WO2007099443A1 - Tool for a bush grubber with double action for a combined cut of grass and of shrubs - Google Patents

Abstract

Tool 1 for a bush grabber made up of a blade 2, of a rectangular shape provided with a central hole 3 for connection to rotating head T of a bush grubber, and of suitable hammers 5 in their turn provided with a couple of going through cylindrical holes 10 for insertion of small strings 11 in nylon or in any other strong plastic material. This tool allows to make at the same time a cut of grass and shrubs, by avoiding assembly and disassembly operations of the blade, and also an efficient crumbling of the same ones owing to action of hammers.

Description

"TOOL FOR A BUSH GRUBBER WITH DOUBLE ACTION FOR A COMBINED

CUT OF GRASS AND OF SHRUBS" DESCRIPTION

Present invention relates to a special tool, which can be used in a common bush grubber which allows to cut at the same time both grass and shrubs.

Bush grubbers are used in gardening, in road maintenance, in agriculture and in forestry; are essentially made by an engine, by a transmission system and by a rotating tool. A model of a bush grubber D among the most used ones in shown in figure 1. It is provided with an internal combustion engine M, two-strokes having a small displacement which reaches a maximum of 50 cc.

The proper working part of it, is the end part of it where cutting members are to be found supported by a rotating head T; this bush grubber can operate by a rotating head provided with wires of plastic material, which go through in number of two, but also much more, or it can be provided with a disc blade.

Many are the shapes that this blade may have in relation to its use or to construction specifications of various manufacturing companies; together with the most popular models with a variable number, but low, of pointed tips, and thickly toothed discs are to be found (like they were a saw) or having a continuous profile.

A growing specialization has brought to introduction of replaceable tools to the blade as, for example, a rotary hoe disc for works which are concerned with superficial soil layers. Transmission system housed in metal pole A connects engine and cutting devices. In mono-block bush grubbers pole is tightly connected to engine by means of a steel cable housed inside a flexible pipe and engine is supported by means of suitable belts.

Other members are handle 1, like a delta or like a handle-bar, which must allow a strong and reliable grip, the additional member to be well carried like a knapsack and provided with a safety belt, a shoulder-belt for bush grubbers of a certain weight is overcome and the rigid protection P said anti-stones guard, provided as a protection to cutting members, oriented in order to allow throwing of material in a direction opposite to that of operator.

As we have already said bush grubbers can be classified according to two typologies: those with a rotating head provided either with two or more going-through wires of plastic material or those provided with a disc blade.

Difference between two typologies is to be found in type of work which has to be done, rotating head provided with wires of plastic material is to be used only when cutting of a grass layer has to be carried out while that with a disc blade can provide a wider use, or when cutting not only of grass but also of shrubs.

Many types use a plastic material wire as only solution because they are facing surfaces to be cut only of grass and manually working in case of either tree sprouts or young bushes. What discourages use of a disc is often fear of a blade use and convenience to avoid necessity of assembling and disassembling a different type of cutting device in relation to work to be done. Wire of plastic material is well suited for works in small areas, in only "finishing" type of works, when there are obstacles near cutting area, small walls and fences, hedges, flower-beds and trees.

For cutting grass on wider surfaces (over 200 - 250 m2) it is necessary to use discs with a lower number of teeth and blades in nylon, because wire usually used is tending to heat up and therefore it is more quickly damaged.

When vegetation to be cut becomes bigger and to grass small shrubs, ferns and canes are added, it is better to use a toothed disc, saw type.

This tool however requires to be driven by a high power motor and to be used with a lot of precautions because it is not so difficult to damage the whole tool, especially transmission. However often there are cases in which vegetation to be cut is mixed or on a determined soil to be worked there is a presence at the same time of grass and of shrubs; this causes a difficulty in tool choice to be assembled in the machine.

In these cases state of art does not provide a tool capable to make a mixed cut in a suitable way without need to replace cutting tool , be they either blades or nylon wires.

Besides also in cases where there is uniform grass vegetation there is necessity of an accurate analysis of grass layer to be cut which may sometimes conceal unevenness which could easily wear out chosen nylon wire.

Another disadvantage of present bush grubbers , in case of a mixed grass layer, or in presence of shrubs besides grass, is given by need of making a double work of cutting, first with blades, to take out all shrubs, and then with nylon wires afterwards, to take out lower grass which by using blades would be difficult to reach.

In order to cut lower grass, really it is not advisable to use rotating blades because possible contacts could take place between blades and soil with consequent contacts of blades with soil with consequent possible frictions which could damage same blades.

In other words present bush grubbers show common inconveniences given by necessity to replace tool according to necessity with loss of time and possible risks of accidents by operator during operations of assembly/disassembly of tool.

Invention characterized by enclosed claims to present description, has the purpose to eliminate above mentioned inconveniences by means of a new type of tool, which can be applied to rotary head of bush grubber, which allows an efficient and at the same time cut of grass and wood shrubs.

Tool object of present invention is made of a blade, which assembled in a bush grubber allows to cut any type of low vegetation without necessity of any kind of replacement, thus improving efficiency of cutting work and its life. Really blade of present invention allows to continuously cut also wide surfaces of grass layers without any action by operator with consequent advantages in time required and in security.

An other advantage of tool subject of this description is to make besides cutting grass and shrubs, an efficient breaking into pieces of same ones by means of suitable devices which are to be found in this same tool.

To all these advantages there is added an other one, which must not be neglected, given by easiness of maintenance and possible replacement of all parts which are to be found in it.

