US3014552A

US3014552A - Ladder construction

Info

Publication number: US3014552A
Application number: US831668A
Authority: US
Inventors: James F Fike
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-08-04
Filing date: 1959-08-04
Publication date: 1961-12-26
Anticipated expiration: 1978-12-26

Description

Dec. 26, 1961 Filed Aug. 4. 1959 J. F. FIKE LADDER CONSTRUCTION 4 Sheets-Sheet 1 INVENTOR Jmyzesll'll'e M fim ATTORNEYS Dec. 26, 1961 Filed Aug. 4, 1959 J. F. F IKE LADDER CONSTRUCTION 4 Sheets-Sheet 2 INVENTOR 3 JmJlT Zke w a fazwz ATTORNEYS J. F. FIKE LADDER CONSTRUCTION Dec. 26, 1961 4 Sheets-Sheet 3 Filed Aug. 4. 1959 INV EN TOR M851 ATTORNEYS Dec. 26, 1961 J. F. FIKE 3,014,552

LADDER CONSTRUCTION Filed Aug. 4. 1959 4 Sheets-Sheet 4 IN VENTOR JamesE aw, mam

ATTORNEYS 3&143552 Patented Dec. 26, 1961 s,e14,552 LADDER CONSTRUTION James F. Film, 533 S. Keystone Ave, Indianapolis, Ind. Filed Aug. 4, 1959, Ser. No. senses 2 Claims. (Cl. l82-27) This invention relates to ladders and more particularly to ladders comprising a plurality of pivotable end-to-end sections.

Various ladders heretofore have been known, which are composed of multiple longitudinal sections disposed end-to-end and pivoted together to permit adjustment of the sections to various angular positions relative to each other. Such prior art ladders have been attended by various disadvantages, including insuificient strength and complex connections between the pivotable sections which are expensive and difficult to operate and maintain.

To overcome the disadvantages of the prior art, it is an object of this invention to provide an improved, highly effective and versatile ladder of the multiple, pivotable section type characterized by great strength and simple, easy to operate connections between the pivotable sections.

Generally described, the invention resides in an adjustable ladder which comprises a pair of sections disposed in end-to-end relationship. Each of the ladder sections includes a pair of wooden rails connected together in laterally spaced relationship by a plurality of transverse rungs at longitudinally spaced locations. Each of the rails has a metal core embedded longitudinally therewithin. The metal cores of the adjacent sections are pivotally connected together at the lower edges of the adjoining rails to connect the adjoining rails in contiguous end-to-end relationship and to permit relative downward pivoting of the adjoining sections about such connections. The cores extend from the connections a substantial distance longitudinally into the rails and are fixed thereto. Further, connecting means are provided which are selectively adjustable to a first condition retaining the sections in a fixed angular relationship, and to a second condition retaining the sections in a straight-line relationship.

The invention having been generally described, various preferred specific embodiments thereof will now be set forth in detail with reference to the accompanying drawings in which:

FIGURE 1 is a plan view of one embodiment of ladder according to the invention with all of the various sections retained in straight-line relationship to form a continuous ladder;

FIGURE 2 is'a side elevation of the ladder of FIG- URE 1 illustrating in phantom lines the manner in which the sections may be retained at fixed angular relationships to enhance the versatility of the ladder;

FIGURE 3 is a side elevation of the ladder of FIG- URE I adjusted to function as a stepladder;

FIGURE 4 is a side elevation of the ladder of FIGURE 1 adjusted to function as a scaffold;

FIGURE 5 is a side elevation of the ladder of FIG- URE 1 in collapsed storage position;

FIGURE 6 is a bottom view of the collapsed ladder shown in FIGURE 5;

FIGURE 7 is a fragmentary vertical sectional View taken along the line 7-7 of FIGURE 1;

FIGURE 8 is a vertical sectional view of one of the ladder rails taken along the line 88 of FIGURE 7;

FIGURE 9 is a fragmentary perspective view of the end of one of the rails of the outer ladder sections;

FIGURE 10 is a vertical sectional view taken along the line lit-10 of FIGURE 1;

FIGURE 11 is a bottom plan view of a modified embodiment of a ladder according to the invention;

FIGURE 12 is a detailed view of the joint between the sections of the ladder of FIGURE 11; and

FIGURE 13 is an end view showing the ladder of FIGURE 11 in a collapsed condition.

