US2812528A

US2812528A - Extensible stairway

Info

Publication number: US2812528A
Application number: US505787A
Authority: US
Inventors: Albert W Odell
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-05-03
Filing date: 1955-05-03
Publication date: 1957-11-12
Anticipated expiration: 1974-11-12

Description

Nov. 12, 1957 A. w. dDELL 2,812,528

EXTENSIBLE STAIRWAY Filed May 3, 1955 3 Sheets-Sheet 1 FIG.I.

53 fl venfor Albert W. Odell ATT).

Nov. 12, 1957 A. w. ODELL 2,812,528

. EXTENSIBLE STAIRWAY Filed May 5, 1955 3 Sheets-Sheet 2 1 7w for Albert W. Odell HTTX 1957 A. w. ODELL EXTENSIBLE STAIRWAY 5 Sheets-Sheet 3 Filed May s, 1955 ATTY.

United States Patent 2,812,528 Patented Nov. 12, 1957 nice EXTENSIBLE STAIRWAY Albert W. Odell, Dallas, Tex.

Application May 3, 1955, Serial No. 505,787

12 Claims. (Cl. 14-71) This invention relates to an extensible stairway constmction and pertains more particularly to structural improvements and refinements in the same.

This invention contemplates improved structural characteristics in connection with sliding, extensible stairways which are particularly adapted for use in aircraft.

One object of the invention resides in the provision of an improved extensible stairway which is of compact form and which is so constructed as to readily be adapted to form an integral part of the structure with which it is associated so as to reinforce the same and generally enhances its structural rigidity.

Another object of this invention is to provide an improved form of extensible stairway which includes two or more slidably, telescopically engaged stair sections having a series of hingedly connected steps secured therebetween such that when the stair sections are collapsed, the steps will be folded within the confines of the sections and when the sections are extended fully, the steps will be constrained to assume positions eifecting a stairway the full length of the sections.

A further object of this invention is to provide an improved collapsible stairway having at least two telescopically interfitted sections acting as carriages which have connected at remote ends a series of hingedly interconnected risers and treads with abutment means located at each hinged connection between the same cooperable with carriage elements so that the treads and risers are held in proper position to present a series of steps when the sections are extended.

Another object of the invention is to provide an extensible stairway which includes at least two telescopically engaged carrier sections each including spaced side wall members with the side wall members of one section receiving therebetween the side walls of the other section and with the inner section having longitudinally extending spaced abutment flanges projecting laterally inwardly from the inner surface of each side wall so as to receive therebetween longitudinally extending abutment runners which are end connected at one end to the outer section and which extend longitudinally thereof but in spaced relation to the side walls of the outer sections so as to be disposed inwardly of the side walls of the inner section, the abutment runner being projected partially between the abutment edges even when the sections are in fully extended position so that the free end of the same is supported by the abutment flanges even in the fully extended position of the sections.

Another object of this invention is to provide an improved form of extensible stairway which includes at least two telescopically engaged carriage sections having abutment means associated therewith serving as the sole support means for a plurality of hingedly interconnected alternate tread and riser plates which, when the sections are fully extended, are constrained to move into a position effecting a series of steps.

Another object of this invention is to provide an improved form of extensible stairway particularly adapted for use in aircraft in that the support means for the stairway includes a pair of spaced parallel uprights which in themselves may be integrated with the aircraft frame constructions so as to rigidity the same and materially enhance the strength of the aircraft frame without appreciably adding to the weight thereof.

Another object of this invention is to provide an improved extensible stairway construction wherein the sole means for support of the steps constitutes abutment means carried by the extensible carriage sections and wherein the step means cooperable with the abutment means to support the steps constitutes in part the means for hingedly interconnecting alternate tread and riser plates wherein the steps may be collapsed when the carriage sections are likewise collapsed.

