CA1215952A - Foldable escape ladder - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A foldable aluminum ladder has a pair of ladder sec-tions each formed of a pair of rigid rails joined by rigid rungs. The sections are hinged together at an exis in line with the edges of the rails so that, when folded, the rails of the sections lie against one another. The rungs are interleaved in the folded position, and are of a depth substantially equal to the sum of the depths of the rails. Pivotable hangers are provided at the ends of the rails of the top section.

Description

~ LS952 :.
~G~UN~ HE INVENTION
~leld ~ thë ~ehtion . _ _ _ This invention relates to foldable ladders, and i~
moxe particularly dlrected to the provl~ion of an e~ergen~y ladder u~eful ln present day high-rise bullding~, e~pecia~ly those with overhanging balcon~es or terraces.
: . . It ~3 general$y not practlcal for the re~ident of h~gh-rise building to be supplied with an emergeney ladder, since t~e provision o~ a ~a~e ladder of su~ficient leng~h ~or . . most floors o~ ~uch bulld~ng~ would be expens~e and unsafe, and ln ~any case~ ~mpos~lble.
m e present lnvention 1~ there~ore d~rected to a ~olu-: ~ion to thi~ problem that ls u.qeful in bulldings of thi~ type.
~hu8, ma~y high-rl~e ~partmen~ building~, condomini~ms and the like are pro~ided ~ith vertically aligned balconie~ on ~he variou~ floor~ Su~h balconie~ frequently have railings or the likQ o~ suffl~ient streny~h that a ~hort ladder afflxed to the railing of one balcony ~ay permit ~ per~on to climb down to the . next balcony. A relatively light-welght ladder may thus b~ ¦
) . employed to enable ~ per~on to proceed from one balcony to the next lower o~e, and then to repvs~tion ~he laddPr for ds~cent : to the next l~wer ~alcony~ and 80 on down to th~ ground.
~n th~ pa~t m~y por WblQ or foldable laddQr~ have .. been provlded O One typ~ o~ such portable ladder 1~ compri~ed ; o a flexible ladder~ for example of rope, wi~h either rigid or flexi~le rungs extending between ~he flexible rails. This type of ladder ~8 unsuitable for safe descent be~ween the bal-conie~ of buildings, since it i~ not restrained rom swinging when ~he user ~ between the balcony sections and the flexible ~ ;
nature of the sides of the ladder render~ descent di~ficult. ¦
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~21S~52 ., Whlle ~ome ladder~ o~ type employ rigi~ material or the slae rail~, they either ~chieY~ the di~Eldv~ntage~ o~ a ~lexible laaaer by provld~ng h4nge~ Zlt each rung, 05r are not ea~ly stor~ble in view o~ the lack of any hinge~ at all.
Previoua portabi~ and emergency ladd~rs o~ the ~sove typs al~o generally have the dl~ad~Antage that, even ~f ~h~y are held steady, for example ag~inst a vertlcal ~upporlt, they do not provlde a ~ure or adeguate ~tepp~ng space on ~h~ n~ng~.
~ he present lnventlon 1~ t~erefore d~rected to tl~e , prov~ion of a portaSle roldable ladder ~hat overcomes the above di~ad~antages of kn~wn porta~le ladder~, ¦
U ~ ~ T~R INVEN~ION
Br~efly stated, in accordance with the inventionr a portable lad~er ha~ at least first and second sec~lons wit~ rigidi rails and a plurali~y of rigid rungs extending between each pair ¦
of rails. The rail~ of the sections are hinged toge~her with h~nqes that penmit rigid locking of the rails when the ladder is ~n it~ open po~ition~ AB a consequence, the ladder may be h~ng from one balcony to extend to the outer surface of a lower bal-cony, thereby preventing~ovements of the ladder during descent, and preventing the ~x~ di9~hçn~ of ladders of flexible material.
~ he rung~ of the ladder have depths equal to ~ubstan-tlally tw~e the depth of the rail~ so that they proje~t from , the ra~ls when the ladder ls in the extended posit~on~ Thi~
extra width of the run~ greatly s~mplif~es descent, and increases I the safety ~n use of the ladder. The extra width of the rungs ! does not lncrease the ~torage space~ h~we~er~ s;nce the rungs are positloned to be interleaved with one another when the l ladder 1~ foldedO The hanger for hanging the ladder from a ) balcony, wlndo~ or the llke ls comprl~ed of ~ir~ular rod~ bent I ~ i ~ 2- 1 I' , I ~2~S952 I
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¦ lnto a WU~ nh~pe and p~votally held ~n the rail~ in the top o~
. ¦ the ladder. These ~anger~; w~en ~ub~ect to the weight of a ¦ user, effect the mo~e~en~ of ~ ~lock ~o ~ po~l~lo~ that prevent~
¦ rotation o~ the hanger. Accordlnglyp ~llppage o~ the ladder i ¦ due to rotation of ~he hangers ~8 prsvented, - : ¦ Slnce ~he l~dder is spe~fi~ally de~lgned for emergency ; ¦ use, ~8 above dlscussed, ~n butlding having balconie3~ itB
length need not be greAt~ for example no more ~han abou~ eight l feet. Accordlngly~ ~hen ~olded the ladder may be r~adily ~tored .0 in an apartment so that it ls acce sl~le for use when necessary.
: ~he resultant ladder, ~en cons~ruc~ea of alumlnum or the ltke, weighs no more than ~bout lS lD~; an~ c~n be readily handled by most indivldual~
In ~ariation~ of t~e l~der in ~ccordanc~ ~ith the ~5 present ~nventlon~ urther sectlon ~ay be hinged ~o the lower . end oP th~ ladder, reitricte~to either a horizontal ~osition ~; or a position held ~ga~n~t the n ~ t above ~ect~on. ~ ~ ~aria-.~... .tion of th9 l~daer thùs provide~ ~ plat~orm upon wh~ch an in-dividual may ~and, for ~xample to ~ork on the out~ide of th~
O buildlng ,. ` ~.
. I~ order that tbe invention may be more clearly under-~tood, lt wlll not ~ disc~osed ln greater detail wlth referen~Q
to the acc~mpanying araw~ng8~
BRIE~ DESeRIPTI~N ~ W~NG~ -5 . ~IG. 1 i6 a per pectlv~ ~lew lllu~tr~t~ng the u~e of ; one embod~m~nt o~ the ladder of t~e ~n~ent~on extending between balconle~ of a bulldlngt FIG 9 2 i8 an enlarge~ perspect~ve vie~ from the rear of the ladder of FI~, 1, in folded cond~tion, 9 PIG. 3 ls an enlarged ~ew of a portion of the ladder O~e FIGo ~S

