US1641591A - Stepladder - Google Patents

Description

Patented Sept. 6, 1927.4

. UNiTED ysri-titres JOHN n. KALGREN, or MrNnnaroLrs, MINNESOTA, rtssrsno'n To anni .'r.y n.- CLARK oor,

or minnaar-oms, Mmnnsorii, A con-remarcar" or innamora. y i

f s'frnBrennan.`

Application led October 25, 1926. Serial NorlSQS. i

My present Ainvent-ion provides an. eX- tremely sim-ple but highly important im provement in step ladder construction and, generally stated, consists kofthe novel" devices and combinations of devices hereinafterY described Vand defined in theclaims.

1n certain ,well known step ladder structures, it has been the prac-tice to provide the ladder` bars with transverse' grooves, to seat the ends of the steps or treads in such grooves,to provide the treads on their under sides with longitudinally extended grooves running from end to end thereof, and to tie the said elements together by rods placed in the longitudinal grooves of the treads and extended through the ladder bars and anchored at their outer ends to the outside of the bars. only hold the ladder bars against spreading, but they hold the treads against edgewise displacement from the grooves in the ladder bars. An objection has been found to the above arrangement in that the treads, by their longitudinal grooves, are weakened at their central portions.

In accordance with my present invention, I provide the treads or steps at their ends only with grooves or channels to receive the end portions of the tie rods. This leaves the central portion of the treads complete and uncut and, hence, of maximum strength; and, moreover, as will hereinafter more clearly appear, the tie rods. by the manner of their application, are caused to form a truss and thereby very greatly reinforce the treads and greatly increase their loadcarrying capacity. 1n the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a side elevation showing a por! tion of a step ladder or the like designed in accordance with my invention, some parts being broken away;

Fig. 2 is a fragmentary view partly in front elevation and partly in section on the line 2-2 of Fig. l;

Fig. 3 is a fragmentarysection taken on the line 3--3 of Fig. 2;

Fig. 4: is a bottom plan View of one of the treads or steps, some parts being broken away; and

Fig. 5 is a section on the line 5-5 ot Fig. 4.

In such structures, the tie rods not The', numeral G; indicates the `ladder bars, the same being provided on their opposing faces withthe customary.grooves 7 that receive, the ends of the.woodenl treads or steps 8. As already indicated, these treads, fat

.their underfsides and at their ends, are pro` yvided with longitudinal grooves 9. The outer-extremities of these grooves, 9, ofcourse,

`entendiinto the grooves 7.: The tie. rods. l0

are extendedin the end grooves 9- and are passed through perforationsinthe ladder bars 6, as best shown in Fig; 2. The tie rods 10, as shown, have heads 11 at one end and` nuts l2 at their other ends. Large washers 13, in the one instance, are placed between the heads 1l and the ladder bars, and in the other instance between the nuts l2 and said ladder bars. lVhen the nuts 12 are turned so as to put the tie rods l0 under tension, Y

said rods will be slightly bent substantially' as shown in Fig. 2 and they will then not only tie the ladder bars against the ends ofl the treads and hold the treads against edgewise displacement, butl will truss and greatly strengthen the treads. VMoreover, as before indicated, the treads themselves are not weakened at their central portions but are left with their full initial strength.

By reference to Fig. 2, it will be noted that when the tie rods are drawn up and put under the customary tension, their central portions may not quite contactrwith the central portions of the treads. Nevertheless,

a very slight depression of the central porture discussed, but, on the contrary,'is capable of being produced at slightly decreased cost and the result of the changed structure is increased strength and durability. It is much the best practice to make ladder steps or treads wider than the ladder bars, and it is common to reduce the same by beveling the ends as at 8EL so that the eXtreme 1 ends will be of the same width as the ladderk bars. This beveling at 8a has hitherto always required a separate operation, and where a rod-receiving groove is cut from end to end of the step, the cutting of such groove required another independent operation. In the structure illustrated, the end grooves 9 and the bevels 8=11 are at the end portions only of the ladder steps and are so nearly co-extensive that both may be simultaneously cut simply by presenting the end of the step to a machine having two simultaneously running cutters. 'Moreoveig the short end grooves 9 may be cut much more quickly than a complete groove and the major portion of the step is left intact, that is, ungrooved and of maximum width.

IVhat I claim is:

1. A ladder comprising ladder bars, interposed `treads and transverse tie rods, said treads' having relatively short grooves at opposite ends thereof terminating abruptly at their opposed ends, and said tie rods anehored in said ladder bars and extending through said end grooves and engaging the end walls thereof, whereby said tie rods are sprung out of engagement with the major Lei/ineeni portion of the respective treads in tying the parts together.

said grooves, treads seated at their ends in the grooves of said ladder bars, said treads having short grooves at opposite ends thereof which register with the grooves in said ladder bars at one end and terminate in relatively Asteep inclined walls at their opposite ends, andtie rods supported in the perforations in said ladder b'arsand extendn ing through said tread end grooves and engaging the inclined end walls of said grooves, whereby the tie rods are caused to arch below and out of contact with the major portion of the respective treads in tying the parts together.

In testimony whereof I affix my signature.

JOHN E. KALGREN.

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