US3042140A - Stepladders - Google Patents

Description

July 3, 1962 G. E. BASILE ETAL STEPLADDERS 2 Sheets-Sheet 1 Filed April 15, 1960 INVENTOPS A TTO'RNE Y N 3 M ET. 3

m m V- B July 3, 1962 G. E. BASILE ETAL 3,042,140

STEPLADDERS Filed April 15, 1960 2 Sheets-Sheet 2 INVENTOFPS GENE E. BASILE EDWARD 7-. LMAN M 9 A T TORNE V United States Patent Ofiice anemia Patented July 3, 1962 3,042,140 STEPLADDERS Gene E. Basile, Newark, and Edward T. Gillman, Rutherford, NJ., assignors to Putnam Rolling Ladder (10., Inc., New York, N.Y.

Filed Apr. 15, 196i), Ser. No. 22,601 3 Claims. (Cl. 182-46) This invention relates to ladders in general, and more specifically to stepladders and the like.

The object of the present invention is the provision of improved cooperative elements in combination to produce a stepladder having a high strength to weight ratio, which is impervious to moisture, convenient in use, and of low manufacturing cost. One of the features of the present invention is the provision in a stepladder of pairs of rails, each rail constructed of a core of light density material wrapped into a plastic impregnated fiberglass material.

Another feature is the provision in a stepladder of novel means for securely mounting the step plates onto the rails forming the front side of the stepladder.

Another feature is the provision in a stepladder of means for securely mounting rung members onto the rails forming the back side of the stepladder, the rungs having means for defining the parallel spaced assembled relation of the rails to each other.

Another feature is the provision in a stepladder of a movable shelf pivoted onto one of the rung members and adapted to support tools or other implements at a convenient position relative to the operator of the stepladder.

Another feature is the provision in a stepladder of a step plate mounted to the top ends of the front side rails for movement as a unit therewith to a position parallel relative to the movable shelf when the latter is set to its operated position.

Another feature is the provision of means operatively connecting the pivoted shelf to the front disposed rails to cause the movement of the shelf in either position upon the operation of the rail assemblies toward the operated and the non-operated position.

Other novel features and advantages will appear from the following description and by the claims appended thereto, reference being had to the accompanying drawing in which:

FIG. 1 is a perspective view of the stepladder of the invention shown in the operated position;

FIG. 2 is a perspective view of a portion of one of the rails and a portion of a step plate shown exploded, also showing the method of keying the step plates to their supporting rails;

FIG. 3 is a transverse sectional view of a side rail taken on line 3-3 of FIG. 1, showing a spindle portion formed with the step plate engaged into a bearing element formed in the side rail, the end portion of the plate being shown in engagement with a key groove formed in such rail;

FIG. 4 is a sectional view of a side rail and one end portion of a rung taken on line 44 of FIG. 1, showing plastic impregnated fiberglass material serving to form securing means between the side rail and the rung;

FIG. 5 is a side elevation view of the ladder of the invention, showing the side rails with portion broken away, the side rail assemblies and the pivoted shelf being shown in the operated position;

FIG. 6 is a view similar to that of FIG. 5 but showing the step supporting side rails and the rung supporting side rails in the non-operated position, the shelf being also shown in the non-operated or normal position;

FIG. 7 is a sectional view showing one of the step plates and its supporting side rail taken on line 7-7 of FIG. 1, also showing the spindle portion of a step plate embedded into a plastic impregnated fiberglass material filling a bearing aperture in the side rail and key holes in the spindle portion of the step plate; and

FIG. 8 is a perspective view exploded showing a portion of a step plate and a portion of a supporting side rail for the step plate, the latter being a modification of the step plate shown in FIG. 2.

The stepladder of the present invention consists of two pairs of similarly constructed side rail members 10-10 and 1111y, FIGS. 1, 5 and 6, each side rail comprising a core C1 of balsa wood, or similar light density material, embedded into an envelope 14 of plastic impregnated fiberglass material, FIGS. 3, 4, 7 and 8, formed by the use of a machine which forms the subject matter of a co-pending patent application Edward T. Gillman-Gene E. Basile, filed December 31, 1959, Serial No. 863,309. In that machine, strips of fiberglass material are held under tension longitudinally of the core while another fiberglass strip is wound helically around the longitudinally disposed strips simultaneously with the impregnation of all the strips and the core with a plastic material.