Still another object of this invention is to provide an improved extensible stairway construction wherein one of the carriage sections includes enlarged, generally circular plate portions at its upper end which are pivotally connected to supporting uprights and which carry gear segments operatively related with drive gear mechanism whereby the stairway may be moved between a substantially vertical inoperative position and a lowered operative and extended position.

With the above and other objects in view, the invention consists in the construction and novel combination and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings and pointed out in the claims hereto appended, it being understood that various changes in the form, proportions, and minor details of construction, Within the scope of the claims, may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings:

Fig. l is a transverse sectional view through an aircraft frame showing the extensible stairway associated therewith and in operative position in full lines, the dotted line position of the extensible stairway indicating the inoperative or stored position within the aircraft frame;

Fig. 2 is an enlarged rear elevational view of the extensible stairway assembly;

Fig. 3 is a vertical section taken substantially along the plane of section line 3-3 in Fig. 2, illustrating details of the internal construction of the stairway;

Fig. 4 is an enlarged transverse section taken along the plane of section line 4--4 in Fig. 3 and illustrating the manner in which the tread and riser plates are supported on the carriage sections;

Fig. 5 is a perspective view of a portion of the outer carriage section;

Fig. 6 is a perspective view of a portion of the inner carriage section;

Fig. 7 is a perspective view of several of the alternate tread and riser plates showing their manner of interconnection;

Fig. 8 is an end elevational view showing the lower end of the outer carriage section;

Fig. 9 is a vertical section taken through the carriage assembly and showing the same in collapsed position with the steps folded therewithin; and

Fig. 10 is an enlarged sectional view taken substantially along the plane of section line 10-10 in Fig. 3.

Referring now more particularly to Figs. 1 and 2, the reference numeral 16 indicates generally an aircraft fuselage section having an outer skin 11, stepped

deck portions

12 and 13 and a vertical wall section 14 substantially vertically dividing the aircraft frame. It will be understood that the precise and exact structural characteristics of the aircraft frame form no part of this invention and those shown in Fig. 1 are illustrative only.

The extensible stairway is indicated generally by the reference character in Fig. l and, as will be more clearly illustrated in Fig. 2, the stairway is supported wholly between a pair of

uprights

16 and 17 which, in themselves, preferably form an integral part of the aircraft frame so as to rigidify the same while at the same time supporting the stairway. As particularly shown in the drawings, the

uprights

16 and 17 are upstanding from the deck portion 12 and extend therefrom into contact with the inner ly interengaged so as to assume the full line position shown in Fig. 1 when fully extended and the dotted line vertical position shown in Fig. 1 when fully collapsed and stored within the aircraft. The construction is such that the stairway movesfrom its inoperative vertical position to full line operative position in Fig. 1 through the entrance opening 18 .of the aircraft.

The means by which the stairway is operated between the two positions shown in Fig. 1 will be more readily apparent from Figs. 2 and 3. The upper carriage section 19 includes a pair of generally circular support plate .

members

21 and 22 which are disposed between the

uprights

16 and 17 in closely spaced relationthereto. Projecting centrally through the

circular portions

21 and 22 are

pivotal members

23 and 24 which also project through suitable openings in the uprights. 16 and 17 and which are provided at their outer threaded ends with retaining

nuts

25 and 26 respectively and

intermediate washers

27 and 28. Preferably there is disposed between the pivotal bolts and the uprights, in surrounding relation to the pivot bolts, bearing or bushing members, not shown, to serve as low friction pivot means for supporting the stairway.

To effect the pivoting movement of the stairway, each

circular plate

21 and 22 is provided with a gear segment as indicated at 29 and 30, each gear segment being rigidly connected to its associated circular plate and disposed along a portion of the periphery thereof such that the gear teeth project radially outwardly of the marginal edges of the plates. Supported on the section 12 which inter connects the

uprights

16 and 17 is a horizontal drive shaft 31 having a pair of pinion members 32-and 33 rigidly fixed thereto which are in engagement with the teeth of the gear segments 29 and such that when the 'drive shaft 31 is rotated, for example counterclockwise in Fig. 3, the stairway 15 will be moved from the position shown ipward the dotted line or inoperative position shown in The -drive shaft 31 may be supported in vertically spaced relation above the deck section 12 by means of the bearing bracket indicated generally by the reference character 34 which includes the spaced

