Patent Description:
In the following context, the term "rotary harrow" is intended to be understood to comprise, in addition to mono-rotor and multi-rotor harrows with a vertical axis, preferably also milling machines or similar mono-rotor and multi-rotor machinery with a horizontal axis. In a preferable manner, the invention is particularly suitable for being fitted to rotary harrows of the first type. Naturally, the invention also relates to agricultural machines of different types, such as, for example, lawnmowers, shredders and the like.

In the specific technical field, it is known that the tools, as a result of the abrasion produced by the movement thereof in the soil, are subjected to powerful wear and have to be replaced periodically.

In order to facilitate this operation, it is known to fit the rotors with tool holders with rapid attachment which are able to facilitate at least one and preferably both operations for removing the worn tool and replacing it with a corresponding replacement.

It is further known that in a tool in which there is defined an attachment shank with respect to the tool holder and a blade which is intended to process the soil, only the blade part becomes worn in practice. Therefore, the replacement of the tools is carried out without uniform consumption of the tools having occurred but only a significant consumption of the blade. With reference to the material consumed by wear, it is readily possible to consider that, for each kilogram of material worn, more than double the quantity of non-worn material which forms the shank is disposed of when the tool is replaced.

Finally, it is known that the tools for rotary harrows (but also for other types of agricultural machines) are produced in two shapes, left and right, respectively, which are different as a result of the profile and the bent portion, in such a manner that the two tools which are normally fitted to a rotor are not interchangeable with each other. This causes troublesome assembly errors and causes both the manufacturer and the final user to supply and keep in stock two different types of tool in order to be able to appropriately equip the same harrow or the same agricultural machine.

The incidence of the costs connected with this disadvantage finally means that, in many cases, it is preferable to construct tools with a high mass from materials which are not particularly sophisticated rather than tools with a reduced mass but with more resistant materials. All this affects the value of the rotating masses and the levels of energy consumption of the harrow or other agricultural machine, it not being possible to construct tools which are thinner and lighter but with greater mechanical strength for inherent reasons of cost.

<CIT> describes a rotary harrow, the rotors of which are provided with tools which include a square element and a blade. The square element is fixed to the tool holder with a branch thereof and to the blade with the opposite branch. It is thereby possible to replace the blade which is the only part which is subjected to high wear while keeping unchanged the square element. The fixing between the two members is of the screw and bolt type, however, which does not allow the change of the worn parts to be carried out rapidly. The replacement of the tools further requires the use of spanners and tools which make this operation long, difficult and subject to losses of the particular members to be assembled and to simple errors.

Substantially similar systems which are similarly disadvantageous are further described in <CIT> and <CIT>.

<CIT> describes a rotary harrow which is provided with a tool holder which is provided with two tools, each one including a blade and a shank with which the blade is fixed in a respective seat of the tool holder. Each seat is provided with rapid fixing means including a respective spring-mounted tooth which is mounted on the seat so as to interfere with the shank when it is inserted in the seat in order to retain it at that location. The insertion of the shank in the seat requires that an extension piece of the tooth be gripped in order to pull it out of the seat, counter to the spring, and then in order to release it so as to engage with a hole which is formed in the shank. The same operation is required to remove a worn tool. In all cases, it is extremely difficult to grip the extension piece of the tooth in order to be able to remove it from the seat, taking into account that it is necessary to work in the lower portion of the harrow, in the presence of encrustations of soil and mud, often using a tool which assists in removing the tooth. This applies similarly and involves the same disadvantages when inserting the replacement tool.

Another example of a system for fixing tools of rotary harrows is known from <CIT>. In this case, the tool is fixed by means of a wedge which is inserted between the shank of the tool and the respective seat. The wedge is connected to the seat by means of a screw which must be tightened in order for the wedge to perform its retaining function on the shank. Therefore, it is extremely complicated to replace the tool, taking into account that it is necessary to work with a screwdriver, in the presence of encrustations of soil and mud, taking care not to lose the wedge or the screw. It may be noted that the wedge in particular is not a standard component which can readily be obtained commercially. In any case, the wedge and the screw are both indispensable in order to be able to securely fix and retain the tool counter to the thrust forces transmitted by the blade during the soil processing. Another disadvantage is that the system for fixing the shank projects out of the area travelled by the blade during the rotation of the tool holder and is therefore subjected to wear during the processing of the soil.

