GB2472045A - Tool with shock-absorbing means - Google Patents

Abstract

A tool, preferably a spade, comprises a shaft with a tool end 1, a handle end 2 and a shock-absorber 5. The shock-absorber preferably includes a spring. Preferably the handle end can rotate relative to the tool end, causing a handle 3 attached to the handle end to rotate relative to the tool end. The shock absorber may have a first portion connected to a proximal end of the shaft and a second portion connected to a distal end of the shaft, the first and second portions being relatively rotatable. An outer sleeve may be mounted over a part of the shaft. One end of the shock absorber may be attached to the sleeve and the other to another part of the shaft such that one part can rotate relative to the other part and, as longitudinal pressure is exerted, the shock absorber compresses and causes the outer sleeve to increase or decrease the amount of overlap with the other portion of the shaft. The shaft portions may be connected with pins.

Description

Hand Tool This invention relates to a hand tool. In particular, but not exclusively, it relates to a hand tool such as a spade or similar tool which is normally used in such a way as to impart an impact to the hand or hands of a user.

Spades are commonly used for many tasks. They are often used to dig holes and to do this an initial impact is often required of the spade with the ground. This impact is passed directly through the shaft of the spade and to the hands of the user. Under certain conditions, this impact can possibly damage the hand or arm, or the muscles thereof, of the user.

The present invention arose in an attempt to provide an improved spade, shovel or other hand tool which reduces impact on a human wrist, forearm, bicep, shoulder or other parts of a human body during use.

According to the present invention there is provided a tool comprising a tool end, a handle end and a shaft including a shock absorbing means mounted between the handle end and tool end.

The shock absorbing means may comprise a spring mechanism or one or more oil-filled dampers/shock absorbers, or other hydraulic, pneumatic, mechanical or other mechanisms.

Preferably, the shock absorbing means is mounted to the shaft in such a way that the proximal end of the shaft can rotate relative to a distal end of the shaft, thereby enabling rotation of a handle at the handle end, relative to the distal end.

The shock absorbing means is preferably a resilient shock absorber having a first portion connected to the proximal end of the shaft and a second portion connected to the distal end of the shaft, the first and second portions being relatively rotatable to enable relative rotation of the proximal and distal portions of the shaft.

An outer sleeve is preferably included at one of the relative shaft portions, adapted to slide respectively, the other shaft portions to overlap therewith.

The tool is most preferably a spade, fork or similar tool having at least one impact based mode of use.

The tool may be entirely human powered or may powered by a motor or other means, or a combination of these.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a spade with damper; Figure 2 shows a spade with handle end rotated; and Figure 3 is a cross-section of part of an embodiment.

Figures 1 and 2 show an embodiment of the invention in the form of a spade.

Referring to Figure 1, the spade comprises, shaft comprising a tool end 1, a tool such as a spade part 6, and handle end 2 bearing a handle 3. A damping/shock absorbing means 5 is provided at any place along the shaft. This may be in its broadest aspect be any form of damper and is connected in such a way that the handle end 2 of the shaft can rotate relative to the tool end. For example, each respective part of the shaft can be securely affixed to a different part of the damper, the parts of the damper being arranged to relatively rotate and thereby cause the appropriate shaft part to relatively rotate.

One of the handle and tool ends may therefore of larger diameter, or have a larger diameter portion, than the other part, or have a larger diameter sleeve or other component, which larger diameter part can slide over the respective other part. The larger part is preferably the handle end. The damping means 5 is resilient or has a resilient element such that when, in use, the spade impacts the ground and a certain amount of the impact is taken up by the damping element and therefore the force which the handle exerts to the hand of a user is reduced compared to an undamped spade. The resilience may, for example, be by a spring mechanism or one or more oil-filled dampers/shock absorbers, or other hydraulic, pneumatic, mechanical or other mechanisms.

The two parts of the shaft may be non-rotatable relative to each other. However, in a much preferred embodiments, the parts are rotatable as described which provides for much greater variety of use of the spade or other tool. It enables the handle to be held comfortably no matter where or how the tool is used. In confined spaces, for example, it may be useful to rotate the handle. The handle may be rotated to any chosen angle within a full 360° range.

Figure 1 shows a normal configuration of the spade.

