GB2105630A - Releasable connection for interchangeable gardening tool heads - Google Patents

Abstract

A shaft 4 has a protruding collar 5 and a smaller diameter extension 8 which is elliptical in transverse cross- section at 9 near where it meets the collar. The extension 8 fits in bore 14 in a shank 2 and is thereby prevented from twisting. Shank 2 is conical to fit into a tool head recess at 16. It is externally threaded at 11, and internally threaded sleeve 3 fits over and holds the collar 5. All parts are made of synthetic polymer. A kit of interchangeable handles and heads is envisaged. <IMAGE>

Description

SPECIFICATION Improvements in gardening tools This invention relates to gardening tools.

It is commonplace that gardening tools are provided each with their own handle with consequent waste of manufacturing capacity and storage space when used. Various proposals have been made to provide gardening tools in the form of individual working heads interchangeable upon a common handle. However, criteria such as sudden failure, rapid wear over a period of use, or corrosion resistance of the interconnecting region are not generally met in a satisfactory fashion.

As an invention sets out to develop a range of tools of this type which are more resistant to the stresses as discussed above and are thus of more general utility and improved lifetime.

In one aspect the invention comprises an interconnection assembly whereby the head of a gardening tool may be secured to a handle so as to be capable of easy disconnection and reconnection, comprising: (a) an elongate cylindrical shaft with a protruding cylindrical collar around the lower end and a coaxial elongate cylindrical extension of smaller diameter than the shaft extending from the lower end, the inner end of which extension is of generally elliptical cross-section as herein defined with its major axis of a length intermediate between the shaft diameter and extension diameter;; (b) an elongate shank member with an externally threaded cylindrical upper end of which the root diameter is not less than that of the cylindrical shaft collar, and an elongate tapering lower end, the shank member having extending from the top along a significant portion of its length an elongate recess complementary with the cylindrical extension and its elliptical inner end, whereby the shaft and shank can be fitted together; and (c) a sleeve slidable on the shaft, provided with an internal threaded surface over part of its length from the lower end thereof, of a size to cooperate with the shank external thread, and further having an internal abutment towards the upper end thereof of a size to abut the protruding shaft collar when the sleeve is screwed over the shank; (d) each of the three members (a), (b) and (c) having an integral construction and being composed of synthetic polymeric material.

By "generally elliptical cross-section" I intend to include not only true ellipses but also sections composed of rounded ends spaced apart at the ends of parallel edges.

The synthetic polymer used as the material of construction can be any strong, light, corrosion resistant polymer such as nylon or polypropylene.

It has the additional advantage that when screwthreads of such material are firmly engaged e.g. by hand, they "bind" more than metal threads under similar circumstances and thus provide a good firm interconnection free from play or risk of ingress of water and grit.

In use the shaft is permanently fixed to a graspable handle, and a shank is fixed, usually permanently, within the hollow tapering metal connection on a tool head (such as the head of a fork, spade, rake, or the like). Thus a kit of parts can be provided (and constitutes another aspect of the invention) with a smaller number, e.g. one, two or three of handles and shafts and a larger number e.g. six to twelve of detachable tool heads and the attached shanks.

I have found that the stresses encountered in gardening, namely, downward pressure, leverage, twisting, and pulling are adequately resisted by such a structure both against sudden damage and against wear over a length period. Downward pressure, for example the pressure on a spade or fork during use, is accommodated by the lower face of the shaft and collar which presses upon the upper face of the shank threaded portion.

Leverage, also encountered in use in a spade or fork, is resisted by the long effective pressure line of the cylindrical extension located within its complementary recess, and this resistance is of a uniform nature from whichever direction the leverage is exerted. Twisting movement, such as is sometimes necessary e.g. to loosen the tool when working in compacted earth, is resisted by the elliptical configuration of the inner end of the cylindrical extension lying within a similar elliptical configuration of recess in the shank, and thereby being incapable of rotation. Pulling forces, such as encountered during raking, are resisted by the abutment of the top surface of the collar pressing against the internal sleeve abutment. This transmits forces in turn to the threads of the shank and the collar.

The whole assembly is preferably such that the major axis of the elliptical portion is effectively at right angles to the general plane of the graspable handle and tool head. This preferred orientation gives a particularly good resistance against leverage forces.

The invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a section through the shaft and shank at their region of interconnection, taken in the plane generally occupied by the graspable handle and tool head; and Figure 2 is a perspective view of the end of the shaft.

The interconnection assembly comprises a shaft generally indicated at 1, a shank generally indicated at 2, and a sleeve generally indicated at 3.

