US3540549A - Foldable ladder - Google Patents

Foldable ladder Download PDF

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Publication number
US3540549A
US3540549A US847099A US3540549DA US3540549A US 3540549 A US3540549 A US 3540549A US 847099 A US847099 A US 847099A US 3540549D A US3540549D A US 3540549DA US 3540549 A US3540549 A US 3540549A
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United States
Prior art keywords
ladder
leg
legs
side piece
tripod
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US847099A
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English (en)
Inventor
George Harvey Emmons
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Individual
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Individual
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    • E—FIXED CONSTRUCTIONS
    • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06C—LADDERS
    • E06C1/00—Ladders in general
    • E06C1/02—Ladders in general with rigid longitudinal member or members
    • E06C1/38—Special constructions of ladders, e.g. ladders with more or less than two longitudinal members, ladders with movable rungs or other treads, longitudinally-foldable ladders
    • E06C1/39—Ladders having platforms; Ladders changeable into platforms
    • E—FIXED CONSTRUCTIONS
    • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06C—LADDERS
    • E06C1/00—Ladders in general
    • E06C1/02—Ladders in general with rigid longitudinal member or members
    • E06C1/14—Ladders capable of standing by themselves
    • E06C1/16—Ladders capable of standing by themselves with hinged struts which rest on the ground
    • E06C1/20—Ladders capable of standing by themselves with hinged struts which rest on the ground with supporting struts formed as poles
    • E—FIXED CONSTRUCTIONS
    • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06C—LADDERS
    • E06C1/00—Ladders in general
    • E06C1/02—Ladders in general with rigid longitudinal member or members
    • E06C1/38—Special constructions of ladders, e.g. ladders with more or less than two longitudinal members, ladders with movable rungs or other treads, longitudinally-foldable ladders
    • E06C1/382—Tripod ladders