Other examples of systems for fixing tools of rotary harrows are known from <CIT>, <CIT>, or <CIT>.

A support for lawnmower blades is known from <CIT>.

The technical problem addressed by the invention is to provide an agricultural machine, such as, for example, a rotary harrow or a lawnmower, and a kit for this machine and, as a component of the machine, a tool for the machine which is structurally and functionally configured to solve at least some and preferably all of the technical problems set out with reference to the cited prior art.

This problem is solved by the invention by means of an agricultural machine, for example, a rotary harrow or a lawnmower, which is constructed according to one or more of the features of the appended claims.

The agricultural machine comprises at least one rotor which is rotatably supported about an axis. The at least one rotor includes a tool holder which extends transversely relative to the axis of the rotor and at least one tool. The at least one tool is secured to the tool holder in a removable manner.

It is preferable for the at least one tool to extend longitudinally.

It is further preferable for the tool holder to extend in a location plane which is transverse to the longitudinal development of the tool when the tool is secured to the tool holder.

Each tool includes a blade and a shank, with which the blade is fixed in a respective seat of the tool holder. Rapid fixing means are provided between the seat and the respective tool in order to secure the shank of the tool in the respective seat.

It may be noted that, in the present context, the term "rapid fixing means" is preferably intended to be understood to be means which can carry out a fixing operation, more particularly a reversible fixing operation, without any need for any tool.

The rapid fixing means include at least one respective spring-mounted tooth which is mounted on the seat so as to interfere with the shank when it is inserted in the seat in order to retain it there.

The spring-mounted tooth comprises a tooth and a resilient element which are preferably operationally associated with each other.

The rapid fixing means and the shank are formed so as to urge the tooth out of the seat counter to the individual spring or resilient element by means of interference between the tooth and shank when the shank is inserted in the seat and to release the tooth to engage with a recess of the shank in order to retain the shank in the respective seat when the tooth and recess are located in a mutually corresponding position.

In this manner, at least the operation for inserting the tooth can be carried out without any tool simply by completely inserting the shank of the tooth in the respective seat.

The spring-mounted tooth is advantageously sufficient per se to ensure the retention of the shank in the seat thereof even (and particularly) with respect to the forces transmitted by the blade during the processing of the soil. Therefore, it is possible (and preferable) for the rapid fixing means to consist essentially of the spring-mounted tooth. In order to secure the shank of the tool in the respective seat, it is further preferable for no additional or different fixing means to be provided with respect to the spring-mounted tooth.

It may be noted that, in this context, the term "spring-mounted tooth" is intended to be understood to mean preferably a tooth which is urged by a resilient element. The resilient element may be a spring, for example, of the leaf spring type, by means of which the tooth is spring-mounted. Naturally, there may be provided a resilient element which is of a different type from the spring, but which is functionally similar.

According to one embodiment, the tooth is formed in a catch-like manner, preferably in the manner of a locking catch, that is to say, with such a form as to move out of the seat counter to the individual spring or resilient element when a surface thereof interferes with a corresponding surface of the shank during insertion of the shank in the seat thereof, and then to snap-fit so as to engage with the corresponding recess when the shank is correctly inserted in the seat. This facilitates the insertion of the tool in the seat and ensures the correct retention thereof.

Advantageously, the catch-like locking tooth is of the type suitable for closing doors in a building in a snap-fitting manner.

The catch-like tooth is preferably movable and is preferably formed with a wedge-like profile, the vertex of which is advantageously directed towards the seat of the shank. The wedge-like profile may be, for example, triangular, in particular a right triangle, preferably with an oblique side which forms a sliding plane for a surface of the shank so as to press the tooth counter to the resilient element out of the seat when the shank is inserted therein.

In some embodiments, the shank comprises opposing sides (more particularly, a pair of opposing sides) which preferably represent the small sides of the shank. Furthermore, the shank may comprise a pair of opposing faces which preferably represent the large sides of the shank.

According to embodiments, the opposing sides of the shank connect the opposing faces of the shank to each other.

