ARRANGEMENT FOR A HAND TOOL

Abstract: The present invention relates to an arrangement for a hand tool (1), for example a spade, a pitchfork or a shovel. The tool comprises a shaft (2), which at one of its ends is attached to a tool component (3) and at its other end is executed with a handle (4). The invention is characterized in that the hand tool component (3) is attached to the shaft (2) in such a way that its principal direction of longitudinal extension (5) forms an angle (v1) of the order of 140 DEG -150 DEG with the shaft (2) at the attachment. The length of the shaft (2) is of the order of 1-1.5 m, and is executed at a point approximately half way along its length with a bend (6), so that the part (2a) of the shaft (2) between the handle (4) and the bend (6) forms an angle (v2) with the part (2b) of the shaft (2) situated between the bend (6) and the tool attachment. The last-mentioned angle (v2) is selected so that the first-mentioned part (2a) of the shaft (2) is approximately parallel with the aforementioned principal direction of longitudinal extension of the tool component (3).

Description: Arrangement for a hand tool The present invention relates to an arrangement for a hand tool, for example a spade, a pitchfork or a shovel, comprising a shaft, which at one of its ends is attached to a tool component and at its other end is executed with a handle. From time immemorial, when mankind first began to till the soil, use has been made in one form or another of spades and shovels. Historical examples of spades have been preserved, which are often made of wood and sheet metal, but which are essentially of similar appearance to present—day spades. No major change has taken place in the appearance of the spade or the shovel. The spade and the shovel have taken on a character which is entirely in accordance with the nature of the soil and with the sense of design and appearance of the local spade maker. The 1930s and 1940s saw the development of a code of practice relating to the execution of hand tools with regard to the length of the shaft and the angle of the implement relative to the shaft. It is a known fact that an individual can easily suffer from backache when working with a conventional hand tool. This is said to be attributable mainly to the fact that such previously disclosed hand tools have a shaft which, through its length and execution in use, invites the user to strain the musculature of the back, or, in other words: previously disclosed hand tools are not well designed from an ergonometrical point of view. The object of the present invention is to make available a hand tool which invites the user to adopt a working position which spares the musculature of the back and instead utilizes the considerably more powerful musculature of the legs. This is achieved through the implement component of the hand tool being attached to the shaft in such a way that its principal direction of longitudinal extension forms an angle of the order of 140°—150° with the shaft at the attachment, that the length of the shaft is of the order of 1 — 1.5 , that the shaft s executed at a point approximately half way along its length with a bend, so that the part of the shaft between the handle and the bend forms an angle with the part of the shaft situated between the bend and the tool attachment, that the aforementioned angle is selected so that the first— entioned part of the shaft is approximately parallel with the aforementioned principal direction of longitudinal extension, and that the aforementioned Length of the shaft is selected so that an individual standing on a level surface who takes hold of the handle and the first—mentioned part of the shaft in an area close to the bend is capabLe," with an essentially straight spine, both of causing the tool component to rest on the ground, and of using it for its intended purpose. Also of importance to good ergonomics is the possibility of taking a secure hold around the shaft of the tool. In accordance with one particular characteristic feature of the invention, the shaft accordingly has, at Least in those areas which are intended to be gripped whilst the tool is being used, a rounded rectangular cross—section, whereby the major axis of the cross—section lies in a plane passing through the centre line of the parts of the shaft. The invention is now described in more detail below with reference to the accompanying drawing, in which Figs. 1a and 1b illustrate in schematic form shafts in accordance with the invention intended for hand tools, and Fig. 2 iLLustrates the use of such a hand tool. Fig. 3 iLlstrates the angles and the Lengths which are typical of the invention, and Fig. 4 shows a cross—section through the shaft in accordance with the invention. In the drawing the designation 1 is used generally in respect of a hand tool. Like a conventional tool shaft, the shaft 2 of the hand tool in accordance with the invention is attached at one of its ends to a tool component 3, which may be a spade (Fig. 1b), a pitchfork CFig. 2) or a shovel (Fig. 1a). At its other end the shaft 2 is executed with a handle 4, which is executed differently for different types of hand tool; see the above-mentioned Figures. Thus, the handle in accordance with Fig. 1a is typical of a shovel, whereas the design of handle illustrated in Fig. 1b is commonly used with spades and pitchforks. In accordance with the invention the tool component 3 is attached to the shaft 2 in such a way that it forms an angle of the order of 140°—150° with the principal direction of longitudinal extension 5 of the tool component 3. The length of the shaft 2 is of the order of 1 — 1.5 m, i.e. approximately 20-80 '/. longer than a conventional tool shaft. At a point approximately half way along its length the shaft 2 is executed with a bend 6, so that the part 2a of the shaft between the handle 4 and the bend 6 forms an angle V2 with the part 2b of the shaft between the bend 6 and the attachment of the tool component 3. The angle V is selected so that the part 2a of the shaft is approximately parallel with the principal direction of longitudinal extension 5 of the tool component 3. In view of the foregoing, the angle lies in the range 30°—40°. With reference to Fig. 2, the combination of the shaft length and the values for the angles i and mean that an individual standing on a level surface who takes hold of the hand tool 1 with one hand on the handle 4 and with the other hand on the part 2a of the shaft close to the bend 6 is capable, with an essentially straight spine, both of causing the tool component 3 to rest on the ground, and of using the tool 1 for its intended purpose. This means that the user is able to execute his work more easily purely from the point of view of performance. The shaft length in accordance with the invention also means that the distance between the user's body and the load which is displaced by means of the tool component is significantly smaller than is the case with a conventional hand tool, which involves less mechanical stress on the vertebrae and the muscles. The cross—sectional profile of the shaft is also of great significance to the ergonomics of the hand tool. The shaft in accordance with the invention exhibits, at least in those areas which are intended to be gripped during use of the tool, a rounded rectangular cross—section, as illustrated in Fig. 4. The rounded rectangular form of the shaft is arranged so that the major axis 7 of the cross—section lies in a plane passing through the centre Line 8 of the parts 2a, 2b of the shaft. It is cLear that the invention may not be regarded as being restricted to the embodiments illustrated in the drawing and described above, but that it may be modified in various ways within the scope of the idea of invention. Thus, the shaft may be made of a suitable material such as wood, plastic, steel or light alloy, or it may be solid or hollow, and types of handle and implement components other than those lLustrated may be encountered. The handle may thus be a rounded end of the shaft.