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l~'t S952 ~TG. 4 i~ an exR~dPd ~e~ o~ a h~nge that ~ay be em~
ployed ln the l~dder o~ the ~n~entl~nJ
FIG. 5 i3 ~ cross~secti~nal ~ew oX ~ hlnge taken along ~ine~ 5-5 o~ FXG, 6 FIG. 6 i~ a ~ro~s~ectional ~iew taken ~long lines 6=S o~ FIG. 2~
FIGo 7 ~ ~ ~ cro~ ection~ ew t~ken along line3 : 7-7 of FIG. 1~
. FIG~ G simpl~iea ~llu~tration of showing ~he O s~orage of the l~dder ~f the inventio~ ¦
FIG. 9 ~B a top ~iew of ~ ~odification of a rung for the lad~er o~ the ~ventlon~ ¦
FIG~ lQ is a re~r ~ew of the r~nq of ~G~ ~S
FIG. 11 i~ a ~iae ~ie~ of a modif~cation of a ~ nger . arrang~me~t ln accordancQ with the ~nventionS
.l FI~o 12 ~8 a side ~lew o~ a modlfied ~orm of a ladder in accordance with kh~ ~n~ent~on~
FIG~ 13 ~llustrates a modiflcation of ~ hinge that . may b8 employed for th9 ladder of FIG, 12j an~
.. FIG, 14 i~ o~ ectional Ylew o~ ~h8 hlnge of FIG. 13, .
. DFT~I~ED ~ES~rPTI~N ~F ~H~ TNVENTIO~ I
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Referr~nq now to the drawings in detail~ and moxe ~ar-. ticularly t~ FIG. lt there iB Illustrated one embod~ment of a ,5 folding ~adder in accordance with the ~nvent~on, ~n extended po~ition and hunq between an upper b~lcony 10 and a lower bal~
cony 11, a~ lt may appear in actual use. In thl~ embodiment of th~ ln~entlon the ladder i5 compriged Of an upper ladder section 20 and a lower ladder sectlon ~l o The upper ladder ~0 sect~on 20 ha~ a pair o~ parallel rigld slde ra~ls 22 and 23 .~ .