Definitions

  • Foldable ladders or step ladders as they are commonly referred to, are old and well known and include the conventional ladder structure having substantially parallel side pieces with connecting rungs to which some form of a foldable brace means of lesser sturdiness than the side pieces is hingedly attached to the top portion of the respective side pieces of the ladder so that it canbe swung out into ground engaging posi' tion.
  • all such step ladders are designed so that the bottom ends of both side pieces engage the ground or supporting surface and generally the brace means also includes a pair of spaced legs.
  • the rear sup porting legs are converged to form a single ground engaging means as exemplified in U.S. Pat. Nos. 5,451 and 46,l05 but in addition to the ground engaging contact of'the ladder side pieces and the single point of contact of the rear leg, there is also utilized additional side leg supports.
  • the present invention utilizes the principle of a tripod type supporting structure wherein three equally sturdy ground engaging legs can be extended or folded out from an apex frame point to provide an extremely rigid and stable frame.
  • a structure in and of itself, for example, would provide a rigid and stable support for a ladder if such ladder were to be mounted thereon without in any way engaging the ground surface.
  • the present invention rather than having a separate ladder and a separate tripod frame support, has incorporated one of the tripod legs as one of the side pieces for the ladder and'by suitably associating the other side piece which is not aground engaging component, with the tripod frame structure, there is provided an extremely rigid and stable foldable ladder structure that substantially increases the safety and efficiency with which such a ladder may be used.
  • Anadjustment means designed for use with any one of the legs is provided for use on unlevel ground and serves primarily to suitably orient the vertical plane of the ladder side pieces.
  • This invention is directed to foldable ladders and the primary object herein is to materially 'improve'the rigidity of the ladder supporting structure and to substantially increase the stability of the ladder while it is being used.
  • This ladder incorporates a ladder component with a foldable tripod supporting structure that provides a highly stable three point ground engaging support means.
  • FIG. of the drawings show basically a tripod frame and a separate ladder having only side rails and rungs which, if properly positioned on the tripod frame without the ladder itself engaging the ground, would provide an extremely rigid and stable support for the ladder.
  • a tripod type support is a marked departure from the traditional means of supporting a step ladder because of the inherent stability of the tripod as compared with the considerably less stable support means on traditional step ladders.
  • the principle as illustrated in FIG. 10 is utilized in the present invention by using one leg of the tripod as one of the side rails of the ladder.
  • the other side rail of the ladder which is required for supporting the rungs is not a ground engaging element but is designed to bear against an adjustably arrangeable brace element on the tripod frame so that weight carried by the ladder will be proportionally transmitted throughout the frame. Means are provided to prevent movement of said other side piece relative to the brace element while the ladder is folded out for use.
  • the side piece of the ladder which does not engage the ground is operatively associated with one of the tripod legs at two vertical spaced points near the upper and lower extremities of said side piece and a curved upper end portion of said side piece is designed to be in a vertical plane when the ladder is extended so that there is no lateral twisting of the ladder component when it is subjected to a weight lead.
  • a removable foot member is adapted for use with either of the legs of the tripod frame to provide an appropriate adjustment for use of this article on uneven ground and primarily such adjustment is for the purpose of properly orienting the vertical plane of the ladder rather than for shimming up one of the legs because of unevenness of the ground as is usually the case involved with the traditional step ladder when the supporting surface is not level.
  • such foot is provided with a bend so that the ground engaging end portion is angularly disposed to the longitudinal plane of the leg being supported and extends in a vertical plane toward the ground. Thebottom of the leg rests upon a shoulder on the vertical portion of the foot member and is suitably removably secured to such foot member.
  • FIG. I is a perspective view of my new ladder in folded position
  • FIG. 2 is a perspective view of this ladder in open or extended position and ready for use
  • FIG. 3 is a perspective view of the lower end of one of the ladder legs showing the removable foot member attached thereto,
  • FIG. 4 is a perspective view of a ladder similar to but taller than the ladder in FIG. 1 and showing a second embodiment of this ladder in open position to illustrate a modified upper structure of this article,
  • FIG. 5 is a fragmentary perspective view of the upper portion of the ladder shown in FIG. 4 in closed position
  • FIG. 6 is an enlarged perspective view taken on the line 6-6 of FIG. 4 to illustrate the latching arrangement between the leg of the ladder and the brace of the tripod frame,
  • FIG. 7 is a top view of the ladder shown in FIG. 1,
  • FIG. 8 is a top view'of the ladder shown in FIG. 4,
  • FIG. 9 is an enlarged perspective view of a modified arrangement for attaching one of the ladder legs to the brace of the tripod frame
  • FIG. 10 is an exploded perspective view for the purpose of illustratingthe principle involved in this invention relative to a tripod supporting frame for a ladder, and
  • FIG. 11 is a top plan view of this ladder in open position and ready for use to illustrate the relative position of the ladder component to the tripod frame.
  • the numeral 24 illustrates the conventional or traditional step portion of a step ladder which includes the standards or side pieces 26 and 28 of like length and the plurality of steps or rungs 30 together with a top plate 32.
  • the usual swinging legs for the conventional step ladder are omitted in FIG.
  • FIGS. 1 and 2 where the step ladder shown is a relatively short ladder in the general range of six to eight feet as distinguished from the ladder shown in FIG. 4 which is in the relatively taller or higher range.
  • the tripod frame structure for this ladder is represented by the three leg members 38, 40 and 42 which in their open position as shown in FIG. 2 terminate at their upper ends at the apex point 44 and thus produces the considerably more stable three legged support frame that the three legged frame of the patents referred to where two of the legs are the traditional side pieces to which lateral legs are attached. No such lateral supports are required or necessary in the present ladder.
