US3556253A

US3556253A - Gravity-type stop hooks

Info

Publication number: US3556253A
Application number: US795823A
Authority: US
Inventors: Hyman Kramer
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-02-03
Filing date: 1969-02-03
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19

Abstract

A gravity-type stop hook or catch for securing the fly section of an extension ladder to the base or ground section thereof, comprising a length of wire of appropriate section bent to the shape of an inverted V, the free end portion of the side legs of which are bent towards one another to define facing partial hook formations which are completed by a cross pin or rivet extending between said end portions, just above said partial hook formations. Another cross pin or rivet extends between said legs just below the crotch of the V to define a crotch opening for the reception of bolt or pin for pivotally connecting the stop hook to a ladder side rail.

Description

United States Patent Primary Examiner-Reina1do P. Machado Att0mey.l. Harold Kilcoyne ABSTRACT: A gravity-type stop hook or catch for securing the fly section of an extension ladder to the base or ground section thereof, comprising a length of wire of appropriate section bent to the shape of an inverted V, the free end portion of the side legs of which are bent towards one another to define facing partial hook formations which are completed by a cross pin or rivet extending between said end portions, just above said partial hook formations. Another cross pin or rivet extends between said legs just below the crotch of the V to define a crotch opening for the reception of bolt or pin for pivotally connecting the stop hook to a ladder side rail.

PATENTED JAN 1 9197:

INVENTOR MFA or ATTORNEY GRAVITY-TYPE STOP nooks This invention relates generally to improvements in extension ladder hardware, and more particularly to an improved gravity-type stop hook (sometimes also-called a catch) for holding the extensible fly section of an extension ladder in an extended or raised position on the base or ground section thereof.

A known gravity-type stop hook'currently in wide use on extension ladders takes the form of a skeletonized cast body member of modified upright isoseles triangular configuration, which is adapted to be pivotally connected at its upper apex portion to the inner face of a side rail of the ladder fly section in position to swing by gravity (depending on the inclination of said section) in a plane extending transversely through the ladder rungs, and which is further provided with laterally spaced-apart, oppositely facing hook formations which project downwardly from and in general continuation of the inclined side legs of said body member and function to hookably engage both a rung of the ladder fly section and a laterally spaced and then adjacent fixed position rung of the ground section, thereby in effect hooking the fly section to said fixed position rung.

The aforesaid known stop hook or catch is also provided with an integral tail piece which extends downwardly from and in general continuation of its one hook formation which hooks to the rung of the fly section. The lower terminus of such tail piece provides a mount for a swingable hook-retracting lever or flipper functioning by its engagement with the mug of the ground section to effect successive retractions of the stop hook to an inactive position which are necessary to lowering of the fly section with respect to said ground section when such is desired. 7

While performing satisfactorily, the stop hook of the just described construction is relatively expensive to manufacture and additionally requires a special mounting fixture for insuring that it will swing freely when connected to its side rail, factors which add substantially to the cost of manufacturing an extension ladder incorporating same. In addition, the rung-engaging hooks of a stop hook formed by casting, such being the accepted manner of fabricating same, were subject to being broken off from the triangular body member proper of the hook if the ladder were subjected to rough usage or improper handling. When this occurred, it becomes necessary to replace the stop hook since with a damaged stop hook the ladder could not function safely or properly as an'extension ladder.

With the above considerations in mind, it is a major object of the present invention to provide a gravity-type hook or catch for extension ladders characterized bydesign and constructional features enabling it to be manufactured and assembled complete at a fraction of the cost of the known stop hook serving similar function as generallydes cribed in the foregoing, yet rendering it equally as serviceable and not as likely to become broken or damaged in use as said known stop hook.