Depicted in FIGURE 1 is a ladder designated generally by the reference numeral l and comprising a relatively short, central step section 2, a pair of relatively long inner leg sections 3 and a pair of relatively long outer leg sections 4. The inner sections 3 and the outer sections 4- are positioned in end-to-end relationship on opposite sides of the central step section 2. The step section 2 comprises a pair of rails S and 6. Each of the inner leg sections 3 comprises a pair of

rails

7 and 8. Each of the outer leg sections 4 comprises a pair of

rails

11 and 12. In each of the sections, the rails are spaced laterally apart and are connected by a plurality of transverse rungs 13 positioned at longitudinally spaced locations.

Each of the rails and rungs of each of the sections is formed of wood. Each of the rails has embedded therein a metal core. As shown in FIGURE 1, the step section 2 has a metal core 14; each of the inner leg sections has a metal core 15; and each of the outer leg sections has a metal core 16. As best seen in FIGURES 7 and 8, each metal core of each of the sections comprises a flat metal bar embedded in the lower portion of each rail along the vertical center line thereof. The long axis of each of the core bars extends vertically of its rail to provide maximum reinforcement against vertical bending of the rail. Desirably, the cores extend throughout the length of each of the ladder rails. It is especially important that the cores extend throughout the length of the rails of the step and inner leg sections because when the entire ladder is employed as a continuous beam, the maximum bending moment exists in the central sections. The cores of each pair of adjoining ladder rails are pivotally connected by pin and socket connections 19. The connections 19 provide horizontal pivots at or near the plane of the lower faces of the ladder rails to permit each pair of adjoining sections to be pivoted inwardly relative to each other. The end faces of adjoining rails abut one another when the adjoining sections are positioned in a straight-line relationship to each other.

When the inner legs 3 are pivoted downwardly until they extend at right angles to the step section 2, as shown in FIGURE 5, the distance between the lower faces of the inner leg sections, as measured in a direction parallel to the step section should be at least as great as the combined width of the outer leg sections 4. This enables the outer leg sections to be pivoted downwardly until they are parallel to the inner leg sections 3 and the inner leg sections then to be pivoted downwardly until all four of the leg sections are parallel, as shown in FIGURE 5. With the sections thus folded, the ladder is in collapsed storage condition. To enable this condition to be achieved, the outer legs 4 can be no longer than the inner legs 3, unless the construction of the connections 19 between the step section and the inner leg sections is such as to leave a gap between the inner end faces of the inner leg sections and the bottom face of the step section when the sections are folded as shown in FIGURE 5. In this case, the outer leg sections could be slightly longer than the inner leg sections without binding against the step section when moved toward collapsed storage position. The outer leg sections, however, may be somewhat shorter than the inner leg sections.

The rungslii are connected to each of the rails by inserting the rungs into corresponding openings in the rails whereupon the rungs are bonded to the rails by any suitable adhesive.

As shown in FIGURES 3 and 4, means are provided to retain the inner leg sections and the step section either in a fixed angular relationship, as shown in FIGURE 3, or alternatively, in a straight-line relationship, as shown in FIGURE 4. At the fixed angular relationship, the ladder may be employed a a stepladder. At the straightline relationship, the ladder may b employed as a scaffolding (FIGURE 4) or as a continuous length ladder (FIGURE 2). A bracket 22 is fastened, as by a plurality of bolts 23, tothe inner side face of each of the

opposing rails

5 and 6 of the step section 2. The brackets 22 depend downwardly from the step section and each is pivotally connected by a pin 24 at its lower end to a pair of elongated links 25. The other end of each of the links 25 may be selectively attached to either of a pair of mounting

elements

27 or 28. Such mounting elements are positioned on the inner side face of each of the inner leg section rails. Each of the mounting

elements

27 and 28 comprises a pin connected to the metal core of the rail on which it is mounted and has a threaded end protruding inwardly from the rail face. The

pins

27 and 28 are spaced longitudinally along each rail on which they are mounted. The free end of each link 25 has an opening therein which may receive a

27 or 28 and be fastened thereto by a wing nut 29. The position and spacing of the mounting

elements

27 and 28 and the length of the links 25 are such that the inner leg sections and the step sections are retained in straight-line relationship when the free ends of the links are attached to the inner pins 27, and in a fixed angular relationship when the free ends of the links 25 are attached to the outer pins 28.

