US3083786A - Stepladder - Google Patents

Description

H. G. ARNOLD April 2, 1963A STEPLADDER 2 Sheets-Sheet 1 Filed Sept. 19. 1961 AT TYS.

April 2, 1963 H. G. ARNOLD 3,083,785

STEPLADDER Filed Sept. 19, 1961 2 Sheets-Skaai'l 2 INVENTOR. HAROLD G. ARNOLD ATT YS United States liatent 3,083,785 Patented Apr.. 2, 1963 3,033,786 STEPLADDER Harold G. Arnold, Wooster, (lino, assigner to The Bauer Manufacturing Company, Wooster, Ollio, a corporation of Ohio Filed Sept. 19, 1961, Ser. No. 139,294 Claims. (Cl. 1232-126) The present invention relates t0 a lightweight metal stepladder.

Heretofore it has been known to construct metal stepladders by riveting the steps directly to the walls of the side rails. This construction was carried forward to the brace members between the prop members and to the pivotal connection between the prop members and the side rails. With this construction the load forces on the ladder were concentrated on the rivets and the walls of the side rails and prop members adjacent the rivets.

This structure results in a maximum sheer forces on the rivets and tends to enlarge the holes in the metal side rails and prop members so that they become out of round. ln this condition the ladder is difficult to operate and impairs the safety of the person on the ladder.

In the conventional stepladder the pail shelves are provided with a plain fiat surface. Slight movement of the ladder may dislodge the pails or tools contained thereon. These ladders often have the further disadvantage that when the ladder is in the closed position the tray has a tendency to fall open.

It is the general object of the invention to avoid and overcome the foregoing and other diiiculties of and objections to the prior stepladders by the provision of an improved durable, strong, and relatively inexpensive ladder.

Another object of the invention is to improve the stability and rigidity of a metal step ladder Without substantially increasing its weight.

A further object of the invention is to construct a metal stepladder which does not gall and bind when it is set up.

Still another object of the invention is to construct a metal stepladder with structural shapes which are eilicient to produce.

The aforesaid objects of the invention, and other objects which will become apparent as the description proceeds, are achieved by providing in a metal stepladder a pair of channel-shaped side rails, a plurality of channelshaped step members secured in spaced relation within and to the channel of the side rails, reinforcing gusset plates having interlocking dimple and groove formations cooperating with complementary `dimple and rib formations in the first step and penultimate step and a flange of the side rails, a pair of reinforced prop members secured to the top step with a ball and socket bearing, spreader means pivotally secured to the prop members and side rails for holding the prop members in spaced relation from the side rails and a box type tray pivotally secured to the upper portion of the prop members and adapted to engage the lower portion of the penultimate step when in the open position, and shoe members secured to the bottom portion of each side rail and each prop member.

A better understanding of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in Iconnection with the accompanying drawings in which like reference numerals designate like parts throughout the gures thereof and wherein:

FIG. 1 is a perspective View of a preferred embodiment of the invention.

FIG. 2 shows a section of the ball and socket joint between the top step and the prop members taken on the line 2-2 of FIG. l.

FIG. 3 shows a section of the gusset reinforcing members taken along the line 3-3 of FIG. l.

FlG. 4 shows a section of the prop member reinforcing structure taken along the line 4-4 of FiG. 1.

FIG. 5 is an enlarged perspective view of the tool tray, in a Slightly tilted position, other portions of the ladder being broken away.

FIG. 6 is an enlarged fragmentary view of the spreader linkage between the side rails and the prop members.

t FfG. 7 is an enlarged fragmentary perspective view of the shoe members secured to the side rails.

With specific reference to the form of the invention illustrated in the drawings, the numeral 1d (see FlG. 1) indicates generally a ladder having a pair of metal side rails 11 and 12. These rails, and the other portions of the ladder, as hereinafter described, are usually made from high strength aluminum or `aluminum alloy. Many of the ladder parts, such as the rails are conveniently made by extrusion. The side rails are channel-shaped in cross section having a web portion 13 and flange portions 14 and 1S. Extending over the outer portion of the web are parallel longitudinally extending grooves 16, primarily for purposes of appearance.