Preferably, the opposing sides and where applicable the opposing faces of the shank extend longitudinally in a removal direction of the tool from the seat. The opposing faces of the shank may comprise an internal face and an external face. When the shank is inserted in the seat thereof, the internal face is preferably directed towards the axis of the rotor while the external face is preferably directed in the opposite direction.

Preferably, the opposing sides of the shank are not facing the axis of the rotor when the shank is inserted in the respective seat.

Advantageously, at least one of the opposing sides of the shank is provided with the recess which is able to receive the tooth for blocking the tool in the tool holder in the removal direction of the tool from the seat.

It will be appreciated that forming the recess in one of the opposing sides of the shank has the technical effect of allowing the shank to be retained in the region of one of the sides thereof rather than one of the faces thereof. The retention of the shank in the region of one of the sides thereof is advantageous because it does not influence the radial spatial requirement of the tool holder. In this manner, the tool holder projects to a lesser extent outside the circular area which is travelled by the blade during the rotation of the rotor, and therefore it is less subjected to wear during the processing of the soil.

In some embodiments, a respective recess is formed at opposite sides of the shank. In this manner, the tool is perfectly reversible and can be used in both seats of the tool holder with no difference. This makes it easier to mount the tools and prevents positioning errors.

In a preferred version, the tool or at least the blade or the shank is axially symmetrical.

It is preferable for the recess to be formed on a side of the shank with a tapered formation, in particular a substantially triangular tapered formation, towards the opposite side.

It may be noted that, in this context, the term "sides" of the shank is preferably intended to be understood to mean the sides which do not face the axis of the rotor when the shank is inserted in the respective seat. There are preferably two opposing sides of the shank. Preferably, none of the sides faces the axis of the rotor when the shank is inserted in the respective seat.

The spring-mounted tooth can be mounted on a flank of the seat. Preferably, the flank of the seat does not face the axis of the rotor. More particularly, when the shank is inserted in the respective seat, the flank of the seat faces the at least one of the sides of the shank at which the recess is formed. In this manner, advantageously, the spring-mounted tooth is arranged radially inside the area travelled by the blade during the rotation of the rotor.

It will be appreciated that the spring-mounted tooth being mounted on the flank of the seat has the technical effect of protecting the spring-mounted tooth from wear to which it would be subjected if it projected outside the area travelled by the blade during the rotation of the rotor.

In a preferred embodiment, the resilient element comprises an extension piece, preferably opposite the tooth. The extension piece may project from the flank of the respective seat outwards, in particular in the tangential direction with respect to the rotor.

The extension piece is preferably arranged radially inside the area which is travelled by the blade during the rotation of the rotor.

The extension piece can advantageously be gripped by the flank of the respective seat in order to facilitate the removal of the tooth from the recess.

It will be appreciated that the extension piece allows the tool to be replaced without having to assemble or disassemble other components and without having to use any particular tool.

In one embodiment, an angle between <NUM>° and <NUM>°, preferably between <NUM>° and <NUM>° and even more preferably between <NUM>° and <NUM>°, is formed between the shank and blade. This angle allows the shank to be inserted in the respective seat more easily by an operator who is at the side of the agricultural machine.

To this end, it appears to be advantageous to note that the shank and more particularly the opposite sides of the shank extend longitudinally in a direction for removing the tool from the seat. Naturally, the seat also preferably extends in the same removal direction.

Therefore, it will be appreciated that the removal direction of the tool from the seat can form, with respect to the plane of the blade, the same angle which is formed between the shank and the blade. More particularly, the removal direction can form, with respect to the plane of the blade, an angle between <NUM>° and <NUM>°, preferably between <NUM>° and <NUM>° and more particularly between <NUM>° and <NUM>°.

It may be noted that, when the shank is inserted in the seat, the blade is preferably located in a plane which is substantially parallel with the axis of the rotor. Therefore, the removal direction of the tool from the seat can form, with respect to the axis of the rotor, substantially the same angle which is formed between the shank and the blade. More particularly, the removal direction can form, with respect to the axis of the rotor, an angle between <NUM>° and <NUM>°, preferably between <NUM>° and <NUM>° and more particularly between <NUM>° and <NUM>°.

This geometry ensures that the shank extends inside the area travelled by the blade during the rotation of the rotor. In this manner, the shank is less exposed to wear during the processing of the soil.

