which prior disclosures are hereby incorporated into the present disclosure by reference. With cargo items tied to the panel by straps or nets that are connected to the cargo-retaining fittings, the cargo items may in effect, be tied to the floor structure of the aircraft in awell known manner by locking dogs thatmake overlapping engagement with the solid margins of the panel as disclosed in the previously mentioned Davidson patent.

For cooperation with complementary cargo fittings the two plates 98 in FIGS. 20 and 21 are formed with identical slots 102 which are narrower than the 96 and register therewith. Each of the slots 102 in the two plates is provided with a pair of enlargements 104 to receive headed studs of the cargo fittings and each of the slots 104 is flanked by pairs of flanges 105 which are formed by narrowing the slot. The pairs of flanges 105 overhang the underlying slot 96 in the panel for engagement with the heads of the studs of the cargo fittings. Since the two plates 98 are identical it is apparent that each of the described sockets may be used for engagement with cargo-retaining fittings on either of the two faces of the reversible panel.

The apertures 96 in the solid material of a reversible panel, do, of course, weaken the panel locally but the added plates 98 reinforce the panel and actually make the panel stronger in the region of each socket.

FIG. 22 shows how the opposite surfaces of a panel may be formed with shallow recesses 106 to seat the two plates 96 respectively, so that each of the plates is partially embedded inthe material of the panel.

FIG. 23 shows how deeper recesses 108 may be provided to seat the two plates 98 with the two plates flush with the opposite faces of the panel. Such a construction greatly lessens the liklihood of damage to the socket structure.

FIG. 24 shows how a relatively thick panel may be provided with recesses 110 which are substantially deeper than the thickness of the two plates 98 whereby the two plates are offset inwardly from the'corresponding faces of the panel for even protection of the sockets.

FIGS. and 26 show the simplest form of sockets for a reversible panel. Each of the sockets comprises an elongated aperture 1 12 in the material of the solid marginal portion of the panel, the aperture being formed with enlargements 114 on the opposite faces of the panel to receive headed studs of cargo-retaining fittings and the aperture being further provided with overhanging flanges 115 on the opposite faces of the panel for engagement with the heads of the studs.

FIGS. 27 29 show how a reversible panel may be provided with two sets of recesses on its opposite faces respectively for engagement with cargo-retaining fittings. FIG. 28 shows how one set of recesses 116 may open on one face of the panel and FIG. 29 shows how a second set of recesses 118 may open onto the opposite face of the panel. Each of the recesses 1 16 and 118 is of the general configuration heretofore described with two enlargements 120 to receive the headed studs of fittings and with overhanging pairs of flanges 122 to engage the heads of the studs. It will be noted that each of the

sockets

116, 118 is of a depth greater than one half the thickness of the panel. I

FIGS. 32 also show how a panel may be equipped with two sets of sockets opening onto its two opposite faces respectively for engagement with cargoretaining fittings. Each socket comprises an elongated recess 124 in the corresponding face of the panel in cooperation with an overlying metal plate 125 that is suitably anchored to the panel, for example by means of rivets 126. As indicated in FIG. 30 each of the recesses 124 is of elongated configuration and each of the corresponding plates 125 is correspondingly elongated. Each plate 125 is provided with a slot 128 which registers with the corresponding recess 124 and the slot has two enlargements 128 each of which is flanked by pairs of overhanging flanges 130 that are provided by the plate.

It is to be noted that although FIGS. 27 32 show how reversible panels may be provided with two sets of sockets opening onto their opposite faces respectively, it is apparent that if a panel is not reversible it may be provided with a single set of such sockets.

FIGS. 33 and 34 show how a socket for a panel may be formed by a metal stamping 132 that is anchored to the upper surface of the panel by rivets 134 without weakening the panel. The metal stamping 132 is offset to form a cavity 135 which is defined in part by the panel and the metal stamping is further formed with a slot 136 of the previously described configuration, that slot having enlargements 136 to receive the headed stud of a cargo-retaining fitting and having pairs of flanges 138 overhanging the cavity 135 to engage the heads of the studs.

FIG. shows a panel which is similar in construction to the previously described panel shown in FIG. 14 in that the panel has a central web 140 and a rectangular marginal frame portion 142 that is integral with the web as indicated in FIG. 37. The frame portion 142 is tapered in that it has an inclined shoulder 144 to serve as a transition to the central web. Frame portion 142 is formed with a suitable number of recesses or sockets 145 of the same character as the heretofore described sockets shown in FIGS. 27 and 29.