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and a pluralit~ 3p~,ced pa~allel 1~un~7~ 24 extenaln51 there~
between. The lower l~ldder ~ecttvn 2~1: h~ a rigld ~de rail 25 having its upper end piYoted to t21e 1awer end o~ r~il 22 at hinge 26, a side r~ l 27 ~la~rlng il~ upper end pivo~d ~o the lt~wer end o~e r~il 23 at hinge 28 " an~ a plurality o~ Nng~ 29 extending bet~eeri the ~de rail~ 25 ~na 27 .
Th~ `ladder al80 has ~I p~ir o~ hanger~ 30 plvotally mounted at t~ uppe~ end~ oî tI~e rall~ 2~ and 23 to enable, for example9 ~e ladder to be h~nq from a r~illrlg o~ the balcony .0 10. q~he ladder pre~erably lla~ an oversll length suffic~ent that the lawer end thereo~.abut~ ide of the next lo~er ..
balcony 11 ~o thereby ~teady the l~dder or use. A~ ~n example, the overall length of ~h~ ladder ~ay be about e~gh~ ~eet, with . each of the ~ect~o~ thereb~ bein~ ~out four feet in le~gth.
.5 It ~g of cour~e ~pparent th~e ~he i~vent~on i~ not llm~ted to ~uch ~ leng~h.
In FIG. 1 lt i8 also'seen that rail~ 22 and 25 and rail~ 23 and 27 are directly ln line with one another i~ the extended po~ition of ths ladder, ~:n ~ddltion~ the rung~ 24 !0 and 29 ex~end ~orward o their re~pectlve ~ida rall~, An enl~rged rear perspective ~iew of the laader in folded conditlon i~ lllustrated in ~, 2, where~ it i~ ~een that the lower ~ectlon 21 has been pi~oted upwardly 30 that ~he forwa~d edge 35 of the ra~l3 of the l~wer section ~e " forward in ~e ex~ended positt on~ engage the forward edges 36 of ~he . rail~ of,~ e upper ~ection- ~i.eO~ ~orward in ~he extended po~
sition3. Thi~ feature ls moxe clearly illustrated ln the en-larged part~al ~lew of F~G. 3, whlch ~hows th~t the side ra~ls may be compr~ed of channel bearm, for example of aluminumt . I

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.-. . w~th ~e ~pen end~ d~ected ~way ~rom one ~nother ln each o~
~he r~ ectlon30 Tn t~e ~ol~e~l conaitlon of ~hE~ ladderO
one flallye of tlle lower sec:~lon rail 25 nbuts ~ flange of thQ
upper ectlon ra~l 22, ~na 3~mil~rl~ one flange of the lower .. ~ectlon ra~l 27 abut~ ~ ~lange o~ t~ë upper ~ection rail 23, A~ urthl3r ~llustrated in TIGS. 2 ~nd 3t thB rungB

