US2942686A - Convertible ladders - Google Patents

Description

June 28, 1960 c. A. osovsxl E'II'AL 2,942,686

CONVERTIBLE LADDERS Filed May 26. 1958 3 Sheets-Sheet 1 INVENTORS uni-ad .fimurkz' and (44/171 07! EJ720082" June 28, 1960 c. A. OSOVSKI EI'AL 2,942,686

CONVERTIBLE LADDERS Filed May 26, 1958 3 Sheets-Sheet 2 HHHH HHHHI'WTHII'YIIIIIIH t WW their-ATTORNEY June 1960 c. A. OSOVSKI ETAL 2,942,686

CONVERTIBLE LADDERS 3 Sheets-Sheet 3 Filed May 26, 1958 v hr m y m w Aw d pv m J mk J 5 M a E Q P a o 2 United States Patent a CONVERTIBLE LADDERS Conrad A. Osovski and Raymond H. Shaver, Newark Valley, N.Y., assignors to Chesebro Whitman Manufacturing Corporation, Newark Valley, N.Y., a corporation of New York Filed May 26, 1958, Ser. No. 737,629

8 Claims. (Cl. 182-26) The present invention relates to ladders in general, and more particularly to a multi-purpose device which may be utilized as a step ladder either on horizontal or uneven ground, and may be converted into an extension ladder.

An important object of the invention is to provide a ladder which is of simple construction, easy to manipulate, and safe in operation either as an extension or as a step ladder.

Another object of the invention is to provide a device of the above character which may be assembled by utilizing component parts of known construction.

An additional object of the invention is to provide a multi-purpose ladder of the above described character which, in addition to being capable of use as an extension or step ladder, may be further adjusted for use as a step ladder on uneven or stepped ground.

A further object of the instant invention is to provide a ladder of the above described character which consists of a relatively small number of component parts, and which may be collapsed into a relatively small and compact package for transport and storage.

A concomitant object of the invention is to provide a multi-purpose ladder one part of which is longitudinally adjustable when used as a step ladder, and which is of adjustable overall length when used as an extension ladder.

The above and other objects of the invention are attained by the provision of a ladder comprising two relatively movable parts so connected with each other that one thereof is slidable with respect to the other in upward and downward directions; of means for locking the two parts in a selected position when they are inclined with respect to each other; and means for locking the parts to each other when the par-ts are in substantially parallel planes but displaced with respect to each other.

Other features, advantages and attributes of the novel ladder will become apparent and will be pointed out in greater detail in the course of the following detailed description of certain embodiments selected for illustration in the accompanying drawings, in which:

Fig. 1 is side elevational view of the improved ladder, showing in full lines relative positions of the stationary front part and of the movable back support on a horizontal floor, and in phantom lines the position of back support when the ladder is used on stairs;

Fig. 2 is rear elevational view of the structure as seen from the right-hand side of Fig. 1;

Fig. 3 is an enlarged detail view of the locking device against downward movements of the back support as seen from line 3-3 of Fig. 1;

Fig. 4 is an enlarged section taken on line 44 of Fig. 2, as seen in the direction of arrows, showing one of the locking means in retaining position to prevent upward displacement of the back support;

Fig. 5 illustrates in section the upper end of stationary front part with the spring lock of Fig. 4 in the position it Patented June 28, 1960 assumes when acted upon by a rung of the upwardly advancing movable part or back support;

Fig. 6 illustrates the novel article in side elevation when used as an extension ladder;

Fig. 7 is an enlarged front elevational view of the converted extension ladder shown in Fig. 6;

Fig. 8 is an enlarged detail view of a portion of the back support, and of the upper end of front part, as seen from line 88 of Fig. 7 in the direction of arrows;

Fig. 9 is an enlarged detail view of a spring lock with certain parts broken away; and

Fig. 10 is perspective view of a modified locking and retaining means against downward displacements of the movable part which can replace the bails of the type shown in Fig. 3.

