US3554318A - Folding ladder - Google Patents

Folding ladder Download PDF

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US3554318A
US3554318A US783360A US3554318DA US3554318A US 3554318 A US3554318 A US 3554318A US 783360 A US783360 A US 783360A US 3554318D A US3554318D A US 3554318DA US 3554318 A US3554318 A US 3554318A
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ladder
sections
end
stiles
folding
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US783360A
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Hugh P Knight
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HUGH P KNIGHT
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HUGH P KNIGHT
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    • EFIXED CONSTRUCTIONS
    • E06DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06CLADDERS
    • E06C1/00Ladders in general
    • E06C1/02Ladders in general with rigid longitudinal member or members
    • E06C1/32Ladders with a strut which is formed as a ladder and can be secured in line with the ladder
    • EFIXED CONSTRUCTIONS
    • E06DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06CLADDERS
    • E06C1/00Ladders in general
    • E06C1/02Ladders in general with rigid longitudinal member or members
    • E06C1/38Special constructions of ladders, e.g. ladders with more or less than two longitudinal members, ladders with movable rungs or other treads, longitudinally-foldable ladders
    • E06C1/39Ladders having platforms; Ladders changeable into platforms
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04GSCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR OTHER BUILDING AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G1/00Scaffolds primarily resting on the ground
    • E04G1/28Scaffolds primarily resting on the ground designed to provide support only at a low height
    • E04G1/30Ladder scaffolds
    • E04G2001/302Ladder scaffolds with ladders supporting the platform
    • E04G2001/305The ladders being vertical and perpendicular to the platform

Abstract

A folding ladder comprises a plurality of ladder sections which are connected together in end-for-end relationship by coupling means and in which at least two of the coupling means are hinge devices, the axes of all the hinge devices being located on the same side of the plane of the ladder, the arrangement being such that when the ladder sections are in alignment, adjacent end portions of adjoining ladder sections or hinge devices are in abutting relationship with one another.

Description

United States Patent Hugh P. Knight 11.1. Knight Limited, East Street, Portslade, Sussex BN41EN, England Appl. No. 783,360

Inventor [5 6] References Cited UNITED STATES PATENTS 1,014,215 l/1912 Forndran 182/163 1,685,632 9/1928 Hammond. 182/24 3,073,414 l/1963 Lavrard 182/24 3,143,185 8/1964 Wenger 182/24 Primary Examiner-Reinaldo P. Machado Attorney-Linton & Linton ABSTRACT: A folding ladder comprises a plurality of ladder sections which are connected together in end-for-end relationship by coupling means and in which at least two of the coupling means are hinge devices, the axes of all the hinge devices being located on the same side of the plane of the ladder, the arrangement being such that when the ladder sections are in alignment, adjacent end portions of adjoining ladder sections or hinge devices are in abutting relationship with one another.

" PATENIEDJAmmn sum 1 or 4 Hue/1 PER c'Fv b K 19 1%H1 ATTORNEYS PATENTEBJAMZEI?! 35545318 sum 2 or 4 j j I] II V l I I I I IN-V ENTOR HUGH PERCIVAL KNIGHT LM M /3;:

ATTORNEYS PATENTEnJmlzmn 3554.318

' sum 3 OF 4 INVENTOR HUGH PERC/VAL KN/QHT lzt WM ATTORNEYS PATENTEDJAN 1 2 I971 sum war 4 m N w w L M. M B M H Pu U H ATTORNEYS FOLDING LADDER This invention relates to folding ladders, and is particularly concerned with a folding ladder which may be usedin any one of a variety of different configurations.

Known ladders of the kind which can be used in a variety of sections configurations suffer from the disadvantage that they consistof a number x separate sections which have to be secured together in the desired configuration.

It is an object of the present invention to provide a folding ladder in which this disadvantage is overcome.