A special feature of this embodiment of the invention is that the frame portion 142 has a number of integral extensions 146 which extend towards the central region of the central web and are integral with the web to serve as reinforcements for the web. In this particular embodiment of the invention the extensions 146 are fingers that are tapered in plan. Each extension 146 is also tapered in thickness in that the transition shoulder 144 of the frame portion continued around each extension. This particular embodiment of the invention is further characterized by a pair of additional extensions 148 adjacent each of the four corners of the panel, the additional extensions being relatively short and relatively blunt as shown.

The

extensions

146 and 148 of the frame portion 142 have the virtue of substantially increasing the rigidity of the panel at the cost of relatively little additional material. When cargo is anchored to the panel by a tensioned net,'the increased rigidity of the panel reduces the upward flexure of the margins of the panel by the tension of the net and thus reduces the liklihood that the margins of the panel will be excessively flexed to interfere with engagement by the panel with the overhanging locks that are provided on the airplane floor. The increased rigidity of the panel is also advantageous in making the panel more capable of withstanding upward loads that are applied to the panel by the cargoretaining net when the cargo tends to move upward relative to the .airplane floor in response to abrupt downward accelerations of the airplane that sometimes occurs in flight because of adverse weather conditions.

The panel shown in FIG. 35 need not be of one-piece construction, i.e. the

extensions

146 and 148 need not be actually integral with the frame portion 142. For example, FIG. 39 which-is a sectional view like FIG. 37

shows a rectangular frame portion 142a may be integral with the central web 140a but the various extensions of the .frame may be riveted or otherwise bonded to the central web 140. Thus in FIG. 39 a finger extension 146a is a separate piece of material which at its outer end is flush with the frame 142a as shown and at its inner end has the usual transition shoulder 144a to the plane of the central web 140.

The advantages of the various described embodiments of the invention over conventional pallets may be appreciated when it is considered that the service life is increased from the usual service life of one to two years to a longer service life of three to five years. At the same time the'new pallet constructions provide more cargo space because of their reduced thickness and the saving in weight. The cost of the new pallet construction is substantially less than the cost of conventional pallets and, in addition, all of the material of the new pallet constructions may be salvaged at the end of the service life of the pallets.

My description in specific detail of the selected embodiments of the invention will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the invention.

Iclaim:

l. A pallet in the form of a rectangular panel for anchorage of cargo thereon in the cargo space of an aircraft by overhanging lock means and to carry cargo to and from the cargo space by gliding over rotary support elements,

said panel having a rectangular marginal frame portion encompassing all of its four sides,

said frame portion being thicker than a major central portion of the panel with the four sides of the frame portion interconnected to cause a transverse force applied to any one side of the panel toward the central portion thereof to be transmitted to adjoining parallel sides of the frame portion for transmission to the fourth side of the frame portion,

said frame portion being equipped with means for engagement with cargo securing means,

the major central portion of the panel being formed by a single sheet,

the frame portion being attached to the single sheet,

a part of the frame portion being of reduced thickness and overlapping the edge of the sheet and being attached thereto in face to face relationship, i

the edge of the sheet being tapered,

the frame portion having a groove of cross section complementary to the cross section of the tapered edge of the sheet, the groove being interlocked with the edge of the sheet to oppose separation of the edge laterally away from the frame portion.

2. A pallet in the form of a rectangular panel for anchorage of cargo thereon in the cargo space of an aircraft by overhanging lock means and to carry cargo to and from the cargo space by gliding over rotary support elements, said pallet having a major central portion formed by a single sheet;

a rectangular marginal frame portion encompassing all four sides of said pallet;

said frame portion attached to the said single sheet forming the central portion of the panel;

said frame portion being substantially thicker than the major central portion of the panel with the four sides of the frame portion interconnected to cause a transverse force applied to any one side of the panel towards the central portion thereof to be transmitted to adjoining parallel sides of the frame portion for transmission to the fourth side of the frame portion,

said frame portion being recessed to receive in overlapping engagement the edge of said sheet and attached to said sheet;

the four sides of said rectangular frame portion being formed by separate members leading into four corners of the frame structure and attached to the sin- I gle sheet;

said four members being interlocked at the corners of said frame portion; and

means carried by said frame portion for engagement with conventional cargo-securing means.