Claims: Patent Claims 1. Arrangement for a hand tool (1), for example a spade, a pitchfork or a shovel, comprising a shaft (2), which at one of its ends is attached to a tool component (3) and at its other end is executed with a handle (4), c h a r a c t e r i z e d in that the hand tool component (3) is attached to the shaft (2) in such a way that its principal direction of longitudinal extension (5) forms an angle vi of the order of 140°—150° with the shaft (2) at the attachment, in that the length of the shaft (2) is of the order of 1-1.5 m, in that the shaft (2) is executed at a point approximately half way along its length with a bend (6), so that the part (2a) of the shaft (2) between the handle (4) and the bend (6) forms an angle - with the part (2b) of the shaft (2) situated between the bend (6) and the tool attachment, in that the aforementioned angle (v2- is selected so that the first—mentioned part (2a) of the shaft (2) s approximately parallel with the aforementioned principal direction of longitudinal extension, and in that the aforementioned length of the shaft is selected so that an individual standing on a level surface who takes hold of the handle (4) and the first—mentioned part (2a) of the shaft in an area close to the bend (6) is capable, with an essentially straight spine, both of causing the tool component (3) to rest on the ground, and of using it for its intended purpose. 2. Arrangement according to Patent Claim 1, c h a r a c t e r i z e d in that the shaft (2), at least in those areas which are intended to be gripped during use of the tool (1), exhibits a rounded rectangular cross—section, whereby the major axis (7) of the cross—section lies in a plane passing through the centre line (8) of the parts (2a, 2b) of the shaft.

Inventors: CEDERQVIST TONY, ENGSTROEM OVE, ERIKSSON MATS, GUMAELIUS JAN, HEDLUND GUDRUN, THORBLAD JAN, TORSTENSSON KICKI, TYLLGREN PER, CEDERQVIST, TONY, ENGSTROEM, OVE, ERIKSSON, MATS, GUMAELIUS, JAN, HEDLUND, GUDRUN, THORBLAD, JAN, TORSTENSSON, KICKI, TYLLGREN, PER
Applicants: NORBERGS REDSKAP AB
Application year: 1989
Main classification: A01B1
IPC codes: A01B1, A01D9, B25G1