vertical leg portions

35 and 36 interconnected between transverse -pO1'- tion 37 and which legs have at their upperends the

bearing bosses

38 and 39 suitably bushed to rotatably receive the drive shaft 31 therein. The

plates

21 and 22 are, of course, spaced from their associated

uprights

16 and 17 respectively a suitable distance to accommodate the width of the

gear segments

29 and 30, it being preferred that very little clearance be had between the outer -22, there-may be provided a power shaft 40 in the manner shown in Fig. 3 whichintersects the drive sl1aft 31 and is providedatsuch intersectiomwith a 'drive pinion 41 mating with a corresponding miter gear 42 feathered to the drive shaft 31. The remote end of the power shaft 40 is connected to any suitable source of power, not shown, such as an electric motor or a hydraulic motor. Also, a suitable support such as the bearing bracket 43 may be provided at a convenient location or locations to rotatably support the power shaft 40.

Having reference at this point most particularly to Fig. 6 wherein a portion of the inner carriage section 19 is shown, it will be seen that this carriage section includes a pair of spaced

side wall members

34 and 35 which are elongate and extend the full length of the carriage section. Each side wall has at its upper and lower longitudinal edges the inturned

flange portions

46 and 47 respectively, and the side walls are interconnected by means of a longitudinally extending bottom wall member 48 which rests upon the bottom flanges 47 and is securely aflixed thereto by any suitable means. Fixedly secured to the inner surface of each side wall44 and is a pair of spaced parallel abutment flanges such as those indicated by the

reference characters

49 and 50. The abutment flanges extend the full length of the

side walls

44 and 45, their purpose being more readily apparent presently.

The generally circular

support plate members

21 and 22 are enlarged continuations of the

side wall members

44 and 45 and may be either formed integrally therewith or pivotally and r-igidlyattached thereto. Thus rotation of the

plate members

21 and 22 directly rotates the upper or inner carriage section 19.

A portion of the lower or outer carriage section 20 is indicated in Fig. 5. The portion shown constitutes only one side of the outer carriage section and it will be seen to include only one side wall portion 51 thereof. In the complete assembly there are two such side wall portions and each is provided with the upper and lower inwardly extending

retainingrflanges

52 and 53 which extend longitudinally the .full length of the side walls 51. Further, each side wall 51 has associated therewith an inverted channel shaped abutment runner 54 which extends longitudinally the full length of the side wall but in slight 1y spaced relation thereto. The runner consists of spaced

leg portions

55 and 56 which extend inwardly of the inner surface of the side wall 51 and which.are connected at their intermost edges by the bight portion 57 which is substantially parallel to the side wall 51.

Fig. 4 illustrates, the manner in which the inner and outer carriage sections are telescopically interengaged, and from a study of the figure, it will be appreciated that the side walls 51.of the outer section are disposed in close ly spaced relationship to the

side walls

44 and 45 of the inner sections with the abutment runner 54 received between the laterally. inwardly projecting abutment flanges 49 and which are connected to the inner surface, of the

side walls

44 and 45 of the inner section. The abutment runners 54 are connected only at their lower ends to the outer section-20. i As will be seen most clearly in Figs. 3 and 8, the lower endof the outer section 20 is provided with a generally U-shaped plate 58 extending transversely thereof and connected between the opposite side walls 51-51. The lower ends of the abutment runner 54 are attached directly and only to this plate 58 so as to extend longitudinally of the outer section in cantilever fashion to derive. support at their upper ends only from the abutment flanges. 49 and 50 even when the carriage sections are fully extended.

