US3269485A

US3269485A - Convertible ladder

Info

Publication number: US3269485A
Application number: US405407A
Authority: US
Inventors: Clayton E Larson
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-10-21
Filing date: 1964-10-21
Publication date: 1966-08-30
Anticipated expiration: 1983-08-30

Description

1966 c. E. LARSON 3,269,485

CONVERTIBLELADDER Filed Oct. 21. 1964 I5 Sheets-Sheet l Aug. 30, 1966 c. E. LARSON 3,259,435

CONVERTIBLE LADDER Filed Oct. 21, 1964 3 Sheets-Sheet. 2

X Consion! CLAYTON E. LARSON who? M l wi;

ATTORNEY 5 Aug. 30, 1966 c. E. LARSON CONVERTIBLE LADDER 5 Sheets-Sheet 1! Filed Oct. 21. 1964 CLAYTON E. LARSON ATTORNEY) United States Patent 3,269,485 CUNVER'E'HBLE LADDER Clayton E. Larson, 30 Moultrie St, Brooklyn, NY. Filed Oct. 21, 1964, Ser. No. 4il5,407 4 Claims. (Cl. Isl-26) This invention relates generally to ladders and more specifically to a multi-use ladder having means to convert the ladder to make it suitable for use under different conditions.

There are and have been many multi-use or combination ladders provided in the prior art. The primary benefit of a combination ladder lies in the provision, in one unitary structure, the capabilities and versatilities of several basic forms of ladders. For example, a step ladder is particularly suitable for use where the ladder must support itself or where it is not desirable to utilize adjacent structural surfaces for supporting the ladder. A step ladder does, however, entail duplicate structure in that it contains a step section and a coextending prop section in a given height. If this duplicate structure were to be utilized to extend the length of the ladder as in an extension ladder, the height capability of the ladder could be essentially doubled. Prior art ladders hawe heretofore incorporated the capability of the combination step and extension ladder, generally by providing a step and prop section pivotally connected to be swung into coplanar relationship when the ladder is to be extended. It would the of further advantage to combine, with the step and extension ladder described above, provisions so that the ladder could also be used on stairwells. This has been accomplished in the prior art by furnishing a ladder with a portion of the ladder supporting or prop structure being te lescopable to provide adjustment for various heights or numbers of steps. Such a device is shown in the ap-plicants prior issued patent US. 2,899,- 008 entitled, Multi-Way Ladder. In that disclosure the prop section of the ladder is telescopable to provide the so-called stair well capability while the prop as a whole is pivotal to be swung upwardly to a substantially coplanar relationship with the step portion to provide an extension of the ladder to essentially double its step ladder height. There are many other prior art references which provide one or more of the above change capabilities and the devices constructed in accordance with these references have, in general, found substantial acceptance among the using public.

In the art of ladder manufacturing considerable importance is placed on economy, lightness, compactness, durability, ease of use and safety. The trend toward lightness and economy has been generally met by manufacturers by the utilization of lightweight metal ladders generally formed from extruded metal components. This type of ladder properly constructed can provide both lightweight, stability and durability. The use of extruded lightweight metal for ladder structures also has allowed the incorporation of structural members having complex and intricate cross sectional configurations without a great increase in the cost thereof.

Prior art ladders also exist in which the prop section thereof may be displaced vertically with respect to the step section, the prop section being either slidably engaged by or disengageable from the step section. These devices provide a step ladder capability by angular configuration of the sections, stair well capability by vertical movement of the prop section with respect to the step section while maintaining the angular configuration therebetween an extension ladder capability by vertical movement between the sections with the sections in parallel relationship to one another.

This invention pertains particularly to improvements on the latter-mentioned class of ladders. Conversion of most the aforementioned prior art ladders is generally awkward, complicated and/ or vulnerable to improper adjustment thereby endangering the user if through oversight or carelessness a conversion of the ladder is improperly made. The above disadvantages of the prior art result chiefly from the necessity of too many separate adjustments or engagements of parts which must be individually accomplished to effect a configurational conversion.