2~ and 28 may bë comprised of met~l sheet, such as al~nln~n, ha~r~ng ~ 1at tread port~on 39, a dsYwnwardly bent front fl~nge : ~1, 40, and dowr~ardly bent 81de flange~ ~1, The ~err~ ~downwardly" ?
O ~3 employed witll reference to the extende~ ition o1!-the laader ~ince, ~n t:he ~olded pos~ tion~ of FIGS. 2 and 3 it is apparent th~t tlle.~l~nges of ttle rung~ 28 ex~er~d upwardly.
;~ i The rear poxtion of the downwzrd1y extendlng ~id~ f1ange~ 41 . and the ru~gs are ~ffi~ed rtgid1y to the respect~e r~ , for example by ~cr~w~ 42, a1though other ~onventional fastening means may a1ternative~y ~e employed; A~ i~ apparent in FIG, f?
. 3, the r~ng~ 24 ~nd 28 ha~e depth~ equal to the sum of the depths o the rai1s on e~ch ~1de o~ the ladder ~o that when the ladder ~ extended, the front h~lves of the rungs extend o : forwara1y o~ the re~pecti~e ra~ Thi~ feature enable~ the use of wider rung~ for ea~ier u~e and ~ncreased safety when ~he ladder 1s emp10yea~ A~ further i11us~rated in FIG, 3, th~
rear edges of the rungs may have reducea wtdth and d~wnwardly . exte~ding flanges 45 for increased strength, The ~read por~ ¦
tion~ of ~e rung~ may ha~e ho1es 46 extending therethrough to reduce further ~he welght o~ th~ ladder.
~ha h~nge~ between ~he 1adder ~ect~on~ are ~oxe clearly ~11ustrated in FIGS~ 4, 5 and.fi. Each hinge i~ ~ompri~ed of a pair of hinge plate~ 50 having a~ extenslon 51 adapted to ~0 ¦ flt a ainst the rear of the web in the end of the ~orresp~nding ,1,1~__ i rail o~ the ladder~,the exten~ion h~vln~ hole~ 52 og ~hat 1~
may be bolted to ~ e respective xa~l~; 0~ cour3e, other con- ¦
ventional fastening technlque~ may be employed~ The extension~
51 o~ the hlnge plates 50 ~xtena from genesally rounded sec- !
tion~ 53 having alignea bore~ 54 e~tending therethrou~h, The bores 54 are of~9~t with re3pect to the exten~ions 51 a d~s~ance such that when the exten~io~3 51 are aff~xed to the re~pective ra~l~, the holes 54 lle ln the pl~nes of the front edge~ of ~he rail~ of the re~pecti~e ~ection~, or at least su~tantially O ~n 8uch planes. ~hi3 po~tlon o~ t~e p~votGl ~xi~ enable~ the rail~ to be aligned when ln th~ extended posltion of F~G, 1, . ; and to.b~ folded wtth th~ r~ 2~tt~ng on~ another a~ in the .
positlon of ~IG. 2.
~ bolt 60 ~ tend~ through the hole~ 54 of th~ h~nga 5 . flange 50 o~ ea~h hlnge, wlth a w~ng nut 61 being threaded onto -¦
bolt 60 and holding ~n a~sembly of a heIlcal spring ~2 between . a palr of washer~ 63 9 betwaen ~he wing nut 61 and the ad~acent plate. I
In a ~olding ladder adapted to extend between balconie~ ¦
~0 of a bullding, the h~nge must rig~aly hola the la~aer ~ection~
together ln ~he extended position, sInce in such u~e ~he ladder may o~herwi~e te~d to ~end at the hinge ~xe~. The h~nge must of course ~l~o be de~igned so that the ladder can be folded and unfolded ea~lly when desirea. For th~ purpose, the hinge ~5 plate~ a~b provlded with meshing rldgeY 65 and groo~es 66 ex-tending parallel to the respectlve ladder ~ections~ ~ illus~
trated ln FIG. 4~ the w~dths o the ridge~ and grooves may be relatiYely lar~e~ ~o that from two to three grooves and two to three rldges are provlded on each plate, although it i~ apparent that other arrangements of interloc~lng surfaces may be provided.
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~ 52 When th~ re~pectiy~3 groove~ and :r~.dge~ interme~h" it is apparent . . :; that the r~ ection~ ~t~nched thereto will be f~rmly held either in the ~old~d po~itlon o~ 2 or the extended po~tlon of ~IGQ 1, When t~ wing nut 61 1~ ~d~acent 'che end of the bolt ~0, there ~rill ~Q ltttle or no pre~sure urging the hinge plate~ toye her, ~ that thë hinge plates may be ea~ly urged apart 'co permlt the pl~oting of ~h~ laader sect~ons, Upon tishltenlng oP 1:he ~rlng rluts, ho~ver, th~ hinge pïatl3z canno~
be fs)rced ap~rt? 80 that the ladder ection~ may be f~rmly D - . locXed in po3ition w~th res`pe~t to on~ another.
~ e as~enibly of the hanger~ 3a ~ 5 ~hown in FI(;S O 2 and 7, wherein it ~8 ~en that th~ hangers 30 are comp~ised oP
inverted U-~hape~ rods > The hori~ont~l port~ on3 70 of t~lese : rod~ i~ of ~ufflcient length ~o enable the llanger to b~ J~o)ced over balcony 1~, wit:h one downwaraly extending portion 71 en-gaged in the rear s~de of thQ bal~ony wall. l~he froDt down~ ¦