Tool of present invention is described in details in the following with reference to enclosed figures in drawings of tables, which show respectively: figure 1 - a model of a bush grubber, hand type well known to which was added cutting tool of present invention; figure 2 — a detail of rotating head of bush grubber shown in figure 1, provided with cutting tool; figure 3 ~ an axonometric view from bottom of cutting tool of above figures, with some parts in pre assembly; figure 4 — an axonometric view from top of cutting tool of figure 3; figure 5 ~ a detail of crumbling device (hammer) with reference to cutting tool of above figures.

Cutting tool or blade 1 for bush grubbers of present invention, described in a preferred embodiment in axonometric views of figure 3 and 4, is made of a metallic plate 2 of rectangular shape provided with a central hole 3 for connection to rotating head T of a bush grubber, as it is shown in figure 2.

Along longitudinal axe of blade, in a symmetrical position with reference to central hole 3, other two smaller holes 4 are provided for connection to plate 2 of two devices 5 called hammers.

Hammers 5, when assembled on bush grubber blade 2, have function to allow a further grass and shrubs crumbling cut by rotating blade 2 during cutting operations of grass layers.

Hammers 5,of which an example is shown in figure 5,are made up of a cylindrical hub 6, suitable to allow insertion in its seat 4 of plate 2, and of a head 7, also a cylindrical one , provided with a container 8 that, by striking repeatedly grass wires and shrubs branches, cause during blade rotation, a hammering action, which allows an efficient crumbling action.

Hammers 5, as shown in figure 4, are solidly connected to plate 2 by means of welding, screwing or any other suitable system.

Cylindrical head 7 in relation to each hammer 5 is provided with a couple of cylindrical going through holes 10 for insertion of a small rope 11 in nylon or in any other strong plastic material, having function to allow a finishing cutting of grass layer, or to allow a more grazing cut with reference to vertical obstacles, like small walls, sidewalks, etc., kind of work which with difficulties a blade could make because there would be possible contacts with obstacle with frictions that could damage both same blade or same obstacle and possibly also to transmission system of bush grubber.

In order to have a correct insertion of said small rope 11 in corresponding holes 10, cylindrical head 7 of hammer 5 is provided with a flat surface 12 which has a further function in order to keep stopped same small rope 11 and not to allow any unthreading during rotation of blade.

In order to allow a better life of small rope 11 in nylon or in any other material, it is advisable that length of same small rope does not overcome twice of distance between flat surface 8 of cylindrical head 7 of hammer and smaller side of rectangular plate 2, in other words that they do not get out of blade; really plate 2 is really a protection for small ropes 11 from possible frictions and deformations due to repeated contact with grass layer to be cut.

In case it is necessary to operate grazing vertical obstacles, small ropes must get out beyond blade.

Plate 2 which is blade of rotating tool is provided with two indents one facing the other which have function to further improve efficiency of cutting action of tool; other two angles one facing the other have a rounded profile.

This tool, above described, is suitable to carry out a cut both of shrubs and of grass even without use of small strings; these are advisable to be used when an English type of lawn has to be cut because surface to be cut increases thus allowing to make a more precise cut.

Cutting tool above described, when it is assembled on bush grubber and being provided both with blade and nylon small strings, allows as a result to make at the same time a cut both of grass and of shrubs and it avoids, with a difference in what is necessary in present bush grubbers, operations of assembly and of disassembly in order to make necessary tooling change.

Tool subject of present invention can also be assembled on any kind of type of bush grubber and it allows an easy maintenance because, in case of wearing of small strings, these can be easily taken out from their corresponding going through holes of hammers thus allowing reinsertion of other new small strings.

Besides, presence of hammers allows to use a new innovating system of grass and of shrubs crumbling by the blade and this makes a more efficient cutting operation.

In an other embodiment, not shown, holes 4 for hammers 5 insertion, made in plate 2, are in a not axial position with reference to central hole 3, even if in any case a symmetrical one. In this embodiment hammers 5 are of a rotating type around their axis and they can be provided with steel small strings; in this case hammers rotation around their axis allows to dampen strokes of metal small strings when obstacles are met with during grass cutting operations.

Both in first one and in this last embodiment notches 13 made in an angular position in plate 2 can have various profiles, besides that one rectangular shown, or, depending on user necessity, can also be absent.

Claims

1) Tool for a bush grubber with double action for a combined cut of grass and of shrubs including a metallic plate (2) of a rectangular shape working as a blade provided with a central hole (3) for connection to rotating head of bush grubber, characterized by fact that on lower surface of blade (2), along its longitudinal axis, are solidly connected two members (5) almost cylindrical ones, provided with going- through cylindrical holes (10) for small nylon string insertion (11) or made of an other suitable plastic material.

2) A tool according to claim 1 characterized by fact that each of two elements (5), called hammers, are made up by a cylindrical hub (6) for insertion in its seat (4) in plate (2) and by a head (7) also of a cylindrical shape and provided with a container (8), that during blade rotation causes a hammering effect for crumbling vegetation to be cut.

3) A tool according to above claims characterized by fact that metallic plate (2) is provided in an angular position, of two notches (13) having function to improve tool cutting efficiency.

4) A tool according to above claims 1 and 2 characterized by fact that in other embodiments hammers (5) may be located in a not axial position with reference to plate 2 or in any other position on the plate but in any case in a symmetrical one with reference to central hole (3).

5) A tool according to claims 1, 2, 4 and 5 characterized by fact that, in other embodiments, hammers (5) are of a rotating type around their own axis and could be provided with small steel strings. ) A tool according to claims 1 and 3 characterized by fact that, in other embodiments notches (13) made in an angular position in plate (2) may have various profiles, besides rectangular one, or, following user necessity, could also be absent.