US749070A - Extension-ladder - Google Patents

Description

No. 749,070. PATENTED JAN. 5, 1904.

M. J. LEWIS. n

EXTENSION LADDER..

P O T I 1 0 No MODEL. AP LI A ION ILED APB 20, 9 3l `UNITED STATES Patented January 5, 1904.

PATENT OFFICE.

EXTENSION-LADDER.

SPECIFICATION forming part of Letters Patent No. 749,070, dated January `5, 1904.

Application filed April 20. 1903.

To @ZZ whom, it may concern:

Be it known that I, MELVIN J. LEWIS, a citizen of the United States, residing at Ypsilanti, county of W'ashtenaw, State of Michigan, have invented a certain new and useful Improvement in Extension-Ladders; and I declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification.

This invention relates to extension-ladders, and has for its object an improved attachment to be used in connection with the parts ot' an extension-ladder by means of which the ladder under certain conditions is automatically lockedin an extended position, and under other conditions the locking device is automatically held in position not to engage in its locked position, but to allow the two parts of the ladder to slide together or telescope.

In the drawings, Figure l is a front elevation of ,a two-part extension-ladder. Fig. 2 is a detail elevation (the rungs in section) showing the attachment. Fig. 3 is a detail elevation showing theattachment in position to lock the two parts of the ladder in an extended position.

In Fig. 2 the attachment is shown in full lines in the position it assumes When the parts are telescoping. In dotted lines in the same figure the attachment is shown iu the position its parts assume when the ladder is extending and will soon take a position to be locked.

In Fig. 3 the guard-piece is drawn over slightly beyond the position it would naturally assume.

The two parts of the ladder are arranged to be slidingly held together by any suitable means. The one part, A, has shorter rungs and is a narrower ladder than the part B, and the side bars of the ladder A engage between the two side bars ct and ZJ of the ladder B and are held in place by any suitable device.

0n the side bars c and d of the ladder A are pivotally secured hooks and guards. There is one hook and one guard on each side bar. The hook l is pivoted by a bolt 2,

that passes into theside bar and through an Serial No. 153,393. (No modell) overhanging guard-bracket 3. The hook is provided at its hanging end or lower end with an arm 4, in which there is an arched slot, arched concentric with the bolt 2, and below the arched slot, at one side, is a horn 5,-that is capable of swing 'ro engage over any one of the rungs 6 of the ladder B. Below the hook and on the side bar of the ladderA is a guard device 7, having a weighted end 8 and a guard-arm 9. The guard 7 is pivotally secured to the side rail by a bolt l0, and normally it swings with its Weighted end down and with its guard end up. When the ladder is extended, the weighted end 8`of the guard drops and the guard end 9 swings forward into engagement with the horn 5. When in this position, the two parts of the ladder may be moved in either direction, and especially the)T may be moved to close the ladders together, as the rungs 6 will pass the end of the hook and the end of the guard-arm without obstruction. If, however, the part B has been drawn up until the rung 1l rises some distance above the rung l2, the upper end of the arm 9 swings slightly backward, and when the rung ll approaches the rung 6 the point of the guard 9 engages behind the rung 6. The guard turns on its pivot and the position of the guard is reversed, and it is no longer in position to prevent the horn 5 from swinging to the rear beyond the line of travel of the rung 6, and a slight closing movement of the two parts of the ladder causes the horn 5 to engage over the rung 6, and the parts can be closed no further together, but are locked in their extended position. If it now be desired to close the-parts of the ladder together, they are carefully distended for a distance until the guard 9 engages under a rung, which we will suppose to be the rung l2. Although at the commencement of the movement the parts are in the position shown in Fig. 3, the parts are distended until the end of the arm 9, engaging under the rung 6, is turned to the position shown in dotted lines in Fig. 2, which is the position it assumes as it passes above the rung. At this time the horn 5 has not yet reached a position to swing back over the rung, but is in the position shown in dotted lines in Fig. v2. Immediately after the end 9 ot the guard rises high enough to clear the IOO rung 5 it swings by and swings under the rung (i and againstthe horn 5, and from this position the two parts of the ladder may now be drawn together, as each rung that engages successively against the guard on its downward travel serves to hold it with its end against the horn 5 and causes it to prevent any locking action on the downward travel.

What I claim is 1. In an extension-ladder, the combination of a hook pivoted to one part provided with an arm furnished with a slotted arch concentric to the pivot and with a horn projecting beyond the arm, a pin through said slot, a guard-piece pivoted to the ladder, provided with a guardarm arranged to engage against the horn of the hook and with a weighted end counterbalancing the guard-arm arranged to hold the guard-arm normally in contact with the horn, substantially as described.

2. In an extension-ladder, the combination ofa hook pivoted to one part thereof provided with an arm extending to the side and a horn projecting beyond the arm, aguard-piece pivoted to the ladder provided with a guard-arm arranged to engage against the horn of the hook and with a weighted arm counterbalancing the guard-arm and arranged to hold the guard normally in contact with the horn, substantially as described.

In testimony whereof I sign this specification in the presence of two witnesses.

MELVIN J. LEWIS.

Witnesses:

EDWARD B. ALLEN, TRACY L. TOWNER.

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