Coupling For Foldable Tubular Parts

Abstract

A coupling for the elongated tubular shaft of a paddle, or the like, made of two lengths of tubing, the coupling incorporating a hinge that is retractible into the shaft when the elongated shaft is in use, the joint between the two parts of the shaft becoming then a splice between the ends of the tubing without external fastenings.

Description

This invention relates to a coupling for foldable devices, including elongated parts where the coupling must be strong under bending stress when in use, but which must be readily foldable for storage when not in use.

For purposes of disclosure, this invention is described as applying to a paddle such as might be used to propel a canoe or an emergency inflatable boat, but it is to be understood that many other devices may also incorporate the coupling of the invention.

Heretofore, it has been suggested that oars, which are a special form of paddle, be made with a hinge joint in their shafts so that the blade could be folded back to be adjacent the loom in order to save storage space. Such an oar is illustrated in the Griffenberg U.S. Pat. No. 1,036,222 of 1912, where a link is pivoted at one end to the loom end of the oar and at the other end to the blade end of the oar and where, to hold the oar in its usable condition, an elongated sleeve encloses the link and a portion of the oar shaft on each side of the link. This oar has not proved to be practical.

A bolt having discontinuous threads has been proposed for a folding tool handle as seen the Sudek U.S. Pat. No. 1,737,275, but this handle is not subjected to bending movements when in use.

The objects of this invention are to provide a foldable coupling or the like, that while readily foldable, has great strength when in extended condition and can be readily assembled and disassembled.

In general, these objects are obtained by a novel hinged joint between the end of tubular elements forming the shaft of the paddle.

The means by which the objects are obtained are described more fully with reference to the accompanying drawing in which:

FIG. 1 is a view, partly in section, of the joint in a folding paddle, the joint being shown in the position to permit folding.

FIG. 2 is a view similar to FIG. 1, with the joint tightened to hold the paddle rigid for use.

FIG. 4 is an end view looking down on the joint, folded in the manner shown in FIG. 3.

FIG. 5 is a general view of the paddle.

The paddle illustrating the use of the present invention has a blade at one end and a handle at the other, which are shown only in FIG. 5. The shaft of the paddle is of tubing of sufficient diameter and wall thickness to withstand the bending stresses to which a paddle handle is subject when in use.

The tubular shaft is made in two parts, the joint between the two parts being midlength of the paddle when in use.

Tubular element 10 may be considered to be the end of the paddle on which the blade is mounted and tubular element 12 may be considered to be the handle end of the paddle. A plug element 14 extends into tubular portion 12 where it is fixed by any suitable means such as annular indentation extending into a groove in plug 14. It will be noted that the fit of plug 14 must be very tight in tube 12 to give the strongest joint. An extension 14A of plug 14 extends outwardly from a flange 14B that lies tight against the end of tubular element 12. Extension 14A is of a diameter to fit snugly into the end of tubular portion 10 and is of considerable length to extend quite far into tubular element 10 to support it and give maximum rigidity to the joint when the paddle is in use.

At the end of extension 14A are at least one, and preferably three, recesses 16 extending in parallel planes across the end of the extension. In a less preferred device, recesses 16 could be slots or saw kerfs. Angular links 18 are pivoted centrally of recess 16. The ends of links 18 lying at right angles to each other.

It will be noted that the ends of recesses 16 be at right angles to each other, and the ends of links 18 be at right angles to each other so that the sides of links 18 contact the ends of recesses 16 in extended condition as seen in FIG. 1 and in folded condition as seen in FIG. 3.

A plug 20 is slidably mounted in tubular element 10. The end of plug 20 is provided with parallel recesses 22 similar to recesses 16 and complementary to recesses 16, in which links 18 are also pivoted. An O-ring 24 is preferably mounted in a groove about plug 20 to exclude water from tubular element 10.

A nut 26 is fixed within tubular element 10 at a considerable distance from its end. A bolt 28 having two threaded portions 30 and 32 extends from the inner end of plug 20. The portion of bolt 28 between the threaded portions having a diameter slightly less than the root diameter of the threads so that when the nut lies between the threaded portions the bolt may slide through it.