According to the present invention, there is provided a folding ladder which comprises a plurality of ladder sections which are connected together in end-for-end relationship by coupling means, and in which at least two of the coupling means are hinge devices, the axes of all the hinge devices being located on the same side of the plane of the ladder, the arrangement being such that when the ladder sections are in alignment, adjacent end portions of adjoining ladder sections or hinge devices are in abutting relationship with one another.

Each hinge device may comprise two hinges, and each hinge may comprise two U-shaped members secured respectively around adjacent end portions of the stiles of adjoining ladder sections, the arms of one of the U-shaped members extending between the arms of the other U-shaped member and being pivotally coupled ther'etoj Preferably, the stile of one of the ladder sections terminates within said one U-shaped member to define a socket therein, whereas the stile of the other latter section projects beyond said other U-shaped member for engagement in the socket when the ladder sections are in alignment;

A folding ladder in accordance with the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a house and illustrating various configurations that the folding ladder of the present invention is capable of achieving;

FIG. 1A is a view showing a further configuration of the folding ladder;

FIG. 2 is a perspective view of an end section and part of an inner section of the ladder; I

FIG. 3 is a cross-sectional view through one stile of one section of the ladder as pivotally connected to one stile of an adjoining section of the ladder;

FIG. 4 is an enlarged detailview of part of FIG. 3;

FIG. 5 is a cross-sectional view taken along the line G-G of FlG.4; J

FIG. 6 is a view showing the manner in which'a plank is securable by clips to the inner sections of the ladder;

FIG. 7 is a view showing details "of stay bars that assist in maintaining the various sections of the ladder in their desired relative dispositions; i

FIG. 8 is a cross-sectional view through an end portion of a stay bar;

FIG. 9 is a cross-sectional view of an alternative device for securing together adjoining ladder sections;

FIG. 10 is a side view of a hinge incorporating a friction device for effectively securing adjoining ladder sections in alignment;

FIG. 11 is a cross-sectional plan view of part of the hinge of FIG. 10; and

FIG. 12 is a perspective view of the whole ladder with all its sections in alignment.

Referring to'FlGS. l and 2, the folding ladder comprises two end sections and two inner sections coupled together in end-for-end relationship, the end sections 1 (FIG. 2) being jointed by hinges to the inner sections 2. In aiirst construction of the ladder, as shown in FIG. 12, the two inner sections are themselves hinged together by a further pair of hinges of the kind shown in FIG. 2. In a second, alternative construction, part of which is shown in FIG. 9, each end 40 of one of the inner sections carries a sleeve 41 which. receives one of the ends 42 of the other inner section.

Referring now more particularly to'FIG. 2, an end section 1 transversely extending rods 4. Each rod 4 supports a transversely extending rods 5, the step 5 being prevented from rocking about the rod 4 by having its two ends let into slots cut in the stiles 3. 1

The lower end of each stile 3 is splayed outwardly, and the remote open end of each stile receive therein a foot 38 of any suitable nonslip material. Each foot 38 is wedged into its associated stile 3 and preferably terminates in a ground-engaging surface that is coplanar with the ground when the end section 1 is inclined relatively to an inner section 2 as illustrated in FIG. 2. The underface of the foot 38 may be ridged if desired.

The inner section 2 is of similar construction to the end section 1, except that the stiles 31 thereof are parallel with each other throughout their lengths.

The hinges jointing an end section I to an inner section 2 will now be described. Each stile 3 of the end section 1 extends through an outer clamp 6 that is of substantially U- shape. It will be seen from FIG. 2 that each stile 3 projects beyond its associated outer clamp 6 in the form of a projection 9. In a similar manner each stile 31 of the inner section 2 projects into an inner clamp 7 that is also of substantially U- shape, the side arms of the inner clamp 7 extending between the side arms of the outer clamp 6 and being pivotally coupled thereto by means of a pin 8. Each stile 31 of the inner section 2 terminates within its associated inner clamp 7 so as to leave a socket 10 therein, the socket 10 being of such configuration that when the end section 1 is swung into a position in which it is in alignment with the inner section 2, the projection 9 enters the socket 10 to ensure a rigid coupling between the inner section 2 and the end section 1. When the adjoining ladder sec tions are in alignment, the ends of the stiles 3 and 31 abut one another, so that a load acting from the opposite side of the ladder to the hinge axis, that is to say the axis of the pin 8, may be borne by the hinge without the need for any additional locking device.