It is an object of this invention to avoid the above disadvantages by providing a multi-use ladder which is simple to use, is composed of the minimum number of separate component parts, requires the minimum amount of adjustment for configurational conversion and is foolproof in operation.

It is another object of this invention to provide a multiuse ladder having a step and prop section thereto in which the prop section is permanently and slidably engaged by a guide member which is in turn permanently and pivotally mounted to the step section, the guide member carrying means to adjustably block the prop section from slidable movement therewith.

It is a further object of the invention to provide, in combination with the aforementioned guide member, a track means on the prop section and a means for slidably engaging the tracks mounted on the step section, the means and the track being formed to automatically engage one another for travel extending the length of the prop section when the step and prop section are brought into parallel, ccoextensive abutting relationship so that the ladder may be safely and effortlessly converted into an extension ladder.

It is yet another object of this invention to provide a new and improved multi-purpose ladder which may be easily converted from one form of ladder to another form of ladder with a minimum of moving parts or alteration of the basic ladder structure itself.

It is another object of this invention to provide a multi purpose ladder in which the prop section is telescopable with respect to the step section to provide both an extension ladder capability and a capability for use on step-like structures.

It is still a further object of this invention to provide a multi-purpose ladder which utilizes to the fullest extent, the benefits made available by lightweight extruded members.

It is another object of this invention to provide a multipurpose step ladder in which the step section is telescopable with respect to the prop section and which has a fully effective combined article support rack and section spreader brace.

It is still a further object of this invention to provide a multi-purpose ladder having an article support rack which is telescopable so that, in the retracted condition, there is no interference with conversion of the ladder from one form to another or with the use of the ladder as a step or stair well ladder and provides a full area article support.

These and other objects of the invention will become more obvious by reference to the following detailed description when viewed in the light of the accompanying drawings wherein like numerals indicate like parts throughout the figures thereof and wherein:

FIGURE 1 is a side elevational view of a ladder ernbodying features in accordance with this invention and configured for use as a step ladder.

FIGURE 2 is an enlarged view of the ladder of FIG- URE 1 taken along the line 22 thereof.

FIGURE 3 is a sectional view partly broken away of FIGURE 2 taken along the line 33 thereof.

FIGURE 4 is an enlarged fragmentary sectional view taken along the line 4-4 of FIGURE 3.

FIGURE 5 is a sectional view taken along the line 55 of FIGURE 4.

FIGURE 6 is an enlarged fragmentary front elevational view of the ladder of FIGURE 1.

FIGURE 7 is an enlarged sectional view taken along the line 7-7 of FIGURE 1.

FIGURE 8 is a side elevational view of the ladder of FIGURE I converted into a configuration for use as a stair well ladder.

FIGURE 9a is a view similar to FIGURE 8 showing the ladder in a parallel abutting and coextensive configuration preparatory to use as an extension ladder.

FIGURE 9b is a view similar to FIGURE 90 showing the ladder in an extension configuration.

FIGURE 10 is an enlarged sectional and fragmentary view take along the line 10-10 of FIGURE 9/).

The above objects are accomplished in general by providing a ladder having a front step section and a prop section, a pivotal guide member mounted proximate the top of the step section, the pivotal member slidably engaging the prop section so that the prop section may be telescoped with respect to the front section to enable use of the ladder as either an extension ladder or a stair well ladder. Other improvements provided by this invention generally consist of means on the pivotal guide member which blocks sliding of the prop section to fix the vertical relationship between the prop section and the front step section of the ladder at desired intervals in a safe, simple easily operated manner. The front step section is further provided proximate the upper portion thereof with means to slidably engage the prop section to maintain the sections in parallel relationship when the ladder is being used in its extended condition. Also provided is a combined bucket or article-support rack and a section spreader brace which is pivotally connected to the front step section of the ladder and adapted to engage prongs provided on the prop section when the ladder is being used as either a step ladder or a stair well ladder to serve as an article support. The support rack is telescopable to be retracted in a coplanar fashion with respect to the front step section when the ladder is being utilized as an extension ladder or adjusted to a stair well configuration.

