US3454135A - Ladder locks - Google Patents

Description

y 8, 1969 v J. c. REDMAN ETAL 3,454,135

LADDER LOCKS v .Filed June 28. 1967 Sheet INVENTORS JAMES 0mm E5 REDMAN F; 1 BY RICH/4R 1. M/[RA/[R TIJH. LOUGH ATTORNEX RICHARD M MONTGOMERY July 8, 1969 c. REDMAN ET AL 3,454,135

LADDER'LOCKS Filed June 28, 1967 United States Patent 3,454,135 LADDER LOCKS James Charles Redman, Hadley, Richard M. Montgomery, Transfer, and Richard L. Werner, Sharon, Pa., assignors to R. D. Werner Co., Inc., Greenville, Pa., a corporation of Pennsylvania Filed June 28, 1967, Ser. No. 649,736 Int. Cl. E06c 7/06 US. Cl. 182-209 14 Claims ABSTRACT OF THE DISCLOSURE There is disclosed herein an extension ladder having nonpivoting retainer means carried by the base section comprising lock members carried by the side rails of the base section adapted to receive a rung of the fly section and transmit the force exerted thereby to a rung of the base section.

This invention relates to an extension ladder and relates more particularly to an improved lock for securing one section of the ladder to the other in any preferred relative adjusted position.

In the prior art with which applicants are familiar, locking devices of the so-called spring loaded gravity type are commonly employed, the look being pivotally mounted on a bracket disposed on the inner face of the fly section and adapted to lock on any selected pair of adjacent rungs of the fly and base sections.

The lock of this invention is particularly adapted for use with front loading extension ladders of the type disclosed and claimed in, Ser. No. 466,241, filed June 23, 1965, and copending application, Ser. No. 504,601, filed, Oct. 25, 1965, now US. Patents Nos. 3,321,042 and 3,343,630, respectively, which applications are assigned to the assignee of the present application.

The lock of this invention is secured to an upper portion of the base section of the extension ladder and engages rungs on the fly section, the said fly section being adapted to be pivoted with respect to the base section wherefor the fly section is moved upwardly, the rungs thereof are moved clear of the lock, and said rungs are then lowered into engagement with said lock. The lock itself is restrained from rotation at all times.

An object of this invention is to provide an improved lock for the fly section, attached to the side rails of the base section of an extension ladder.

A further object of this invention is to provide an improved lock of the type referred to wherein the moment induced into the lock by the fly section is not transmitted to the side rails of the ladder but is transmitted to a rung of the base section.

Another object of this invention is to provide an improved lock of the above type whereby the fly section is secured against both vertical down-ward movement and movement outwardly away from the base section.

Another object of the invention is to provide an extension ladder wherein the base section has outwardly projecting retainer means and the fly section is both slidably and tiltably mounted to the base section whereby said fly section can be tilted away from said base section beyond said retainer means during vertical adjustment thereof.

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Other objects of the invention and the invention itself will become more readily apparent from a purview of the following specification and appended drawings, in which drawings:

FIGURE 1 is a front elevational view of an extension ladder including the improved lock of this invention;

FIGURE 2 is a side elevational view of the ladder of FIGURE 1 showing in broken lines a different operative position of the fly section than that shown in full line and in FIGURE 1;

FIGURE 3 is an enlarged detail of the upper end portion of the base section of the ladder showing its association with the fly section;

FIGURE 4 is a section taken on the line 4-4 of FIGURE 3;

FIGURE 5 is a vertical section taken along the line 5-5 of FIGURE 1;

FIGURE 6 is a section taken along the line 66 of FIGURE 5;

FIGURE 7 is a view, partially broken away, as seen from the line 77 of FIGURE 5; and

FIGURE 8 is a section taken along the line 88 of FIGURE 5 showing the lock only.

Referring now to the drawings in all of which like parts are designated by like reference numerals, and referring particularly to FIGURES 1 and 2, an extension ladder is generally shown at 10 comprising a fly section 20 which is longitudinally slidable with respect to a base section 40. The extension ladder 10 may be constructed of any suitable material such as wood, steel, fiber glass, or the like and as herein illustrated and described preferably comprises extruded aluminum side rails joined by tubular aluminum rungs.

The fly section 20 comprises a pair of channel-shaped side rails 21 joined by vertically spaced, transversely disposed tubular rungs 22. The base section 40 similarly comprises channel-shaped side rails 41 joined by transversely disposed tubular rungs 42. The lower end of the side rails 41 are preferably provided with means for gripping a supporting surface of the ladder, the means herein illustrated comprising plates 50 secured to the lower ends of the said side rails in any suitable manner, such as by rivets S1, and having downwardly projecting teeth 52 for biting into smooth or slippery surfaces such as icy sidewalks or driveways.