As illustrated in FIG. 2, the clamps 6 and 7 may be riveted to their associated stiles 3 and 31, or alternatively, as illustrated in FIG. 3, the clamps 6 and 7 may be secured by bolts 1 l.

Each end section 1 of the ladder may be secured in fixed angular relationship with its adjoining inner section 2 by means of stay bars 12, as shown in FIGS. 2 and 7. Each stay bar 12 consists of an elongated rod with bent over end portions 32 and 33, the two end portions extending parallel with one another, and perpendicular to the body of the stay bar. One end portion 32 of the stay bar 12 is pivotally mounted, in a bush 24, in one of the stiles 3 of the end section I. The other end portion 33 terminates in a shaped head portion 35, and also carries a metal coupling plate 25 which is rigidly secured to the end portion 33.

The head portion 35 of the stay bar 12 is shaped asshown in FIG. 8, for releasable engagement in a gripping device provided by an aperture in a resilient plate 27 of plastics material. The resilient plate 27 is secured behind an aperture 13 in the stile 31, the aperture in the resilient plate 27 being of smaller diameter than the aperture 13. The head portion 35 consistsof a narrower neck part 36 and an en'largedterminal part 37, the aperture in the resilient plate being of slightly smaller diameter than the enlarged part 37 of the head portion. The en.- larged part '37 can be pushed through the aperture against the resilience of the plate 27, and the stay bar 12 is locked in position by the plate 27 settling into place around the neck par-{36 of the head portion 35.

A series of further apertures 13 (FIG. 2), each backed b a resilient gripping device, are provided along the stiles 31 in order to permit the end section 1 to be secured at different inclinations to the inner section 2.

Referring now to FIG. I, there are shown a number of configurations of the ladder.

At A, the ladder is illustrated as a long ladder in which all comprises two tubular stiles 3 interconnected by a plurality of the four sections are rigidly arranged in alignment.

By folding the upper end section out of the plane of the remaining three sections, the ladder can be used, as illustrated at B, as an eaves ladder in which the upper section is horizontally disposed, and the remaining three sections, which are rigidly arranged in alignment, are inclined slightly away from the vertical.

By folding the uppt' end section through 180, relative to the inner section to wh ch it is pivotally coupled, the ladder can be transformed to a short ladder as illustrated at C. At D the ladder is illustrated as a trestle, this arrangement being achieved by pivoting each end section downwardly relative to the two inner sections, which are maintained in alignment.

At E the ladder is illustrated as a step ladder by so folding the ladder that the two inner sections are inclined relative to each other, the end section associated with each inner section being in alignment therewith.

At F the ladder has been transformed into a stair trestle in that only one end section is inclined relative to the remaining sections, the remaining sections being supported at their other end on a stair of a staircase.

In FIG. 1A the ladder is also in the form of a stair trestle formed by folding the two inner sections as shown, the end section associated with each inner section being in alignment therewith. This arrangement allows the ladder to be used higher up the stairs.

When the ladder is used as a step ladder, two stay bars are connected together to provide a tie between the two sections. Referring to FIG. 7, one of the ladder end sections carries a stay bar 12 having a coupling plate 25 attached to it, while the other end section (not shown) carries a stay bar 52 without a coupling plate. The stay bar 52 has a head portion shaped in the same way as the end portion 35 of the stay bar 12, and is releasably engaged by an aperture 54 in a resilient member 55 secured to the plate 25. The plate 25 has a larger aperture 56, and the device functions in the same way as the device shown in FIG. 8.