wardly ex~endtng section 72 exten~ in t~e hc>llow portlon of the . channel of the re~;E?ectlve rail~; through `the hole~ in two spaced apart guiae~ 73 and 74 Afflxed to the rAll~" A helical ~pring 75 i~ retained at t~e lower edge of the guide 74 by a cotter pin 76 and washer~ 77 on the lower end of the rod sec~
tion 72. A cotter pin 78 and wa~her 7~ ar2 al~o pro~rided be~
neath the guld~ 73 . Th~ ~ arrangement thereby ensureg that the ~upport~ 30 are flrmly held to the re~pective ~all~ of ~he ladderO ~en the ladd~r ~upport~ are placed over a ~alcony wi~hout wé~:ght thereon9 the slprlng 75 reslliently ho:ld~
ladder O Upon the appl ~ s~at~on oi~ weight ~o ~he ladder ~ the spring 75.i~ compressed and eventually the wasller 75 abut~ the guide 73 to inhi~it any fur~her downward mo~rement of the ladder, O
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~hen t~ ladde~ not lrl u3e~ h~ver~ the E~UpportB 1na~ be p~voted into ~l~g~nent ~h; the ladder;
further gu~d~ 80 ~s pro~id.ed af f ixed to the rall . . intermediate th~ gu~d~ 73-and 7~; the guid~ 80 ha~tlng a non-clrc~l~r o,perture 81 through wh`lch the rod sec~lon 72 al~o extneds, The xod ~ect~n 72 h~ a ~lock B2 aff~xed thereto of a sha~?e ma~chislg th~t of th~ aperture 81. The block 82 i~
aff~xed to th~ EOd ~ecti~3n-72 at ~ po~ition such tha~ when the wash~r 73 es~gages th2 underslde oil~ d~ 73, ~e block 82 1~
.~ po~it~ oned ~n the paertur~3 81. ~8 a con~equence, ~hen the lad-. ~ der i~ in u~e w~th th~ hanger~ ~upporte~ on the l:alcony wall, . - the hanger~ cannot ~ t~ted ~tl~ resp~:t to the laddf~r" Th~
apertur~ 81 ~nd block 82 are pre~e~abIy squar~ or recta~ular . ~;n section. .
,5; ~; q!h~ ~olding ladder oP the ~nvention may be ext~emel~
.` `. light weight~ for e~cample `~boùt 15 l!bE~o~ and may be readlly ~tored in an ~partment~ For example~ ~ lllustrated ir~ FIG~ 8, the ladder 85 of t~e ~nvention may con~reniently ba3 ~tored under a cc)nvent~onal bed 86, !0 In the mod~icat~on o~ rung~ lllustrate~ in FIGS~, 10 and llt the rung~ may be fabricated of ~n embos~ed me~al 88 for added trac:tlon 9 t nstead o~ ~mploying hole~ ; n thicker s~eel~
material a~ abov8 de~cribed. Of cour~e ,, bo~h expedient, i ,e ., holes for,lighter weight and embos~ing or added traction, can tS lbe employ~d.
In the moaiflcation o the hanger a~ illustrated in ~IG, 11,, in~teaa o~ angle sh2ped member~, the sllppor~ rod quide~
may be webs welded or otherwise hela ;In the channels of the rails. :Cn additionp the spring 75 may be provided between the I bloc~c 82,and tlle ~ide gulde 84~.
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I~ ~e ~bc~e de~c;~ bed e~ d~nt~ o2' the lnyen~lonr i~ ppa~ent th~lt the h~nge~ on ~e a~ o~ ladder ~ec:~
t~on~ t not be equl~i~tan~ be~e~n ~he rung~ of the ladder section~ ad~ acent ~ereto ~ in order ~hat the rung section do not interf~re with one ~nother upo~ folalng o~ ~he ladderD
, ~ anothsr embodi:~nen1: o~ the in~Tentlon, a~ illu~trated l~ FIG. 12, further hinged ~ectton 100 may b~ provided~ hin~ed to the bot~om of the l~er section ~1, Th~s l~rer section 100 may be employed a~ ~ horizontzllly extendlng step, upon which O a u~er may ~tand ~or p~nt~ng or other pl~rpose~ ~f th~
., ladder i8 ~upported ~t ~ ~lnaow or the like. ~he ladder ~ec-tlon 100 ~ hinged to the ~ottom e~ ladder ~ectic~n 21 In ~ manner el~lar to tha~ ~3 abc~e a~scribedt ~ hough in thl~
ca~e if nnating 3roo~re~ and ridges are pro~d~d ln the hinge element~ y prefera~l;y ext~nd ~n dlrectlc~n~ to firmly hol~d th~ ladder ~ect~on 100 h~rizont~l. Tnstead of providing ~uch groove~ and ridge~ o~er, tlle la~der may be provided with a cha~n 101 ~xtend~ng bet~eel~ the end o~ th~ ladder sectlon 100, at each rall~ to a point on the rail~ og the ladd~r se~:-O ~ion 21 as ~llu~trated.~ !
~ embodiment o~ l~erition, the ladder ~ec~
tion lOû may ha~e one or more rungs 102 posltioned such ~hat they wlll not lnterfers w~th the l~wer rung~ o the îadder ~ection 21 upon folding . It i~ further 2~r1dent tha~ p ln the embodi~e~t o~ F~G. 13, ~e lower ladder ~ectlon ~1 mu~ b~s ¦
longer t~aD the upper section 20~ at lea~ by t~e length of the ladder ~e~tlon 100, ~o that th~ l~aaer se~tlon 100 may be folded to about the ladder section 21 ~ithout interfering wlth the upper ladder ~e::tion 201D