The shaft, of which only the lower part is shown, is of integral construction and has a main body 4 terminating at its lower end in a protruding collar 5 with upper surface 6 and lower surface 7.

From the lower end it possesses a cylindrical coaxial extension 8, this extension meeting the main portion of the shaft at a region 9 described more fully below in relation to Figure 2.

Shank portion 2 consists of a conical or tapering lower region 10 and an externally threaded upper portion 11, the screw threads being referenced as at 12. This upper portion possesses a top surface 13, and an internal recess 14 complementary to the shape of the cylindrical extension on the shaft. This shank member is secured by a rivet 1 5 within the conventional hollow metal attachment of a tool head such as a fork or spade shown diagrammatically at 1 6. It will be observed that the rivet 1 5 is considerably lower than that conventionally encountered in such attachments when a permanent handle is required.I have found that such a lower position is advantageous since it allows a rivet of this nature to be incorporated (for additional security to any frictional or adhesive engagement between the shank and the tool head) without interfering with the recess 14.

Sleeve 3 has an upper bore 1 7 such that the sleeve can slide readily upon shaft portion 4. It also possesses an abutment surface 18, whereby there is defined a lower bore 19 of generally larger diameter. The lowermost end of this bore is internally threaded as at 20 so as to cooperate with the threads on the shank portion.

Figure 2 shows in perspective view the lower portion of the shaft 1. From this it will be seen that the inner end 9 of the cylindrical extension 8 is generally elliptical in transverse cross-section, although in the actual embodiment shown the region in question is not a true ellipse but has two rounded ends 21 connected by generally flat sides 22.

In use a tool head 16 is permanently attached by friction, adhesive, or rivet 1 5 (or a combination of all three) to the shank member 2. To use the tool, this head is slid over the extension 8 of a chosen handle. It will be convenient to have in the kit at least two handles, one for lighter tools and one for heavier tools. The shaft and the shank are twisted relative to one another until the inner portion 9 fits securely into its complementary recess. At this point the surfaces 7 and 13 are abutting. The sleeve 3 is then screwed over the threaded external surface 12 of the shank, until the threads 20 are in complete engagement. At this point the abutment surface 1 8 is engaged fully with the top surface 6 of collar 5. Since the polymeric material used for the construction is slightly resilient, the interconnection can be made of a firm nature purely by hand-twisting.

Various modifications may be made within the scope of the invention as defined above. For example, the rivet which holds the shank in position within the tool can be replaced if desired by a split-pin with an associated pull-ring, so that further disassembly is possible. This is of particular value in the provision of an anglers bait fork.

Claims (7)

1. An interconnection assembly whereby the head of a gardening tool may be secured to a handle so as to be capable of easy disconnection and reconnection, comprising: (a) an elongate cylindrical shaft with a protruding cylindrical collar around the lower end and a coaxial elongate cylindrical extension of smaller diameter than the shaft extending from the lower end, the inner end of which extension is of generally elliptical cross-section as herein defined with its major axis of a length intermediate between the shaft diameter and extension diameter;; (b) an elongate shank member with an externally threaded cylindrical upper end of which the root diameter is not less than that of the cylindrical shaft collar, and an elongate tapering lower end, the shank member having extending from the top along a significant portion of its length an elongate recess complementary with the cylindrical extension and its elliptical inner end, whereby the shaft and shank can be fitted together; and (c) a sleeve slidable on the shaft, provided with an internal threaded surface over part of its length from the lower end thereof, of a size to cooperate with the shank external thread, and further having an internal abutment towards the upper end thereof of a size to abut the protruding shaft collar when the sleeve is screwed over the shank; (d) each of the three members (a), (b) and (c) having an integral construction and being composed of synthetic polymeric material.

2. An assembly as claimed in Claim 1 in which the polymeric material is nylon.

3. An assembly as claimed in Claim 1 in which the polymeric material is poiypropylene.

4. An assembly as claimed in Claim 1, 2 or 3 in which the shaft is permanently fixed to a graspable handle, and the shank is fixed within a hollow, tapering connection on a tool head.

5. An assembly as claimed in Claim 4 in which the major axis of the elliptical portion is effectively at right angles to the general plane of the graspable handle and tool head.

6. An assembly as claimed in Claim 1 and substantially as herein described with reference and as illustrated in the accompanying drawings.

7. A kit of parts for selective combination into a desired assembly as claimed in Claim 3 or 4, comprising a relatively smaller number of handles and a relatively larger number of detachable tool heads.