  • legs 38, 40 and 42 would correspond respectively with the legs 20, 16 and 14 of the illustrative tripod frame shown in FIG. 10.
  • the tripod leg 38 serves also as one of the side pieces for the ladder component, said component being designated generally by the numeral 46.
  • the upper end of leg or side piece 38 is preferably fixedly attached to a short cross piece 48 and the upper end of leg 42 is pivotally attached to the other end of member 48 by any suitable means such as the pin 50 so that leg 42 may be moved toward leg 38 in its folded position as shown in FIG. I.
  • the upper end of side piece 38 may be pivotally attached if desired, but this is not necessary so long as one of the legs 38 or 42 is foldable toward and away from the other.
  • a hinged brace means 52 connects legs 38 and 42 for stabilizing the same when the ladder is in open position and such brace 52 would correspond generally to brace 22 shown in FIG. 10.
  • the ladder component 46 utilizing the frame leg 38 as one of the ladder side pieces, includes the general parallel complementary side piece 54 secured in the usual ladder relationship to side piece 38 by a plurality of spaced steps or rungs 56 and including a top plate 58.
  • side piece 54 is parallel to side piece 38 from about point 57 spaced somewhat below its upper extremities and slightly above the top rung 56 only down to point 60 which corresponds to the location of the second step 56 from the bottom of the ladder structure.
  • the plane'of the top edge or side of side piece 54 is provided with a sufficient bend toward its underside so that when this ladder structure is in open position, the plane of side piece 54 between point 60 and the lower extremity of such side piece, point 62, will be in a substantially vertical line relative to the ground.
  • Side piece 54 has the curved portion 63 above point 57 to its upper end that connects to the top plate 58 and such portion will be in a vertical plane when the ladder is open.
  • Plate 58 is suitably secured to the upper end of members 38 and 54 as shown so that weight forces on plate 58 will be directly downwardly to avoid any twisting.
  • Leg 40 of this ladder frame which would correspond to leg 16 of the illustration in FIG. 10, is pivotally attached at point 64 to the upper portion of the side piece 54 by a bolt means 66.
  • Such bolt is located relatively high on side piece 54 just above the top step 56 and from point 64, leg 40 is slightly angled so that in the open position of this ladder, the upper end 68 of leg 40 will bear against member 48 at the apex 44 of this tripod structure.
  • the top plate 58. as best seen in FIG. 7 is provided with the slot 70 to permit the free movement of the tip end 68 of leg 40 when the ladder structure is moved to folded position as shown in FIG. 1.
  • leg 40 In the movement of leg 40 from closed to open position and for the purpose of properly orienting the ground engaging positions of the tripod frame legs, point 64 on leg 40 will move slightly away from side piece 54 as can be seen from the shape of slot 70 in FIG. 7 and to accommodate this movement, bolt 66 is provided with a suitable length for this purpose.
  • a foldable V-shaped brace arrangement for stabilizing legs 38, 40 and 42 in open position corresponding to the brace elements l2 and 18 in FIG. 10 is provided by means of brace member 72 comprising the respective elongated arms 74 and 76 which are pivotally connected in endwise relationship as at 78.
  • the outer end of arm 74 is pivotally attached as at 80 to the lower end of leg 42 and the outer end of brace arm 76 is similarly attached as at 82 to the lower end of side piece or leg 38.
  • Brace arms 74 and 76 will at all times define a generally V- shape of greater or lesser degree depending upon whether the ladder is opened or closed and brace 72 is related to leg 40 in one embodiment as follows.
  • An elongated rod 84 as perhaps best seen in FIG.
  • a movable paint tray 88 may be provided in any suitable manner as shown although such tray comprises no part of this invention.
  • edge 92 will bear against brace arm 76 when the ladder is in open position as shown in FIG. 2 and it has been determined from experiments that such point of contact is approximately at point 60 which is the second step 56 from the bottom.
  • the vertical plane of side piece 54 between points 60 and 62 provide a structure whereby when weight is first placed on the lowermost step 56, the weight forces are directed downwardly directly against brace 72 so that the weight forces are properly transmitted and absorbed by the tripod frame structure.
  • edge 92 is provided with a shoulder 93 which is engageable with arm 76 as a precaution against edge 92 being accidentally moved out of bearing contact with such arm'.
  • a weight placed on the lowermost step 56 would result in some lateral twisting of ladder 46 even though a portion of the weight load would be taken by brace 72.
  • the curved portion 63 at the top of side piece 54 provides for the vertical support under top plate 58 and avoids the twisting that would occur if the upper end of member 54 continued parallel to leg 38 and a weight load were applied to plate 58 at this point.
  • leg 40 in the use of this ladder, the purpose of the upper angled upper portion of leg 40 is to permit the pivot point 64 to be as high as possible relative to side piece 54 and at the same time afford the engagement of leg end 68 with the apex end 44 of the frame structure.
  • Such arrangement particularly on the smaller ladder as seen in FIG. 2, has been found to provide a most adequate, stable and sturdy frame support.
  • legs 38 and 42 With this ladder in open position, it will be seen from the top plan view in FIG. 11 that legs 38 and 42 extend in opposite directions but in the same plane and that leg 40 forms a right angle with each of the other legs. This permits the side of the ladder represented by legs 38 and 42 to be placed substantially flush against a building, for example, if work on such building requires the use of a ladder.
  • extension 92 serves to maintain the ladder component 46 in a properly oriented position for use as seen'in FIG. 11.
  • Member 94 includes an elongated generally rectangular body portion 96 which is formed with an angularly extending and ground engaging lower or foot portion 98.
  • Member 94 is designed so that body portion 96 can be removably attached to the lower ground engaging end of any one of the frame legs by any suitable means which is here illustrated by the use ofa pair of spaced removable encircling clips 100 and a bolt and wing nut 102 mounted through a hole 104 in the respective legs ofthis ladder as illustrated on leg in FIG. 2.
