US2162040A - Ladder construction - Google Patents

Description

June 13, 1939. w. M. WEBSTER I LADDER CONSTRUCTION 2 Sheets-Sheet 1 Filed Feb. 28, 1938 HUU L:

11v VENTOR ATTORNEY June 13, 1939.

W. M. WEBSTER LADDER CONSTRUCTION Filed Feb. 28, 1938 2 Sheets-Sheet 2 W// a MET Z 9 4 e 5 er BY ATTORNEY Patented June 13, 1939 UNITED STATES PATENT orr cs 4 Claims.

This invention relates to an extensible step ladder.

Among the objects of the invention are, to provide a step ladder in which either one or both of the swingable ladder units can be adjusted in a dependable manner as to its length, thus adapting the ladder to be used upon uneven ground to a better advantage than other ladders now on. the market and also to be used advantageously when one or both of its units are to be placed'upon the steps of'a flight of door steps or of a stairway; to provide a superior means for hinging together two swingable ladder units; to provide an improved twin extension ladder in which said two ladder units can be more readily detached and used independently of each other; and to otherwise improve upon prior step ladder constructions, as. will hereinafter more fully appear.

The present invention relates to an improvement, in certain particulars, upon the combination step and extension ladder described and claimed'in my copending application Serial No. 120,238, filed January 12, 1937, now Patent Number 2,133,003.

Referring to the accompanying drawings, which illustrate what is at present deemed to be a preferred embodiment of the invention,

Fig; 1 is a perspective view of "the complete structure as used for an extensible step ladder.

Fig. 2 is a side elevation of the upper portion ofthe structure shown in Fig. 1.

Fig. 3-is a plan view of the top portion of the structure shown in Fig. 2.

Fig. 4 is a fragmental view of the step ladder structure showing the same slightly modified and forming part of a scaffold or trestle.

Fig. 5'is a sectionalview on line 5-5 of Fig. 4.

Fig. 6 is a section on line 6-6 of Fig. '7, showing the invention in use as extension ladders forming a part of a lean-to trestle.

Fig. '7 is a front elevation showing the upper portions of both the twin ladders forming the supporting means of Fig. 6.

Fig. 8'shows, in side elevation, two of the ladders in use in a self-supporting trestle structure.

Fig. 9"is an enlarged sectional detail, the line 99 on Fig. 1 indicating the plane of section.

Referring in detail to the drawings, the structure as a whole comprises the two units 3 and 4; eachof which embodies, in a general way, the entire structure set forthin my copending application hereinbefore referred to. Hence each of said units comprises the ladder sections 5 and 6 formed by theside rails. 1- and 8 respectively, the

steps 9 and I0 being secured between said rails. Each rail 8 is furnished with a socketed orrecessed casting II which is secured to the upper end portion of each rail 8 by rivets l2 or in some other suitable manner; and each of the other rails I has attached to its upper. end portion a male casting member 13 which cooperates with the first recited members both to keep the two ladder sections in anattached relation tov each other and to limit properly the outward swing of their foot' portions.

The socketed attachments H are furnished with attaching plates I la which overlie the inner sides of the side rails 8. Said plates Ila. by preference and as shown, are of a rim.-like arcuate character enclosing a considerable open area I lb. Each male member I3 is furnished with an attaching arm or plate l3a which is secured to the outer side of the rail I at its side of the ladder;

Describing first the detailed construction of the male ladder head 13. its-attaching arm l3a is furnished at its upper end with a laterally extending stop arm IS the base portion of which, preferably amounting to about half its length, fits within a groove I6 being desirably made approximately rectangular in cross-section .within said groove. Said stop arm is furnished with an inner end portion I! which cooperates with the socketed end of member 1, as will hereinafter be described. Said 'male member [3 further is furnished with a bracket or extension 20 having an angularly directed base portion 2| which seats upon the adjacent edge portion of the rail to which the male member is attached, and which is integral with the arml3a already described.

The member l3 has a right angular extension I 39: which overlies the outer edge of the rail 1 thus stabilizing the male member I3 in its relation to the ladder.