Referring now in greater detail to the drawings, and first to Figs. 1 and 2, the improved convertible ladder 20 therein shown comprises a stationary front part or ladder 21 and a movable part or back support 22. The front part comprises a pair of rails 23, 24 which are connected by means of steps 25 so mounted as to have their major surfaces in substantially horizontal planes when the ladder 20 is in the position of Fig. l. A certain amount of hardware, such as tie rods 26, nails 27 driven into each end face of steps 25, and Washers 28, as well as stops or blocks 29 inserted between each tie rod and the underside of the adjacent step, is shown in these figures but has been omitted in other illustrations because the construction of front part 21 or back support 22 by itself is well known and forms no part of the present invention. It will also be noted that the lower end faces of front rails 23, 24, as well as the lower end faces of rear rails 30, 31, are provided with customary antiskid attachments, preferably rubber feet 32, 33, respectively.

The back support, in addition to rails 30, 31, comprises a number of preferably uniformly spaced connecting rungs 34. The step ladder shown in Figs. 1 and 2 is one of medium height having five steps 25 and six rungs 34, but it will be readily understood as this description proceeds that the length of parts 21, 22, i.e. the actual size of the multi-purpose ladder 20, has no bearing on the invention which is equally applicable to relatively short, medium-length, or relatively long step ladders.

Front part 21 carries two releasable locking assemblies 35a, 35b, respectively, whose purpose is to prevent upward movements of back support 22 when the article is used as a step ladder, while the other locking assembly 36a, 36b prevents descent of the back support when the novel device is used as an extension ladder. 'In addition, back support 22 is slidably connected with the front part 21 by means of a guide device 37 which leads the back support during its displacements with respect to the front part and prevents excessive spreading of device 20 when used as a step ladder. A

Each of the first mentioned locking means 35a, 35b comprises a hook-shaped member 38 defining therein a recess 39 for the reception of a rung 34 when the device is used as a step ladder on horizontal, uneven, or stepped ground (see Fig. 1). Members 38 of respective locks 35a, 35b are pivotally connected to front rails 23, 24 and are preferably resiliently urged into the position of Fig. 4 by means of a spring or the like, as will be described in greater detail in connection with Fig. 9.

.Each of locking means 36a, 36b for preventing descent of back support 22 with respect to the front part 21 comprises a hook or bail 40, one of which is shown greatly enlarged in Fig. 3. The bails are pivotally connected to the inner surfaces of front rails 23, 24, respectively, at a suitable distance from guide means 37, each bail defining an upwardly facing cavity or recess 40a when in the position of Figs. 1 to 4 and 6 to 8. These bails become active when the'novel device 20 is used as an extension ladder as shown in Figs. 6 to 8. During lifting of back: support 22 with respect to the front part 21 in the directien of arrow X, bails 40' are pivoted into the position of Fig. 5. The bails are integrally formedwith abutment or stop plates 41, thelatt'er having flanges 42 traversed by'rivets 43 which connect the locking means 36a, 36b to "the respective front rails 25, 24; The position 'of rivets '43 is so selected that the undersides of plates 41 bear against the upper face of adjacent step 25 when the 'lock- 3 87 2 6 3 ,713,617 are in the position of Figs. 1 .to 4 and 6 to 8. This can-be observed in Fig. 4.

Gu de ,mi=?-ns;37 comprises aEU-shap'ed metallicmemi ber of fiat stock having a base 44 and two legs 45, 46 with il s a er r gid yic n e te 'a o pec 2 2 y.

me ns of r ets 47 adja ent to the upp end o f 21. It will-be-notedin-Figs54 and '5 that the base adjacentiend faces of rear rails 30, 31 when the novel device used a step ladder, that is, :whenthc hack V QVPPQ 1 n l n i i hr pwt t f om p 2.

