US2610875A - Extension ladder - Google Patents

Description

Sept. 16, 1952 H. L. WHEELDEN EXTENSION LADDER Filed March 26, 1948 INVENTOR. 117i Wee/dz BY Patented Sept. 16, 1952 TENT QFFICE EXTENSION LADDER Harry L. Wheelden, Bangor, Maine. Application March 26, 1948, Serial No. 17,149

1. Claim.

This; invention. relates toextensionladders. and particularly to that type. of extension ladder wherein the. longitudinalside .members or. up.- rights thereof. arev telescoped in, idlecondition of the ladder.

The main object of; the invention is to, provide an, extension ladder of, simple, effective and economical construction, which may be made of metal, plastics or other suitable material, and be certain and eliective in operation despite the simplicity of its construction, a

Another object is to. have a special extension ladder wherein the. longitudinal side members or uprights are, tubular and telescope when collapsing the ladder.

A further object is to have.- such an, extension ladder providedwith automatically-engaged supporting catches or latches which retain the lad.- der sections in extended position when the ladder sections are drawn or. pushed apart. 7

It is also an object to have the extension ladder provided with manually-operated release members for releasing the extended ladder sections and allowing telescoping or. collapsing thereof. I

Other objects and advantages will be more fully disclosed hereinafter as thefspeoification proceeds.

In order to bring out comprehensively the features of the invention, thelatter is illustrated in the accompanying drawings forming a part hereof, and in which:

Figure 1 is a front elevation of an extension ladder embodying the invention in a practical form and displaying the. salient features there- Figure 2 is, a side; elevation of the same extension, ladder;

Figure 3 is an enlarged fragmentary section taken on line 33 of Figure 1;

Figure 4 is also an enlarged fragmentary sectiontaken on line 4-4 of Figure 1.

In the four views, the same referencenumerals indicate the same or like parts. I

Extension ladders are veryconvenientin many situations and frequently a necessity, being used in emergencies and especially at, fires and other disasters. Such, ladders, are all too often. bulky and unwieldy, expensive, and-far from simple in construction and operation, and by virtue of such dra-wbacksysometimes. defeat: the very purpose of their use. Moreover, such. ladders are almost always-made inlarge sizes. and are thereforelimited in their field of use.

However. by adopting a new approach to this and thus even tend to displace ordinary stepladders, as will immediately bedescribed in detail.

Hence, in thepractice of my invention, and referring now again to the drawings, the ladder, generally indicated at 6, primarily includes a main ladder section indicated at l and a secondary or upper extensible ladder section 8 connected thereto in special manner. The longitudinalside sections or uprights 9, 9 of the main ladder section 1 are split upon their inner facing sides, by an, open longitudinal slot ID for a purpose which will presently appear. Linking the two uprights 9, 9 are a series of steps or rungs H, II having theupper edges thereof doubled over at I 2, 12 to reinforce. the same and render them rigid, the ends of the rungs being riveted, brazed or welded to these uprights close to slot In on each member 9. Obviously, the ends of the rungs could terminate in tongues or lugs extending downwardly through slots in the inner sides. of the. ladder uprights, or any conventional con.- nection between the ends of the rungs and the uprights may be used.

In the ladder as actually illustrated, the uprights 9 are tubular and hollow, and although shown round, they may, of course, be oval, square or rectangular in section, if desired, but in any case, into these hollow members project tubular uprights, l3, l3 of secondary ladder section 8 provided with, rungs or steps I 4, I4 having the reinforced; upper edges I5, l5 similar to rungs H with their upper edges [2 already described, and preferably riveted, brazed or welded at their ends to the uprights [3 just described. These last-mentioned rungs at points adjacent to their ends have clearance slots I6, I 6 of sufficient length to allow for the thickness ofthe metal or other wall ll of main ladder upright 9, as best seen in Figure 4- 0n the other hand, the single, thickness of' the metal remainingof rungs [4 at the slotted portions IE is accommodated by open longitudinal: slots ill in uprights 9 of main ladder sections 1, these rungs sliding down into the slots when the upper ladder; section 8 is allowed to descend into collapsed or coextensive relation with main section 1.

