GB2069914A - Improvements in or relating to hand tools - Google Patents

Abstract

A hand tool, for example a shafted garden tool such as a spade or fork, or other tool having a cutting edge or point for digging, chopping or post-hole-boring comprises a tool head (10) or holder therefor carried by a shaft portion (14) and an impactor member (16), movable longitudinally of the shaft portion to apply impact blows to the tool head or holder. Such a tool is of particular utility in situations, such as digging trenches in, or cultivating, hard, gravelly or clayey soil, where the force which can be applied to the tool by hand or foot is inadequate, yet the use of a power tool is unjustified. The tool may comprise a plurality of interchangeable shaft portions, each with different tool head, for example spade, fork, chisel, pick-axe, punner. <IMAGE>

Description

SPECIFICATION Improvements in or relating to hand tools The invention relates to hand tools, especially shafted garden tools, such as spades or forks, but is also applicable to other tools having a shaft and a cutting edge or point, such as a bolster chisel or a pick, or a blunt end such as a punner for tamping earth.

Occasions often arise in digging trenches, cultivating land, or similar activities, when the force which can be applied to a tool by hand or foot is inadequate for satisfactory progress to be made, yet use of a power tool cannot be justified.

For example, gardeners may have difficulty, especially in new gardens, in applying sufficient force to a spade or fork for it to penetrate hard, gravelly or clayey soil, but the situation may not justify the expense of hiring a mechanical rotavator.

An object of the present invention is to overcome or at least mitigate this problem.

According to the present invention there is provided a shafted hand tool comprising a tool head or holder therefor carried by a shaft portion and an impactor member movable longitudinally of the shaft portion to apply impact blows to the tool head or holder.

The shaft portion and impactor member may comprise respective parts of a telescopic shaft, for example a pair of tubes or a rod and a tube.

In one embodiment the impactor member comprises a rod or tube slidably housed in an outer tube, closed at one end, the closed end being secured to the tool head or holder. The relative lengths of the parts are such that the interior end of the inner tube or rod can strike against the closed end of the outer tube.

An advantage of this arrangement is that the impact blow is applied close to the tool head, ensuring optimum stability and avoiding undue stress on the outer tube.

Preferably a pair of abutments are provided to limit extension of the tool. Conveniently, where one elongate member comprises a tube, an annular cylindrical space is provided between the interior of the tube and the inner telescopic part.

Then one abutment may comprise one or more transverse bars, or a collar fixed to the inner member. Preferably this is a sliding fit in the outer tube, to help to guide and centralise the inner tube or rod.

The other abutment of the pair may comprise a collar fixed to the outer tube, conveniently adjacent its open end. This abutment may be removable, for example as part of a screw threaded plug or end cap, enabling separation of the impactor member from the tool head. An advantage of such an arrangement is that the tool may be provided with several interchangeable tool heads or holders.

Provision may also be made for limiting relative rotation of the relatively movable parts in use, for example, the sliding parts may be of polygonal cross section or have splines. This is of particular advantage for tools like spades or forks where the orientation of the tool head relative to the handle is to be maintained.

Specific embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figures 1 and 2 show a shafted hand tool having a tool head in the form of a garden fork; and Figures 3, 4, 5 and 6 show alternative tool heads interchangeable with that shown in Figure 1.

Referring to Figures 1 and 2, a shafted garden tool comprises a tool head 10 in the form of a fork having four tines 12, each about one foot long, secured to one end of a shaft portion comprising a steel tube 14 which is about two feet long. A T-shaped impactor member 1 6 comprises a rod or tube 18 having, at its upper end, a cross-bar handle 20 equipped with hand grips 22 of rubber or plastic. The lower end portion of the rod or tube 1 8 extends in telescope fashion into the tube 14, the lower end of which is closed. The end wall 24 of the tube 14 constitutes an anvil surface for the opposed end face 26 (see Figure 2) of the rod or tube 18.

The diameter of the rod or tube 18 is less than that of the interior of tube 14, leaving an annular cylindrical space 26 between them.

The rod or tube 1 8 is slidably accommodated in a clearance hole 27 in an annular end cap 28 which is secured to the upper end of the tube 14.

The cap 28 has an internally screw-threaded skirt portion 30 which engages a corresponding external screwthread on the end portion of the tube. It will be appreciated that, alternatively, an annular plug could be screwed into the end of the tube and, in either case, other means of attachment than screwthreads could be used, for example bayonet couplings or pins.

A collar 34 is secured to the rod or tube 18, for example by a pin or weld, and is a sliding fit within the tube 14. The collar 34 and internal wall of the end cap 28 serve as abutments to limit withdrawal of the rod or tube 1 8.

As shown in Figure 2, the positioning of the collar 34 is such that, when it abuts the end cap 28, the lowermost end of the rod or tube 18 is spaced from the bottom of the tube 14 by a distance of about six inches.

In use, the fork is positioned in the normal way and with the handle in the raised position shown in Figure 2. The handle is then lowered sharply causing the end of the rod or tube 18 to impact against the closed end of the tube 14. The impact force thus applied to the tines is much greater than could be applied by steady pressure and makes it easier to penetrate hard, gravelly or clayey soil. Normal leverage can then be used to break up the soil.