The upper ends of the side rails 41 are provided with guide brackets 46 which are best understood by reference to the enlarged details of FIGURES 3 and 4. As particularly shown in FIGURE 4, it will be noted that each side rail 21 of the fly section 20 comprises a web 23 having flanges 24 along the side edges thereof, said flanges being parallel with each other and projecting outwardly of the ladder away from the rungs 22. The outer edges of the flanges 24 are provided with small inturned lips 25 which are directed inwardly toward each other. Similarly, each side rail 41 comprises a flat web 43 having outwardly projecting flanges 44 terminating at their outer edges in inturned lips 45. When the base and fly sections are assembled for use, a flange 24 of the fly section 20 is disposed flatwise over a flange 44 of the base section 40 and is adapted to slide there along for adjusting the fly section vertically with respect to said base section.

Each guide bracket 46 comprises a flat base 47 secured flatwise against a web 43 of one of the side rails 41 in any suitable manner such as by means of rivets 47a. Each J said guide bracket has an outwardly offset, generally C-shaped portion 48 which has a central slot or opening 49 loosely receiving portions of the adjacent flanges 24 and 44 and the lips 25 and 45, respectively, thereof. The C-shaped portions 48 effectively retain the fly section 20 in slidable engagement with the upper end of the base section 40 and at the same time provide suflicient play or looseness in the assembled parts whereby said fly section can be tilted at an angle with respect to the base section by pulling the bottom thereof outwardly away from said base section as illustrated in broken lines in FIGURE 2.

Retaining means are provided for retaining the lower end of the fly section 20 against the base 40 and for simultaneously maintaining said fly section in any elevated position relative to said base section, said retainer means being in the form of lock members 60, one of which is detailed in FIGURES -8. Each lock member 60 is made of substantially heavy sheet metal or other strong, rigid material shaped to provide an angled body portion 61 having a depending and laterally offset mounting portion 62. Each mounting portion 62 is secured to the inner surface of a web 43 of a side rail 41 by means of a nut and bolt assembly 63. The lock members 60 are spaced downwardly with respect to the upper end of the base section 40 immediately below a rung 42, the present illustrations showing the lock members disposed just below the third rung from the top of said base section. The upper edge of the body portion 61 is provided with a generally semicircular cutout or recess 64 having a slightly larger radius than the adjacent rung 42 which is adapted to be disposed within said recess. The body portion 61 has an upwardly directed extension 65 which projects upwardly behind the adjacent rung 42 or on the side of said rung opposite to the fly section 20. The extension 65 has an inwardly angled, flat edge portion 66 which interrupts the otherwise semicircular shape of the recess 64. The edge portion 66 is tilted forwardly from the vertical approximately l7 /2 and contacts the outer peripheral surface of the adjacent rung 42 above the horizontal level of the axis of said rung approximately at the two oclock position. It will be noted that no other point in the entire recess 64 actually touches the adjacent rung 42 other than the aforementioned point on the flat edge portion 66, said contact point being indicated at X in FIGURE 5.

The body portions 61 extend obliquely downwardly and forwardly at an angle of substantially 17 /z from the horizontal and project beyond the associated side rails 41 in overlapping relationship with the adjacent side rails 21 of the fly section 20. Each forwardly directed end of each body portion 61 is provided with an upturned hook 67 which defines a generally semicircular cutout or recess 68. The end of the hooks 67 project vertically upwardly to a level well above the horizontal level of the axis of the recesses 68 whereby a rung 22 of the fly section disposed in said recesses is effectively retained against forward displacement away from the base section 40. It will be readily understood that the fly section is retained in any adjusted position by seating a selected rung 22 thereof into the aligned recesses 68 of the hooks 67. When seated in this position, the fly section is then held firmly against the base section by two means: the guide brackets 46 at the upper end of the base section 40 and the upwardly directed extension 67a disposed somewhat below the upper end of said base section as illustrated in FIGURE 2. The fly section 20 is also retained against downward movement by the hooks 67 The base section 40 and the fly section 20 are initially assembled by longitudinally inserting flanges 24 and lips 25 of the fly section into the slots -or openings 49 of the guide brackets 46. The fly section is then tilted at an angle as illustrated in broken lines in FIGURE 2 whereby the rungs of said fly section will clear the outer edges of the hooks 67 and allow the user to move said fly section longitudinally to the extent desired. At a rung selected by the user, the lower end of the fly section 20 is pivoted inwardly against the base section 40 with the selected rung disposed above the ladder locks 60. The fly section 20 is then released and the selected rung is allowed to drop downwardly into the recesses 68 behind the extensions 67a whereby the extension ladder is ready for use in the usual manner. The extensions 67a effectively retain the lower end of the fly section against the base section While the user is manipulating the ladder into position for climbing, but it will be readily understood that when said ladder is angled against an upright surface with the fly section disposed generally above and in front of the base section, the lower end of said fly section is naturally pressed inwardly, the guide brackets 46 serving as fulcrums, from the weight of the ladder and the weight of the user thereon.