The side rail members Ill-10y serve for securely mounting at equal spaced relation a number of step plates P1, P2, P3, P4 and P5, and at the top ends of side rail members 1ll10y is mounted a step plate P6 which is secured to angle bars 17 and 118 as by rivets 1516, while the angle bars are, in turn, secured as by bolts 12-20 extending through shoe- shaped steel members 21 and 22, FIGS. 1, 5 and 6, and through their respective side rail 16 and 10y, the step plate P6 being positioned at an angle relative to the longitudinal axis of the supporting rails 10 and lily so as to take a horizontal position, as shown in FIGS. 1 and 5, when the stepladder is set in the operated position.

Each step plate P1, P2, P3, P4 and P5, which may be in any number desired, is formed at both ends, as shown in FIG. 8, with a cylindrical portion 25 having diametrically opposite drilled holes 26 and a hole 27, which, when the cylindrical portions 25 are positioned into respective bearing aperture 28 formed in the side rails 10-10y register with circular grooves 26y and 27y, as best seen in FIGS. 3 and 7. Each bearing aperture 28 is made with a sufficiently large diameter for permitting the formation of a blind sleeve 28F of a plastic impregnated fiberglass material which also fills the circular grooves 26y and 27y and the key holes 26 and 27 while bonding the end portion of the blind sleeve 28F, the envelope 14, the adjacent end portion of a plug 29 inserted into the tubular cylindrical end 25 of the step plates P1, P2, etc. and around the peripheries of the spindle portions 25 formed at the opposite ends of the step plates.

The step plates are formed at their opposite ends with similarly shaped portions F1, best seen in FIGS. 3 and 8, adapted to engage respective slot 30 formed in each side rail Ill-10y to serve for securely keying the step plates to the rails in addition to the keys formed by the plastic impregnated fiberglass sleeve 28F filling the bearing apertures in the side rails and in the key holes 26 and 27 in the spindle-like portions 25 of the step plates, while 3 effectively holding the latter and the side rails in the assembled relation to each other.

FIG. 2 shows a modification of the step plate shown in FIGS. 3, 7 and 8. This modified step plate is formed with a tubular reenforcing rib 31 of substantially square crosssection extending from both ends of the plate to form the projections TP, the diagonal distance of which is substan tially equal to the diameter of the bearing apertures 281) formed in the rails. Each projection TP is provided with diametrically opposite perforations, or key holes 52 which register with a circular groove 33 formed in the bearing aperture 28D into the core C1, and a key hole 35 disposed to register with the annular groove 36 when the projection engages the bearing aperture which has been previously filled with a plastic impregnated fiberglass material adapted to form. a bushing between the projecting end portion of the step plate and the wall of the bearing aperture, thereby forming homogeneous securing means therebetween when in the assembled relation, in which relation the portions X-X1 of the step plate engage the slots 36y formed in position tangent to the bearing apertures in the side rails to hold the plate securely against rotation.

In the combination of elements comprised in the stepladder of the present invention, the rail members 10- 10y and 1111y are pivoted at their top disposed ends by similarly constructed hinge members 2323x and 24- 24x secured to their respective rail by belts or rivets 41 and 42, FIGS. 1, and '6.

The rail members 11 and 11y forming the back of the stepladder are held in parallel assembled relation to each other by a plurality of rung members m1, m2, m3, m4 and m5, which, like the step plates P1, P2, P3, etc. may be of any number, depending upon the height of the stepladder desired. The rung members m1, m2, m3, m4 and m5, as shown in FIG. 4, are in the form of splined tubings constructed of alight density material, such as aluminum or metallic magnesium, having, as an important feature of the invention, both ends constricted so as to reenforce these portions of the rungs. This construction permits the use of relatively small diameter bearing apertures into the rails 1111y while forming annular spaces concentric to the reduced ends of the rungs and the walls of the apertures in the side rails, thereby avoiding the weakening of the side rails at these points.

Each constricted end portion of the rungs m1, m2, m3, etc. is formed with two pressed-in annular peripheral recesses or grooves 45 and 46 which register with annular grooves 45y and My formed in each of the bearing apertures in the cores of side rails 1111y for locking the rungs laterally into the plastic impregnated fiberglass material filling the apertures, the annular grooves, and the end of a plug inserted into the constricted ends of the rungs to form a homogeneous securing means between the side rails and the rungs, while the splines at the peripheries of the constricted end portions effectively hold the rungs from rotation. The shoulders formed by the constricted portions at the ends of each rung serve as abutments or stops for readily defining the spaced relation between the rails 11 and My while forming a seal SP between the envelope 14 and the enlarged ends of the rungs.