3. A pallet for the placing of cargo thereon and the securing of the cargo thereto for movement of the cargo over rotary elements to and from the cargo space of a cargo carrier and to permit the cargo to be releasably secured in the cargo space by overhanging lock means, comprising:

a rectangular panel having a central load carrying portion and a rectangular frame surrounding the central portion and united therewith,

said central load carrying portion formed of a substantially incompressible material of such thickness and mass to resiliently flex locally in response to impact loads produced by cargo dropped thereon and to resiliently flex locally in response to engagement with a rotary support element spaced above the supporting plane of adjacent rotary elements supporting the pallet as the same moves into and over the elevated support element to distribute a substantial portion of the cargo load carried by said central portion to supporting rotary elements adjacent the rotary element producing the flexure whereby high unit load stresses in the central portion and the elevated rotary element are reduced;

said frame member comprising a plurality of elements each having a greater rigidity than said central portion and each formed with a recess receiving one marginal edge of said central portion to support and reinforce the edge received therein;

means for permanently anchoring a marginal edge of the central portion in a recess of an element of the frame member; and

means carried by said frame member for engagement with cargo-securing means for holding said pallet in a selected position within the cargo space of the cargo carrier.

4. A pallet as defined in claim 3 in which a face of said frame member is substantially coplanar with a corresponding tace of said load carrying central portion.

5. A pallet as defined in claim 3 in which said central portion is formed of an aluminum sheet.

6. A pallet for the placing of cargo thereon and the securing of the cargo thereto for movement of the cargo over rotary elements to and from the cargo space of a cargo carrier and to permit the cargo to be releasably secured in the cargo space by overhanging lock means, comprising:

a rectangular panel having a metallic sheet-like central portion and a rectangular frame surrounding the central portion and united therewith,

said central portion. having high resistance to permanent deformation, being substantially incompressible and of an area and thickness to resiliently absorb impact loads and to resiliently flex in response to local forces produced by a rotary support element spaced above the supporting plane of adjacent rotary elements supporting the pallet as the-pallet moves over the elevated support element, to distribute a substantial portion of the cargo load to supporting rotary elements adjacent the rotary element producing the flexure of said central portion, whereby high unit load stresses produced in the central portion by the elevated rotary element are reduced;

' said frame member being more rigid than said central portion and comprising a plurality of elements, each formed with a recess receiving one marginal edge of said central portion,

said recess defining at least one sidewall which overlies and face wisely engages a surface of a marginal edge of said central portion;

7. A pallet as defined in claim 6 in which said recess defines a pair of sidewalls which engage opposite surfaces of a marginal edge of said central portion.

8. A pallet as defined in claim 6 in which a face of said frame member is substantially coplanar with a corresponding face of said central portion.

9. A pallet as defined in claim 6 in which said central portionis formed of a single sheet of aluminum.

10. A pallet for the placing of'cargo thereon and the a rectangular sheet forming a central load carrying element of said pallet,

said sheet formed of a metal highly resistant to permanent deformation under impact loads and of such thickness and mass to resiliently flex locally in response to forces produced by cargo dropped thereon and to resiliently flex in response to engagement with a support element spaced above the supporting plane of adjacent elements supporting the palletas the same moves into and over the elevated support element to distribute a substantial portion of the cargo load carried by said pallet to supporting elements adjacent the element producing the flexure whereby high unit load stresses in the sheet .and the elevated rotary element are reduced;

a frame member comprising a plurality of elongate members, each element being thicker than and having a greater rigidity than said sheet;

each of said elements being formed with a cavity receiving one marginal edge of said sheet, the cavity having a length equal to the marginal edge received therein;

means for permanently securing a marginal edge of the sheet received within a cavity of the element of 40 the frame member whereby the frame member encompasses all four sides of the sheet to reinforce the same; and

11. A pallet as set forth in claim 10 in which the edge of the sheet is tapered and in which each elongate element has a groove of a cross section complementary of the cross sectionof the tapered edge of the sheet that interlocks with the edge of the sheet and thereby opposing separation of the edge of the sheet laterally away from the elongate element.