  • Foot portion 98 is somewhat wider than body portion 96 to provide the shoulder 99 at the top of portion 98 on which the bottom of the ladder leg is seated and supported and by reason of the angled foot portion 98, such portion will be in a vertical plane relative to the ground when the ladder is extended so that with the attachment of leg adjustment member 94 to any one of the frame legs, any weight forces on the frame will be directed vertically toward the ground. It will thus be appreciated that member 94 serves primarily to properly orient the ladder frame and the ladder component and is not for the specific purpose of stabilizing the frame as is usually the situation in shimming traditional step ladders.
  • FIGS. 46 and 8 I show this tripod frame supported ladder structure with certain modifications particularly applicable to relatively tall ladders of this type but for those elements of this article which are the same as those previously described, like numbers will be given to like parts and to the extent that modified parts correspond substantially to parts previously described, they will be given like numerals primed.
  • leg 40 having the upper curved portion as described for FIG. 2 is replaced in the structure of FIG. 4 by the straight leg 40.
  • the area of the triangle formed by the ground engaging legs will be relatively larger than in the shorter structure of FIG. 2 and by reason of this fact, the plane of intersection between leg 40' and side piece 54 will be somewhat lower than point 64 in FIG. 2 and approximately on the plane of the second step 56 from the top of the ladder.
  • an integral depending arm 106 is provided as shown and terminates at approximately the horizontal plane of the second step 56 from the top.
  • Such arm I06 together with the upper portion of side piece 54 provides an inverted V side piece top portion.
  • a rigid rod 108 is secured between the lower end of arm I06 and side piece 54 at approximately the second step 56 from the to so that rod 108 is on substantially a horizontal plane.
  • Leg 40' is pivotally and slidably journaled on rod 108 at point 64' so that in the open position of the ladder as seen in FIG. 4, the
  • leg 40' will be at that end of slot 70 in top plate 58' that is adjacent the apex point 44 of the tripod frame structure.
  • the closed position of this upper portion of the ladder shown in FIG. 4 is illustrated in FIG. 5 where it will be noted that leg 40', when folded inwardly, will move on rod I08 closer to side piece 54.
  • FIG. 6 I show asecond embodiment ofrelating brace 72 to leg 40 as follows. Intermediate the bottom of leg 40' and point 64' thereon, there is secured a transversely extending rod 110. A snap latch means IIZ is secured to brace arm 76 near the hinge point 78 so that as the ladder is opened for use, latch I12 will become removably locked onto rod I10 for stabilizing the tripod frame. In other respects, the ladder of FIG. 4 is similarly constructed and used as the ladder in FIG. 2.
  • this ladder structure is considerably more stable than traditional step ladder structures due to the relatively wide spread three legs which converge to the apex 44.
  • the nonground engaging ladder side piece 54 is adequately and sturdily supported at two vertically spaced points on either leg 40 or leg 40 of the tripod frame such as points 64 or 64' and against brace arm 76 at element 90.
  • the effect of this arrangement is to distribute the weight load on ladder component 46 to all of the frame legs and thus provide a greatly improved and highly efficient article for its intended purpose.
  • This ladder is easily opened and folded and may be compactly stored or transported. Accordingly, from all of the foregoing, is thought a full understanding of the construction and operation of this invention will be bad and the advantages ofthc same will be appreciated.
  • a foldable ladder structure comprising: first and second spaced elongated side pieces having respective upper and lower ends and with a plurality of longitu' dinally spaced step members disposed intermediate said side pieces and secured thereto to form a ladder component; said first side piece serving also as a first ground engaging leg of a three legged tripod frame ladder support; said second side piece being of a shorter length than said a first piece at their lower ends so that the lower end of said second side piece is free of engagement with any supporting surface for said first side piece; a second elongated ground engaging leg having an upper and lower end and pivotally secured at its upper end to the upper end of said first leg to form an apex;
  • a third elongated ground engaging leg having an upper and lower end and pivotally secured near its upper end to the upper end portion of said second side piece so that when the lower end of said third leg is moved outwardly, the upper end thereof will bear against said apex;
  • foldable brace means connected to said first and second legs and releasably lockable to said third leg when said legs are extended into a tripod shape;
  • a ladder structure as defined in claim 1 including:
  • a ladder'structure as defined in claim 1 including: a leg adjustment member comprising:
  • a ladder structure as defined in claim 1 including:
  • said third leg when extended being in a plane perpendicular to that of said first and second legs.
  • a ladder structure as defined in claim 1 including:
  • said top plate being provided with an elongated slot to provide a passageway for the upper end of said third leg when it is moved into and out of engagement with said apex.
  • a ladder structure as defined in claim 5 including: said second side piece being provided at its upper end portion with a sufficient bend-towards its upper side so that when said legs are extended into tripod shape, the longitudinal axis of said bent portion is in a substantially vertical plane when receiving any weight load on said top plate.
  • a l'oldable ladder structure comprising:
  • a tripod-type frame defining first, second and third ground engaging support legs each having an upper and lower end;
  • said first leg also serving as the side piece for a ladder component
  • said second side piece terminating at a point spaced upwardly from the lower end of said first leg so that said second side piece is free of engagement with any supporting surface for said frame legs;
  • a foldable ladder structure as defined in claim 7 includait] second side piece being provided at its lower end portion with a sufficient bend toward its underside so that when said legs are extended into tripod shape, the plane of said second side piece below said bend is substantially perpendicular to but free of engagement with the supporting surface for said legs; the lowermost step on said ladder component being substantially planar with the lower end of said second side piece so that a weight load on said lowermost step will be directed vertically downward; and the point of engagement of said second side piece with said brace means being substantially at the plane of said bend.
  • a leg adjustment member comprising:
  • a ladder structure as defined in claim 7 including: a top plate secured across the upper ends ol'said side pieces;