A shelf for the stepladder, as shown in FIGS. 1, 5 and 6, consists of a relatively large transversely disposed ribbed plate 50, held as by rivets 51 to a pair of parallelly disposed angle bars 52 and 53 to which are secured two inverted U-shaped bolts 54 and 55 serving as bearings for the pivotal movement of the shelf from its normal position, shown in FIG. 6, to the operated position shown in FIGS. 1 and 5, wherein the free ends of angle bars 52 and '53 abut against the underside of step plate P5 which thus limits the angular movement of the shelf toward its operated position, while a pair of link members 56 and 57 are pivoted at one of their ends to respective rail 19 lily, and their opposite ends to the angle bars 52 and 53 supporting the shelf, the length of links 56 and 57 being such as to cause the pivotal movement of the shelf from the position shown in FIG. 6 to the operated position shown in FIGS. 1 and 5 upon the movement of the rails 10-40 carrying the step plates P1, P2, P3, etc. relative to the side rails 11-11y carrying the rung members m1, m2, m3, etc.

The movement of rails 10-16 and 11-41 toward their operated position is limited or controlled by pivoted link bars 5859 connecting the rails lily-11, and the pivoted link bars 6i)61 connecting with the rails 10- lly, while the pivotal movement of these link bars from the position shown in FIG. 6 to a position a small distance past their dead center line, as shown in FIGS. 1 and 5, being controlled by yoke members 62 and 63, also pivoted at the common connecting points of the link bars and abutting against the upper disposed sides of these link bars.

Stepladders embodying the novel features of the present invention have been found to possess a high strength to weight ratio, are convenient and safe in use, and cheap to manufacture.

It is understood that minor changes may be made to the stepladder of the invention without departing from the scope of the appended claims.

What we claim is:

.1. A stepladder having two front side rails of elliptical cross section with circular bearing apertures formed at equal spaced relation along the length of the rails and a plurality of step plates, the improvement in the side rails and the step plates which consists in forming the step plates with reinforcing ribs of square cross section extending beyond the plates for engaging the circular apertures in the rails and forming slots in a part of the curve formed by the periphery of the rails in position tangent to the bearing apertures and to the elliptical curvature of the rails for receiving the end portions of the step plates and thereby securing the latter against rotation relative to the rails, and a plastic material filling the bearing apertures and the slots to form a homogeneous rails step plates assembly.

2. A stepladder having two side rails of elliptical cross section, each rail formed of a wood core of unit structure covered with an envelope of plastic impregnated fiber glass material and step plates carried by the rails, the rails having circular blind bearing apertures for receiving elements of the step plates, the improvement in the stepladder which consists in forming each of the step plates with a reinforcing rib of substantially square cross section extending from both ends of the plate to a distance corresponding to the depth of the blind bearing apertures in the rails, forming an elongated keyway in the form of a slot into the plastic impregnated fiberglass envelope in position tangent to the curve formed by the ellipse peripheral surface of the rail and tangent to the circle formed by the bearing apertures in the rail and forming key portions at the ends of the step plates for engaging the slots in the rails and filling the bearing apertures and the slots with a plastic material to form a homogeneous rails step plates assembly.

3. A stepladder having two front side rails of elliptical cross section, each rail composed of a core of unit structure covered with an envelope of plastic impregnated fiberglass material, the rails having circular blind bearing apertures and step plates having elements for engaging the bearing apertures in the rails, the improvement in the stepladder which consists in forming each step plate with key portions and with a reinforcing rib of square cross section, forming keyways in the form of slots into the envelope of the core in position tangent to the curve formed by the ellipse periphery of the rails and tangent to the bearing apertures, the reinforcing rib extending beyond the ends of the step plate for engaging the bearing apertures and engaging the key portions formed with the plates into the slots in the rails and afterwards filling the spaces between the sides of the square reenforcing rib and the circular apertures with a plastic material to form a homogeneous rails step plates assembly.

References Cited in the file of this patent UNITED STATES PATENTS 6 Snyder Apr. 1, 1958 Campbell May 5, 1959 Hopfeld Apr. 12, 1960 Larson Oct. 25, 1960 FOREIGN PATENTS Austria Apr. 26, 1954 France Nov. 17, 1958 France Aug. 3, 1959

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