US514020A

US514020A - mclaren

Info

Publication number: US514020A
Authority: US
Publication date: 1894-02-06
Anticipated expiration: 1911-02-06

Description

(No Model.)

J. R. McLAREN, Jr.

EXTENSION LADDER.

No. 514,020. Patented Feb. 6, 1894.

fig l. E192. ,42 /d '3.

NITED STATES Brion.

JOHN ROBERT MOLAREN, JR, OF BURLINGTON, VERMONT, ASSIGNOR To SARAH B. MOLAREN, OF sAME PLACE.

EXTENSION-LADDER.

SPECIFICATION forming part of Letters Patent No. 514,020, dated February 6, 1894.

Application filed February 28, 1893. Serial No. 464,078. (No model.)

To a/ZZ whom it may concern:

Be it known that 1, JOHN ROBERT MoLAREN, J r., a Canadian, subject of the Queen of Great Britain, residing in Burlington, in thecounty of Ohittenden and State of Vermont, have invented certain new and useful Improvements in Extension-Ladders; and I do hereby declare that the following specification, taken in connection with the drawings furnished and forming a part of the same, is a clear, true, and complete description of my invention.

Many extension ladders have been heretofore devised, and certain classes thereof have been constructed and organized for heavy service, as for fire duty, and some others have been specially adapted to light duty and household service, this latter being thetype to which my invention pertains.

The objects of my improvements are to secure in such ladders, reliability, durability and strength, without undue weight, and to provide for convenience in manipulation and adjustment, as for service, and also for economical construction, and to these ends, I employ a base ladder section, provided as heretofore, with rungs or foot bars, secured to both edges of both side rails or stiles, so as to afford an interior housing space, for the reception of extensible section of the ladder when not in use; and said stiles are also, as heretofore, longitudinally grooved at their inner sides. In myladder the rings or rounds of the extensible ladder section, are projected at their ends through holes in and beyond the outer surfaces of their stiles or side bars, so that said ends occupy central grooves in the side bars of the base section, and not only serve as guiding studs, but also as looking studs with which appropriately located locking pawls may engage, for longitudinally securing the two sections, as for service, at any desired degree of extensible adjustment. These locking pawls are provided with springs which render them automatic in their engaging action, and they can be simultaneously disengaged. Two of such pawls are employed, one on each of the base section stiles, but mechanically coupled together, and provided with a hand line, ac-

cessible at the foot of the ladder, so that the pawls, when necessary, may be readily released from engagement, without requiring the raising or lifting of the extensible section.

The ladder sections may be readily set to any desired length, whether held vertical, horizontal, or inclined, by means of an endless hoisting line, carried on grooved pulleys, mounted on the base section, said line being secured to and near the foot of the extensible section, and well housed against wear, in a groove, at the inner side of the base section stile, in line with its pulleys.

To more particularly describe my invention, I will refer to the accompanying drawings, in which Figure 1, is a front view'of-one of my ladders, shown to be partially extended, and partially'in section, for disclosing the looking pawls. Figs. 2 and 3, are edge views of the same. Fig. 4, is an enlarged cross-section of the same, on line as. Fig. 5, in section, illustrates a reinforcement of the rungs of the extensible portion of the ladder, as is sometimes desirable.

The extensible ladder here shown, embodies a base A, and an extensible section B, it being understood that certain portions of my invention are restricted to a ladder having two sections only, and that other portions of my invention may be embodiedin the combination of the lightest or top section, with the next lower section, whether this latter be a true base, or an intermediate section, serving as a base to the upper section. The base ladder or base section A, has two stiles or side rails a, a, and numerous rungs or foot bars I), and b, firmly secured to the front and rear edges of the stiles, and afford-ing as heretofore, an interior space for the reception of the extensible section B. Both stiles, at their inner sides, as heretofore, are longitudinally grooved, as at 19 these grooves being located centrally. The stile a, is however also provided at its inner side, with another longitudinal groove at b located at the one side of the groove b The extensible ladder section B, has two stiles c, c, and the rungs d, are tenoned therein with their ends (1, projecting beyond the outer faces of the sides of the stiles, and these ends occupy their respective grooves 12 in the stiles of the ladder base. An endless hoisting line e, is carried on two pulleys e, e respectively near the top and bottom of the groove 19 in the stile a of the base, and said line is secured near the foot of the extensible section B to its stile c, as at a As thus far described, it will be seen that the rung ends (1, in occupying their grooves, perform a guiding function independently of the two sets of foot bars I), and b, on the base section, and that said rung ends when the ladder is extended, will co-operate with the stiles of the base section in affording reliable union of the two sections in resisting weight bearing strains, regardless of the means by which the two sections maybe locked in their extended adjustment. These rung ends d, also serve as reliable locking lugs or shoulders, with which the automatic locking pawls f, f, engage, so that the extension of the ladder may be Varied and adjusted with reference to each rung d. These locking pawls f, and f, are respectively housed in the stiles a, and a, at proper points near their tops, and each pawl has at its upper end, a suitable bearing seat with which the rung ends 01', may engage in supporting contact; and at its base, each pawl has a pivot bolt d the adjacent underlying portion of the stile being so shaped, that should the bolt or stud get broken while the ladder is in use, the pawl will still reliably perform its supporting duty. Each pawl has a spring g, for throwing its upper end inwardly, for securing the automatic locking action of the pawl. For simultaneously releasing both pawls, each is provided with an outwardly projecting arm f near its base, and both of said arms are connected by links f f with the arms of a rocking lever h, which is journaled at the two edges of the stiles a, and a, so that by pulling downwardly upon the releasing line h, which is secured to one of said lever arms, both pawls will be released from their locking duty, in whatever position the ladder may be, and without requiring any preparatory lifting or moving of the extensible section.

It will be seen, that the pawls may operate at each rung, thus enabling the ladder to be readily adjusted to particular heights, which is an important feature in household duty,

and that however adjusted the union of the two sections will be strong and reliable, and that the ladder as a whole, can be very economically constructed without undue weight, or sacrificing durability.

In some cases, I deem it desirable to reinforce the rung ends, for not only securing them against undue wear, as from contact with the pawls, but also to add to the strength of the structure when extended. 7

As shown in Fig. 5, the ends of the rung d, are provided with split metal ferrules or sleeves (1 so that on properly driving the usual endwise wedges into the wooden ends of the rungs, the ends will not only be tightly expanded within the sleeves, but the latter will be also tightly expanded in the holes in the stiles, thus afiording a specially strong light ladder, and avoiding undue wear by contact with the locking pawls. Such reinforced rungs may usually be restricted to the three or four projecting ends nearest the foot of the extensible section.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- In an extensible ladder, the combination of a suitable base section, having stiles centrally grooved longitudinally, at their inner sides; an extensible section, or ladder, having rungs which are tenoned in, and have their ends projected through their stiles, and occupy the central grooves in the stiles of the base section; a pawl, pivoted upon each base section stile, projecting into its groove, and provided with a spring, and also with an outwardly projecting arm; a rock shaft and links connected with the projecting arms of both pawls; a pawl releasing line connected with said rock shaft, and an endless hoisting line carried on one of the stiles of the base section, connected with the extensible section, and housed in a groove provided for it at the inner side of one of the base section stiles, substantially as described.

JOHN ROBERT MOLAREN, JR.

Witnesses:

H. G. BENDER, CHAS. HoLDsTooK.