When the ladder is to be used in any of the configurations shown in FIG. I, or FIG. 1A, the free ends of the stay bars 12 and 52 are coupled either to their own stiles 3 of their end sections 1 as shown in FIG. 12, or to the stiles 31 of their associated inner sections 2, as shown in FIG. 2, as may be necessary according to the particular form of ladder required. Further stay bars are provided for interconnecting the two inner sections, in order that the configuration of FIG. 1A may be achieved.

When the ladder is used as a trestle, a plank 20 may be secured in position between the stiles 31 (or 3) of the inner (or end) ladder sections, as shown in FIG. 6. The plank 20 has secured to its underface a plurality of clips 21 having downwardly projecting ends 22. Each end 22 terminates in a lower portion 23 that is bent slightly to one side so as to form an end finger. One of these end fingers 23 will engage under a correspondingly shaped recess in one of the stiles 31, in a manner sufficient to prevent inadvertent removal of the plank 20 from the ladder.

The trestle D of FIG. I may, of course, be inverted, and a plank supported at the desired height on corresponding steps of the two end sections.

In order to assist in climbing up onto the horizontal portion of the ladder when it is used as a trestle, a removable handle H (FIG. 2) is inserted into the upper open end of one of the stiles 3. The handle H is of cylindrical form for the major part of its length, but is somewhat flattened at its lower end so as to be a squeeze fit in the upper end of the stile 3.

If the two inner sections are joined by a pair of sleeves, as shown in FIG. 9, then it is possible to extend the length of the ladder by inserting an additional length of ladder (not shown) having a similar pair of sleeves at one end. In order to be able to use such a ladder as a step ladder, holes may be provided in all four ends of the stiles, to receive a long pivot pin or two shorter pins. The sleeves may be of generally U-shaped cross section and may function in a similar manner to the clamp 7 of FIG. 2. In these circumstances, the holes for receiving pivot pins may be provided in the projecting arms of the U-shaped sleeves.

A further configuration of the ladder may be achieved in the case where the inner sections are joined by sleeves. The two halves of the ladder are used separately as trestles to support a plank of desired length. The height of the plank may be adjusted by placing it on different steps of the trestles, or by varying the heights of the trestles themselves. This latter variation may be achieved by providing corresponding series of gripping devices along the stiles of the adjoining ladder sections, and securing the sections at the desired inclination by the use of stay bars with shaped heads on both end portions.

In order to make the ladder easier to manipulate once it is in its desired configuration, the hinges may be effectively prevented from folding by means of a locking device. or by means of a friction device. A locking device will now be described with reference to FIGS. 3, 4 and 5.

FIG. 3 is an end view of one of the stiles 3 of an end section 1, when folded through l relative to the stile 31 of its associated inner section 2, there being a lock lever 14 associated with the two clamps 6 and 7.

Turning now to FIGS. 4 and 5 it will be seen that the pivot pin 8 has a central portion of enlarged diameter surrounded by a compression spring 15. The portion of enlarged diameter of the pivot pin 8 also extends through an aperture in the lock lever 14. The two sidearms of the U-shaped inner clamp 7 have apertures formed therein that are of less diameter than the enlarged central portion of the pivot pin 8, in order that said enlarged central portion of the pivot pin 8 shall present end shoulders that maintain the two sidearms of the inner clamp 7 in a spaced-apart condition. The ends 28 of the pivot pin 8, which are of lesser diameter than the central portion of the pivot pin, extend through corresponding openings in the sidearms of the inner clamp 7 as well as through corresponding openings in the sidearms of the outer clamp 6. The arms of the clamp 6 are spaced from the arms of the clamp 7 by washers 16.