'An attaching rivet 22 is shown extending through the arm 13a. The outer end of the extension 20 is furnished with an angular flange 24 which projects oppositely to the base portion 2| of the extension. When each ladder is in an upstanding position with its foot portions separated as far as possible said flange 24 abuts against the adjacent edge portion of the rail 8 to arrest farther separation of the foot portions of the ladder. The extensions or flanges 24 and I311; at opposite ends of the male'member cooperate to secure this result; The male member I3 is shown furnished at about its midwidth with an angularly disposed reinforcing rib 25 which extends along a portion of the inner part of the arm l3a and thence up over the extension 20 across the outer side of the angular flange 24. The part 26 of said reinforcing rib which overlies the outer side of the angular flange 24 is shown engaging the inner angle of said flange 24 and tapering to a point as it approaches the outer edge of said flange 24.

Referring to another detail of construction. The angular stop flange 24 of the male member has an upper flange portion 24a which glides V smoothly over the adjacent edge portion of the rail 8 against which this part of the flange abuts when the ladder is being extended or retarded as an extension ladder. Hence the two flange portions of the part 24 abut in a flatwise manner with the edge of the rail either as a stop means or for reducing sliding friction.

Each socketed member II has at its inner side an attaching flange which overlies the edge portion of the rail 8 and said socketed member hasialso: an'inwardly. extending flange 3!, the

latter flange extending across the top surface of the rail to which said member is attached. These flanges 30 and 3| are both straight and join each other at an acute angle as shown. Above the flange 3i thesocketed member is furnished with a top flange 33 in parallel spaced relation to'the flange'3l thereby forminga groove32 the width of which is somewhat greater than the diameter ofithelstop arm' l5 of the male member; Said groove is opened atone end and at'its opposite end is furnished with a stop wall 34 to limit the sliding movement of the stop arm l5 of the male "member which travelsalong said groove. When the. foot portions of the ladder are swung as far apart as possible, said stop arm will engage said stop wall simultaneously with the engagement of thev flange 24 of the male member with the edge portion ofthe rail of the ladder with which it cooperates, thus affording a stable and depend- Table limited movement i of the foot portions of the ladder with 'relationto each other- It is to be understood that the arrangement of the cooperating rail .and socketed members which have been described will be duplicated at opposite sides of the top portion of each ladder.

'The. socketed members ll each have a flange portion 36 at the top of the ladder as shown in my aforesaid co-pen-ding application, but in the present improvement an extension 42 is added to this flange part .36, said extension "having through it a'slotted bolt aperture 43, and pref erably having also an upstanding portion 31 which protects the ladder from wear when'restingjagainst a wall. A reinforcing flange. 38 is shown below the top flange 33 at'the' opposite end thereof which is provided with an overhangingportion. In the completed ladder it is possible to swing the stop arms of the male members out of the ends of the grooves 'of'the socketed members with which they cooperate and thereby permit the extension of each ladder as shown in Fig. 8. It is impossible to separate the two ladder sections 5 and 6 from each other except in an endwise manner. 40 designates a pivotedstop member whereby the upper section of each ladder when used as an extension ladder is prevented from'sliding downwardly overthe other section while the ladder is in use. 'A construction is thus provided whichwill not allow the structure to function as a step ladder until the stop arm l5 comes to the proper position to slide into the socketed member;

The pivotally mounted, gravity controlled stop device 40,- when present in the extensibletwin step ladder combination shown in Fig. 1, produces a cooperation between the ladder structures 3 and 4 which enables the user to quickly adjust the structure as a whole for use in a situation where one unit (3 or 4) requires adjustment to a length which may differ widely from that of the other. 7

The foot portions of each ladder cannot be swung apart when the ladder is in any degree extended because the stop arm l5 and guide extensions l3a of each male member travel upon the track afforded by the rail between them and the rungs 9 also afford an auxiliary guide means and support for the rails 8 when each ladder is used as an extension ladder.

The top flange 33 of the socketed or female member is shaped with a flat upper face to support a platform 4| against one side edge of which the upstanding flange 31 of said member abuts.

