US2729516A - Adjustable scaffold - Google Patents

Description

Jan. 3, 1956 H. coLvlN ADJUSTABLE SCAF'FOLD 2 Sheets-Sheet 1 Filed Feb. 13. 1952 QN MN .WN mw INVENTOR.

Jan. 3, 1956 H. coLvlN ADJUSTABLE SCAFFOLD Filed Feb. 15. 1952 INI/ENTOR.

ADJUSTABLE SCAFFOLD Harry Colvin, Mayville, N. Y. Application February 13, 1952, Serial No. 271,349 1 Claim. (ci. 304-6) This invention relates to an adjustable scaffold and more particularly to a scaffold the four legs of which are individually adjustable as to height so that the scaffold can be supported ondifferent base levels, such as one end being supported on the floor of a room while its other end is supported onthe stair of a stairway at a higher elevation.

One of the principal objects of the present invention is to provide such a foldable scaffold which can readily be adjusted to have each of the pair of legs `at its opposite `ends adjustable to different lengths tomeet the varying conditions encountered in a` home and have the platform of the scaffold level to receive planks or the like.

Another most important jobject of the invention is to provide such a foldable scaffold with adjustable legs which is secure and sturdy and `rigidlyzbracedfso that there is no danger of the same collapsing while in use.

Another important object of the invention is to provide such a foldable scaffold in which the legs and braces fold against the platform of the scaffold so that it can be readily transported from place to place.

Another object isto provide such a foldable scaffold which is light in weight without sacrifice of strength.

j Another object is to provide `such a foldable scaffold which is low in cost and at"the saine timewill stand up under conditions of adverse and constant use without getting out of order or requiring repairs.

Other objects and advantages of the invention will be apparent from the following description and drawings in which:

Fig. 1 is a side elevation of the foldable scaffold embodying the present invention and showing the pairs of legs at opposite ends thereof adjustedto different lengths with the shorter length supportedon an elevated surface such as the stair of a stairway. The rear elevational view of the scaffold is substantially identical to the front elevation illustrated in Fig. l. l" l y y Fig. 2 is a top plan view of Fig. `1 with a portion broken away.`

Fig. 3 is an end `elevational viewwith parts broken away and showing one of the adjacent pair of legs shorter thanthe other. t

Fig. 4 is a side elevational view with the leg structures and braces folded. v

The scaffoldforming the subject of the present invention includes an upper elongated platform structure 5 supported at its oppositeends on both extensible and foldable leg structures indicated generally at 6. For lightness the upper elongated platform structure 5 is preferably specially constructed as follows:

The platform structure 5 comprises two wooden rectangular side rails 8,8 which extend the full length of the platform and have a greater depth than horizontal thickness so `as to provide the necessary strength required of a span. These side rails are connected at intervals by round cross `bars or members 9 and which are preferably secured to the side rails in the manner of ladder rungs. To this end these round cross `laars hare preferably doweled "ice into the opposing faces of the side rails 8, 8 and secured by nails 10 driven through the top faces of the rails into the imbedded ends of the round cross bars 9. These cross bars are preferably arranged below the upper surfaces of the side rails a distance equal to the thickness of deck boards 11 which run lengthwise of the platform and are supported on the round cross rods. Accordingly it will be seen that the upper surfaces of these deck boards 11 are flush with the upper edges of the side rails 8. These deck boards are preferably spaced from each other and p from the side rails and can be secured to the round cross bars 9 by nails 12. In order to conveniently move the scaffold, when collapsed, from place to place the center deck board 11 is preferably indented along its opposite edges at its center, as indicated at 11a, these indentations providing convenient finger and thumb holes for lifting the scaffold.

The leg structures 6 at opposite ends of the platform 5 are identical in construction and hence a. description of one will be deemed to apply to both. Each of these leg structures comprises a rectangular wooden leg bar 13 which is pivotally secured at its upper end, as by a bolt 14, to the outer face of the corresponding side rail 8 near the end of this side rail. The rounding; head of each bolt 14 projects from the outer face of the corresponding leg bar 13. The two legs 13 of each leg structure pivot on these bolts 14 and are cross connected by a pair of round cross bars 15. These cross bars 15 are preferably secured in the same manner as the round cross bars 9 of the platform structure, that is, the ends of these cross hars are doweled into the legs 13 and secured against displacement by nails 16.