The side walls 51-'51 of the outer carriage section 20 are rigidly affixed in spaced relationship by any de' sired number of cross members 59 extending thercbetween. Such cross members are rigidly secured to the undersurface of the lower. flange members 52 which extend longitudinally along the side walls 51-51 so that the net effect of these cross members is to fix the spacing between the side walls and form a rigid unit of the lower Y carriage section.

' As seen most clearly in Figs. 3 and. 8; there is connected to the lower end of the outer section 20 a riser plate 60. This riser plate is hingedly connected to the outer section through the medium of a hinge which includes the hinge plate 61 directly attached to the cross plate member 58 at the lower end of the outer section and the secondary hinge plate 62 which is fixed along the lower edge of the riser plate 60.

At the upper end of the inner section 19 is attached an uppermost tread plate 63. This tread plate is hingedly afiixed to the inner section by means of a hinge which includes the hinge plate 64 attached directly to the upper end of the bottom wall 48 and the hinge plate 65 which is attached to the undersurface of the tread plate 63 at its rear edge.

Extending between the lowermost riser plate 60 and uppermost tread plates 63 are a plurality of alternate tread and

riser plates

66 and 67 which are arranged in zig-zag fashion and which are hingedly secured together so as to be collapsible and extendable. The rear edge of each tread plate 66 is hingedly secured to the lowermost edge of each adjacent riser plate 67 by means of the

hinge plates

68 and 69 connected to these members respectively, the hinge plates being pivotally or hingedly interconnected by means of the transversely extending pintles '76. Likewise, each tread plate 66 is connected adjacent its forward edge to the upper edge of the next adjacent riser plate by means of the hinge plate 71 and 72 respectively and with associated pintles 73. As will be seen most clearly in Figs. 4 and 7, each

pintle

70 and 73 is projected laterally from the side edges of the tread and

riser plate

66 and 67, the lateral projections of the pintle 70 being indicated by the reference character 74 where as the lateral projections of the pintle 73 are indicated by the reference character 75. The

projections

74 and 75 of the pintles are such as to extend nearly the full distance between the opposed inner surfaces of the

side walls

44 and 45 of the inner carriage section and are arranged so that alternate pairs of the

pintle projections

74 and 75 straddle the

abutment flanges

49 and 50 and the abutment risers 54. Thus, the

carriage sections

19 and 20 may be extended only to such position as will be permitted by engagement of the

pintle projections

74 and 75 with thecorresponding surfaces of either the

abutment flanges

49 and 50 or the abutment runner 54. That is to say, the pintle projections form stops engageable with the abutment means to limit the extensibility of the assembly. When all of the pintle projections have engaged with their associated abutment means, further extension of the

carriage sections

19 and 20 is precluded and in that position the sole means of support for the series of stops provided by the tread and riser plates is by the engagement of the pintle pin projections with corresponding surface portions of the

abutment flanges

49 and 50 and the abutment runners 54.

Since the abutment runners 54 are narrower than the distance between the abutment flanges 49, those steps which are below the lower end of the inner section 19 when the stairway is fully extended, must, of necessity, have their pintle pin projections disposed in slightly closer relationship than those steps which are above the lower end of the inner section 19. For this reason, the lowermost steps shown in Fig. 3 are effected by hingedly connecting the upper edge of the riser plate 67 to the tread plate 66 at a point which is more remote from the forward edge of the tread plates than is the same connec-, tion in the uppermost steps in that figure.

Since either the

abutment flanges

49 and 50 or the abutment runners 54- carry the full weight of the steps and any load placed thereon,.it is important that the upper end portions of the abutment runners 54 are never disengaged from between the

abutment flanges

49 and 50 since such engagement is eflective to support the upper free ends of the abutment runners when the carriage sections are fully extended. This is necessary because 6 the abutment runners 54 are connected only at their lower ends to their associated carriage section 20.