The' ladder is further provided'with customary .col:

lapsibie side arms or spreaders 48, '49 which, however,

cannot be rigidly connected with the back-support 22 since the latter should not be permanently fixed to front part Therefore, each spreader has one of its ends 44 is so inclined as to ofier full-surface, support to the V but must be slidable with respect thereto, when neces- .Sa 'Y- pivotally connected to one of front rails-23, 24, its other end being pivotally fixed to one of cuffs 50, 51 which are so shaped as to permit slidingmovements of rear rails 30,

31, respectively. Cuffs 50, 5?. are connected tolegs 45, .46 of the guidemeans 37 by straps 52 53, respectively,

which latter maintain the cuifs at a constant distance horn base44.

When the ladder 20 is in the position shown in full lines iijr Fig. 1, its front part 21 and back support 22 are prevented from movements with respect to eachother (a) hooks 380i respective locking assemblies 35a,

3512 whose recesses 39 receive the uppermost mg 34 or the back support andthus prevent the latters upward displacements with respect to the front part 21;

(b) By Spreaders 48, 49 over cum 5!), 5-1; and

(0) By an faces 23a, 24a of front railszs, 24 which,

together spreaders 48-, 49, prevent angular displacemerits of the back support; Inclined end faces 23a, 24a'bear againstthe longitudinal end faces 30a, 31a of the back supports rails, and the other end faces 30b, 31b

of'the'latterb'ear against the inner faces of cufis'SD, 5-1. 1 5 t esse may he ta n up by he bas T44 of guid 2 1 y When theback support is to be moved into it Phantomiineposition -22 whereby its legs 33 rest upon the stair 354, hooks 38 are pivoted away from the engaged rung 34 to permit upward displacement'sof the back support to the extent sufficient to move its legs into positions 33' inwhich they rest upon the stair 54. Hooks 3 8'theres an engage the second rung 34. During such displacement, rear rails slide, in cuffs 50, 51 and in guide means 37, their surfaces 300:, 3 151 moving along the end faces 461,015 the front rails. V r V When the novel device 29 is to-be used as an extension ladder, bails 40 of locking assemblies 36a, 36b a'refirst moved into the positions corresponding to that ersah shown in Fig. 5, and the spreaders 48, 49 are -colla'psed. Hooks 38 (if-upper locking assemblies 35a,

'35]; ate thereupon disconnected tom the adjacent'rung 34 and the backsupport is free to slide respect to front part 21in the direction of arrow 'When the iadder is extended'to a desired length, bails 40 are re- .to strike against the hooks terminals 38a.

4 bout he meetin dge o sur ce v23: am 24 24b of respective front rails 23, 24. It will be seen that the bails 40 not only perform asupporting but also an antipivoting function; therefore, their recesses 40a must be deep enough to prevent movement of a rung 34 therefrom even ifthe ladder is subjected to considerable pivoting stresses in directions tending to move the lower ends of rear rails 30, 31 away from the front raiis. A modified one-piecelocking and retaining deviceagainst downward displacements of back support 2 2 is illustrated in Fig. 19 and w li de c ed in g e e detail hetciuait As before stated, each locking devicfifi a, :5b n s-FI ferred formcomprises a spring biased hook 3; 8 constantly tending to move into the positionrof Fig. 4 in which its recess 39 receives a 34 .To. that end, shank 55 of the hook 38 is pivotally connected tooue of front rails 23, 24 by means of a bolt 56 (see Fig. 9), the

;bolt" also passing through a mounting plate 57 and a cover platei58 whose side walls 59, 60 are bent intoplanes 20 atright angles to its main plane and arefixed tomouuting plate 57. One leg of leaf spring v 61 bears against the shank 55 of hook 38 while its other leg abutsfig imt the side wall 59 and thus constantly urges hook -38 in thedirection of arrow Y; The spring 61 forms a loop about a rivet 62 which connects the cover plate 58 tomounting plate 57. The latter hasa number of aper- *tures.57a. for the passage of bolts or rivets connecting it to one of the front rails. V