It will be noted that the lock lever 14 is cranked somewhat, the cranked portion having an aperture through which extends a pin 17 that is secured to the two sidearms of the inner clamp 7. On the pin 17 is a washer 18, this washer 18 being between the lock lever 14 and the nearest adjacent sidearms of the inner clamp 7. By manually rocking the lock lever 14 in the direction of the arrow, a peg 19, on the lock lever 14, can be caused to retract from aligned openings in adjacent sidearms of the clamps 7 and 7. The openings in the sidearms of the clamps 6 and 7 are only in alignment when the end section 1 is in alignment with its associated inner section 2. Thus while an end section 1 is in the disposition relative to an inner section 2 as illustrated in FIG. 2, the peg 19 will not extend through the aperture in the outer clamp 6 but will only bear against the inner face thereof. As the end section I is swung into alignment with the inner section 2, the peg 19'will automatically slip through the aperture in the side arm of the outer clamp 6, as in FIG. 4, to lock the sections in alignment. The lock lever 14 is only associated with the clamps 6, 7 on one side of the ladder, such locking means not being necessary on both sides.

It will be appreciated that the clamps 6 and 7, the stay bars 12, and the locking lever 14 are also incorporated in the other end section I, and also between the inner sections of the ladder when these are hinged together.

A friction device for retaining the ladder sections in alignment will now be described with reference to FIGS. 10 and 11. Two clamps 46 and 47, of similar construction to the clamps 6 and 7 of FIG. 2, are secured to the ends of stiles 43 and 53 of adjoining ladder sections, and are pivoted on a pin 48. The stile 53 projects through the clamp 47 to form a projection 59, whereas the stile 43 terminates within the clamp 46 to leave a socket for receiving the projection 59.

Frictional engagement of the inside walls of the projection 59 is provided by a generally U-shaped member 44 which is mounted transversely within the stile 43 on the shanks of long rivets 45. The rivets 45 extend through the clamp 46 and stile 43 to secure them together. A compression spring 50 coiled around the shank of one of the rivets urges apart the two limbs of the member 44.

The end portions 51 of the limbs of the member 44 terminate in convergent portions which extend just beyond the ends of the clamp 46. As the stile 53 is moved-around into alignment with the sti'e 43, the end portions 51 of the member 44 are forced inwardly, against the outward pressure of the spring 50, by the'inside walls of the projection '59. The U- shaped member 44 accordingly grips strongly the inside walls of the stile 53. In this way, the ladder sections are effectively maintained in alignment to prevent folding of the ladder during manipulation thereof. In an alternative form of friction device (not shown) a gripping device secured to one of the clamps frictionally engages the outside surface of the other clamp.

The construction of the ladder having hinged inner sections may be folded at the center hinge to facilitate storage and transportation, or alternatively the two end sections may both be folded in. In the construction in which the two inner sections are connected together by sleeves, the two ladder halves may be separated, and each half-folded.

lclaim:

l. A folding ladder comprising a plurality of ladder sections each consisting of a pair of stiles and a plurality of rungs connecting each pair of stiles, coupling means at least two of which are hinge devices connecting said ladder sections in end-to-end relationship, each said hinge device consisting of a pair of hinges connecting the stiles of adjoining ladder sections, a friction member connected to one stile, being provided in at least one hinge of each of said pair of hinges and adapted to frictionally engage the other stile when the ladder sections are in alignment, and the axes of all of said hinges being located on the same side of the plane of the ladder whereby when the ladder sections are in alignment, the adjacent end portions of adjoining ladder sections are in abutting 6 relationship.

2. A folding ladder according to claim I, wherein each hinge comprises two U-shaped members secured respectively around adjacent end portions of the stiles of adjoining ladder sections, the arms of one of the U-shaped members extending between the arms of the other U-shaped members extending between the arms of the other U-shaped member and being pivotally coupled thereto.

3. A folding ladder according to claim 2, wherein the stiles of one of the ladder sections terminates within said one U- shaped member to define a socket therein, whereas the stile of the other ladder section projects beyond said other U-shaped member, for engagement in the socket when the ladder sections are in alignment.