For the purpose of providing a hand rail for .the stairway, it is preferred that a rather large tube be bent into the substantial J-shape indicated in Figs. 1 and 3 with the upper end of each tube so bent being connected as at 76 to the

corresponding plate

21 or 22 with the remainder 77 of such tube projecting substantially in parallelism with the inner section 19. A second hand rail tube 78 is secured at its lower end portion 79 to the cross member 58 at the lower end of the outer section 20 by any suitable means, such as welding or the like, and the uppermost free end portion 80 of this hand rail tube is projected into the lower free end of the upper tube portion 77. Therefore, as the carriage sections are collapsed or extended, the hand rail tube members are likewise associated, it being merely necessary that the inside diameter of the tube portion 77 be sufiicient to telescopically receive the lower tube portion 78. Of course, one such hand rail assembly is provided at each side of the stairway.

Fig. 9 illustrates the approximate position of the tread and riser plates when the device has been disposed in the collapsed position. It is illustrated in Fig. 9 that the lowermost riser and, tread plates, due to the close disposition of their pintle pin extensions, are disposed in relatively closely spaced relationship since the free ends of the

abutment flanges

49 and 50 engage the same and force the lowermost. steps which are shown uppermost in Fig. 9 into a position in which the plates are closely folded. The remainder of the plates are suspended within the confines of the inner section 19, some of them stacking up at that portion of the intersection which is lowermost in the position of the carriage sections illustrated in Fig. 9 similar to the stacked position of the plates shown uppermost in that figure.

' Fig. 10 illustrates the guide means which services to stabilize the stairway construction between the

uprights

16 and 17. Each

upright

16 and 17 is provided with an arcuate slot 81 whose center of radius is the axis of the

pivot bolts

23 and 24 and within which a ball bearing 82 is disposed. The inner race of the ball bearing is fixed on the shank 83 of a retaining bolt member 84 which projects through both the circular plate and its associated upright, there being a washer 85 disposed between the plate and the upright and a washer 86 on the outer side of, the upright between the same and a retaining nut 87 secured on the threaded end of the bolt 84. Thus, as the

plates

21 and 22 are rotated the associated bearingst82 roll within the arcuate slots 81 and stabilize the assembly.

It will be appreciated that Fig. l is not intended to show an exact aircraft frame construction with which the stairway is used but is only illustrative in showing the manner in which the stairway is mounted within a theoretical aircraft frame. ,The top step plate, of course, would have to be associated with a floor plate of the aircraft so that a passenger ascending the steps would step directly from the uppermost tread plate onto the floor of the aircraft. This floor is indicated by the reference character F in Fig. land it is to be understood that this showing is only illustrative and need not be strictly adhered to. It will be further noted that as the stairway 'moves from the full line lowered position of Fig. 1 to in connection with a ships ladder or gangplank, for a fire escape or for attic or basement steps, in other words wherever ,it may be desired to utilize, the feature "ofextensibility and compact storage.

I claim:

1. An extensible stairway comprising a pair of spaced parallel uprights, a plurality of telescopically engaged carriage sections, one of said sections at one end of the carriagesections being pivotally connected at one end to .said uprights and between the same for movement between asubstantially vertical inoperative position and an operative lowered position, a step assembly comprising a series of alternate tread and riser plates hingedly secured together and connected at opposite ends to opposite remote ends of the carriage sections, and stop means on the step assembly disposedin alternate straddling relation with erally circular enlarged plate portions disposed between said uprights, pivot means projecting centrally through said plate portions and through said uprights whereby to pivotally connect said carriage section between the uprights, an arcuate gear segment secured to each plate portion, a drive shaft having a pair of gears thereon in mesh with said gear segments to rotate said carriage section between a substantially vertical inoperative position to a lowered, operative position, each of said uprights having an arcuate slot therein, and guide means canied by said plate portions received in said arcuate slots.

3. In an extensible stairway, a pair of spaced, parallel uprights, an elongate carriage section including opposed side walls, said side walls terminating at one end in generally circular enlarged plate portions disposed between said uprights, pivot means projecting centrally through said plate portions and through said uprights whereby to pivotally connect said carriage section between the uprights, an arcuate gear segment secured to each plate portion, a drive shaft having a pair of gears thereon in mesh with said gear segments to rotate said carriage section between a substantially vertical inoperative position to a lowered, operative position.