Further, means are provided to retain the inner and outer legs either in a straight-line relationship as shown in said lines in FIGURES 2 and 3, or in a fixed angular relationship as shown in phantom lines in FIGURE 2 and in solid lines in FIGURE 4. In the former relationship, the ladder may be employed as a stepladder or as a continuous ladder. In the latter relationship, the ladder may be employed as a scaffold. A pair of mounting

elements

31 and 32 are mounted on the inner and

outer leg sections

3 and 4 on opposite sides of the pivotal connection therebetween. Each of the mounting

elements

31 and 2 comprises a pin threadedly connected to a rail and having a head spaced outwardly from the outer side face of the rail. The

pins

31 and 32 are positioned on longitudinal lines near the tops of the rails above the pivotal connection 19 between the

leg sections

3 and 4. The positioning of the

pins

31 and 32 is such that the line therebetween is above such pivotal connection 19 when the

leg sections

3 and 4 are in Straight-line relationship; is below such pivotal connection 19 when the

leg sections

3 and 4 are in the fixed angular relationship; and in each case is equal in length. A link or strap 33 is pivotally connected at one end to the pin 31 and has a socket and a hook at its other end to permit connection to the pin 32. The effective length of the link 33 is equal to the distance between the

pins

31 and 32 when the

leg sections

3 and 4 are in either the straight-line or fixed angular relationship. Thus, when the

leg sections

3 and 4 are moved either to the straight-line or fixed angular relationships, the link 33 may be connected between the

pins

31 and 32 to retain the legs in such relationship.

A modified embodiment of a ladder according to the invention is shown in FIGURES 11 through 13 and is generally identified by the reference numeral 51. The ladder 51 can be employed either as a straight elongated ladder, as shown in FIGURE 11, or as a stepladder, as shown in FIGURE 12.

The ladder 51 comprises two

sections

52 and 53, which are positioned in contiguous end-to-end relationship. The section 52 comprises a pair of elongated generally parallel

wooden rails

54 and 55 connected by a plurality of transverse wooden rungs 56 positioned at longitudinally spaced locations. The rungs 56 are formed from round bars which are received in appropriate openings 62 in the

rails

54 and 55. The section 53 comprises a pair of generally parallel

wooden rails

57 and 53 which are connected by a plurality of transverse wooden rungs 59 positioned at longitudinally spaced locations. Desirably, the

rail

57 and 58 are tapered slightly outwardly toward their lower ends as is common in stepladder construction. The rungs 59 are formed from flat boards which are set in slots 61 in the

rails

57 and 58. The slots 61 are so inclined relative to the axis of the rails that the rungs or steps 59 are positioned approximately horizontally when the ladder 51 is employed as a stepladder, as shown in FIGURE 12. Preferably, the

rungs

56 and 59 are secured to their respective rails by glued connections but other suitable connections may be employed.

Each of the

rails

54, 55, 57 and 58 has embedded therein, a metal core 63. Each metal core of each of the rails comprises a flat metal bar embedded in the lower portion of each rail along the vertical center line thereof. The long cross-sectional axis of each of the core bars extends vertically of its rail to provide maximum reinforcement against vertical bending of the rail. The cores of each pair of adjoining ladder rails are pivotally connected by pin and socket connections 64. The connections 64 provide horizontal pivots at or near the plane of the lower faces of the ladder rails to permit the adjoining sections to be pivoted inwardly relative to each other.

' The end faces of adjoining rails abut one another when the adjoining sections are positioned in a straight-line relationship to each other. As shown in FIGURE 12, the core bars 63 of the

rails

54 and 55 are provided with arcuate slots 65 to receive the ends of the rungs 56.

As shown in FIGURE 11, the cores 63 extend a substantial distance into their respective rails to provide maximum reinforcement against vertical bending of the rail because, when the ladder is employed as a straight elongated ladder, the maximum bending moment occurs at the connection 64 and in the portions of the ladder sections adjoining the connection 64. In the embodiment of FIGURE 11, the cores extend approximately to the midpoint of the rails but, if desired, may extend throughout the length of the rails.