Referring now more particularly to FIGURE 1, a ladder embodying features in accordance with the invention is shown in a step ladder configuration and is made up of a front or step section 12 having a guide means or member 14 pivotally mounted at the upper end thereof. The guide means 14 slidably engages a prop section shown generally at 16 which, in the configuration of FIGURE 1, serves to support or prop the step section 12. An article support shown generally at 18 is pivotally mounted proximate the upper end of the step section 12 and is composed of a first or spreader bar portion 20 having telescopically mounted therein a second or support portion 22. The article support 18, in the configuration of FIGURE 1, serves as a combined article support and spreader bar for the ladder.

Referring now to FIGURE 2, an enlarged detail of the cross sectional configuration of both the prop section 16 and the guide members 14 is shown in detail. The prop section 16 is made up of a pair of side rails shown generally at 24 generally comprising inwardly extending U-shaped channels having a web section 26 and forward and rear

transverse sections

28 and 30 respectively. A track 32 extends transversely from the outer side of the web 26 for purposes to be described later. The guide member 14, slidably engaging each of the side rails 24, is generally composed of hinge sections 34 disposed on either side of the step section 12 and hingedly connected thereto by a pivot pin 36 and a pair of prop section side rail engaging members 38 generally conforming to the prop section side rails 24 to slidably provide engagement therefore. The sections 38 are connected together by a cross member 40.

The portion of the front step section 12 shown in FIG- URE 2 includes a pair of side rails 42 connected together at the top end thereof by a step member or ring 44.

Referring now to FIGURES 3 and 5, the cross member has a retaining pin 46 reciprocably mounted at either end thereof, the pins being adapted to engage holes 49 (FIGURE 5) disposed in spaced vertical relation along the rear transverse member 30 of the prop section side rail 24. When the pins 46 are in engagement with the holes 49, the side rails 24 are locked from sliding movement with respect to the guide member 14. The pin 46 is provided with a head 48 which engages a cross connector 50 (FIGURE 2) disposed between the pins and slidably disposed over the cross member 40. The cross connector 50 serves to coordinate withdrawal of the pins 46 as will be explained below. A spring 52 is coaxially wound around and connected to the pin 46 and abuts the inner back surface of the cross member 40 to bias the pin into engagement with the holes 49. A spacing washer 54 is concentrically disposed around the pin 46 within the cross connector 50 to provide the necessary spacing between the cross connector 50 and the cross member 40 when the pins are in full engagement.

In the operation of the device as thus far described, when the vertical adjustment of the prop section relative to the step section 12 is required, the cross connector 50 is pulled outwardly to withdraw the pins 46 from the holes 49 thereby permitting sliding movement between the prop section 16 and the guide members 14. The holes 49 are disposed vertically at equal intervals substantially corresponding to the spacing of the steps 44 of the step section 12. When the prop section 16 is rearranged vertically in the desired relationship with the step section 12, the holes 49 corresponding to the steps are arranged so that they are coaxially aligned with the pins 46. The cross connector 50 is then released allowing the pins to engage the holes under the influence of the bias from springs 52.

Referring now particularly to FIGURE 3, rearrangement of the prop section 16 with respect to the step section 12 is accomplished by telescoping the support portion 22 of the article support 18 into the spreader portion 20. The spreader portion is then pivoted upwardly into the position shown in broken lines and remains in this disposition until the desired relationship is adjusted between the prop and step sections. Once this relationship is adjusted, the prop section 20 is then pivoted downwardly and engages a rung 56 on the prop section 16 and is thereby re-established as the spreader for the ladder in the new configuration. The support portion 22 may then be extended outwardly into the position shown in FIG- URE 3. The spreader portion 20 is provided with a hook-like member 58 depending therefrom, which member is further provided with laterally and inwardly extending shoulders 60 conforming generally to the lower surface of the rung 56. Once the spreader portion 20 is in place, angular movement of the prop section either toward the step section or away from the step section brings the rung 56 into engagement with either the side faces of the hook portion 58 and into alignment with one of the shoulders 60 so that angular motion of the prop section 20 is thereby blocked. This feature provides an additional safety to prevent accidental dislodging of the prop section when the ladder is in use.