A more particular object of the invention is the provision of a gravity-typestop hook or catch for extension ladders which is capable of being manufactured from readily available inexpensive material and parts, yet which is of rugged construction and is thoroughly dependable in use. I

The above and other objects and features of advantage of a gravity-type stop hook or catch for extension ladders accord ing to the present invention will be apparent from" the following dcraiied thereof, in whichireference is had'to the accompanying drawing illustrating the improved stop hook and the manner of its functioning whenapplied to an extension ladder, in which FIG. I is a fragmentary vertical section, taken on a plane extending transversely through the rungs thereof, of an extension ladder whose fly section is shown to be secured in extended position with respect to the base or ground section of the ladder by a stop hook constructed in accordance with the principles of the present invention;

FIG. 2 is a detail view illustrating the stop, hook in a retracted position to which it moves by gravity during the course of raising movement of the fly section;

FIG. 3 is a similar detailview but illustrating the stop hook being retracted to an inactive position as takes place when lowering of the fly section is beingeffected; and

FIG. 4 is a perspective view of the stop hook of the present invention shown apart from the ladder which it is to serve.

Referring to the drawing in detail, reference numeral I0 (FIG. I) designates the right side rail of the ground section A of an extension ladder, with reference numeral I2 indicating vertically spaced, transversely extending rungs thereof, and reference numeral 14 designates the right side rail of the upper or fly section B of said ladder, with reference numeral 16 indicating its cross rungs. In said view, the fly section B is shown to be secured in a raised or extended position to the ground section A by a stop hook or catch 18 of the so-called gravity type constructed according to the present invention and whose detailed construction will be best understood by reference to FIG. 4.

More particularly, the extension ladder stop hook as herein proposed basically comprises a body member 20 fashioned from a length or readily available, inexpensive wire stock, preferably having rectangular section; bent to the form of an inverted, somewhat modified V, the free ends of whose divergent side legs are curled inwardlytowards one another so as to form o'ppositely facing, partial ho'ok formations designated 2221, 22b, of which the right sidehook formation 22a is formed with a downwardly extending, integral tail piece 14 serving a function to be later explained. g

I Adjacent the crotch or apex end of said body member 20 the wire fo'rining same is drilled to provide horiiontally aligned holes in which is received a cross pin or rivet 26, which completes a small crotch opening 28' from beneath. Similarly, the bent wire 20 just above its aforesaid hook formations 2221, 22b is provided with a second set of horizontally aligned holes, in which latter is received a cross pin or rivet 32 whoseunder peripheral surface in efi'ect completes the

partial hook formations

22a, 22b initiated by the inward curling of the free ends of the strap legs as aforesaid. 7

As seen in FIGS. l-3 inclusive, a stop hook or catch constructed as in the foregoing may be pivotally connected to a side rail 14 of the upper or fly section B of an extension ladder by a hang bolt 34 passed through the aforesaid crotch opening 28 of said hook and thereafter threadedly or otherwise secured to said side rail. Such mounting will permit the stop hook to swing more or less freely in a fixed plane which-is transverse to the axis of the rungs I2 and 16 of the ladder sections, which is of course the movement required of an extension ladder stop hook.

It will be understood that the location of the hang bolt 34 is such as to provide a swing axis for the stop hook which disposes its relatively rearwardly facing hook formation 22a at a level such that said formation will tend to swing against a particular cross rung 16 of the ladder fly section B, usually the lowermost or next lowermost run'g thereof, when the ladder is inclined as in FIG. l and further that the lateral spacing of the

hook formations

22a, 22b is equal to the lateral spacing between the rungs I2 and 16 of the ladder sections when said rungsare juxtaposed, also in FIG. 1.

Referring to FIGS. 1-3, a stop hook according to the invention functions normally to secure the ladder fly section B in extended position with respectto the lower or ground sectioh A thereof by its ability to in effect said upper fly section to a rung 12 of the ground section A, which is then disposed laterally with respect to therung 16 of the fly section against which the hook formation 22a is adapted to swing, as in FIG. I. Should it be desired to further extend (raise) the upper or fly section B with respect to the ladder base section A, such may be simply achieved by firstbodily swinging the ladder to approximately vertical position (as in FIG. 2)and thereupon exerting pull on the cable conventionally employed to raise the fly sections of extension ladders (not here shown). The aforesaid swinging or straightening up of the ladder will result in the stop hook swinging by gravity either to an wholly inoperative position or to a position in which it will be successively and positively retracted by the camming action which the successive rungs 12 of the base section A exert on its relatively rearward surface X (FIG. 2) as the fly section moves upwardly past said successive rungs.

