US2727671A - Ladder construction - Google Patents

Description

Dec. 20, 1955 R. H. oLLERHl-:AD

LADDER CONSTRUCTION Filed March 25, 1955 United States Patent O LADDER GNST'RUCTION Ronali-Hl lleilad;` Somerville, Massa assigner to Modrnt'ladderglnc, West Somerville,"Ma'ss:, a corporatin of MassachusettsA4 Application Mamma1953,.serieifNdsuai 1" Claim; (CIL 22836)" Thisainventionlrelates tota folding ladtenoffthe type having a` pair'4 of si'de-` rails: Vcollapsibly." secured together and-in' whiclr'thei sidefrails 'pivotally support arseriesof spaced-apart: rungs adapted'T tofbe loekedf in an' operative position: i

It-isv anlobjectoffthe presentfinventon 'to devise a collapsiblefladder-construction in whicn'is provided: an

improved locking: 'rnechanisrn` which l will automatically' become effective as soon as the ladder side rails are opened into a p'a'rall'el 'spaced-:apart position, and which can be instantly: disengaged when it`is desired to close the ladder rails upon one another. It is also-V- an object'loflthe invention toA devise a lockingmechanism-,which yis combinedl with 4a lspecial'doubl'e channel railwconstruction whereby a maximum of strength and rigidityl is provided for with little increase in Weight and without, in any Way, interfering with the normal functions for which the ladder is designed. p

Still another object of the invention is to devise a ladder side rail construction of novel fabricated channel form especially designed to facilitate the support and pivotal mounting of ladder rungs in a position such that they may be conveniently located in a horizontal operating position and, when desired, may be snugly fitted in a folded position with the ladder side rails occurring in overlapping relationship with respect to one another.

These and other objects and novel features will be more fully understood and appreciated from the following description of a preferred embodiment of the invention selected for purposes of illustration and shown in the accompanying drawings, in which:

Fig. 1 is a front elevational view showing the ladder of the invention in a fully opened position and particularly illustrating the locking mechanism of the invention in an engaged position;

Fig. 2 is a side elevational view showing the ladder in a completely collapsed position with the rungs and locking mechanism occurring in folded relationship;

Fig. 3 is a cross-section taken on the line 3 3, Fig.1;

Fig. 4 is a cross-section taken on the line 4--4, Fig. l; and i Fig. 5 is a cross-section taken on the line 5 5 of Fig. 2.

In the structure shown in the drawings, numerals 2 and 4 denote a pair of side rails which, as shown in Fig. 4, are constructed of a U-shaped cross-section to deline inner elongated passageways, as 6. Lyingwithin these side rails 2 and 4` in spaced relation to their side wall portions are respective channel members 8 and 10 also of U-shaped cross-section and having their bottom sections solidly secured to the side rails by means of welding rivets, or the like. If desired these channel members 8 and 10 may be constructed as an integral part of the ladder rails 2 and 4.

Pivotally secured between the rails 2 and 4 at spacedapart points therealong are a series of ladder rungs 12, 14, 16 and 18 which are intended to be representative of any desired number of such rungs. In Fig. 3 the rung 18 has been illustrated in cross-section, and it will be 2. observed. from an inspection of` this# figure that i thefrung, when arranged'lin a manner suchl as that? illustratedlin Fig. `Land-supported on the-pivotpins` Zlkand 221in a substantially righty angularly disposed position, presents a' roughened upper' horizontal treadsurfacev24f Itlwill be observed tha'tthe rung-is ofhollowftubulanconstruction and combines rigidity andlightrweighnias'wellas constituting amember of'fsu'llicient strength.' to'properly support a--pinnedy constructionrin theVsidei'lrails:rv Tliese rung members, are adapteddna collapsed positionsof the side rails'fto lie f in` anl overlapping;` relationship" to :one another, a's indicated in dotted lines in-Fig:2,lwitl-ivI all of the rung structure being containedV between :theiside'i-walls of theladder rails.-

In accordance withthe inventionw II. provide: a` special locking mechanism-- for use with: this'.` tubular# typef rung and channel side rail structure: This-locking mechanism', ingeneral, includes-1a pair of pivoted braces` whiclizco.- operate ywith a xed bracket against which the;I may-'be detachably supportedin an operative:position:` Innde tail this mechanism includesa anged bracket 26 having a'dependingflugZS. Thefflangedlportion ofl the. bracket mayJ be conveniently securedfagainst the liatfunder side of! the `tubular rungr18,r for example, bymeanslfofi the screw` fastenings- 38" andk 32; Asf may 'be' observedin Fig.. 3, the lowenend ofthe lugfportion28ds 'recessed tofprovide a notched'surfacerl Arranged t0 engage inthebnotchedll surface:r 34'? are two-brace elements? 36-`andf38f which;` asishownlinzFig. 5, are preferably constructed of U-shaped cross-sections which permit the ends of the brace elements to be fitted snugly, one within the other, and which also permits the upper extremities of the `brace elements to be pivotally secured together by a pin 40, shown in Figs. l and 3. The pin member 40 functions as a bearing or support member adapted to rest against the notched surface 34 when the brace elements are in an extended position, such as that shown in Fig. l.