Referring to FIGURE 6 of the drawings, an overall end view of the ladder is illustrated. The vertical disposition of the holes 49 is more clearly shown in this view and it should be noted that, they are equally spaced with relation to the rungs 56 but displaced therefrom for purposes to be described later. The spreader bars 20 are provided with spreader bar rails 62 which slidably engage the support portion 22 of the article support 18 to provide for telescoping action therebetween. Angular braces 64 are disposed at suitable intervals between the rungs 56 and the side rails 24 to provide added rigidity for the ladder structure as neeed.

In FIGURE 7, an enlarged sectional view of both the step section 12 and the prop section 16 shows in detail another of the features of this invention. A prop section retaining hook 66 is disposed on the side rails of the step section 12 vertically adjacent a gap 68 (FIGURE 1) in the track 32. The purpose of this structure and arrangement will be described in greater detail below.

Referring to FIGURE 8, the ladder is shown in a configurational variation adapted for use in a stair well. As was described above in the operation of and referring momentarily to the device of FIGURE 3, the pins 46 are disengaged from the holes 49 in the prop side rails 24 and the prop section 16 is vertically moved with respect to the step section 12 a desired amount. If, for example, the ladder is to be used with the prop section 16 disposed on a first step 76 and the step section 12 on a landing 72 of a stair well, as shown in FIGURE 8, the prop section is moved with respect to the step section to the next subjacent set of holes 49. These holes are disposed at least in equally spaced relationship and are vertically offset a suitable distance from the rungs so that when the prop section is engaged by the pins 49, the ladder structure may be disposed in a substantially level configuration on the steps. f the ladder is to span two steps then the prop section is moved to the second subjacent set of holes 49 and so forth.

Referring now to FIGURES 9a and 9b of the drawings, the ladder is shown in a configurational variation adapted for use as an extension ladder against a wall 74 (FIG- URE 9b). In FIGURE 9a, the article support 18 has been rotated upwardly in line with the step section 12 and the prop section has been angularly swung into abutment with the step section so that the hooks 66 are disposed through the gap 68 in the tracks. By withdrawing the pins 49 as was described in the operation of the structure as shown in FIGURE 3, and by slidably displacing the prop section I6 with respect to the step section 12 while keeping the sections in abutting relationship, the hooks slidably engage the track 32 as is shown in FIGURE 10. When the ladder is extended to the desired length, a set of holes 49 are aligned with the pins 46 and the pins are released to engage the holes under the influence of the bias from the springs 52. The ladder is then in the extended configuration shown in FIGURE 9b where angular displacement between the step section 12 and the prop section 16 is prevented by the coaction of the guide members 14 holding the prop section at one point and the hooks 66 riding in the tracks 32, holding the prop section at spaced subjacent points. To give greater choice as to the extendable lengths available, the holes 49 could be spaced at more frequent intervals than specifically described above.

It is intended that the ladder be fabricated from extruded lengths of lightweight material such, for example, as aluminum or magnesium or the like. The extruded form of metal is preferred since intricate cross sectional configurations such as exemplified by the side rails 24 and members 38 can be inexpensively provided with the resulting benefits realized thereby. Fabrication of the components of the ladder can be accomplished in any suitable manner such as riveting (as shown), bolting or welding. Riveted joints offer certain additional benefits over the other forms of connection in that interference blocks such as shown between rivets 76 and '78 (FIG- URES 3 and 6) on the spacer portion 20 and the support portion 22 of the article support 18 respectively may be furnished to provide a positive stop for movement between the portions.