12. A pallet for the placing of cargo thereon and the securing of the cargo thereto for movement'of the cargo over rotary elements to and from the cargo space of a cargo carrier and to permit the cargo to be releasably secured in the cargo space by overhanging lock means, comprising:

a rectangular sheet of metal forming a central load carrying element of said pallet, said sheet being of such thickness as to resiliently flex locally in response to impact forces produced by cargo dropped thereon and to resiliently flex in response to engagement with a support element of the car 0 carrier spaced above the supporting plane of a jacent elements supporting the pallet as the same moves into and over the support element to distribute a substantial portion of the cargo load carried by said pallet to supporting elements adjacent the element producing the flexure whereby high unit load stresses in the sheet and the elevated totary element are reduced;

a frame member of a thickness greater than said sheet extending about the four marginal edges of the same to reinforce and stiffen the edges of the sheet,

said frame being substantially rigid and resistant to flexing stresses produced by bending loads induced in said frame; and t 4 means carried at spaced locations about said frame for holding said pallet in a preselected position within the cargo space of the cargo carrier and receiving and cooperating with means carried by a load confining element adapted to hold cargo to said pallet.

13. A pallet as defined in claim 12 in which said frame is integral with said sheet of metal.

UNITED STATES- PATENT- OFFICE v CERTIFICATE OF CORRECTION Patent No. 2,693,677 Dated nni'n'hpr 17 1079 Invent r( ROBERT LOOKER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 14, at the end of the column the following claim is added:

"14. A pallet as set forth in Claim 2 which includes reinforcement inserts at the four corners of the frame portion, said inserts interlocking the four members.--

Signed and sealed this 17th day of April 1973 (SEAL) Attestz' EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents ORM PO-105O (10-69) uscoMM-Dc 60376-P69 k Hi5. GOVERNMENT PRINTING OFFICE: 1969 0-366-334

Claims

1. A pallet in the form of a rectangular panel for anchorage of cargo thereon in the cargo space of an aircraft by overhanging lock means and to carry cargo to and from the cargo space by gliding over rotary support elements, said panel having a rectangular marginal frame portion encompassing all of its four sides, said frame portion being thicker than a major central portion of the panel with the four sides of the frame portion interconnected to cause a transverse force applied to any one side of the panel toward the central portion thereof to be transmitted to adjoining parallel sides of the frame portion for transmission to the fourth side of the frame portion, said frame portion being equipped with means for engagement with cargo securing means, the major central portion of the panel being formed by a single sheet, the frame portion being attached to the single sheet, a part of the frame portion being of reduced thickness and overlapping the edge of the sheet and being attached thereto in face to face relationship, the edge of the sheet being tapered, the frame portion having a groove of cross section complementary to the cross section of the tapered edge of the sheet, the groove being interlocked with the edge of the sheet to oppose separation of the edge laterally away from the frame portion.

2. A pallet in the form of a rectangular panel for anchorage of cargo thereon in the cargo space of an aircraft by overhanging lock means and to carry cargo to and from the cargo space by gliding over rotary support elements, said pallet having a major central portion formed by a single sheet; a rectangular marginal frame portion encompassing all four sides of said pallet; said frame poRtion attached to the said single sheet forming the central portion of the panel; said frame portion being substantially thicker than the major central portion of the panel with the four sides of the frame portion interconnected to cause a transverse force applied to any one side of the panel towards the central portion thereof to be transmitted to adjoining parallel sides of the frame portion for transmission to the fourth side of the frame portion, said frame portion being recessed to receive in overlapping engagement the edge of said sheet and attached to said sheet; the four sides of said rectangular frame portion being formed by separate members leading into four corners of the frame structure and attached to the single sheet; said four members being interlocked at the corners of said frame portion; and means carried by said frame portion for engagement with conventional cargo-securing means.

3. A pallet for the placing of cargo thereon and the securing of the cargo thereto for movement of the cargo over rotary elements to and from the cargo space of a cargo carrier and to permit the cargo to be releasably secured in the cargo space by overhanging lock means, comprising: a rectangular panel having a central load carrying portion and a rectangular frame surrounding the central portion and united therewith, said central load carrying portion formed of a substantially incompressible material of such thickness and mass to resiliently flex locally in response to impact loads produced by cargo dropped thereon and to resiliently flex locally in response to engagement with a rotary support element spaced above the supporting plane of adjacent rotary elements supporting the pallet as the same moves into and over the elevated support element to distribute a substantial portion of the cargo load carried by said central portion to supporting rotary elements adjacent the rotary element producing the flexure whereby high unit load stresses in the central portion and the elevated rotary element are reduced; said frame member comprising a plurality of elements each having a greater rigidity than said central portion and each formed with a recess receiving one marginal edge of said central portion to support and reinforce the edge received therein; means for permanently anchoring a marginal edge of the central portion in a recess of an element of the frame member; and means carried by said frame member for engagement with cargo-securing means for holding said pallet in a selected position within the cargo space of the cargo carrier.