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The ladder ~f ~G" 12 ~a~ be ~urt~er pralrided wlth a ~helf 110 hi:ngea ~t ~ c:c~n~r2nient locatioll on the lo~er ;Ladder sect~on 21 to enable th~ u~er ta ~upport p~in~ c n~ tools~ ¦
. or th~ l~ce thereon, there~i ~ur~her ~ncre~s.~ng ~e utility of th8 fO~ dder o~ th~ - lnvention, .
- Tn ~n alterntltl~ ge that may b2 employed or tbe lawer hlnge of the ~odinent o~ F~G~ 13~ the hlng~3 m~y be : ~ompr~se~ of ona ~lng~ plate 120 ~XGS" 14 and 15) ext~nding upwardly l~nd ~d~pte~ to ~e ~ffixe~ to t~e lower end of the O ra~l~ o the ïo~er ladder ~ectlon 210 and a second h~nge ele-ment 121 ~dapted to be ~lxea to thei lhorizont~lly extenaî~g 1 adder sectlon 100 of FIG~, 13, ~e ~wo hin~e ~lement~ 120 and 121 are pivotet~ toge~l~erz for example by a bolt 122 on an axi~ lying lr~ plana of the ~rorl~ edge3 of th~ r~ f ladd~r ~e~tion ~l and the upper edge~ o ~ rall sectlc:~n~ c~f ladder ~ection loa~ Thl~ placement, as diBCUB9ed above, per mits the slding o~ the ladder sections w~ ih the rall ~ectlons abutting edge to ~dg~, .
In add~tiorl~ the lower eage of the hinge elemen~ 120 ;0: i~ bent oYe:r tc~ pravlde.a ~lange 1~5 under the hinge element 121~ the end of flange 1~5 being turned up, at 126,, T~e h~nge element 121 has a ~tral~h~ hor~zontal ~ottom edge that engage~
the horizontal gxoove formed by th~ flanga3 125 when the hinge element 121 1~ ~xtendea horizont~lly, Th~ Pea~ure inhibits ¦ .
,5 rntation;~f the ladder ~ectlon 100 to arlgles grea~er tharl 90 w~th r~3~pect to ladd~3r sec~on 21, Tt i~ of ~ourse~ preferred that ~ chaln al50 be employed for ~upporting the end of ladde~
8es:tiO~1 lOû" even though the ~inge of F~t:S~, 14 and 15 is employed Wh~le.~e irl~elltlon ha~ been di3~1Osed and described ~a with referenc~ to a limited number o~E embodiments, i~
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appa,rent th~t ~ra,~iat~oal~ and ~nodi~icatlorl~ ma~f ~e ma,d~ th~e-in, and lt i~ intended lr the ~oll4wlng cln~m~ to c~v~r each such varlatic~rl and ~nodi~lcatlon a~ fhllg within the ~plrit and ~cope o~ the invention~
O ~ a~ C al~e~3 i9:

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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A foldable ladder comprising at least first and second ladder sections with parallel rigid side rails, each section having a plurality of rigid rings extending between the respective side rails, unitary hinge and locking means joining one end of each rail of the first section to one end of the second section, and pivotable hanger means on the other end of each rail of said first section, said unitary hinge and locking means having a pivotable axis offset with respect to the rails, whereby the rails of the first and second sections may be moved to an extended and locked position with the rails of the second section being in line with the rails of the first section, and a folded position with the edges of the rails of the second section abutting the edges of the rails of the first section.

2. The foldable ladder of claim 1 wherein said hinge means are spaced a different distance from the rungs of the ladder sections adjacent thereto, whereby the rungs of the first and second sections are interleaved in the folded posi-tion.

3. The foldable ladder of claim 2 wherein the depths of the rungs are substantially equal to the sum of the depths of the side rails of the first and second ladder sec-tions, whereby said rungs extend from one side of said ladder in said extended position.

4. The foldable ladder of claim 1 wherein said hinge means for joining each rail of said first section to each rail of said second section comprises a hinge element affixed to a rail of said second element, said hinge elements being pivoted about an axis, said axis lying in the plane de-fined by the edges of the rails of one side of said second ladder section,

5. The foldable ladder of claim 4 wherein said hinge elements have grooves and ridges extending parallel to the longitudinal direction of the respective ladder section, where-by the ridges and grooves of the hinge elements intermesh in the extended and folded positions of said ladder.

6. The foldable ladder of claim 5 wherein said hinge elements are releasably held with their respective grooves and ridges intermeshing.

7. The foldable ladder of claim 1 wherein said pivotable ladder means comprises rods of circular cross-section bent to a U-shape, one end of said rod being mounted to extend parallel to said rails for moving longitudinally with respect thereto and rotation about the axis of the rod, and means inhibiting relative separation of said rod from the respective said rail.

8. The foldable ladder of claim 7 further comprising means for inhibiting rotation of said rod about its axis at a determined longitudinal displacement of said rod with respect to the respective rail.

9. The foldable ladder of claim 8 wherein said means for inhibiting relative rotation comprises means defining a non-circular aperture and affixed to the respective said rail, and block means on said rod of a non-circular cross-section and adapted to mate with said aperture in said determined location.

10. The foldable ladder of claim 1 further comprising a third ladder section pivotally mounted to the other ends of the rails of said second section, said third section being pivotable to a first position engaging the edges of the rails of said lower section and a second position extending horizon-tally to said second section.

11. The foldable ladder of claim 10 further comprising means for inhibiting rotation of said third section to an angle of greater than 90° with respect to said second section.

12. The foldable ladder of claim 1 wherein said rails are aluminum channels having the open sides facing away from one another in the respective section, said rungs being rigidly affixed to the closed side of said channels.