A plurality of consecutively shorter step members 17, 1S, 19, 20, and 21, each of inverted channel-shaped section, are secured through their flanges by conventional rivets 22 at equal vertical intervals to the ilanges of the side rails. The anges of the step members are at other than a right angle with the base web at each step member, so that with the ladder open, as in FIG. 1, the top of each step member is horizon-tal and the flanges are at the angle of the side rails. Thus the flanges of the side rails 'and of the step members closely and iiatly engage where riveted together. Additionally, the ends of each step member are cut at a slight angle to assure a flush abutment with the web of the side rails. rlfhe taper of the side rails (slightly together in a vertical direction) determines the angle at which the ends of the step members are cut. Each step member has a series of longitudinally extending grooves 23 and a longitudinally extending rib 24 on the top side of the web to increase the frictional characteristics of the step surface, as best shown in FIG. 3.

Right and left-hand triangular-shaped gusset plates 25 and 251 'are riveted to the outside of the fiange of the first step member 17 and to the outside flange of the penultimate step member 21. Each gusset plate has three bores, one in each corner. Surrounding the bores in the acute angles of the plate is a spherical dimple formation 26, as best shown in FIG. 3. The outer flange of the step member 17 and 21 have complementary dimple formations, and rivets 22 complete the subassembly. The dimple formations provide bearing surfaces for the load on the step members, but primarily take the loads to hold the ladder rigid laterally. To further increase the structural rigidity of the assembly the gusset plate is provided with 1a horizontally extending groove 27 which embraces a rib 28 on the lower portion of the ange of the step members 17 and 21. An additional purpose of the dimple formations is to make up for a diiference in metal in the riveting operation. At some points there are three pieces of metal, that is, the channel ange of the side rail, the thickness of the gusset plate and the flange of the step members through which the rivet must pass to hold all three pieces together. At other points there will be only two thicknesses of metal. The dimple makes up for the lacking third thickness to permit the use of the same length rivet. Dimpling also allows the outermost portion of the rivet to be ush with the outer surface of the ladder thereby improving appearance and eliminating a protruding rivet head on the front of the step member.

The top step member 29 has a rectangular base 30, end Walls 31 bend substantially normal to the base and parallel side walls 32 disposed with respect to the plane of the base at an oblique angle equal to the slope of the side rails with the ladder open. r["he top step member ts over the upper end portions of the side rail-s and is riveted or otherwise secured thereto.

Supporting the ladder `in an upright position are a pair of channel- shaped prop members 33 and 34. The prop members are pivotally 'secured to .the end walls of the top step `by a ball and socket connection 35, yas best shown in FIG. 2. Each prop member has an outwardly extending spherical dimple formation 36 surrounding a bore. On each end wall of the top step there is a complementary outwardly extending dimple lformation 37 surrounding =a bore. Each dimple formation has a convex and a concave surface. Between the convex surface of the dimple formation 36 and the concave surface of the dimple formation 37 is disposed an anti-friction washer 38 which may be of nylon or similar material. The action of aluminum on `aluminum causes a galling condition in which a metal ball will be rolled up by the scratching or galling of metal on metal. The dimples forming a pocket for the nylon washer, permit the washer to act as a separator at this important pivotal point and eliminate galling. A rivet 39 extends through the bore in the dimple formations and the washer to pivotally secure the prop members to the end walls 4of the top step.