The leg structures, when the scaffold is set up, are arranged in downwardly diverging relation to obtain maximum stability. To this end the scaffold is provided with a brace bar 18 which is pivotally connected at its upper end to the platform 5 and at its other end is removably connetced to the corresponding leg bar 13. Each of these braces is identical in construction, being `in the form of a rectangular wooden bar secured at its upper end by means of a pivot bolt 19 to the inner face of a corresponding side rail 8 a short distancefrom the end thereof. The other end of each of these brace bars 18 is provided with a hole 20 fitting a bolt 21 the shank of which projects horizontally inwardly from the corresponding leg 13. The rounding head 21a of each bolt 21 protrudes from theouter face of the corresponding leg bar 13 for apurpose which will presently appear and each bolt 21 is providedwith a removable nut 22. Upon removing the nut 22 it will be seen that the hole Ztl of the brace 18 can be fitted over the projecting end of the bolt 21 and that upon replacing the nut the leg will be adequately braced in its operative position. Y

" A feature of the invention resides in the individual extensibility of each of the legs Y13. To this end an eX- tension piece or bar 23 is adjustably secured toteach of the legs 13, the parts beingidentical in constructionfor each leg.

Each extension piece or bar 23 is in the form of a rectangular wooden bar of approximately the same dimensions as the leg 13 and having a longitudinal slot 24 extending therethrough perpendicular to thetmating faces of the leg bar and extension `bar; In this longitudinal slot is arranged a bolt 25 which is anchored in the leg 13, this bolt having a threaded end projecting `out through the slot 24. A wing or handledclamping nut 26 is secured to each of the projecting ends of each bolt 25 and screws against a washer 28 which in turn bears against the outer face of the corresponding extension piece or bar 23.

Near its extremity each leg 13 is provided with a U- shaped strap 29 the legs of which are secured, as by rivets andere.

30, to the edges of the corresponding legs 13 and the cro'ss part of' which sli'ding'ly embraces the extension piece 23. It will be seen that each of these U-shaped strap?, Proyides a` slideway yand, abutment,l at the lower endfo'fA each leg 13, for the correspondingextension piece- 23 andat thesame time permitsthe extension piece to bemoved along the-leg 13 and. secured at any desired position of extension by. tighteningv the corresponding handled or wing bolt 2,6.`

It will be noted` that in all. positions of the extension piece 23l the projecting head 21d of the bolt 21 to which the corresponding brace 18. is secured is out of line with the slot 24c and is in contact with. the inner face of the extension piece23. Accordingly, not only aregthese bolts 2 1 prevented from slipping out and being lostybut the Projecting head 21a is.. in position to embed itself in, thel extensicnfpiece 2 3 asV clearly, shown in Fig. 3 when the clamping; nut, 2,6 is tightened@ Such indentation, f. cQlllS, Provides insurance against slipping of each extens'ion'piece 23 along its legv 13 when a load* is placed on the, platform 5. It will further be noted that the pivot bolt 14,for each leg 13 is locatedy toward the bottom ofthe side rails 8 and inwardly ofthe center line of the corresponding leg 13. By thisA means, when the structare is collapsed, thecross bars 15, of the leg structuresA 6 lay alongside the lower edges ofthe side rails 8 and these leg structures are substantially parallel with these side rails. i

`In use', in the collapsed condition ofthe scaifold the brace bars- 18 aredisconnected fromk the bolts21 of the legs 13 and are folded against the inner faces ofthe side rails 8. In the collapsed condition each leg structure 6 isl also swung around the pivot bolts 14 so thatV its round crossl bars 15 lay in closely spaced relation to the lower edges of theiside rails 8 and so that the ,legs 13 are generally parallel with thesey side rails` to provide a compact structure. It will also be noted that the lower cross bar 15l of each leg structure 6 is arranged against the folded brace bar 18 so that this bracel bar 18 cannot swing out and is held in its nested condition. In the folded condition of the platform the extension pieces 23 for the legr- 13 can` bein any positiony of adjustment since these extension pieces are arranged parallel with the legs and hence whether vthey projector not does not materially affect thecompactnessw of the structure.