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  • Ladders (AREA)
US847099A 1969-08-04 1969-08-04 Foldable ladder Expired - Lifetime US3540549A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US84709969A 1969-08-04 1969-08-04

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US3540549A true US3540549A (en) 1970-11-17

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US847099A Expired - Lifetime US3540549A (en) 1969-08-04 1969-08-04 Foldable ladder

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US (1) US3540549A (fr)
JP (1) JPS508384B1 (fr)
BE (1) BE754089A (fr)
CA (1) CA937911A (fr)
CH (1) CH519091A (fr)
DE (1) DE2034858A1 (fr)
FR (1) FR2056514A5 (fr)
GB (1) GB1270786A (fr)
NL (1) NL7011544A (fr)
SE (1) SE365021B (fr)
ZA (1) ZA705084B (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE20101777U1 (de) * 2001-01-29 2001-08-09 Laug, Horst, 49809 Lingen Stabilisierungsstütze für Leitern
GB2428068A (en) * 2005-07-05 2007-01-17 Univ Huddersfield Stepladder
USD757959S1 (en) 2015-04-28 2016-05-31 Tokuo AOI Stepladder
USD758615S1 (en) 2015-04-28 2016-06-07 Tokuo AOI Stepladder
USD761442S1 (en) 2014-07-10 2016-07-12 Tokuo AOI Stepladder
USD765269S1 (en) 2015-04-28 2016-08-30 Tokuo AOI Stepladder
US9689204B2 (en) * 2013-02-26 2017-06-27 Tokuo AOI Stepladder

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE20101777U1 (de) * 2001-01-29 2001-08-09 Laug, Horst, 49809 Lingen Stabilisierungsstütze für Leitern
GB2428068A (en) * 2005-07-05 2007-01-17 Univ Huddersfield Stepladder
US9689204B2 (en) * 2013-02-26 2017-06-27 Tokuo AOI Stepladder
USD761442S1 (en) 2014-07-10 2016-07-12 Tokuo AOI Stepladder
USD757959S1 (en) 2015-04-28 2016-05-31 Tokuo AOI Stepladder
USD758615S1 (en) 2015-04-28 2016-06-07 Tokuo AOI Stepladder
USD765269S1 (en) 2015-04-28 2016-08-30 Tokuo AOI Stepladder

Also Published As

Publication number Publication date
ZA705084B (en) 1971-04-28
BE754089A (fr) 1970-12-31
JPS508384B1 (fr) 1975-04-03
CH519091A (fr) 1972-02-15
CA937911A (en) 1973-12-04
SE365021B (fr) 1974-03-11
DE2034858A1 (de) 1971-02-18
NL7011544A (fr) 1971-02-08
GB1270786A (en) 1972-04-12
FR2056514A5 (fr) 1971-05-14

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