4. In an extensible stairway, a pair of telescopically engaged carriage sections, each section including spaced elongate side walls with the side walls of one section disposed inwardly of and closely adjacent the corresponding .side walls of the other section, said one section having a pair of spaced, longitudinally extending abutment flanges secured to each side wall and extending inwardly therefrom, said other section having a pair of elongate abutment runners secured at one end to the free end of such section and extending longitudinally along the inner sides of the associated side walls and in slightly spaced relation thereto so as to be received between the corresponding pairs of abutment flanges on said one section, a plurality of alternate tread and riser plates hingedly secured together, there being a lowermost riser plate at one end hingedly secured to the lower end of said other carriage section and there being an uppermost tread plate at the other end hingedly secured to the upper end of said one carriage section, and there being a laterally projecting abutment pin on either side of each hinged connection between adjacent tread and riser plates, adjacent pairs of such abutment pins being positioned to straddle an associated pair of abutment flanges and an associated abutment runner so as to limit the extensibility of the carriage sections.

5. In an extensible stairway, a pair of telescopically disposed inwardly ,of and closely adjacent the corresponding side walls of the other section, said one section havinga pair of spaced, longitudinally extending abutmentflangessecured to each side wall and extending inwardly therefrom, said other section having a pair of elongate abutment runners secured at one end to the free end of such section and extending longitudinally along the inner sides of the associated side walls and in slightly spaced relation thereto so as to be received between the corresponding pairs of abutment flanges on said one section, a plurality of alternate tread and riser plates hingedly secured together, there being a lowermost riser plate at one end hingedly secured to the lower end of said other carriage section and there being an uppermost tread plate at the other end hingedly secured to the upper end of said one carriage section, the hinged connection between adjacent tread and riser plates consisting of a pair of hinge plates afiixed to the adjacent members and a pintle pin pivotally connecting the hinge plates, said pintle pins being elongate so as to project on opposite sides ,beyond their associated tread and riser plates with adjacent pairs of the pintle pins straddling the associated abutment flanges and the associated abutment runner whereby to limit the extensibility of the carriage sections.

6. In an extensible stairway, inner and outer carriage sections, the inner section including an elongate bottom wall having upstanding side walls extending along opposite sides thereof, and said side walls having a pair of spaced, parallel and longitudinally extending abutment -outer section t and extending longitudinally along its associatedwall and in spaced relation thereto, whereby the inner carriage section is ,slidably, telescopically received within the outer carriage section with the abutment runner of the outer section disposed between said abutment flanges of the inner section, an upper tread plate hingedly secured at its rear edge to the uppermost end of said inner section, a lowermost riser plate secured at its lower edge to the lowermost end of said outer section, there being a plurality of alternate tread and riser plates hingedly secured together and to said uppermost tread plateandsaid lowermost riser plate so as to form a series of steps when the carriage sections are fully extended, each tread and riser plate having a pair of laterally projecting abutment pins straddling the associated abutment flanges and abutment runner so as to limit the extensibility of the carriage sections.

7. In an extensible stairway, inner and outer carriage sections, the inner section including an elongate bottom wall having upstanding side walls extending along opposite sides thereof, and said side walls having a pair of spaced, parallel and longitudinally extending abutment .flan ges projecting laterally inwardly therefrom, said outer section including spaced side walls each having laterally :flanges ofithe inner section, an upper tread plate hingedly secured at its rear edge to the uppermost end of said inner section, a lowermost riser plate secured at its' lower edge to the lowermost end of said outer section, there being a plurality of alternate tread and riser plates hingedly secured together and to said uppermost tread plate and said lowermost riser plate so as to form a series of steps when the carriage sections are fully extended, the hinged connection between adjacent tread and riser plates consisting of a pair of hinge plates affixed to the adjacent members and a pintle pin pivotally connecting the hinge plates, said pintle pins being elongate so as to project on opposite sides beyond their associated tread and riser plates with adjacent pairs of the pintle pins straddling the associated abutment flanges and the associated abutment runner whereby to limit the extensibility of the carriage sections.