Shank 55 of each hook 38 carries a camplate 63, best shown in Figs. 4 and 5, connected thereto by a pivotpin 64. Cam plate 63 has an arcuate end face 65 and a lip or flange 66 substantially at right angles to "its main body portion. 'The lip 66 is adjacent to the iowerqend 38a of the book 33 and abuts thereagainst when a'r'u'ng 34 strikes against the end face 65 of thecam piate. Thus, as the back support advances in the direction of arrow X (see Fig. 5), its rungs 34 consecutively abut against the end faces 65 of cam plates 63 compelling the latter to pivot about members 64and to thus cause their lips 66 The hooks thereupon pivot about members 56 in the direction'of arrow Z against the force of resilient members :61 to the extent necessary to permit passage of a rung 34 past the cam plates 63. Hooks 38 thus perform a series of oscillating movements, the number of oscillations depending upon the extent of'upward displacement of the back support, i.e. upon the number of rungs 34 consecutively abutting against the cam plates.

To return ladder 20 from the position of Figs. 6 and 7 into that of Figs. 1 and 2, back support 2a is lifted beyond its position of Fig. 7 enabling the bails 46 of locking means 36a, 36b to be pivoted into the position of Fig. '5. The back supportis thereupon free t'o'desc'end and the downwardly advancing rungs '34 ride over {the 'arcuate end faces 38b of hooks 38 causing the latter to swing in the direction of-arrow Z to permit descent of the back support. Cam plates 63 ofier no resistance 63 are pivoted either by hand or by suitable manipulation ofiback support 22 to'c'ause entry of a selected rung 34 into the recesses '39 of hooks 38. Spreaders 48, 49 are then expanded and the art-ieleiz0may a'gain 'be utilized as a step ladder. I

Fig. 10 shows a unitary bai'l type hook 67 whi'ch-ean replace the locking means 36a, 36b. Instead of abutting against the step 25 in the manner of plates .41 forming part of lockingmeans 36a, i36b, the assembly 67 is formed with a pair of prongs 68, 69 which abut against the end-surfaces 23b, 24b ofrespective front rails 23, -24. The portion of-locking and retaining device 67 intermediate rails 23, 24 defines a pair of abutmentsf70, 71 against downward displacements of the movable back support 22, and a portion of inverted U-shape consisting of sections 72, 73 and 74 to prevent pivoting movements of the back support. Portions 75, 76 are pivotally held in brackets 77, 78 fixed to respective front rails 23, 24.

The advantage of locking and retaining device 67 is in that it is made of a single piece and thus requires a single step for pivoting it out of retaining position or back into retaining position. It may be pivoted into idle position by the upwardly advancing rung 34 of back support 22 when the operator desires to convert the device back into a step ladder. The distance between front rails 23, 24 at the point of connection of device 67 being greater than the distance between parallel rails 30, 31 of back support 22, a rung 34 of the latter merely engages the portions 70, 71 to pivot the locking device 67 into idle position. The pivoting movement of abutments 68, 69 is unimpeded.

It will be observed that the back support 22 need not carry any hardware, as all locking, retaining, and guide means are carried by the front part 21. This is desirable because any known type of simple ladder having parallel rails spaced by rungs or other connecting means may be combined with the front part to form a stepor extension ladder therewith. Moreover, while it is preferred to utilize rungs of circular cross-sectional contour, the use of such rungs is not absolutely necessary, since the locking means 35a, 35b and 36a, 36b may be modified in such a way as to accommodate rungs or steps of different configuration.

Members 57, 58, 61, 62 and 63 may be omitted and each hook 38 merely connected to the front rail by its bolt 56. Of course, in such simplified construction, the hooks must be manipulated by hand to be moved into positions out of path of the rungs 34 at least when the latter advance in upward direction.

If the step ladder consists of two identical parts similar to front part 21, the locking and guide means are con- 'nected to one of the parts, the other part being moved with respect thereto in the previously described manner.