4. A folding ladder according to claim 2, wherein said friction-member is mounted within and extends beyond the stile which terminates within said one U-shaped member, said fric tion member being spring urged into frictional engagement with the inside wall of the adjacent sidearm of the adjoining ladder section when the ladder sections are in alignment.

5. A folding ladder according to claim 1, wherein rigid stay bars are provided to maintain the ladder sections at a predetermined inclination to one another, said stay bars being pivotally coupled at one end to the stiles of one ladder section for detachably engaging the other end of said stay bars.

6. A folding ladder according to claim 5, wherein said gripping device comprises a resilient plate having an aperture for engagement by said other end of the stay bar, said other end having an enlarged terminal portion wider than said aperture, and a narrower neck portion adapted to be gripped by the resilient plate after insertion through the aperture of the terminal portion.

7. A folding ladder according to claim 1, wherein there are four ladder sections which are connected together in end-forend relationship by three pairs of hinges.

Claims (7)

1. A folding ladder comprising a plurality of ladder sections each consisting of a pair of stiles and a plurality of rungs connecting each pair of stiles, coupling means at least two of which are hinge devices connecting said ladder sections in endto-end relationship, each said hinge device consisting of a pair of hinges connecting the stiles of adjoining ladder sections, a friction member connected to one stile, being provided in at least one hinge of each of said pair of hinges and adapted to frictionally engage the other stile when the ladder sections are in alignment, and the axes of all of said hinges being located on the same side of the plane of the ladder whereby when the ladder sections are in alignment, the adjacent end portions of adjoining ladder sections are in abutting relationship.
2. A folding ladder according to claim 1, wherein each hinge comprises two U-shaped members secured respectively around adjacent end portions of the stiles of adjoining ladder sections, the arms of one of the U-shaped members extending between the arms of the other U-shaped memberS extending between the arms of the other U-shaped member and being pivotally coupled thereto.
3. A folding ladder according to claim 2, wherein the stiles of one of the ladder sections terminates within said one U-shaped member to define a socket therein, whereas the stile of the other ladder section projects beyond said other U-shaped member, for engagement in the socket when the ladder sections are in alignment.
4. A folding ladder according to claim 2, wherein said friction member is mounted within and extends beyond the stile which terminates within said one U-shaped member, said friction member being spring urged into frictional engagement with the inside wall of the adjacent sidearm of the adjoining ladder section when the ladder sections are in alignment.
5. A folding ladder according to claim 1, wherein rigid stay bars are provided to maintain the ladder sections at a predetermined inclination to one another, said stay bars being pivotally coupled at one end to the stiles of one ladder section for detachably engaging the other end of said stay bars.
6. A folding ladder according to claim 5, wherein said gripping device comprises a resilient plate having an aperture for engagement by said other end of the stay bar, said other end having an enlarged terminal portion wider than said aperture, and a narrower neck portion adapted to be gripped by the resilient plate after insertion through the aperture of the terminal portion.
7. A folding ladder according to claim 1, wherein there are four ladder sections which are connected together in end-for-end relationship by three pairs of hinges.
US783360A 1967-12-13 1968-12-12 Folding ladder Expired - Lifetime US3554318A (en)

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CH (1) CH491278A (en)
DE (1) DE1812628A1 (en)
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GB (1) GB1250781A (en)

