US783292A - Extension-ladder. - Google Patents

Description

No. 783,292. 'PATENTED FEB. 21, 1905. F. R. LEWIS.

EXTENSION LADDER.

APPLICATION FILED JAN 21 1904 Elwuewifoz friend R. 136M C1 iter/"M10.

UNTTED STATES Patented February 21, 1905.

PATENT EETEE.

FRIEND R. LEWIS, OF SCRANTON, PENNSYLVANIA, ASSIGNOR OF ONE-HALF TO FREDERICK T. BARROWMAN, OF SGRANTON, PENNSYLVANIA.

EXTENSION-LADDER.

SPECIFICATION forming part of Letters Patent No. 783,292, dated February 21, 1905.

Application filed January 21, 1904. Serial No. 90,00

To a who/n it may concern.-

Be it known that I, FRIEND R. LEWIS, a citizen of the United States, residing at Scranton,

in the county of Lackawanna and State of Pennsylvania, have invented certain new and useful Improvements in Extension-Ladders; and I do hereby declare the following to bea full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in ladders, and particularly to extension-ladders which are capable of adjustment, so as to reach various heights.

The invention consists in an extension-ladder provided with ladder-sections, lockingpawls carried by the ladder-sections, and releasing-cams used in connection therewith and carried by one of the ladder-sections.

The invention also consists in an extension step-ladder formed with telescoping laddersections and telescoping leg or supporting sections, the said ladder and leg sections being provided with locking-pawls and releasepawls cooperating with each other.

The invention further consists in certain other novel constructions and arrangements of parts, as will be more fully described and claimed.

In the accompanying drawings, Figure 1 is a central vertical longitudinal section through an extension-ladder constructed in accordance with the present invention. Fig. 2 is an enlarged detail view showing the ladder-sec tions in such a position that the release-cams will carry the locking and supporting pawls past the shoulders which they normally engage. Fig. 3 is a similar view showing the position of the cam as it lifts the locking and supporting pawl. Fig. 4 is a detail perspective view of one of the locking and supporting pawls, the bracket carrying the said pawl being also shown.

The present invention is designed to supply a sectional extension-ladder which may be raised and lowered and altered in length at will by merely putting it in proper position and raising the sections sufficicntly to lock or release, as the case may be, the supportingpawls of the ladder-sections.

While the invention is applicable to ladders of all kinds, I have illustrated it as applied to a step-ladder and will proceed to describe the novel features of my invention referring to the illustration.

1 in the drawings represents a ladder the step or ladder portion of which is formed of a plurality of sections, as 2 and 3. Section legs or supports 4 and 5 are also provided and connected, by means of hinges, to the upper end of the step portion. The ladder-sections 2 and 3 may be provided with rungs or steps, as 6 or 7 of any usual or ordinary type, as shown in Fig. 1. The lower ladder-section 3 is adapted to slide upon the upper laddersection 2 and is provided with guide-plates 8, which engage the sides of the upper laddersection 2. The inner ends of these guideplates are turned inwardly, so as to engage the under edge of the upper ladder-section and prevent the separation of the laddersections, while permitting of their longitudinal movement with respect to each other. The upper section 2 is also provided with guideplates, as 9, bent inwardly at their outer ends, so as to engage the sides of the lower ladder-sections in the same manner as just described with respect to the plates 8. One of the ladder-sections, preferably the upper one, 2, is formed with notched or shouldered portions 10, which are engaged by locking and supporting pawls 11, carried by the other ladder-section, 3. The pawls 11 are pivotally secured to each side of the laddersection 3 at their lower ends, and their upper ends are free to rest against the outer edge of the upper ladder-section 2. When the ladder-section 3 is drawn outwardly a sufficient distance to permit the pawl 11 to drop beneath one of the shoulders 10, it will lock the sections against movement in one direction and accomplish the extension of the ladder, as shown in Fig. 1. The sides of the ladder-section 2 below the shoulders 10 are beveled outwardly, so that when the ladder section 3 is further pulled outwardly the pawl 11 will again ride upon the edge of the upperbe pivoted directly to the side of the laddersection, I preferably use a bracket 14 for securing the pawl in position. This bracket 14 may be made in a simple and yet strong manner by folding a piece of metal upon itself, as shown in Fig. 4:, one end of the said piece being offset, as at 15, to provide a suitable space between the ends of the metal piece to receive one end of the pawl 11. A rivet or pivot-pin 16 is passed through the ends of the brackets and the end of the pawl for pivotally securing the pawl in place. The bracket is then secured to theinner face of the side bar of said ladder-section, as clearly illustrated in the drawings.

It will be evident that in order to extend the length of the ladder it is only necessary to pull the ladder-sections apart-until the pawl engages the desired notch or shoulder 10. It is also desirable to so construct the ladder that the pawl can be readily disengaged from any one of the shoulders 10 and the secto a suitable extent upon each other.