A plurality of successively shorter channel-shaped brace members 40, 41, 42, and 43 are secured through their bases at spaced intervals by means of rivets 44 to the back flange orf the channel-shaped prop members. The entire prop member portion of the ladder is additionally reinforced against lateral movement with left and right-hand triangularly 'shaped ` gusset plates 45 and 46 secured between members 40 and 43 and the prop members. The gusset plates 4S and 46 have a ilange 47 `bent at right angles. The flange 47 has -two downwardly extending dimple formations 48, each surrounding a ybore as best seen in FIG. 4. The lower flange Iof the channel members includes a dimple formation 49 surrounding a bore which is complementary to the -dimple formation 48. Extending through the 4bore in the dimple formations are rivets Sil to rigidly secure the gusset plate to the channel member. Each gusset plate is provided with a third dimple formation surrounding `a -bore in the acute angle thereof. A rivet `51 extends through the bore in the third dimple formation and a bore in the flange of the prop members to rigidly secure the gusset plate to the prop member.

To mount a vtray 56 on the ladder, a pair `of supporting brackets 52 and 53 (FIG. 5) are rigidly secured lby means of rivets or the like to a black flange of each of the prop members midway Ibetween the top step and the .top channel member 43. The brackets have a laterally extending ear portion or stop 54 and a normally extending flange 55 forming an L shape in horizontal section. Pivotally secured on pivot pin 551 to the flange 55 is the box type pail and vtool tray 56. The pivotal axis of the tray 56 is slightly above the stop 54. The tool tray has a rectangular flat base portion 57 which at its end extends under and engages the penultimate step 21 and which extends an equal distance in the opposite ldirection and engages the stops 54. Secured to the edges of the 4base portion 57 are side flanges 58 and a cross llange 59 thereby `forming a box-like structure.

A pair of folding spreader members 60 are positioned between each side rail and the corresponding prop member to hol-d the prop members in spaced relation from the side rails. Each spreader member has a hat link member 61, a second flanged link member 62 and a pivot pin 63 connecting one end of the first link member to the second flanged link member at a point slightly inw-ardly from one end thereof. In this construction, when the link members are moved from the inverted V with the ladder closed -to the straight line horizontal position with the ladder lopen, the hanged end of the flange link lying beyond the pivot point engages with the link member' to prevent the link members from moving beyond dead center. The .opposite ends of the respective angle members are pivotally secured on pivot pins to stamped spreader supports 64 and 65. The support 64 is rigidly secured to the outside llange of the prop member and the support 65 is rigidly secured to the inside flange of the side rail. This construction places the spreader member on the inside of the ladder.

As best shown in FlG. 7, on the lower ends of each of the pro-p members and the side rails are secured shoe elements 66, 67, 68 and 69. Each shoe element has a base plate 7i) that is rectangular in shape and extends slightly beyond the outer edges of the flange member and web member of the channel-shaped rail. This structure prevents the ends of the flanges from being damaged in use. A securing tab 71 projects normally from the upper surface of the plate member and. lies against the inner surface of the web. A conventional rivet or the like 72 secures the foot member to the end of the rail. A rubber sole 73 is vulcanized, riveted 'or otherwise secured to the underside of. the base plate to provide an increased frictional contact with the ladder supporting surface. Since the shoes 68 and 69 on the ends of the prop members are substantially the same as the shoes 66 and 67, they are not described in detail.

Even though it is believed the operation of the apparatus will be apparent from the foregoing description, a brief review thereof will now be made for purposes of summary and simplication. When the stepladder is in the folded position the stops S4 on the tray brackets 52 and 53 prevent the tray 56 from falling open. The stepladder is set up by rotating the prop members 33 and 34 about the ball and socket joint 35 in a clockwise direction. When the angular spreader members 6 1 and 62 are in the same horizontal plane the prop members are .in a fixed relation to the side rails. The tool tray is then placed in the open position by rotating it in a counterclockwise direction.