Such and many other modifications will readily occur to persons skilled in the art, and are therefore considered to be within the nature of the present invention as defined in the appended claims.

What we claim and desire to protect by Letters Patent is:

1. A convertible ladder comprising, in combination, a first part having a pair of spaced rails each having a first end and a second end; a second part comprising two parallel rails and a plurality of spaced connecting elements therebetween; guide means attached to the first part adjacent to the first ends of said first mentioned rails for so leading the rails of said second part that the latter is free to perform sliding movements in its own plane toward the first and the second ends of said first mentioned rails and limited pivotal movements between a position of parallelism with the first part and inclination with respect to said first part; two collapsible spreaders each pivotably fixed to one rail of said first part; a substantially tubular element connected to each spreader and each slidably receiving one rail of said second part; a pair of straps each connecting one of said tubular elements with said guide means; and locking means fixed to the first part intermediate said guide means and the second ends of said first mentioned rails for releasably engaging a selected connecting element and for holding the second part against sliding movements toward the second ends of said first mentioned rails and against pivotal movements from the position of parallelism with respect to said first part when said spreaders are collapsed.

2. A convertible ladder comprising, in combination, a first part including two rails each having a first end, a second end and an inclined surface adjacent to the first end, and a plurality of steps between said rails; a second part having two parallel rails and a plurality of connecting elements therebetween; guide means consisting of a bracket fixed to the rails of said first part of the proximity of said first ends thereof; a pair of substantially cuffshaped elements each articulately attached to said bracket and each slidably receiving one rail of said second part in such a way that the second part is free to perform sliding movements in its own plane and said bracket permitting pivotal movements of said parts with respect to each other between a first position in which the second part is substantially parallel with the first part and a second position in which the rails of the second part abut against the inclined surfaces of the first mentioned rails; first locking means comprising at least one hook-shaped member pivotally fixed to the first part adjacent to the first ends of the first mentioned rails for releasably engaging a connecting element against sliding movements of the second part in a direction toward and past the inclined surfaces of said first mentioned rails; and second locking means comprising at least one hook-shaped member connected to the first part intermediate said bracket and the second ends of said first mentioned rails for releasably holding a selected connecting element against sliding movements of the second part in a direction toward the second ends of said first mentioned rails and against pivoting movements from a position in which the second part is substantially parallel with the first part, whereby the ladder may be utilized as a step ladder when a connecting element is engaged by said first mentioned locking means and the second part is inclined with respect to the first part, and as an extension ladder when the second part is displaced with respect to the first part in a plane parallel thereto and said second locking means engages the adjacent connecting element.

3. A multi-purpose ladder comprising, in combination, a front part including a pair of rails each having a first end and a second end, and a plurality of steps for interconnecting said rails; a back support having two parallel rails and a plurality of rungs for so spacing said rails that their distance corresponds to the distance between the first ends of the first mentioned fails; a substantially U- shaped bracket having a pair of legs each fixed to one of the first mentioned rails in the proximity of said first ends thereof, and a base spaced from the front part and embracing the back support; a pair of extendable and collapsible spreading members each having a first end pivotally fixed to one of said first mentioned rails at a point spaced from the legs of said bracket intermediate said bracket and the second ends of said first mentioned rails, and a second end; a pair of substantially cuff-shaped elements each connected to the second end of one of said spreading members each articulately connected to and spaced from said bracket, and each slidably receiving one rail of said back support whereby the latter is freeto perform sliding movements in its own plane and pivotal movements with respect to the front part between a first posltion in which the spreading members are expanded, and a second position in which the spreading members are collapsed and the back support is parallel with and adjacent to the front part; first locking means comprising a pair of hook-shaped members each pivotally connected to one of said first mentioned rails adjacent to the first ends thereof for releasably engaging a selected rung and for holding the back support against sliding movements in its own plane in a direction toward and past the first ends of said first mentioned rails; and second locking means comprising at least one hook-shaped member fixed to at least one of said first mentioned rails intermediate said second end thereof and said bracket for releasably engaging a selected rung when said spreading members are collapsed and said back support is adjacent and parallel to the front part in such a way that the back support is held against sliding movements in its own plane in a direction toward the second ends of the first mentioned rails, and against pivoting movements with respect to the front part.