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US4448283A (en) * 1982-09-13 1984-05-15 Andral Corporation Portable fold-up ladder
US4457397A (en) * 1981-11-10 1984-07-03 Scala John J Platform for stairs
US4457391A (en) * 1981-01-26 1984-07-03 Andral Corporation Fold-up ladder
US4463826A (en) * 1982-08-23 1984-08-07 Pearce Richard H Airplane tow bar and step stool combination
US4493392A (en) * 1981-01-26 1985-01-15 Andral Corp Convertible fold-up ladder
US4648481A (en) * 1986-04-21 1987-03-10 Alpha Metal Corp. Multipurpose aluminum folding ladder equipped with a detachable stand-on board and supporting handrails
US4699246A (en) * 1985-10-29 1987-10-13 Wang Yaw C Multipurpose ladder
US4719990A (en) * 1986-08-27 1988-01-19 Branko Markovic Step ladder for stairs
DE3627303A1 (en) * 1986-08-12 1988-02-18 Geis & Knoblauch Gmbh & Co Kg Climbing apparatus
US4842098A (en) * 1988-01-22 1989-06-27 Haison Yuen Adjustable folding ladder
US4926967A (en) * 1988-07-27 1990-05-22 Baker Mervyn R Folding ladders
US5358069A (en) * 1992-07-23 1994-10-25 Krause-Werk Gmbh & Co. Kg Stepboard for ladders
US5715910A (en) * 1995-07-20 1998-02-10 Koch; Michael W. Stairway platform
US20050028320A1 (en) * 2003-08-07 2005-02-10 Latimer Brett A. Locking hinge for folding ladder
US20100163340A1 (en) * 2008-12-30 2010-07-01 Allred & Associates Inc. Ultra lightweight segmented ladder/bridge system
US20110056764A1 (en) * 2009-07-28 2011-03-10 Mark Cross Ladder and support stand
US20110209947A1 (en) * 2008-12-30 2011-09-01 Allred & Associates Inc. Ultra lightweight segmented ladder/bridge system
US20120080263A1 (en) * 2010-10-05 2012-04-05 Ge Lee Adjustable Hang Ladder with Fall Arresting and Cushioning Arrangement
CN103147681A (en) * 2013-03-28 2013-06-12 河南省电力公司信阳供电公司 Multifunctional meter reading ladder
US20140251729A1 (en) * 2006-12-22 2014-09-11 Werner Co. Flip Ladder with Tray and Method
US20140274571A1 (en) * 2011-10-17 2014-09-18 Ildefonso Aral Diaz Workout device
JP2016503442A (en) * 2012-11-07 2016-02-04 バイエル・マテリアルサイエンス・リミテッド・ライアビリティ・カンパニーBayer MaterialScience LLC Method of incorporating an ion-conducting polymer into a polymer product to achieve antistatic behavior
US9404305B1 (en) * 2014-03-26 2016-08-02 Mark S. Messick Portable and adaptable platform
US10012000B2 (en) * 2015-12-29 2018-07-03 Thomas Yoo Collapsible work platform
US20180187486A1 (en) * 2016-12-21 2018-07-05 James B. Ford Safety ladder
US10214904B2 (en) 2016-06-06 2019-02-26 Michael Callahan Trusses and similar structures

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EP0079852A3 (en) * 1981-11-13 1984-05-30 Ruedi Giezendanner Multipurpose ladder
FR2546960A1 (en) * 1983-04-22 1984-12-07 Alufort Sa Locking device for a double ladder with hollow rungs
GB8416639D0 (en) * 1984-06-29 1984-08-01 Gostling P T Trestle support
US5353892A (en) * 1993-10-14 1994-10-11 Lu Feng Hui Ladder joint for a folding collapsible ladder
DE102006003171A1 (en) * 2006-01-23 2007-09-06 Irwin Industrial Tools Gmbh Working stand, especially sawhorse, and workbench rack

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Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4457391A (en) * 1981-01-26 1984-07-03 Andral Corporation Fold-up ladder
US4493392A (en) * 1981-01-26 1985-01-15 Andral Corp Convertible fold-up ladder
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Also Published As

Publication number Publication date
BE725438A (en) 1969-05-16
CH491278A (en) 1970-05-31
DE1812628A1 (en) 1969-07-03
FR1602056A (en) 1970-10-05
GB1250781A (en) 1971-10-20

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