As best seen in FIGURE 12, means are provided to retain the

ladder sections

52 and 53, either in fixed angular relationship or alternatively in a straight line relationship. .In the fixed angular relationship, shown in FIG- URE 12, the ladder may be employed as a stepladder. In the straight-line relationship, shown in FIGURE 11, the ladder may be employed as a continuous length ladder. A link or a strap 66 is pivotally connected at one end to a pin or mounting element 67 which is connected to the rail 54. A pair of pins or mounting

elements

68 and 69 are connected at spaced locations along the outer face of the rail 53. Each of the

pins

68 and 69 is adapted to receive a socket of a hooked end of the strap 66 opposite to the end connected to the pin 67. The

pins

67 and 69 are positioned on longitudinal lines near the tops of their respective rails above the pivotal connection 64 between the

ladder sections

52 and 53. Thus the line between the

pins

67 and 69 is above the pivotal connection 64 when the

sections

52 and 53 are in straight-line relationship. The spacing between the

pins

67 and 69 is such that the strap 66 may be connected therebetween to lock the

sections

52 and 53 in the straight-line relationship. The pin 68 is positioned such that the strap 66 may be connected between the

pins

67 and 68 to lock the

sections

52 and 53 in the fixed angular relationship shown in FIGURE 12. Thus, when the

sections

52 and 53 are moved either to the straight-line or fixed angular relationships, the straps 66 may be connected between the pin 67 and one of the

pins

68 and 69 to retain the sections in such relationship.

An identical connecting means comprising a link 66 and pins 67, 68 and 69 are connected to the

rails

55 and 58.

A tray 71 is pivotally connected between the

rails

54 and 55 to support paint cans and the like when the ladder is employed as a stepladder. The tray may be pivoted to an out-of-the-way position parallel With the rails as shown in FIGURE 11.

There has been illustrated and described what is considered to be certain preferred ladder embodiments according to the invention. It will be understood, however, that many modifications may be made by persons skilled in the art without departing from the scope of the invention as defined in the appended claims.

I claim:

1. An adjustable ladder which comprises a relatively short centrally located step section, two pairs of relatively long leg sections disposed in end-to-end relation-ship on opposite ends of said step section, each of said sections comprising a pair of wooden rails connected together in laterally spaced relationship, with the rails of said leg sections being connected by a plurality of transverse rungs at longitudinally spaced locations, each of said rails having a metal core embedded longitudinally therewithin and extending to each end thereof which adjoins another section, the cores of at least the step section and the inner leg sections extending throughout the length thereof, the cores of adjacent sections being pivotally connected together at the lower edges of the adjoining rails to connect the adjoining rails in contiguous end-to-end relationship and to permit relative downward pivoting of each pair of adjoining sections about said connections, connecting means selectively adjustable to a first condition retaining the inner leg sections and the step section in a straight'line relationship and the inner and outer leg sections in a fixed angular relationship and to a second condition retaining the inner leg sections and the step sections in a fixed angular relationship and the inner and outer leg sections in a straight-line relationship, said connecting means including a pair of brackets connected to and depending from opposite sides of said step section, each-of said brackets having pivotally connected to the lower end thereof one end of each of a pair of links,

and a plurality of pairs of fixed mountingelements, one pair of said mounting elements being connected at longitudinally spaced locations to the metal core of each of said inner leg sections, the other end of each of said links being selectively attachable to either mounting element of one of said pairs of mounting elements, the position and spacing of each of said pairs of mounting elements and the length of each of said links being such that said inner leg sections and said step section are retained in their straight-line and angular relationships when said other ends of said links are attached to inner and outer ones, respectively, of said pairs of mounting elements.

2. An adjustable ladder as recited in claim 1 wherein said connecting means further includes a plurality of pairs of second mounting elements and a plurality of straps, each pair of said second mounting elements being mounted at positions spaced above and on opposite sides of the pivotal connections between adjoining inner and outer leg sections, and each of said straps being connectable between a pair of said second mounting elements to fix the relative position of the associated leg sections in either of their straight-line or fixed angular relationships.

References Cited in the file of this patent UNITED STATES PATENTS