In a preferred embodiment of the invention the lower ends of the brace elements 36 and 38, as viewed in Fig. 1, are pivotally supported in respective side rails of the ladder in a special manner, such that one of the brace elements will be permanently attached to one ladder rail, while the remaining brace element is detachably secured to the other ladder rail, thus permitting the two brace elements, when so desired, to be folded over against one another at the time the ladder rails are collapsed upon one another.

Thus in Fig. 1 the brace element 36 is pivotally secured by a pin 42 between the sides of the channel member 8, while the remaining brace element 38 is detachably secured in the channel member 10 by means of a compressible plunger type locking mechanism better shown in Figs. 4 and 5. As noted in Fig. 4 the locking mechanism may conveniently comprise two tubular sections 44 and 46 which are resiliently held apart by a spring 47 having its ends attached to the tubular sections. The spring and tubular sections are slidably contained in a sleeve member 49 located between the sides of the brace element 38. The lengths of the tubular sections 44 and 46 are so chosen that they may be forced together against the action of the spring 47 into a position in which they are free to slide out of the channel member 10 and thus disengage the brace element 38 therefrom.

It is pointed out that by thus combining two channel members, one Within another, with the innermost channel lying in spaced relation to the outer channel, I am enabled to detachably support a pair of compressible tubular sections in the inner channel member through holes formed in the sides of the channel member and, at the same time, I provide spaces at either side of the 'a sa inner channel member into which spaces the thumb and forenger may be inserted to conveniently compress the sections when desired. At the same time by using a brace of U-shaped cross-section I am enabled to mount a retaining sleeve and to conveniently pivot the base in the inner channel and upon its own side wall portions.

Figs. 2 and 5 show the brace element 38 fully collapsed upon the brace element 36 when the side rails 2 and 4 are folded into contact with one another. It is pointed out that the brace element 36 is formed with an aperture 50 into which the compressible plunger sections may be received. Likewise, the inner channel 8 is formed with a slot 52 so that the compressible plunger sections may also move freely into a position such as that shown in dotted lines at the bottom of Fig. 2.

It vll be evident from the foregoing description that I have provided a simple, easily operated, and extremely rigid ladder construction which is capable, by means of the various channeled components including those in the side rails and the rungs and braces, of resisting extremely heavy loads with a large safety factor. The locking mechanism is so combined with the nested channeled sections of the braces and rails as to safely lock the ladder in an operative position from which it cannot possibly escape to become collapsed upon itself until such time as two separate pins are compressed, one upon another, and the brace element disengaged from its respective channel retaining element. The entire channel assembly is capable of being very conveniently and cheaply manufactured either by forming separate elements or by forming one extruded rail section having the inner channeled element integrally formed therewith.

This application is a continuation-in-part of my applid cation Ser. No. 291,485, led June 3, 1952, now abandoned.

While I have shown a preferred embodiment of the invention it should be understood that various changes and modifications may be resorted to in keeping with the spirit of the invention as defined by the appended claim.

Having thus described my invention, what I desire to claim as new is:

In a collapsible ladder, a pair of side rails, each of said rails being recessed to define inner elongated passageways, channel forming members extending along said elongated passageways and having side wall portions lying in spaced relation to said adjacent recessed portions of the said side rails, a plurality of rungs pivotally pinned in the channel members, and means for securing the said side rails in parallel spaced-apart relationship, the said securing means including a bracket solidly secured to the underside of one of the rungs, a pair of brace elcments having two ends pinned together and adapted in one position to be supported against the bracket, an offset extremity of one of the brace elements being permanently pivoted in a channel member and an opposite extremity of the other of the said brace elements having a compressible locking pin supported transversely therethrough and said pin being adapted to be received in openings therefor in the opposite channel member.

References Cited in the le of this patent FOREIGN PATENTS 60,737 Switzerland Oct. l0, 1912 323,411 France Apr. 22, 1903 586,178 France Mar. 16, 1925

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