US3559763A

US3559763A - Ladder structure

Info

Publication number: US3559763A
Application number: US869486A
Authority: US
Inventors: Melvin J Stern
Original assignee: LAWNLITE CO
Current assignee: LAWNLITE CO
Priority date: 1969-10-27
Filing date: 1969-10-27
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02

Abstract

A ladder structure having a pair of parallel hollow rails, the hollow rails having slotted portions, a plurality of hollow steps having a rectangular cross section with tabs formed at the ends thereof received by the slotted portions and fastened to the sidewalls of the hollow rails.

Description

United States Patent Inventor Melvin J. Stern Miami, Fla. App]. No. 869,486 Filed Oct. 27, 1969 Patented Feb. 2, 1971 Assignee Lawnlite Company Miami, Fla. a corporation of Florida LADDER STRUCTURE 4 Claims, 5 Drawing Figs.

US. Cl 182/215, 1 82/228 Int. Cl E06c 7/08 Field of Search 182/ l 94. 228, 215

[5 6) References Cited UNITED STATES PATENTS 901.755 10/1908 Tiepolt 182/194 2,466,838 4/1949 Buell 182/228 3,005,513 10/1961 Larson .4 182/228 Primary Examiner-Reinaldo P. Machado AttorneySalvatore G. M ilitana ABSTRACT: A ladder structure having a pair of parallel hollow rails, the hollow rails having slotted portions, a plurality of hollow steps having a rectangular cross section with tabs formed at the ends thereof received by the slotted portions and fastened to the sidewalls of the hollow rails.

PATENTEU FEB '2I97l 3,559,763

Inn. 1 II/Il/IIIII/II/IIIIIIIII IIIIIIIIIIIIII/III/[IL/I77 INVENTOR MELVIN J. STERN ATTORNEY LADDERSTRUCTURE This invention is directed to ladder structures.

A principal object of the present invention is to provide a ladder structure whose connection between the rungs or steps and side rails are rigid, durable and strong which results in a one-piece unitized ladder construction.

Another object of the present invention is to provide a ladder structure with hollow side rails and steps that may be extruded or rolled which when spot welded together eliminates any racking and side sway of the ladder.

A further object of the present invention is to provide a ladder structure which is simple in construction, easy to assemble and inexpensive in cost.

With these and other objects in view, the invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawing forming a part of this specification, with the understanding, however, that the invention is not confined to any strict conformity. with the showing of the drawing but may be changed or modified so long as such changes or modifications mark no material departure from the salient features of the invention as expressed in the appended claims.

In the drawing:

FIG. 1 is a perspective view of a ladder constructed in accordance with my invention;

FIG. 2 is a fragmentary cross-sectional view taken along the line 2-2 ofFIG. 1;

FIG. 3 is an exploded view illustrating the manner of assembly of the rung or step and the side rail;

FIG. 4 is a fragmentary cross sectional view similar to FIG. 2 showing a modified structure of the side rail; and

FIG. 5 is an exploded view similar to FIG. 3.

Referring to the drawing wherein like numerals are used to designate similar parts throughout the several views the numeral l0 refers to a ladder constructed in accordance with my invention and consisting of a pair of side rails R and a plurality of steps or rungs S extending therebetween. Both the side rails R and the steps S are hollow members produced by the extrusion or rolled methods of manufacture.

Referring now in particular to FIGS. l-3 inclusive, the side rails R consists of a pair of

elongated wall portions

11 and 12 that are spaced from each other and in parallel relation, the inner wall portion 11 being slightly larger in width than that of the outer wall portion 12. The inner wall portion 11 is provided with flange portions 13 along its edges, while the outer wall portion 12 is provided with flanges 14, the flanges 13 being considerably longer than the flanges 14 with the flanges l3 and 14 being joined together at their ends. Since the rail R may be formed by the process of extruding or rolling, it is manufactured as a unitary hollow member.