8. An extensible stairway comprising a pair of spaced parallel uprights, a plurality of telescopically engaged carriage sections, one of said sections at one end of the carriage sections being pivotally connected at one end to said uprights and between the same for movement between a substantially vertical inoperative position and an operative lowered position, a step assembly comprising a series of alternate tread and riser plates hingedly secured together and connected at opposite ends to opposite remote ends of the carriage sections, and stop means on the step assembly disposed in alternate straddling relation with portions of the carriage sections said stop means being engaged with such portions when the sections are extended to support the tread and riser plate and limit the extension of the carriage sections and being moved out of engagement therewith when said carriage sections are collapsed, said stop means including pintle pins projecting laterally from opposite sides of said tread and riser plates and constituting part of the means for hingedly interconnecting said plates.

9. In an extensible stairway, a pair of spaced, parallel uprights, an elongate carriage section including opposed side Walls, said side walls terminating at one end in generally circular enlarged plate portions disposed between said uprights, pivot means projecting centrally through said plate portions and through said uprights whereby to pivotally connect said carriage sections between the uprights, an arcuate gear segment secured to each plate portion, a drive shaft having a pair of gears thereon in mesh with said gear segments to rotate said carriage section between a substantially vertical inoperative position to a lowered, operative position, there being another carriage section telescopically engaged with the first mentioned carriage section, each section including spaced elongate side walls with the side walls of one section disposed inwardly of and closely adjacent the corresponding side walls of the other section, said one section having a pair of spaced, longitudinally extending abutment flanges secured to each side wall and extending inwardly therefrom, said other section having a pair of elongate abutment runners secured at one end to the free end of such section and extending longitudinally along the inner sides of the associated side walls and in slightly spaced relation thereto so as to be received between the corresponding pairs of abutment flanges on said one section, a plurality of alternate tread and riser plates hingedly secured together, there being a lowermost riser plate at one end hingedly secured to the lower end of said other carriage section and there being an uppermost tread plate at the other end hingedly secured to the upper end of said one carriage section, and there being a laterally projecting abutment pin on either side of each hinged connection between adjacent tread and riser plates, adjacent pairs of such abutment pins being positioned to straddle an associated pair of abutment flanges and an associated abutment runner so as to limit the extensibility of the carriage sections.

10. In an extensible stairway, a pair of spaced, parallel uprights, an elongate carriage section including opposed side walls, said side walls terminating at one end in generally circular enlarged plate portions disposed between said uprights, pivot means projecting centrally through said plate portions and through said uprights whereby to pivotally connect said carriage section between the uprights, an arcuate gear segment secured to each plate portion, a drive shaft having a pair of gears thereon in mesh with said gear segments to rotate said carriage section between a substantially vertical inoperative position to a lowered, operative position, there being another carriage section telescopically engaged with the first mentioned carriage section, each section including spaced elongate side walls with the side walls of one section disposed inwardly of and closely adjacent the corresponding side walls of the other section, said one section having a pair of spaced, longitudinally extending abutment flanges secured to each side wall and extending inwardly therefrom, said other section having a pair of elongate abutment runners secured at one end to the free end of such section and extending longitudinally along the inner sides of the associated side walls and in slightly spaced relation thereto so as to be received between the corresponding pairs of abutment flanges on said one section, a plurality of alternate tread and riser plates hingedly secured together, there being a lowermost riser plate at one end hingedly secured to the lower end of said other carriage section and there being an uppermost tread plate at the other end hingedly secured to the upper end of said one carriage section, the hinged connection between adjacent tread and riser plates consisting of a pair of hinge plates aflixed to the adjacent members and a pintle pin pivotally connecting the hinge plates, said pintle pins being elongate so as to project on opposite sides beyond their associated tread and riser plates with adjacent pairs of the pintle pins straddling the associated abutment flanges and the associated abutment runner whereby to limit the extensibility of the carriage sections.