Obviously many variations of structural features and arrangements can be achieved in light of the above disclosure. It should therefore be understood that what has been set forth is intended to be exemplary to enable those skilled in the art to understand the workings and practice of the invention and that, Within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is new and desired to be protected by Letters Patent of the United States is:

1. A combination step, stair well and extension ladder including a front step section comprising vertically extending side rails joined together by a plurality of vertically spaced rungs, guide means pivotally mounted to said step section proximate the end thereof, a prop section comprising side rails connected together by a plurality of vertically spaced rungs, said guide means slidably engaging said prop section to provide pivotal connection between said sections, a first means mounted on said guide means to selectively engage said prop section at points along the length thereof to block sliding movement thereof, said first means comprising a pin reciprocably mounted in said guide member proximate each of the side rails of said prop section, the side rails of said prop section having a plurality of horizontally corresponding sets of holes disposed therein, each of said sets of holes being disposed when the set is vertically aligned with said pins to receive said pins therein and block sliding movement of said prop section with respect to said guide member, means to bias said pins into said holes, and a cross connecting member between said pins to provide simultaneous movement thereof, a second means pivotally mounted on said step section, said second means being adapted to engage a horizontally adjacent rung on said prop section to rigidly connect said sections when said sections are angularly disposed with respect to one another to restrain further angular movement therebetween, and a third means mounted on said step section to slidably engage the side rails of said prop section when said sections are in parallel relationship to one another to provide for parallel movement between said sections while blocking angular movement therebetween.

2. A combination step, stair well and extension ladder including a front step section comprising vertically extending side rails joined together by a plurality of verticailly spaced rungs, guide means pivotally mounted to said step section proximate the end thereof, a prop section comprising side rails connected together by a plurality of vertically spaced rungs, said guide means slidably engaging said prop sect-ion to provide pivotal connection between said sections, a first means mounted on said guide means to selectively engage said prop section at points along the length thereof to block sliding movement thereof, a second means pivotally mounted on said step section, said second means being adapted to engage a horizontally adjacent rung on said prop section to rigidly connect said sections when said sections are angularly disposed with respect to one another to rest-rain further angular movement therebetween, said second means comprising a combined article support and spacer, said support comprising a first portion pivotally mounted on said step section intermediate the ends there-of, a second portion slidably mounted in said first portion for telescoping movement therewith, means associated with said first portion to engage said rung of said prop section when said prop section is disposed in a predetermined angular relationship to said front section to fix angular relationship between said sections, said second portion extending transversely from said prop section to provide an article supporting surface for said ladder when telescoped from said first portion and with said first portion engaging said rung. said support being pivotal between the rungs of said step section when said second portion is telescoped into said first portion, and a third means mounted on said step section to slidably engage the side rails of said prop section when said sections are in parallel relationship to one another to provide for parallel movement between said sections while iblocking angular movement therebetween.

3. A ladder in accordance with claim 2 wherein said first portion is formed with integral hooks depending therefrom, said integral hooks being formed with a for- Ward and rearward rung engaging surfaces thereto, said surfaces being spaced from one another a distance in excess of the transverse width of the rungs of said prop section, a projection extending transversely from each of said surfaces, said projection being disposed to engage the lower surface of said rung when the surface from which it extends is engaging said rungs to prevent accidental disengagement of said first section from the rung of said prop section.

4. A combination step, stair well and extension ladder including a front step section comprising a first pair of vertically extending side rails, a plurality of rungs connecting said first side rails in spaced parallel relationship, a rearwardly extending hook mounted on each of said side rails;

a prop section comprising a second pair of vertically extending side rails, a plurality of rungs connecting said second side rails in spaced parallel relationship, a guide rail disposed along each of said first side rails, said hook being adapted to engage said guide rail when said sections are in parallel abutting relationship, each of said second side rails having a plurality of vertically spaced holes disposed therealong;

a guide member pivotally mounted proximate the upper end of said step section, said guide member slidably engaging said prop section to provide hinged connection between said sections, pins reciprocably mounted in said guide section adjacent each of said second side rails, said pins being biased to engage a hole of said holes when said hole is axially aligned therewith to selectively vblock sliding movement between said prop section and said guide member, a connecting cross member between said pins to provide for simultaneous movement therebetween;

a combination article holding rack and section spacer comprising a first portion pivOtally mounted to and disposed intermediate the ends of said step section, said first portion adapted to engage a rung on said prop section when said sections are at an acute angle with respect to one another to maintain a predetermined angular relationship therebetween, a second portion slidab ly mounted on said first portion and movable in a coplanar relationship from a retracted to an extended condition with respect thereto, said second portion when disposed in said extended condition being adapted to extend transversely from said prop section to provide an article support when said first portion is in engagement with a rung on said prop section.

