US 3130814 A
Description (OCR text may contain errors)
April 28, 1964 F. DEL AQUILA COLLAPSIBLE SAFETY STEP LADDERS Filed June 5, 1959 2 Sheets-Sheet 1 April 28, 1954 F. DEL AQUILA 3,130,814
COLLAPSIBLE SAFETY STEP LADDERS Filed June 5, 1959 2 Sheets-Sheet 2 rNvENToR h/'s ATTORNEY filtres Unite The present invention relates to ladders in general, and more particularly to a mobile safety step ladder.
Safety step ladders of presently known construction -consists of uprights, steps, handrails and eventually of a platform, all such parts being welded together to form an integral, and rather bulky structure. Consequently, the shipping of such ladders and their handling during transport confronts the manufacturer and the shipper with a series of problems. Thus, the fully assembled ladders require rather bulky crates and occupy comparatively large space on transportation vehicles; in addition, they cannot be handled by a single Workman during transfer from or into storage, as well as from and onto a conveyance.
An important objectof the present invention is to provide a collapsible safety step ladder.
Another object of the invention is to provide a collapsible safety step ladder which may be taken apart and its component parts stored in a flat receptacle or crate for storage and transport, and which may be assembled by the user on the do-it-yourself basis.
A further object of the invention is to provide a collapsible safety step ladder which consists of a small number of component parts and which is of very simple construction so as to present no problem to a person with little or no technical skill during assembly into condition for actual use.
Still another object of the instant invention is to provide a collapsible safety step ladder of the above outlined characteristics in which the means for supporting the legs, the wheels, the connecting braces, the handrails and the steps are combined into only very few sturdy units of simple construction and of flat shape so as to occupy very little space when separated from the parts which they normally support.
T he above and many other objects of the invention are attained by the provision of a safety step ladder which consists essentially of two lateral main supporting units, a plurality of horizontal steps removably connectable to or supportable on and normally extending between the two main supporting units, and a plurality of horizontal braces removably connectable to both units to reinforce the structure sufficiently for permitting one or more persons to stand on the steps. Each main supporting unit preferably comprises a suitable structural element which Serves as a handrail when the ladder is assembled, a substantially vertical support or upright, one or more connecting braces extending between the handrail and the upright, and suitable members, made preferably of tubular stock, which support at least one step in horizontal position. The steps may be connected to the main supporting units by means of bolts and/or studs, or their ends may be removably held in suitable channelor otherwise shaped receptacles which are carried by the main supporting units.
The invention will be described with greater detail with reference to the accompanying drawings, in which FIG. l shows in side elevational view one embodiment of my collapsible safety step ladder in fully assembled condition;
FIG. 2 is front elevational View of the ladder;
FIG. 3 is top plan view of the ladder;
FIG. 4 is side elevational View of a main supporting unit;
3,130,814 Patented Apr. 28, 1964 FIG. 5 is front elevational View of the uppermost step with a portion of its longitudinal end wall broken away; FIG. 6 is an end view of the step shown in FIG. 5;
FIG. 7 is an end view of a lower step;
FIG. 8 is side elevational View of a slightly modified live-step ladder in which the steps are releasably connected with the main supporting units by means of pins or studs, and which comprises an additional reinforcing brace adjacent to the lowermost step;
FIG. 9 is front elevational view of the ladder as seen from the left-hand side of FIG. 8;
FIG. 10 is enlarged front elevational view of a step forming part of the ladder shown in FIGS. 8 and 9;
FIG. llshows a rectangular receptacle secured to one of the main supporting units for receiving one end of a step, such arrangement constituting a further modification of my invention;
FIG. 12 is a side elevational view of the structure shown in FIG. 11, further showing a portion of a step whose end is inserted into the receptacle; and
FIG. 13 shows an additional modification of the invention in a View similar to that of FIG. l1, according to which the upper end of the receptacle is open to permit insertion of a step from above.
Referring now in greater detail to the illustrated embodiments, and first to that shown in FIGS. 1 to 7, a fully assembled safetyl step ladder 20 is shown in FIGS. 1 to 3. It comprises two main supportingunits 2l, 22, the latter of which is shown'in FIG. 4; three steps 23, 24, 25; two horizontal connecting braces 26, V27; and four yieldably mounted wheels 28, 29 and 30, 31 which are carried in pairs by units 21, 22, respectively. Each of braces 26, 2'7 is formed at its ends with two externally threaded studs 32 which extend through bores 33 formed in the uprights 34 forming part of main supporting units 21, 22, and are releasably secured to the uprights by nuts 35.