Figure 2 shows a configuration of the spade in which the upper part of the shaft has been rotated by about 90° relative to the lower part so that the handle has also been rotated and thus only the side view of this is shown. This enables the user to be able to use the spade in more applications. The relative rotation may be any angle of course, such as 45°, 30° or any angle up to 3 60°.

The spade is preferably one designed for use in work such as railway work, railway installation, where relatively heavy digging is involved and therefore heavy impact, for maximum benefit of the damping effect.

Figure 3 shows schematically a partially cut-away example of a damped spade in more detail.

In this embodiment, an upper sliding outer shaft is mounted to the handle end and a lower shaft of reduced diameter 1 is mounted at the spade end. A compression spring 5a is mounted between them. A compression clearance zone 7 (typically of 30mm nominal length) allows the inner lower shaft unrestricted movement in order to absorb the impact.

The spring is held under compression between the upper 8 and a lower retaining boss 9 by a compression tension rod 10 and locking nuts 11.

Securing pins 12a, 12b secure the bosses to, respectively, the lower and upper shaft portions.

Both shafts are hollow, of course, and will generally be cylindrical. The upper sliding outer shaft is connected to the upper retaining boss by means of a welding or pinning method. The lower shaft is connected to a lower retaining boss by means of a welding or pinning method. The compression spring tension rod passes through the compression spring and each boss and is then secured with a NYLOC TM or similar type locking nut at each end.

When an object of resistance is struck by the spade, the interface joint shown absorbs this impact and therefore minimises transference of the shock to an operators wrist, or shoulder.

Since the shafts can rotate relative to each other, the upper handle shaft can therefore rotate through 360° and give the user the most advantageous and comfortable hand position. The assembly is formed with sufficient resistance between the two shaft portions such that the load upon the spade end cannot rotate and drop off. The upper shaft slides over the lower shaft to give added stability and support to the shock absorber. In one embodiment, the movement gap is nominally 30mm although this may vary.

The upper and lower shafts may be constructed from milled steel or stainless steel extruded tube in some embodiments, or of any other material and/or grade or thickness.

Thus, the outer sliding sleeve extends an amount overlapping the lower shaft portion and can rotate therewith, thus rotating the handle.

Claims (12)

1. Claims 1. A tool comprising a tool end, a handle end and a shaft including a shock absorbing means mounted between the handle end and tool end.
2. 2. A tool as claimed in Claim 1, wherein the shock absorbing means includes a spring mechanism.
3. 3. A tool as claimed in Claim 1, wherein the arrangement is such that the handle end can rotate relative to the tool end, thereby enabling a handle affixed to, or integral with, the handle end to rotate relative to the tool end.
4. 4. A tool as claimed in any preceding claim, including a resilient shock absorber having a first portion connected to a proximal end of the shaft and a second portion connected to a distal end of the shaft, the first and second portions being relatively rotatable to enable relative rotation of the proximal and distal portions of the shaft.
5. 5. A tool as claimed in any preceding claim, which is a spade.
6. 6. A tool as claimed in any preceding claim, comprising an outer sleeve mounted over a proximal or distal part of the shaft, a shock absorbing means having one end attached to the sleeve and another end attached to the respective other part of the shaft such that one part of the shaft can rotate relative to the other part, and, as longitudinal pressure is exerted the shock absorber compresses and causes the outer sleeve to increase or decrease the amount of overlap with the other portion of the shaft.
7. 7. A tool as claimed in Claim 6, wherein the shaft portions are attached via connecting pins.
8. 8. A method of inserting a shock absorbing element into a hand tool comprising a handle end, a tool end and a shaft having longitudinally arranged handle and tool portion, comprising inserting a shock absorbing element between the portions of the shaft and securing to this to the respective portions of the shaft.
9. 9. A method as claimed in Claim 8, wherein the shock absorbing element is attached in such a manner that the handle end of the tool is rotatable relative to the tool end.
10. 10. A method as claimed in Claim 8, wherein the shaft portions are hollow and one portion of the shaft has at least a portion that is of greater inner diameter than the outer diameter of the outer portion.
11. 11. A spade or other hand tool substantially as described with reference to, and as illustrated by, the accompanying drawings.
12. 12. A method of assembling a shock absorbed hand tool substantially as hereinbefore described, with reference to the accompanying drawings.