References Cited by the Examiner UNITED STATES PATENTS 672,945 4/1901 Kloepfer 18225 757,616 4/1904 Herder 182-424 X 851,696 4/1907 Schaefer 182-26 2,926,746 3/1960 St-M-ars 18226 3,068,957 12/1962 Best 182--26 FOREIGN PATENTS 24,202 5/1906 Austria.

HARRISON R. MOSELEY, Primary Examiner.

R'EINALDO P. MACI-LADO, Examiners.

Claims

1. A COMBINATION STEP, STAIR WELL AND EXTENSION LADDER INCLUDING A FRONT STEP SECTION COMPRISING VERTICALLY EXTENDING SIDE RAILS JOINED TOGETHER BY A PLURALITY OF VERTICALLY SPACED RUNGS, GUIDE MEANS PIVOTALLY MOUNTED TO SAID STEP SECTION PROXIMATE THE END THEREOF, A PROP SECTION COMPRISING SIDE RAILS CONNECTED TOGETHER BY A PLURALITY OF VERTICALLY SPACED RUNGS, SAID GUIDE MEANS SLIDABLY ENGAGING SAID PROP SECTION TO PROVIDE PIVOTAL CONNECTION BETWEEN SAID SECTIONS, A FIRST MEANS MOUNTED ON SAID GUIDE MEANS TO SELECTIVELY ENGAGE SAID PROP SECTION AT POINTS ALONG THE LENGTH THEREOF TO BLOCK SLIDING MOVEMENT THEREOF, SAID FIRST MEANS COMPRISING A PIN RECIPROCABLY MOUNTED IN SAID GUIDE MEMBER PROXIMATE EACH OF THE SIDE RAILS OF SAID PROP SECTION, THE SIDE RAILS OF SAID PROP SECTION HAVING A PLURALITY OF HORIZONTALLY CORRESPONDING SETS OF HOLES DISPOSED THEREIN, EACH OF SAID SETS OF HOLES BEING DISPOSED WHEN THE SET IS VERTICALLY ALIGNED WITH SAID PINS TO RECEIVE SAID PINS THEREIN AND BLOCK SLIDING MOVEMENT OF SAID PROP SECTION WITH RESPECT TO SAID GUIDE MEMBER, MEANS TO BIAS SAID PINS INTO SAID HOLES, AND A CROSS CONNECTING MEMBER BETWEEN SAID PINS TO PROVIDE SIMULTANEOUS MOVEMENT THEREOF, A SECOND MEANS PIVOTALLY MOUNTED ON SAID STEP SECTION, SAID SECOND MEANS BEING ADAPTED TO ENGAGE A HORIZONTALLY ADJACENT RUNG ON SAID PROP SECTION TO RIGIDLY CONNECT SAID SECTIONS WHEN SAID SECTIONS ARE ANGULARLY DISPOSED WITH RESPECT TO ONE ANOTHER THE RESTRAIN FURTHER ANGULAR MOVEMENT THEREBETWEEN, AND A THIRD MEANS MOUNTED ON SAID STEP SECTION TO SLIDABLY ENGAGE THE SIDE RAILS OF SAID PROP SECTION WHEN SAID SECTIONS ARE IN PARALLEL RELATIONSHIP TO ONE ANOTHER TO PROVIDE FOR PARALLEL MOVEMENT BETWEEN SAID SECTIONS WHILE BLOCKING ANGULAR MOVEMENT THEREBETWEEN.