Each of steps 23, 24, 2S comprises a pair of transverse or shorter end walls 35 formed with two tapped bores 37 whose threads mesh with the threads on the bolts 38 when the ladder Ztl is fully assembled, as is shown in FIGS. 1 to 3. Bolts 38 pass through bores or apertures 39 formed in the inclined tubular members 4t), 41, in handrails 42, and in upper horizontal braces 43. Members 40-43 and the aforementioned uprights 34 constitute component parts of main supporting units 21, 22. The lower ends of handrail 42 and of upright 34fin each main supporting unit are rigidly connected by a lower horizontal brace 44 which also carries a pair of brackets 45 on which the wheels 28, 29 (unit 21) or 30, 31 (unit 22) are mounted. Each handrail 42 and each upright 34 carries at its lower end a leg 46; these legs are normally lifted above the ground when the ladder 20vis not under load but come into tirm contact with the ground as soon as a person stands on one of the steps 23-25 or when a package or other weight is placed onto one or more steps.
'The construction and mounting of wheels 28-31 on brackets 45 is well known in the art. The bearing plates 47 of each wheel are connected to a vertical shaft 48 which extends into and through a tube 49 carried by the respective bracket or plate 4S and is constantly biased in downward direction by a coil'spring 50 Whose strength is suicient to lift the ladder when the latter is not under load, but will yield to permit contact of legs 46 with the ground as soon as a load is placed onto one or more steps. Thus, when the ladder is not in use, it rests on wheels 23-31 and may be readily moved from one to another location but will remain stationary as soon as a person chooses to stand on one of its steps 23-25.
As is best shown in FIGS. 6 and 7, the width of the uppermost step 23 is greater than that of lower steps 24, 25; thus, the upper step constitutes a small platform which armata may accommodate a person and a number of packages, boxes etc. which are handled by the persons standing thereon. In addition to aforementioned transverse end walls 36, each step comprises a top plate l, two longitudinal end walls 52, and one or two reinforcing ribs or webs 53 which extend between transverse end walls 36 beneath the top plate 51. The upper surfaces of plates 5l are preferably roughened (see FIG. 3) to reduce the likelihood of slippage.
When the ladder is in disassembled condition, it comprises a comparatively small number of separated components, i.e. two main supporting units 21, 22, the latter of which is shown stripped of all its parts in FIG. 4; three steps 23-25; two braces 26, 27; four nuts 35 for the studs 32 of braces 26, 27; and twelve bolts 3S for securing the end walls 36 of steps 23-25 to tubular members 40, 41, to horizontals 43, and to handrails 42 of the main supporting units. If desired, the wheels 2S, 29, 31B and 3i and even the springs 50, too, may be removed from their respective tubes 49 by unscrewing the nuts 54 at the externally threaded upper ends of shafts 4S.
In assembling the ladder 20, the studs 32 of braces 26 27 are inserted into corresponding apertures 33 in the uprights 34 of main supporting units 21, 22, and are secured to the uprights by nuts 35. The step 23 is then connected with the upper horizontals 43 by inserting four bolts 38 into the tapped bores 37 in its transverse end walls 36. The median step is secured by four bolts 3S to the inclined tubular members 40, 41 of both main supporting units, and the lowermost step is finally secured by four bolts 38 to the members 41 and handrails 42. In a nal step, the wheels 28-31 are mounted on brackets 45 by inserting the springs 50 into respective tubes 49, by passing the shafts 48 through the tubes, and by securing the upper end of each shaft 48 with the help of a nut 54.
In disassembled or collapsed condition of ladder 20, its major components, i.e. two main supports 2l, 22, the removable braces 26, 27, and the steps 23-25, may be stored in a comparatively small and flat package, eg. a box or crate, which is convenient for storage and shipment, and which may be readily handled by a single workman.
The modified ladder 20a, shown in FIGS. 8 and 9, comprises two main supporting units 21a, 22a normally supported on wheels 18a-31a as the ladder 2t), tive steps 55-59, two removable horizontal braces 26a, 27a between the uprights 34a of both main supporting units, and a removable horizontal brace 60 extending between the handrails 42a.
The uppermost step 55 is shown in front elevation in FIG. l0. Each of its transverse end walls 61 supports a pair of studs 62 receivable in holes 63 formed in the upper horizontals 43a of main supporting units 21a, 22a. The lower steps 56, 57 and 58 are formed with similar studs 62 which extend into holes 63 of inclined tubular members or step supporting means 46a, 41a. Studs 62 of the lowermost step 59 are received in the lowermost holes 63 formed in members 41a and in holes 63 formed in handrails 42a.
The ends of horizontal braces 26a, 27a and 60 are connected to and preferably integral with threaded studs or pins 32a which mesh with nuts 35a, the latter thus maintaining the parts of modied ladder 20a in assembled condition. While the device 20a requires an additional horizontal reinforcing brace 60 and two additional nuts 35a, its advantage over the ladder 20 is in that the bolts 38 may be replaced by simple studs 62 and that no tapped bores must be drilled into t he transverse end walls of the steps. In addition, the studs 62 are integrally connected, e.g. welded, to the steps and the danger that they may become lost during storage or shipment is fully eliminated. Thus, despite the fact that the ladder Ziiacomprises iive steps 55-59, the number of its components, when taken apart, is less than that of that ladder 20, the latter having 23 separable components if one considers the wheels 2.8-31
to form part of main supporting units 2l, 22, and the ladder 26a having only 17 components by again considering that the wheels 28a-31a and their supports from part of units 21a, 22a.