It should be understood, of course, that the Iforegoing disclosure relates to only a preferred embodiment of the invention, and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. A stepladder comprising a pair of side rails each having a web and flanges forming a channel shaped cross section, a plurality of dimple formations surrounding bores in one of each of the flanges of the side rails, a plurality of step members having a web and anges forming a channel shaped cross section, one of the fianges of the bottom and penultimate step members having a plurality of dimple formations surrounding bores and a rib projection, the opposite ends of the step members being positioned at spaced intervals in the channels of the side rails so that the channels of the step members open in a downward direction, a pair of gusset plates each having a plurality of dimple formations surrounding bores complementary to the dimple formations in the anges of the bottom and penultimate step members and the ilanges of the side rails and having a groove compiementary to the rib of the flanges of the step members, means securing the flanges of the step members to the anges of the side rails, and including means positioned in the bores for securing the gusset plates to the anges of the side rail and the flanges of the bottom and penultimate step members, a rectangular shaped top step having a flat base, end walls substantially normal to the base and side Walls angularly disposed with respect to the base disposed over the top ends of the side rails, means securing the top portion of side rails to the end walls of the top step, a pair of prop members, brace means holding the prop members in substantially parallel relationship, and anti-friction ball and socket means pivotally securing the prop members to the end walls of the top step, folding spreader means for holding the prop members in a fixed space relation from the side rails, means pivotally securing the spreader means to the prop members and the rail members, bracket means secured to the upper inside portion of the prop members, a tray pivotally secured to the bracket means and adapted to engage the lower surface of the flanges of the penultimate step, shoe means slightly Wider and longer than the cross section of the side rails and prop members, and means securing the shoe means to the base end of each of the side rails and prop members.

2. A stepladder comprising a pair of extruded metal side rails each having a web and flanges forming a channel shaped cross section, a plurality of dimple formations surrounding bores in one of each of the flanges of the side rails, a plurality of extruded metal step members having a web and anges forming a channel shaped cross section, one of the flanges of the bottom and penultimate step members having a plurality of dimple formations surrounding bores and a rib projection, the opposite ends of the step members being positioned at spaced intervals in the channels of the side rails so that the channels of the step members open in a downward direction, a double pair of gusset plates each having a plurality of dimple formations surrounding bores complementary to the dimple formations in the anges of the bottom and penultimate step members and the anges of the side rails and having a groove complementary to the rib of ilanges of the step members, and means securing the flanges of the step members to the ilanges of the side rails, and including means positioned in the bores for securing the gusset plates to the -anges of the side rail and the flanges of the bottom and penultimate step members.

3. The construction described in claim 2 wherein each step member upwardly from the bottom step is shorter in length than the preceding step member and has its ends cut at a slight angle complementary to the ladder taper resulting from the consecutively shorter step members.

4. In a stepladder, a rst member having a web and flanges forming a channel shaped cross section, a second member having a web and ilanges forming a channel shaped cross section, the flanges of the iirst and second members having dimple formations surrounding bores, a rib on one of the flanges of the second member, an end portion of the second member disposed in the channel of the first member substantially normal to the web of the first member, a gusset plate having a plurality of dimple for-mations surrounding bores complementary to the dimple formations on the flanges and having a groove complementary to the rib on the lange of the second member, and means extending through the bores for securing the flanges of the members and gusset plates together.

5. In a stepladder, a pair of side rails, a plurality of horizontally directed, vertically spaced steps joining the side rails, a pair of prop members pivotall'y vsecured at their upper ends to the side rails near the upper ends thereof, means securing the prop members in parallel relation to each other, a pair of stamped metal brackets of L-shape in horizontal section, each bracket having the long leg of the L secured to a prop member to position the short leg of the L in a vertical plane directed toward the side rail, a metal tray having a ilat base and upstanding side flanges, means pivotally securing opposite side flanges of the tray to the short leg of the L of each bracket, said tray having its inner end engaging under a step when in horizontal operating position, and an extension on the long leg of the L of each bracket extending underneath the tray to limit the movement thereof into horizontal position, and to take the weight off of the means pivotally securing the tray to the brackets when the tray is in horizontal operating position.