Referring now to FIGURE 5, the nut and bolt assemblies 63 are not tightened sufficiently to prevent rotative movement of the lock members 60, and this allows the moment or torque induced into the lock members as a result of the moment arms existing between the nut and bolt assemblies and the fly section rung engaging points to be transmitted to the adjacent base section rung 42 at the points X on the fiat edge portions 66. The nut and bolt assemblies 63 are therefore, designed to transmit only vertical shear force to the webs 43 of the base section side rails 41 whereby no moment or torque is transmitted to the base section side rail at all. From the foregoing it will be readily seen that the lock members are so designed that the moment induced by the fly section is applied by the edge 66 of the lock bearing on the base section rung 42 at approximately the two oclock position, this arrangement minimizing the moment arm of the resistive force which is needed to balance the moment or torque induced by the fly section.

It will be understood that many changes in the details of the invention as herein described and illustrated may be made without, however, departing from the spirit thereof or the scope of the appended claims.

What is claimed is:

1. An extension ladder having a base section and an overlying fly section, each of said sections comprising generally parallel side rails connected by transverse rungs; means connecting said fly section to said base section adjacent to the upper end of said base section for both longitudinal sliding movement, and tilting movement of said fly section whereby the bottom of said fly section is moved away from said base section; retainer means carried by said base section; said retainer means having forwardly projecting, upturned hook means adapted to receive a rung of said fly section whereby said fly section can be tilted outwardly beyond said hook means and longitudinally adjusted to dispose a selected rung of the fly section above said hook means after which said fly section is moved inwardly against said base section and said selected rung is dropped into said hook means; said hook means having upwardly projecting extension means extending upwardly in front of and above the level of the axis of said selected rung to retain said fly section against forward movement away from said base section; said retainer means comprising a pair of lock members mounted on the inside surfaces of the side rails of said base section; each said lock member comprising a body portion having means defining a recess in the upper edge thereof; said lock members mounted below and adjacent to one rung of said base section with said rung disposed in said recesses; each said lock member mounted to its respective base section side rail by fastener means which allows pivotal movement of the lock member with respect to its adjacent base section side rail, said pivotal movement being restrained by engagement of said recesses with said one base section rung.

2. An extension ladder as set forth in claim 1: each said fastener means being disposed below the recess associated therewith; each said recess having a surface portion which presses against said one base section rung at the back of said rung when said selected rung of said fly section presses downwardly on said hook portions whereby the moment induced into said lock member resulting from the moment arm existing between said fastener means and the selected fly rung engaging point is transmitted to said one base section rung.

3. An extension ladder as set forth'in claim 2: said surface portion of said recess being disposed above the level of the axis of said one base section rung.

4. An extension ladder having a base section and an overlying fly section, each of said sections comprising generally parallel side rails connected by transverse rungs; means connecting said fly section to said base section adjacent to the upper end of said base section for both longitudinal sliding movement, and tilting movement of said fly section whereby the bottom of said fly section is moved away from said base section; retainer means carried by said base section; said retainer means having forwardly projecting, upturned hook means adapted to receive a rung of said fly section whereby said fly section can be tilted outwardly beyond said'hook means and longitudinally adjusted to dispose a selected rung of the fly section above said hook means after which said fly section is moved inwardly against said base section and said selected rung is dropped into said hook means; the side rails of said sections being channel shaped, each comprising a central web and laterally directed flanges, the side rails of both sections being laterally spaced the same distance apart whereby a flange of each said fly section side rail slidably overlies a flange of a base section side rail; said means connecting said fly section to said base section comprising a guide bracket carried adjacent to the upper end of each base section side rail; each said bracket having a substantially C-shaped portion engaging a flange of the side rail to which it is attached and the overlying flange of the fly section side rail; said C-shaped portions having means defining slots therein for receiving the superimposed flanges, said slots being sufliciently large to allow said fly section to pivot outwardly at the bottom thereof to clear said hook.