In order to retain the extension attained by the secondary or upper ladder section 8" when raising the same, the stiles 9 of the main section 3 a'reindividually provided with pendent, triangular latch heads l8 on the lower ends of resil- 3 ient arms I9 extending longitudinally of the stiles secured at their upper ends by rivets or screws to the stiles and tensioned toward the stiles so as to urge the latch heads inwardly. The inwardly positioned, inclined working faces 2| of the latch heads terminate at their upper ends at the inward ends of the right-angular transverse locking faces 22. The latch heads normally project inwardly through slots 23 in the stiles 9 and into slots 24 in the stiles 13 of the upper ladder section 8, with the locking faces 22 of the latch heads engaging with the tops 25 of the slots 24. The arrangement is such that as the upper ladder section 8 is raised while the main section remains on the ground, the inclined working faces 2| of these latches slide over the front surfaces of uprights 13 of the secondary section and jump out of slots 24 in succession in the manner of a ratchet action until the secondary section has been raised to the desired position. At this point, the upper resilient tail portions I9 of the latches force the latter into the final slots 24 to retain the upper ladder section in its raised position. This, however, does not prevent further extension of the ladder as the ratchet action of the latches in slots 24 while looking the upper ladder section in an attained position, automatically releases the same for further extension. The engagement of the latches 'in the mentioned slots is thus automatic and is arranged to be released by special means for collapse of the ladder.

In other words, in order to release the latches from engagement with the slots 24 in the upper or secondary ladder section, and allow the ladder to descend into the telescoped idle position with respect to the main or lower ladder section, the uprights 9 of the ladder also carry individual release sliders 26, 26 slidably mounted in guides 21, 21 secured to said uprights by rivets or screws 28, 28. The lower ends of the sliders are furnished with finger pieces 29, 29 by which to manipulate these members, while at an intermediate pointon each slider is a stop 39 projecting therefrom and preventing it from' accidentally dropping out of the guides. The upper end 3| upon each slider is inclined and abuts the inclined working face 2| of the respectively adjacent latch IB, but normally does not interfere with the regular operation of the latches in holding the upper ladder section in attained raised positions.

When the upper ladder section is to be lowered, however, the latches are released by pushing the sliders 26 upward by means of finger piece 29,

which will push the latches sufiiciently far out of slots 24 to clear the latter and the upper ladder uprights I3 and allow the ladder to telescope into lower uprights 9 while rungs H! of said upper section enter slots Ill and pass some'of the rungs H of the main ladder section 1.

As indicated in Figures 1 and 2, a further ladder section 3| could be added to the ladder in order to lengthen the same, and in this case the secondary ladder section 8 is provided with latches and release sliders as before so that the further ladder section is controlled thereby even as section 8 is supported or released by the latches I8 and released by sliders 26. The latches and sliders on section 8 are given the same references as those which were described for the main ladder section 7.

Due to the compact structure which results when the ladder sections are collapsed or tele- 4 scoped, the entire ladder is portable and readily placed beneath small trees out in the country or in orchards or within buildings or against the latter and readily extended as required.

From the foregoing, it is evident that the extension ladder described is both simple, compact and effective in construction and operation, and involves no complex manipulation or difliculties, but operates smoothly to be quickly extended and used or to be as quickly telescoped or collapsed and put aside until again needed for use.

Manifestly, variations may be resorted to and parts and features may be modified or used without others within the scope of the appended claim.

Having now fully described my invention, I claim:

In combination, an outer member, an inner member, means assembling said members for longitudinal movement relative to each other, said outer member being formed with an opening exposing a side of said inner member,'a longitudinal resilient latch arm secured at one end to said outer member, said latch arm being tensioned toward said inner member, a latch head on the other end of said latch arm yieldably held in said opening by the tension of said arm, said latch head having a transverse locking face on one end thereof and a cam face, said cam face being inclined with respect to the longitudinal axis of the latch arm, said side of the inner member being formed with longitudinally spaced slots into which said latch head is adapted to be selectively engaged so as to lock the outer and inner members against longitudinal movement relative to each other in one direction, the inclined cam face of the latch head being arranged to be engaged by an edge of a slot in the inner member upon relative longitudinal movement of the members in the opposite direction whereby the latch head is cammed out of the slot in the inner member so as to permit further relative longitudinal movement of the members in said opposite direction, said outer member having a slider mounted for longitudinal movement therealong at the end of the latch head remote from the transverse locking face thereof, said slider being normally out of contact with the latch head and being movable along the outer member to engage the cam face of the latch head so as to cam the latch head out of a slot of the inner member and free the outer and inner members for relative longitudinal movement in either direction.

HARRY L. WHEELDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 346,575 Bailey Aug. 3, 1886 514,020 McLaren Feb. 6, 1894 575,759 Perkins Jan. 26, 1897 657,932 Gardner Sept. 18, 1900 700,343 Lincoln May 20, 1902 783,773 Brown Feb. 28, 1905 839,297 Kennedy et a1. Dec. 25, 1906 918,062 King Apr; 13, 1909 1,595,450 Christian Aug. 10, 1926 2,363,520 Fish Nov. 28, 1944 2,380,632 Cousino July 31, 1945

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