Each of the side rails R are slotted as at 15 on the inner wall portion 11 adjacent the side edges and in alignment with the space 16 formed between the flanges l3 and 14; of each pair of slots 15, one slot is approximately 17 above the other slot 15. The steps S are made from a hollow member having the cross section of a parallelogram with top and

bottom walls

17 and 18 joined by sidewalls 19 at 17 from right angle. Tabs 20 are formed at each end of the steps S by cutting and removing rectangular portions of the

walls

17 and 18 at their end portions as at 21. The tabs 20 are inserted into the slots 15 and spot welded or otherwise fastened to the flanges l3 and 14 as indicated by FIG. 2.

In the normal manufacture of my ladder 10, the side rails R are either extruded or rolled and then cut to proper lengths and slotted as at 15. The steps S which are extruded are cut at each end to form the tabs 20 as explained hereinabove. The tabs 20 at the end of each of the steps S are then inserted into rails R and spot welded to complete the manufacture of my ladder 10.

Referring now to FIGS. 4 and 5 where an alternate structure 30 of my ladder 10 is shown, the rails RR are modified in construction while the steps S are identical to those described hereinabove.

The rails RR, which are extruded consist of inner and

outer wall portions

31 and 32 joined in spaced parallel relation by sidewalls 33. The sidewalls extend beyond the position of the outer wall 32 to form a flange portion 34 which is bent upon itself as at 35 and returned as a wall 36 in spaced parallel relation to the position of the inner wall 31 to form a slotted portion 37, the width of the slotted portion 37 being equal to the thickness of the tabs 20.

The steps S previously described hereinabove are then positioned along a pair of parallel and spaced apart rails R with the tabs 20 inserted into the slotted portions 37 and spot welded or otherwise fastened to the

walls

34, 35 and 36 to form a light, rigid and rack free ladder.

I claim:

1. A ladder having a pair of spaced and substantially parallel side rails and a plurality of substantially equally spaced steps extending between said side rails, each of said side rails comprising an elongated inher and outer walls mounted in spaced relation to each other, a slotted wall portion joining said inner and outer walls at each side thereof, tabs formed on each end of said steps received by said slotted wall portions and fastening means securing said tabs to said slotted wall portions.

2. The structure as recited by claim 1 wherein said steps having an upper and lower wall joined at their edges by sidewalls inclined at substantially l7 from the vertical, and said tabs formed by removing a portion of said upper and lower walls from the ends thereof.

3. The structure as recited by claim 1 wherein said slotted wall portion comprises flanges extending from the side edges of said inner and outer walls and joinedat their ends, said inner wall being larger in width than said outer wall and said flanges of said inner wall being longer than said flanges of said outer wall and slots formed in said inner wall adjacent its flanges.

4. The structure as recited by claim 1 wherein said slotted wall portion comprises flanges extending from the side edges of said inner wall, said outer wall extending between said flanges adjacent the end thereof, said end of said flanges being bent and folded on itself in spaced relation, said fold portion terminating in substantially the same plane as that of said inner wall, whereby a slot is formed for receiving said tabs.

Claims

1. A ladder having a pair of spaced and substantially parallel side rails and a plurality of substantially equally spaced steps extending between said side rails, each of said side rails comprising an elongated inner and outer walls mounted in spaced relation to each other, a slotted wall portion joining said inner and outer walls at each side thereof, tabs formed on each end of said steps received by said slotted wall portions and fastening means securing said tabs to said slotted wall portions.

2. The structure as recited by claim 1 wherein said steps having an upper and lower wall joined at their edges by sidewalls inclined at substantially 17* from the vertical, and said tabs formed by removing a portion of said upper and lower walls from the ends thereof.

3. The structure as recited by claim 1 wherein said slotted wall portion comprises flanges extending from the side edges of said inner and outer walls and joined at their ends, said inner wall being larger in width than said outer wall and said flanges of said inner wall being longer than said flanges of said outer wall and slots formed in said inner wall adjacent its flanges.