tions so folded as to shorten the ladder. I accomplish this purpose in a simple manner by providing one of the ladder-sections, as 2, withrelease cams or pawls 17, which are pivoted, as 'at'18, to the side bars of said section at points adjacent to the shoulders 10. The release-cams 18 are elongated in shape and so poised upon their pivots that when the ladder is in an upright position the said release-cams will lie approximately in a horizontal position. Each release-cam is preferably pointed at one end, as 19, and adjacent to said end is formed with a lifting-shoulder 20, which engages the locking and supporting pawl 11 for lifting it over the space beneath the shoulder 10. \Nhen the ladder is to be reduced in length, the sections are pulled apart sufliciently to draw the pawls 11 below the release-cams 17, the said cams then assuming the position with respect to said pawls shown in Fig. 2. The ladder-sections are next forced together, when the pawl 11 will be engaged by the liftingshoulders 20 of the releasing-cam, and carried past the-shoulder 10, as illustrated in Fig 3. The releasing-cams 17 act automatically to control the movement of the pawls 11, so that the ladder may be extended or reduced in length at will by merely sliding the sections W hen the laddersections are extended only far enough for the pawls I1 to drop beneath the shoulders 10, as shown in Fig. 1, the releasecams 17 will be merely pushed to one side. When, however, the sections are separated sufficiently for the free ends of the pawls 11 to pass the points of the release-cams, the sections may then be collapsed or forced together, the said cams carrying the pawls over the shoulders 10.

The leg or standard supporting portions 4 and 5 of the step-ladder are constructed in a similar manner to the step-sections 2 and 3,being capable of sliding upon each other and being guided in their movement by means of plates 21 and 22. These supporting sections or legs are also provided with locking and supporting pawls, as 23, which are pivoted to one section and adapted to engage shoulders 24 upon the other section. Brackets 25 may also be used for pivotally supporting these pawls in position. Releasingearns 26 are pivoted to one of the leg-sections of the stepladder, acting in conjunction with the pawls I 23, so that said leg-sections may be extended or reduced in lengthat will and in the same manner as described in the step-sections of the ladder.

When the invention is applied to a step-ladder, the leg-sections are connected with the step-sections by pivoted links 2-7 for limiting the extent to which the ladder may be spread or opened. sections 2 and 3 may be strengthened by steel rods 28, which are arranged beneath the steps and extend from one side bar of the laddersection to the other side thereof.

It will be evident that the pawls 11 may be pivoted directly to the side bars of the ladder-sections and of the leg-sections without the use of brackets 14: and without departing in the least from the spirit of the invention. It will also be evident that other minor changes may be made in putting the invention into practical form all within the scope of the said invention. The construction of the parts, while efiective for the desired purpose, is simple and. yet not likely to getout of order. The release-cams can be made in various shapes without altering the invention, it being only necessary to suspend them so that when it is desired to fold the ladder the said cams will be capable of lifting the locking and supporting pawls over the recesses at the shoulders 10.

Having now described and ascertained the nature of my said invention, what I claim, and desire to secure by Letters Patent, is

1. An extension-ladder comprising laddersections, a supporting and locking pawl car- 'ried by some of said sections, means formed in the other sections for engaging said pawls, and releasing-cams carried by said pawl-engaging sections.

2. An extension-ladder comprising sliding ladder-sections, locking and supporting pawls carried by one section, supporting-shoulders formed in the edge of the other section for If desired, the steps of the ladder- 5 engaging said pawls and pivotally-mounted releasing-cams carried by the said section provided with shoulders.

13. An extension-ladder made up of sliding sections, pivoted pawls carried by one of said sections,pawl-engaging means assembled with the other sections, and gravity-actuated releasing-cams carried by said section provided with pawl-engaging means and cooperating with said pawls.

4. An extension-ladder comprising laddersections and leg-sections, locking-pawls carried by some of the ladder and leg sections, pawlengaging means assembled with the other ladder and leg sections, and releasing-cams carried by said ladder and leg sections provided with pawl-engaging means.

5. An extension-ladder comprising sliding sections, locking-pawls carried by some of said sections, pawl-engaging means assembled with the other sections, pivoted, releasingcams carried by said sections provided with pawl-engaging means and formed with lifting shoulders, said shoulders lifting the pawls out of locking position when the sections are to be telescoped.

6. An extension-ladder com-prising telescoping sections, pivotally-mounted locking and supporting pawls carried by some of said sections, means formed in the other sections for engaging the same, and brackets for pivotally supporting said pawls upon said sections.

7. An extension-ladder comprising sliding sections, means for holding said sections movably together, supporting-pawls carried by some of said sections, brackets for securing the pawls to saidsections. each bracket comprising a single piece of metal folded upon itself and spread apart at one end, and means for pivotally securing a pawl between said ends.

8. An extension-ladder comprising slidin ladder-sections, said sections provided with cut-out portions formed upon their meeting edges, locking and supporting pawls carried by one section and normally engaging said cutout portions, and gravity-actuated releasingcams assembled with the other section and cooperating with said pawls.

9. An extension-ladder comprising a plurality of slidable sections, each section having a shoulder formed in one edge thereof, locking .means movably mounted Within said shouldered portions, and means for moving said locking means.

10. An extension-ladder comprising sliding sections, locking and supporting pawls carried by one section, each of said pawls comprising a body portion, an integral extension projecting at right angles from one end of said body portion, means formed upon the other section for engaging and retaining said pawls in a locked position, and releasing means for actu- I ating said pawls carried by said pawl-engaging sections.

11. An extension-ladder comprising a plurality of sliding sections, each section provided with recessed portions formed upon one edge, pawls mounted upon some of said sections and engaging said recessed portions comprising a support, a body portion pivotally mounted on said support, an integral extension projecting from the outer edge of said body portion and at right angles thereto, said extension normally engaging said recessed portions, and automatically-actuated pawl-releasing means mounted upon the other sections. s

In testimony whereof I hereunto afiixmy signature in presence of two witnesses.

FRIEND R. LEWIS.

Witnesses:

W. W. BAYLoR, WV. S. ROBINSON

Images