To effect successive and positive retracting movements of the stop hook from its locking position necessary to the lowering of the ladder fly section B with respect to the ground section A, the tail piece 24 which extends downwardly from the hook formation 22a as aforesaid mounts a so-called flipper designated 40 whose construction and manner of pivotal connection to said tail piece may be conventional. As is seen in FIG. 1, said flipper 40 normally hangs downwardly from the tail piece 24 to an inactive position but in which it is nevertheless in vertical alignment with the rungs l2 of the ladder ground section A. However, said flipper becomes active when, upon raising the fly section from any extended position thereof in which it is held by the stop hook the limited amount as brings its free nose end into engagement with the rung 12 of the base section A from which the stop hook has just disengaged (as in FIG. 3) and thereupon permitting the fly section to lower, said flipper will not only close the opening to the hook formation 22b but also it will effect positive camming of the stop hook to an inactive position in which it will clear the rung 12 to which it has just previously locked. it will be understood that this closing and retracting movement of the stop hook is repeated every time the flipper 40 engages a rung 12 of the base section during the course of lowering of the fly section.

While an extension ladder stop hook as herein proposed has been described and illustrated as one mounted to the fly section in such manner that its opening faces downwardly, it may instead be mounted to the ground section and so that its opening faces upwardly. In the latter type of mounting, it would operate generally similar to the stop hook of the O'Keefe US. Pat. No. 2,895,660, although it would be pivotally connected to the ground section rather than to the fly section as in said patent and would further be devoid of the flipper or hookclosing lever thereof.

Without further analysis it will be appreciated that the invention provides not only an extremely simplified construction of a gravity-type stop hook or catch for extension ladders but also one which may be readily fabricated from relatively inexpensive and readily available materials, ie metal wire of rectangular section, including bar and strap stock, and simple cross pins or rivets. However, as many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

lclaim:

1. A gravity-type stop hook for securing the fly section of an extension ladder in extended position with respect to the ground section thereof comprising:

a length of rigid wire" of uniform section throughout its length and being bent to the shape of an inverted V and providing an inverted V-shaped hook body member, the free end portions of the divergent side legs of said V- shaped body member being curled inwardly towards one another and providing oppositely facing, partial hook formation;

a first crossmember extending between said side legs a short distance below the crotch portion of said V-shaped body member and cooperating therewith to provide a closed crotch opening for the reception of pivot means adapted to pivotally mount the stop hook in operative position on the ladder fly section;

and a second crossmember extending between the end portions of said side legs at locations thereof disposed just above the partial hook formations and cooperating with the latter to complete said hook formations relatively from above;and said crossmembers compnsing pms extending through upper and lower pairs of horizontally aligned holes drilled through said side legs.

2. A gravity-type stop hook according to claim 1, wherein one side leg of the body member is extended below the partial hook formation provided on its end portion, and a flipper of length as to extend fully across the open end of the V-shaped body is pivotally connected at its one end to the end of the extended side leg for swinging movement between an inactive position in which it depends from said body member to an active position in which it extends across and closes the open end of said body member.

Claims

1. A gravity-type stop hook for securing the fly section of an extension ladder in extended position with respect to the ground section thereof comprising: a length of rigid ''''wire'''' of uniform section throughout its length and being bent to the shape of an inverted V and providing an inverted V-shaped hook body member, the free end portions of the divergent side legs of said V-shaped body member being curled inwardly towards one another and providing oppositely facing, partial hook formation; a first crossmember extending between said side legs a short distance below the crotch portion of said V-shaped body member and cooperating therewith to provide a closed crotch opening for the reception of pivot means adapted to pivotally mount the stop hook in operative position on the ladder fly section; and a second crossmember extending between the end portions of said side legs at locations thereof disposed just above the partial hook formations and cooperating with the latter to complete said hook formations relatively from above; and said crossmembers comprising pins extending through upper and lower pairs of horizontally aligned holes drilled through said side legs.