References Cited in the tile of this patent UNITED STATES PATENTS 1,107,440 Olson Aug. 18, 1914 1,592,109 Jacobs July 13, 1926 2,126,171 'Carbis Aug. 9, 1938 2,235,976 Best Mar. 25, 1941 2,294,333 Fay Aug. 25, 1942 2,533,391 Miller Dec- 12, 1950 2,899,008 Larson Aug. 11, 1959 3,005,513 Larson Oct. 24, 1961 3,016,103 Studer Jan. 9, 1962

Claims (1)

1. A STEPLADDER COMPRISING A PAIR OF SIDE RAILS EACH HAVING A WEB AND FLANGES FORMING A CHANNEL SHAPED CROSS SECTION, A PLURALITY OF DIMPLE FORMATIONS SURROUNDING BORES IN ONE OF EACH OF THE FLANGES OF THE SIDE RAILS, A PLURALITY OF STEP MEMBERS HAVING A WEB AND FLANGES FORMING A CHANNEL SHAPED CROSS SECTION, ONE OF THE FLANGES OF THE BOTTOM AND PENULTIMATE STEP MEMBERS HAVING A PLURALITY OF DIMPLE FORMATIONS SURROUNDING BORES AND A RIB PROJECTION, THE OPPOSITE ENDS OF THE STEP MEMBERS BEING POSITION AT SPACED INTERVALS IN THE CHANNELS OF THE SIDE RAILS SO THAT THE CHANNELS OF THE STEP MEMBERS OPEN IN A DOWNWARD DIRECTION, A PAIR OF GUSSET PLATES EACH HAVING A PLURALITY OF DIMPLE FORMATIONS SURROUNDING BORES COMPLEMENTARY TO THE DIMPLE FORMATIONS IN THE FLANGES OF THE BOTTOM AND PENULTIMATE STEP MEMBERS AND THE FLANGES OF THE SIDE RAILS AND HAVING A GROOVE COMPLEMENTARY TO THE RIB OF THE FLANGES OF THE STEP MEMBERS, MEANS SECURING THE FLANGES OF THE STEP MEMBERS TO THE FLANGES OF THE SIDE RAILS, AND INCLUDING MEANS POSITIONED IN THE BORES FOR SECURING THE GUSSET PLATES TO THE FLANGES OF THE SIDE RAIL AND THE FLANGES OF THE BOTTOM AND PENULTIMATE STEP MEMBERS, A RECTANGULAR SHAPED TOP STEP HAVING A FLAT BASE, END WALLS SUBSTANTIALLY NORMAL TO THE BASE AND SIDE WALLS ANGULARLY DISPOSED WITH RESPECT TO THE BASE DISPOSED OVER THE TOP ENDS OF THE SIDE RAILS, MEANS SECURING THE TOP PORTION OF SIDE RAILS TO THE END WALLS OF THE TOP STEP, A PAIR OF PROP MEMBERS, BRACE MEANS HOLDING THE PROP MEMBERS IN SUBSTANTIALLY PARALLEL RELATIONSHIP, AND ANTI-FRICTION BALL AND SOCKET MEANS PIVOTALLY SECURING THE PROP MEMBERS TO THE END WALLS OF THE TOP STEP, FOLDING SPREADER MEANS FOR HOLDING THE PROP MEMBERS IN A FIXED SPACE RELATION FROM THE SIDE RAILS, MEANS PIVOTALLY SECURING THE SPREADER MEANS TO THE PROP MEMBER AND THE RAIL MEMBERS, BRACKET MEANS SECURED TO THE UPPER INSIDE PORTION OF THE PROP MEMBERS, A TRAY PIVOTALLY SECURED TO THE BRACKET MEANS AND ADAPTED TO ENGAGE THE LOWER SURFACE OF THE FLANGES OF THE PENULTIMATE STEP, SHOE MEANS SLIGHTLY WIDER AND LONGER THAN THE CROSS SECTION OF THE SIDE RAILS AND PROP MEMBERS, AND MEANS SECURING THE SHOE MEANS TO THE BASE END OF EACH OF THE SIDE RAILS AND PROP MEMBERS.

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