The stop device 40 comprises a main pivotal at one side by which is pivotally supported a weighted dog 400,.the pivot 40d of said dog being located between its weight W and tongue N. Oneof the rungs ID of the ladder rails 8 (to one of which rails said device 40 is pivoted) will always cooperate with the extension 43b to limit the gravitational swing of the device so that it will. properly engage the desired rung. 9 of the lower ladder rails 1, when operated in the proper manner." A downwardly directed ear 40:: at the side of the device opposite to its aforesaid 'ex tension 40b adds to the cer'titude of its operation.

If the upper ladder section'is lowered by a continuous downward movement the tongue N of the dog will be caused to incline upwardly as it moves down upon each rung 9 and will cause the pivoted device 40 as a whole to glide over each rung 9 with a swinging movement. Likewise a continuous upward" movement of the rails 8 will not be interfered with by the dog 49. If, however, such upward movement be stopped just before the dog tongue N clears a given rung 9, then a slight downward movement of the ladder section being raised will permit the dog ear 49a to glide back over the rung 9, and the dog will come to the stop position shown in Fig. 9. 7

In order to. construct the lean-to trestle structure shown in Fig. 6 the two step ladders 3 and 4'shown in Fig. 1 are'detached from each other, the hinge bolt 44 being first removed to permit this to be done. Each step ladder is then extended to support the trestle walk or platform. 45 at the desired height, said walk resting upon the lower platforms 49. 'One of these extended ladders is'shown in Fig. 6 and the showing in Fig. '7 indicates that at least two cooperating extended step ladders 3 and 4 are used to support the platform portion 45 of the structure. Each of these ladders has connected to its upper portion a knee-brace 46 by means, for example, of a hook 4! connected to a ladder rung, the upper end of saidknee-brace being connected to a depending lug 48 carried by the inner portion of the platform 49. Each platform 49 also has depending outer lugs 50 and these are each connected with one of the step ladder extensions 36 by means of any suitable fastener, for example a pin or bolt 5|.

Fig. 8 shows a self supporting trestle structure wherein the two step ladder assemblies 3 and 4 are both extended and the plank rests upon them, being securely held in place by two kneebraces 56 and 51 while, lower down in the structure one or more tie members 58 are used below the mid-height of the structure to keep the extended step ladder assemblies from spreading apart. Caster wheels 60 are shown under the foot portions of the structure to provide for wheeling it about, as described.

I claim:

1. A ladder construction comprising two step ladders, each of said step ladders being convertible into the extension type ladder, and a pair of laterally projecting bracket arms carried by the top portion of each of said step ladders, there being a platform overlying a portion of each of said pair of bracket arms, and means to detachably connect together that portion of each pair of bracket arms which projects beyond the platform at its side of the connected step ladders.

2. A ladder construction comprising two step ladders, each of said step ladders being convertible into the extension type ladder, and including a pair of laterally projecting bracket arms carried by the top portion of each of said step ladlers, there being a platform overlying a portion of each of said pair of bracket arms, and a hinge pin to detachably connect the portion of each pair of bracket arms which projects beyond the platform at its side of the connected step ladders, to the corresponding projecting portion of the other pair of bracket arms, said projecting portions of said pairs of bracket arms being formed as hinge-wing members.

3. A ladder construction comprising two step ladders each of said step ladders being convertible into the extension type ladder, and which when converted into such a ladder has its most upwardly extending section furnished with a pair of brackets adapted to support a platform, each member of said pair of brackets having formed on it a hinge-wing member, and means to couple together said pairs of hinge-wing members.

4. A ladder construction comprising two step ladders, each of said step ladders constituting a unit which is convertible into the extension type ladder and including two cooperating sections which are swingably connected to each other only when in the completely retracted relation, one of said sections of each of said units being surmounted by a pair of brackets which constitutes a hinge element of the construction whereby said sections are swingably connected to each other, said pair of brackets of each of the aforesaid ladder units having a laterally projecting pair of hinge-wing members formed upon it, and means to connect together said pairs of hingewing members thereby forming a unitary ladder structure.

WILLARD M WEBSTER.

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