5. Retainer means for retaining a fly section of an extension ladder in a longitudinally adjusted position with respect to a base section thereof, said retainer means comprising a pair of lock members adapted to be mounted on the inside of the base section side rails; each said lock member comprising a flat body portion disposed generally in a vertical plane and having a first recess at the upper edge thereof engaging one rung of the base section from below; each said body portion extending forwardly in overlapping relation to the adjacent side rail of the fly section; the forwardly extending portion of each said body portion having a second recess at the upper edge thereof adapted to receive a selected rung of the fly section; and fastener means for attaching each said body portion to its associated base section side rail below said first recess for transmission of vertical shear only to said side rail.

6. Retainer means as set forth in claim 5: each said first recess of each said lock member having a surface portion which abuts said one rung of the base section at the back of said rung opposite said fly section when the selected rung of the fly section presses downwardly on said forwardly extending portions whereby the moment induced into said lock member resulting from the moment arm existing between said fastener means and the selected fly rung engaging point is transmitted to said one base section rung.

7. Retainer means as set forth in claim 6: said surface portion of said recess being disposed above the level of the axis of the one base section rung.

8. Retainer means as set forth in claim 7: said body portions and extending portions projecting obliquely forwardly and downwardly with respect to the base section whereby the axis of said second named recesses is disposed below the level of the axis of said first named recesses in use of said lock members.

9. Retainer means as set forth in claim 8: said body portions being disposed obliquely at an angle between 15 and 20 with respect to the horizontal.

10. Retainer means as set forth in claim 9: said forwardly extending portions of said body portions having upwardly projecting extension portions extending upwardly in front of the selected rung of the fly section and above the level of the axis of the selected rung to retain the fly section against forward movement away from the base section.

11. An extension ladder having retainer means as set forth in claim 5: the side rails of said sections being channel shaped, each comprising a central web and laterally directed flanges, the side rails of both sections being laterally spaced the same distance apart whereby a flange of each said fly section side rail slidably overlies a flange of a base section side rail; means connecting said fly section to said base section for longitudinal sliding movement, and tilting movement of the fly section whereby the bottom of said fly section is moved away from said base section, said means comprising a guide bracket carried adjacent to the upper end of each base section side rail; each said bracket having a C-shaped portion engaging a flange of the side rail to which it is attached and the overlying flange of the fly section side rail; said C-shaped portions having means defining slots therein for receiving the superimposed flanges, said slots being sufliciently large to allow said fly section to pivot outwardly at the bottom thereof to clear said lock members for longitudinal adjustment of said fly section.

12. Retainer means as set forth in claim 7: said transverse rungs having generally circular outer peripheral surfaces; said surface portions of said first recesses contacting the outer peripheral surface of said one base section rung at approximately the two oclock position.

13. An extension ladder having a base section and an overlying fly section, each of said sections comprising generally parallel side rails connected by transverse rungs; means connecting said fly section to said base section adjacent to the upper end of said base section for both longitudinal sliding movement, and tilting movement of said fly section whereby the bottom of said fly section is moved away from said base section; retainer means carried by said base section; said retainer means having forwardly projecting, upturned hook means adapted to receive a rung of said fly section whereby said fly section can be tilted outwardly beyond said hook means and longitudinally adjusted to dispose a selected rung of the fly section above said hook means after which said fly section is moved inwardly against said base section and said selected rung is dropped into said hook means; said retainer means comprising a pair of lock members mounted on the inside surfaces of the side rails of said base section adjacent to one rung of said base section; each said lock member mounted to its respective base section side rail by fastener means which allows pivotal movement of the lock member with respect to its adjacent base section side rail; each said lock member having a portion overlapping said one base section rung and bearing against said one base section rung and restraining said lock member against pivotal movement when said selected rung of said fly section is seated in said hook portions whereby the moment induced into said lock member resulting from the moment arm existing between said fastener means and the selected fly rung engaging point is transmitted to said one base section rung.

14. An extension ladder having a base section and an overlying fly section, each of said sections comprising generally parallel side rails connected by transverse rungs; means connecting said fly section to said base section for longitudinal sliding movement relative thereto; retainer means carried by said base section; said retainer means having forwardly projecting, upturned hook means adapted to receive a selected rung of said fly section; said retainer means mounted to said base section by fastener means which allows pivotal movement of the retainer means; said retainer means having surface portion means radially spaced from said fastener means and overlapping one base section rung and bearing against said rung and retaining said retainer means against pivotal movement when said selected rung of said fly section is seated in said hook means whereby the moment induced into said retainer means resulting from the moment arm existing between said fastener means and the selected fly rung engaging point is transmitted to said one base section rung.

References Cited FOREIGN PATENTS 237,355 2/1962 Australia.

REINALDO P. MACHADO, Primary Examiner.

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