11. In an extensible stairway, a pair of spaced, parallel uprights, an elongate carriage section including opposed side walls, said side walls terminating at one end in generally circular enlarged plate portions disposed between said uprights, pivot means projecting centrally through said plate portions and through said uprights whereby to pivotally connect said carriage section between the uprights, an arcuate gear segment secured to each plate portion, a drive shaft having a pair of gears thereon in mesh with said gear segments to rotate said carriage section between a substantially vertical 7 inoperative position to a lowered operative position, an

outer carriage section telescopically receiving the inner first mentioned carriage section, the inner section including an elongate bottom wall having upstanding side walls extending along opposite sides thereof, and said side walls having a pair of spaced, parallel and longitudinally extending abutment flanges projecting laterally inwardly therefrom, said outer section including spaced side walls each having laterally inwardly projecting retaining flanges along the top and bottom thereof with the side walls being interconnected by a plurality of cross members secured to the undersurfaces of said bottom retaining flanges and extending therebetween, an elongate abutment runner secured at its lower end to the lower end of each side wall of the outer section and extending longitudinally along its associated wall and in spaced relation thereto, whereby the inner carriage section is slidably, telescopically received within the outer carriage section with the abutment runner of the outer section disposed between said abutment flanges of the inner section, an upper tread plate hingedly secured at its rear edge to the uppermost end of said inner section, a lowermost riser plate secured at its lower edge to the lowermost end of said outer section, there being a plurality of alternate tread and riser plates hingedly secured together and to said uppermost tread plate and said lowermost riser plate so as to form a series of steps when the carriage sections are fully extended, each tread and riser plate having a pair of laterally projecting abutment pins straddling the associated abutment flanges and abutment runner so as to limit the extensibility of the carriage sections.

12. In an extensible stairway, a pair of spaced, parallel uprights, an elongate carriage section including opposed side walls, said side walls terminating at one end in generally circular enlarged plate portions disposed between said uprights, pivot means projecting centrally through said plate portions and through said uprights whereby to pivotally connect said carriage section between the uprights, an arcuate gear segment secured to each plate portion, a drive shaft having a pair of gears thereon in mesh with said gear segments to rotate said carriage section between a substantially vertical inoperative position to a lowered operative position, an outer carriage section telescopically receiving the inner first mentioned carriage section, the inner section including an elongate bottom wall having upstanding side walls extending along opposite sides thereof, and said side walls having a pair of spaced, parallel and longitudinally extending abutment flanges projecting laterally inwardly therefrom, said outer section including spaced side walls each having laterally inwardly projecting retaining flanges along the top and bottom thereof with the side walls being interconnected by a plurality of cross members secured to the undersurfaces of said bottom retaining flanges and extending therebetween, and elongate abutment runner secured at its lower end to the lower end of each side wall of the outer section and extending longitudinally along its associated wall and in spaced relation thereto, whereby the inner carriage section is slidably, telescopically received within the outer carriage section with the abutment runner of the outer section disposed between said abutment flanges of the inner section, an upper tread plate hingedly secured at its rear edge to the uppermost end of said inner section, a lowermost riser plate secured at its lower edge to the lowermost end of said outer section, there being a plurality of alternate tread and riser plates hingedly secured together and to said up permost tread plate and said lowermost riser plate so as to form a series of steps when the carriage sections are fully extended, the hinged connection between adjacent tread and riser plates consisting of a pair of hinge plates afixcd to the adjacent members and a pintle pin pivotally connecting the hinge plates, said pintle pins being elongate so as to project on opposite sides beyond their associated tread and riser plates with adjacent pairs of the pintle pins straddling the associated abutment flanges and the associated abutment runner whereby to limit the extensibility of the carriage sections.

References Cited in the file of this patent UNITED STATES PATENTS