From FIG. 1 it will be seen that the length of bolt 28 and the position of nut 26 is such that when the outer end of plug 20 is flush with the end of tubular element 10, the threaded portion 30 is at the inner side of nut 26 and prevents the inadvertent disassembly of the paddle. As the plug 20 is thrust into tubular element 10 to place the paddle in usable condition, the threaded portion 32 will contact nut 26 to prevent direct axial movement of the plug 20 into element 10. The length of bolt between threaded portions 30 and 32 is such that when the axial movement of the plug 20 is stopped by contact of threaded portion 32 with nut 26, tubular element 10 has enveloped most of extension 14A of plug 14. The edge of tubular element 10 at this point must be a distance from flange 14B slightly less than the axial length of threaded portion 32 so that as threaded portion 32 enters nut 26 upon relative rotation between tubular elements 10 and 12, tubular element 10 is pulled strongly against flange 14B to assure a very strong joint as seen in FIG. 2.

As noted above, the threaded portion 30 prevents inadvertent disassembly of the paddle, but in the original fabrication and assembly it will be understood that relative rotation of tubular element 12 carrying plug 14, hinge links 18 and slidable plug 20 with the bolt 28, when it is thrust into tubular element 10, is all that is required to assembly the paddle. As seen in FIG. 1, disassembly can be effected by unscrewing threaded portion 30 through nut 26. While the invention has been described as having but the one hinged joint, it is clear that two, or even more, such hinged joints could be provided so that any length of paddle, or other elongated device, may be folded into a desirable compact package. If such a joint should be placed at a location where the user's hand would normally grasp the shaft, the handle grip 34 may be frictionally slidable along the shaft.

It will be noted that links 18 are generally curved so that, as seen in FIG. 3, no slots are required in tubular element 10, nor does plug 20 need to extend beyond the end of tubular element 10 when the paddle is folded.

Claims

I claim:

1. In a foldable paddle or the like having a handle at one end and a blade at the other end and an elongated tubular shaft comprising at least two lengths of tubing connecting said handle and blade, a solid double-ended fixed plug, a first end of which is secured in the end of one of said tubing lengths and the second end of which extends a considerable distance outwardly therefrom to form a plug fitting snugly but slidable into the end of the said second of said tubing lengths, at least one shallow slot like recess extending into the end of the said second end of said double-ended fixed plug, said recess being formed to present diverging walls at right angles to each other diverging toward the end of said second end, a slidable plug in said second of said tubing lengths, at least one slot like recess in said slidable plug complementary to the recess in said second end of said fixed plug, and of the same angular shape, at least one flat angular hinge link pivotally secured in said recesses in said slidable plug and in said fixed plug, said angular link being formed on one edge with portions lying at right angles to each other to engage one wall of each of said recesses when said hinge link is moved to one extreme position, and the other edge being formed with portions parallel to corresponding portions of said one edge lying at right angles with each other to engage the other wall of each of said recesses when said hinge link is moved to the other extreme position, a retaining bolt extending coaxially of said slidable plug inwardly of said second tubing length from said slidable plug, said retaining bolt including a first threaded portion adjacent said slidable plug, an elongated body portion of reduced diameter extending therefrom, and a second threaded portion at the extremity of said bolt remote from said slidable plug, and a nut threaded to operatively engage said threaded portion secured in said second tubular length, said nut being positioned in said second tubular length at a distance from its end such that said nut acts in cooperation with said first threaded portion to forceably pull said second end of said fixed plug into said second tubular length, the elongated body portion of said bolt being of a length so that when the outward edge of said slidable plug is even with the end of said second tubular length, said second threaded portion acts, in cooperation with said nut, as a stop to prevent further outward axial movement of said slidable plug.

2. The paddle of claim 1, in which said slidable plug is provided with an annular groove, and an O-ring is provided in said annular groove providing a waterproof seal with said second tubing length, whereby said second tubing length cannot fill with water to destroy the buoyancy of the paddle.