4. A pallet as defined in claim 3 in which a face of said frame member is substantially coplanar with a corresponding face of said load carrying central portion.

6. A pallet for the placing of cargo thereon and the securing of the cargo thereto for movement of the cargo over rotary elements to and from the cargo space of a cargo carrier and to permit the cargo to be releasably secured in the cargo space by overhanging lock means, comprising: a rectangular panel having a metallic sheet-like central portion and a rectangular frame surrounding the central portion and united therewith, said central portion having high resistance to permanent deformation, being substantially incompressible and of an area and thickness to resiliently absorb impact loads and to resiliently flex in response to local forces produced by a rotary support element spaced above the supporting plane of adjacent rotary elements supporting the pallet as the pallet moves over the elevated support element to distribute a substantial portion of the cargo load to supporting rotary elements adjacent the rotary element producing the flexure of said central portion, whereby high unit load stresses produced in the central portion by the elevated rotary element are reduced; said frame member being more rigid than said central portion and comprising a plurality of elements, each formed with a recess receiving one marginal edge of said central portion, said recess defining at least one sidewall which overlies and face wisely engages a surface of a marginal edge of said central portion; means for permanently anchoring a marginal edge of the central portion in a recess of an element of the frame member; and means carried by said frame member for engagement with cargo-securing means for holding said pallet in a selected position within the cargo space of the cargo carrier.

9. A pallet as defined in claim 6 in which said central portion is formed of a single sheet of aluminum.

10. A pallet for the placing of cargo thereon and the securing of the cargo thereto for movement of the cargo over rotary elements to and from the cargo space of a cargo carrier and to permit the cargo to be releasably secured in the cargo space by overhanging lock means, comprising: a rectangular sheet forming a central load carrying element of said pallet, said sheet formed of a metal highly resistant to permanent deformation under impact loads and of such thickness and mass to resiliently flex locally in response to forces produced by cargo dropped thereon and to resiliently flex in response to engagement with a support element spaced above the supporting plane of adjacent elements supporting the pallet as the same moves into and over the elevated support element to distribute a substantial portion of the cargo load carried by said pallet to supporting elements adjacent the element producing the flexure whereby high unit load stresses in the sheet and the elevated rotary element are reduced; a frame member comprising a plurality of elongate members, each element being thicker than and having a greater rigidity than said sheet; each of said elements being formed with a cavity receiving one marginal edge of said sheet, the cavity having a length equal to the marginal edge received therein; means for permanently securing a marginal edge of the sheet received within a cavity of the element of the frame member whereby the frame member encompasses all four sides of the sheet to reinforce the same; and means carried by said frame member for engagement with cargo-securing means for holding said pallet in a selected position within the cargo space of the cargo carrier.

11. A pallet as set forth in claim 10 in which the edge of the sheet is tapered and in which each elongate element has a groove of a cross section complementary of the cross section of the tapered edge of the sheet that interlocks with the edge of the sheet and thereby opposing separation of the edge of the sheet laterally away from the elongate element.

12. A pallet for the placing of cargo thereon and the securing of the cargo thereto for movement of the cargo over rotary elements to and from the cargo space of a cargo carrier and to permit the cargo to be releasably secured in the cargo space by overhanging lock means, comprising: a rectangular sheet of metal forming a central load carrying element of said pallet, said sheet being of such thickness as to resiliently flex locally in response to impact forces produced by cargo dropped thereon and to resiliently flex in response to engagement with a support element of the cargo carrier spaced above the supporting plane of adjacent elements supporting the pallet as the same moves into and over the support element to distribute a substantial portion of the cargo load carried by said pallet to supporting elements adjacent the element producing the flexure whereby high unit load stresses in the sheet and the elevated rotary element are reduced; a frame member of a thickness greater than said sheet extending about the four marginal edges of the same to reinforce and stiffen the edges of the sheet, said frame being substantially rigid and resistant to flexing stresses produced by bending loads induced in said frame; and means carried at spaced locations about said frame for holding said pallet in a preselected position within the cargo space of the cargo carrier and receiving and cooperating with means carried by a load confining element adapted to hold cargo to said pallet.