A convertible ladder comprising, in combination,

7 'afirst part including two rails each having a first end, a

asecond end and an inclined surface adjacent ame first end, anda plurality of steps for soconnectin g ther i rails of'said front part" and embracing the back support; -two expandable and collapsible spreaders each "having a first end' pivotally connected .to one rail of said front P t a d "a s co e a Substantially bu rel m n cte t9 h s con d 9 eac sp e d r an a slidably' receivingone rail of the back support, each tubular element ibeing s'peacd ufrorn and pivptally connected to said bracket whereby the "back support is tree to perform pivotal movement s between a first position in which its railsabut against the inclined surfaces of said first mentioned railswhen'said spreaders are ex panded, n a e o d p i n i w he b k supp r is adjacent to and parallel with the frontpart when said spreaders are collapsed; "a pair of spring biased hookshaped' locking members each fixed to one of said first mentioned rails adjacent tothe latters first end, said locking members being permanently urged into a position in i which they engage a selected rung to prevent sliding 'rails of said first part, and a second positionin which the second part is inclined with respect to the first part; first locking means connected to'the first part adjacent to the ends of said first mentioned rails and goniprisjng'at least one hook-shaped member pivotally f xed to shame part in the path of the connecting: elements when thesecond 7 part is inclined with respect to the first partand its rails pointdistantifrom the first locking means for engaging a selected connecting element and for holding th e second part against movements in a direction opposed rto said first mentioned direction. when the spreading means is in said first position, and for maintaining the spreader means in said first position; whereby the ladder may be utilized as an extension ladder."

6. The combination according to claim 5 wherein said second locking means comprises a pair of hook-shaped members each pivotally fixed to DB6 ofrsaid first mentioned trails-and eaoh'pomprising a portion so' mounted movements'of the rails of said back support in a direction toward the inclined surfaces of said first mentioned rails, and being. movable into "a second position away from the rungs when the back support slides with respect to said front part; and at least one hook-shaped locking member pivotally fixed to the -fiont part intermediate the second ends of its railsfand saidbracket for releasably engaging a selected rung when the spreaders are collapsed and the back support is adjacent to and parallel with the front part in such a way that the back support is held against sliding movements toward the second ends of said first 'mentioned rails and against pivotal movements with respect to said front part. 7 V

' 5. A convertible ladder. comprising, in combination, a first part havinga pair of rails each having an end, and spaced steps therebetween; a second part having a pair of parallel rails and a plurality of connecting elements therebetween; guidermeans connected with the front part adjacent to the ends of saidfirst mentionedtrails; Vapair of substantially tubular elements each slidably' receiving one rail of the second partrformovements of the latter in its own plane and each connectedto said guide means; a pair of spreading means each connected with one rail of the first part and with one of said tubular elements, each of said spreading means having a first position in which the rails of said second part are adjacent to' the as to abut against the adjacent step of said first part when the members are in'one extreme position for engaging a connecting element.

7. The combination "according to claim 5, whereintsaid second locking means comprises a single hook-shaped member extending substantially between and pivotaliy fixed to said first mentioned rails tor rotation about an a p r l l t Said steps s d'men bs ha n a le s one portion abutting againstione of said first mentioned rails n he is n h rpa i ihn fhrehsas ns a selected connecting element. a i 8. The combination according to claim 5, wherein each of said first mentioned rails has a s lrface at said end thereof of such inclination'as to be in contact with the rails of said second part when the spreading me n .is in said second position. 7

7 References Cited in the file of this patent UNITED STATES PATENTS I Bair a ,Apr. 13,1954

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