It should be noted from Figures 1 and 2 that a substantial mass of metal is provided at the "frog" between the impact surface and the fork itself, thus providing adequate strength to withstand and distribute the impact force.

In Figures 1 and 2 a second collar 36 is shown near the lower end of the rod or tube 1 8 to ensure that it remains coaxial with the tube 14. If desired, the second collar may be an integral enlargement of the end of the rod or tube, the consequent increased area of the end face 26 distributing the impact force and reducing wear or deformation.

Other wear or deformation reduction measures may also be employed, such as heat treatment of the parts subject to the impact, or use of a different material.

It will be appreciated that the invention is not limited to farden forks, or even to garden tools, but can be applied to virtually any shafted tool used by a gardener or construction worker for digging, chopping timber, bricks or paving stones, boring post-holes, breaking concrete or the like, or compacting earth.

Removal of the impactor member from the tube 14 is possible simply by removing the end cap 28.

The tool head and shaft portion can therefore be replaced quickly and easily by a different tool head. Examples of such interchangeable tool head parts are shown in Figures 3, 4, 5 and 6, comprising, respectively, a garden spade 40, a bolster chisel 42, for splitting bricks, paving stones or logs, a punner 44, for tamping loose earth, and a fine pointed chisel 46, similar to a pick-axe point, for breaking concrete and the like.

It is further envisaged, therefore, that a hand tool embodying the invention might comprise an impactor member and a plurality of interchangeable tool head parts.

For heavier work it may be desirable to increase the mass of the impactor member. This may be achieved by providing a weight 46 adjacent the handle, as indicated in broken lines in Figure 1.

Alternatively, and perhaps preferably, the additional weight might be provided nearer to the lower end of the rod or tube 18, inside the tube 14, giving better stability in use. More particularly, the extra weight might be achieved by making the rod or tube 18 a sliding fit in the tube 18 for a distance equal to the spacing of the collars 34 and 46. The collars could then be dispensed with, the required abutment being provided by the step between the enlarged portion and that part of the rod or tube projecting through the end cap 28.

It is also envisaged that the tool might be adapted to prevent or restrict, relative rotation of the tool head and handle. This might be achieved by providing keys or splines on the cooperating sliding surfaces of those parts. For example, in the specific embodiment, the end cap 28 and cooperating part of the rod or tube might be splined. A more robust construction might be obtained, however, by providing the splines on the part of the rod within the tube and the inside of the tube itself.

Alternatively, and perhaps preferably, the sliding parts could have a polygonal cross-section, for example triangular or rectangular, to prevent their relative rotation.

It should be noted that the impactor member could comprise the outer tube and the tool head part be carried by the inner tube or rod. Then the impactor tube could abut with its lower end against a shoulder part of the tool head or holder.

An advantage of this arrangement is that the mass and strength of the impactor tube can be readily increased i.e. giving greater impact.

Claims (14)

1. A shafted hand- tool comprising a tool head or holder therefor carried by a shaft portion and an impactor member movable longitudinally of the shaft portion to apply impact biows to the tool head or holder.

2. A shafted hand tool as claimed in claim 1, wherein the shaft portion comprises one of two telescopically cooperating parts, the impactor member comprising the other of the parts.

3. A shafted hand tool as claimed in claim 2, wherein the shaft portion comprises a tube, closed at the tool head or holder end, and the impactor member comprises a rod or tube extending slidably into the shaft-portion tube, such that the internal end of the impactor rod or tube is abuttable against the closed end thereof.

4. A shafted hand tool as claimed in claim 2, wherein the shaft portion comprises a rod or tube extending into a tubular part of the impactor member.

5. A shafted hand tool as claimed in claim 4, wherein the lowermost end of the tubular part is abuttable against the shoulder of the tool head or holder therefor.

6. A shafted hand tool as claimed in claim 2, 3, 4 or 5, wherein the telescopically cooperating parts comprise means for limiting withdrawal of the one from the other.

7. A shafted hand tool as claimed in claim 6, wherein withdrawal limiting means comprises a transverse pin fixed to the inner part and abuttable against a shoulder or collar fixed to the outer part.

8. A shafted hand tool as claimed in claim 6 or 7, wherein the withdrawal limiting means comprises an end cap or plug removably secured to the outer telescopic part.

9. A shafted hand tool as claimed in any preceding claim, wherein the impactor member comprises transverse handles spaced from the shaft portion and a weight portion between the handles.

10. A shafted hand tool as claimed in any preceding claim, including means for limiting relative rotation of the shaft portion and the impactor member or a handle therefor.

11. A shafted hand tool as claimed in claim 10, as appendent to claim 2, wherein the telescopically cooperating parts are each of polygonal cross-section and interfit to prevent their relative rotation.

12. A shafted hand tool as claimed in claim 10, as appendent to claim 2, wherein the means for limiting relative rotation comprise splines or keys on one member cooperating with grooves or notches of the other member.

13. A hand tool as claimed in any preceding claim, comprising a plurality of interchangeable shaft portions each having a different tool head.

14. A hand tool substantially as herein described with reference to and as shown in the accompanying drawings.