A When itjis desiredtofsetup the scaiold the leg structurel 6 .at each end ofthe platform 5 is swung out on its pair of pivot bolts 14 and at the same time. the corresponding pair of brace bars 18 are swungout about their pivotbolts 19. The nuts22 of the bolts 21 on the legs 13 are then' removed and each of these bolts is inserted intheliole/Zl)l ofthe companion brace bar 18. The yn uts 22 are then replaced and itV will be seen that a rigid scaffold` is provided havingV divergent legs for greatery Stability. 1 Y

If the scaffold is Vto be used on a dat doorl each of theextension pieces 2 3 wouldbe adjusted vto have the same degreev of extensionfrorn, the companion leg ,13. This extension is obtained Vby loosening the handled v clamping nuts 26' and sliding the. extension` pieces 23 outwardly so that upon tightening the clampinggnut 26 theextension pieces are secured to the legs-13 to have the'sanre degree ofextension. Itwill be seen that, these extension pieces are vreliably clamped inV any position 0f adjustment, the U-sohaped straps 2.9 providing apositive abutment and slideway at the lower endof each` leg lyand, the. Clamping nuts 2.6 securing each extension 2 3to theleg 13so `as to embed the heads 21ak of bolts 2.1..` in.: the, extension; bars 23, these `heads being out ofV line-wf f1hr slots 24. f

,Ihwillparticular1y-- be notedthat by.- lhaving` each; in:

'diyiduall leg 13 extensible throughV outward adjustment p in Figs. 1 and 2, it may be desirable to set one end of the scaffold on a stairway ink which event the exten* sion pieces 23 of the leg structure at one end of the scaffold would be adjusted outwardly Vwhereas the extension pieces 23 of the leg structure at the opposite end of the scaffold wouldrbe, adjusted to provide a shorter leg structure. It will be appreciated that conditions are encountered wherel one leg of the leg structure 6 at one end of this scaffold wouldV be desirably shorter than its companion leg and in such event, the extension pieces 23 of these two legswould be adjusted accordingly, as illustrated in Fig. 3.V

From the foregoing it will be seen that the present invention provides a very lightweight and at the same time sturdy and secure, scaffoldv which can readily be collapsed to; provide a very compact and easily handled structure 'and at thesame time has each of its four legs, conveniently and securely. extensible so as to be adaptable to the varyingy levels. encountered inthe use of scaffolding within a building.

I claim:

A foldable scaffold', comprising a platform structure i having'- a ypair of longitudinal sideA rails and cross bars rigidly connecting saidnside rails, a leg structure at each end of said platform structure and comprising a pair of leg bars with their yopposing. faces. severally opposing the outer, side faces of Said side rails, a horizontal lpivot securing; the, upper -end of yeach legl bar to the correspending end of a companionfside. rail, and a crossV member connecting eachv companion pair of leg bars and foldable. with. said leg structure Yinto engagement with thelower edges of said side'rails, a diagonal brace rfor eachr leg bar with its upper end arranged against Vthe inner vertical face of the companion side rail, a

an independently extensible extension bar arranged against and parallel withY each, leg bar, and alongside the outer face thereof and extending over and adapted to embed said, boltiheadi: a U-shaped metal strap having` its legs secured to the, lower end. of one of saidv bars and slidingly `embracing the other of said bar s, a` longitudinal slot provided in each of one of said bars out of line with said bolt head and generally-perpendicular to the mating facesv of said bars, ay stud Vbolt secured toV the other of said bars and having a threaded end extending through Vand projectingvr from said slot, and a handled nut on ,the threadedfend of saidl stud bolt and arranged to clamp each pair of leg and extension4 bars together and 'toembed s aidbolt heads, in said. extension bars.

References Citedfin .the file of. this patent i 'UNITED I STATES PATENTS t 2,062,473'v Norton Dec. 1, 1936

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