The manner in which the ladder 2da is either assembled or taken apart is self-evident. The tfully assembled structure of FIGS. 8 and 9 may be collapsed upon removal of six nuts 35a olf the respective studs 32a, there being no positive connection between the studs 62 and parts 40a, fila, 42a and 43a.
The modified assembly of FIGS. 11 and l2 comprises a rectangular receptacle 65 which is welded to inclined tubular members 4%, Lilb of the main supporting unit 2lb. The transverse end wall 67 of a step 66 is receivable in the receptacle 65 when the ladder utilizing two such main supporting units is assembled. It will be readily understood that the use of receptacles 65 in a safety step ladder constitutes a reinforcement of the entire assembly since the ends of steps 66 are fully received therein. 'The four walls 65a-65d of each receptacle 65 fully surround the end of respective step 66. In fact, the end 65e is used solely to increase the area of contact with inclined tubes 46h, #lib since the latter could prevent longitudinal movements of a step even if the receptacles 65 were formed without bottoms. Each supporting unit carries as many receptacles as there are steps in the ladder.
The structure shown in FIG. 13 constitutes a further modication and simplification of the assembly shown in FIGS. ll and 12. The modiiied receptacle 65 has an end plate 65e' welded to tubes lltc, tlc of a partially shown main supporting unit 21e, and further comprises three walls 65a', 65b and, 65C', the top wall corresponding to wall 65d of the assembly shown in FIGS. 11 and l2 having been omitted in order to permit insertion or removal of a step while the remaining parts of the ladder are fully assembled. The walls or flanges 65a', 65h and 65e and the plate 65e safely retain the step against all movements excepting in upward direction; however, there is little likelihood that a step would be moved upwardly when the ladder is fully assembled. An important advantage of the construction shown in FIG. 13 is in that the steps may be inserted, removed or interchanged while the remaining parts of the safety step ladder are fully assembled, i.e. the removal of steps does not necessitate that any other components of the ladder be disconnected from each other.
It will be understood that the ladders in which the steps are mounted as shown in FIGS. 11-12 and in FIG. 13 utilize a horizontal brace corresponding to the part 60 shown in FIGS. 8 and 9 in order to connect the handrails of both main supporting units at a point below the lowermost step. Also, the number of steps in the ladder may be chosen at will and, if desired, a second reinforcing brace may be provided between the handrails at a point below the lowermost step, as well as between the uprights intermediate the braces which connect their upper and lower ends, respectively.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapted it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
What I claim and desire to protect by Letters Patent is:
l. A collapsible safety step ladder comprising, in combination, two spaced main supporting units each disposed in a substantially vertical plane, a plurality of horizontal steps disposed at spaced levels between, and having ends releasably supported by, said units; and at least two horizontal reinforcing braces disposed between, and having ends releasably clamping, said units together, each of said units, steps and braces being substantially flat or straight, whereby they can lie one on another in a compact package when dis-assembled, but are readily assembled and secured into a rigid laterally extended structure, each main supporting unit comprising an upright, a handrail, an upper and a lower substantially horizontal brace member between the upright and the handrail, and a pair of inclined tubular members one connected to the upper brace member and the lower brace member, and the other connected to the upper brace member and the handrail, respectively; the uppermost step being releasably supported by said upper brace members, the lowermost step being releasably supported by said handrails and one each of said tubular members, and at least one step between the uppermost and lowermost steps being releasably supported by both said tubular members; and further comprising a plurality of substantially rectangular horizontal receptacles one connected to the upper brace member of each main supporting unit, one connected to one tubular member and to the handrail of each unit, and at least one connected to the tubular member of each unit, each receptacle receiving and releasably holding one end of a step,
t3 and further comprising at least one horizontal reinforcing brace extending between and releasably connected to the handrails of said units below the level of the lowermost step.
2. A safety step ladder as set forth in claim 1, wherein each receptacle has an open top side for permitting insertion and removal of respective steps when the ladder is fully assembled.
References Cited in the le of this patent UNITED STATES PATENTS 426,180 Hammill Apr. 22, 1890 805,570 Maldaner 'Nov. 28, 1905 1,109,559 Underwood Sept. l, 1914 2,192,521 McGraw Mar. 5, 1940 2,265,735 Lambert Dec. 9, 1941 2,380,160 Fieroh July 10, 1945 2,518,745 Batelja Aug. 15, 1950 FOREIGN PATENTS 791,282 Great Britain Feb. 26, 1958