There is provision for the blade to have a progressively tapered cross-section in the direction away from the shank, preferably with a cross-section which is initially trapezoidal near the shank in order to taper into a triangular cross-section at the opposite side.

Preferably, the blade and shank are made in one piece, that is to say, they are monolithic, and in one embodiment the tool does not have any bent portions.

In one aspect, the present invention relates to a kit for an agricultural machine, such as, for example, a rotary harrow or a lawnmower, the kit comprising a tool holder, at least one tool and rapid fixing means between the tool holder and the tool according to one or more of the above-mentioned features. The at least one tool is removably secured to the tool holder. Each tool includes a blade and a shank with which the blade is fixed in a respective seat of the tool holder, the shank being an end portion of the tool. The rapid fixing means are provided between the seat and the respective tool in order to secure the shank of the tool in the respective seat. The rapid fixing means include at least one respective spring-mounted tooth which comprises a tooth and a resilient element which are mounted on the seat so as to interfere with the shank when it is inserted in the seat in order to retain it there. The rapid fixing means and the shank are formed so as to urge the tooth out of the seat counter to the resilient element by means of interference between the tooth and shank when the shank is inserted in the seat and to release the tooth to engage with a recess of the shank in order to retain the shank in the respective seat when the tooth and recess are located in a mutually corresponding position.

The invention further relates, as a component of an agricultural machine, to a tool therefor according to one or more of the above-mentioned features.

In one aspect, the invention relates to a tool for tool holders of a rotor for a rotary harrow, the tool comprising a blade and a shank according to one or more of the above-mentioned features. With the shank, the blade can be removably secured to the tool holder. The blade and shank are in one piece. An angle between <NUM>° and <NUM>° is formed between the shank and blade. The blade has a cross-section which progressively tapers away from the shank.

The shank can be inserted in the seat of the tool holder and at least one of the opposing sides of the shank is provided with a recess which can receive a tooth in a catch-like manner for blocking the tool in the tool holder in the removal direction of the tool from the seat.

The recess is transverse relative to the removal direction of the shank from the seat so that the tooth interferes with the recess when the shank is inserted in the seat, in order to retain it there.

At least one wall of the recess is located in a plane which is transverse to the removal direction of the shank from the respective seat so that the tooth interferes with the wall when the shank is inserted in the respective seat in order to retain it there.

It is further preferable for, on at least one of the sides of the shank at the side opposite the blade, a surface which has an inclined plane or which is rounded and which can interfere with the tooth to be provided in order to urge it when the shank is inserted in the seat in the removal direction.

As a result of the above-mentioned features, it is possible to construct lighter tools, in which the mass of the blade is predominant with respect to the mass of the shank so as to dispose of extremely small amounts of material when the tools have to be replaced. This, together with the form of the blade, allows a reduction in the overall mass of the tools with many advantages. These include the fact of reducing the rotary masses and the problems of balancing the rotors, and the fact of being able to use, for the same production cost, steels with high resistances which are capable of withstanding wear or other materials with high performance levels. This leads to the possibility of further reducing the thicknesses and the cross-sections of the blade providing inter alia less resistance to the penetration into the ground with the advantageous result of a reduced energy requirement in order to obtain the same processing of the soil and therefore lower consumption levels for the same performance levels.

The features and advantages of the invention will be better understood from the following detailed description of a number of preferred though non-limiting embodiments thereof which are illustrated with reference to the appended drawings, in which:.

In the Figures, there is generally designated <NUM> a rotor for a rotary harrow which is constructed according to the present invention. The remaining structure of a harrow suitable for being provided with similar rotors generally comprises a box-shaped carrying element which is elongate in a longitudinal direction which is perpendicular to the advance direction of the harrow and on which a plurality of rotors <NUM> are supported with axes X which are mutually parallel and vertical.

Naturally, there is also the possibility that the rotor according to the invention may be fitted to an agricultural machine of a different type, such as, for example, a lawnmower, a shredder or the like. Therefore, it will be appreciated that, although preferred characteristics will be described below in relation to embodiments in which the agricultural machine is a rotary harrow, these characteristics may also equally well be used if the agricultural machine were a lawnmower or the like.

Each rotor <NUM> preferably comprises a rotor shaft <NUM> with an axis X which carries at one end a plate or flange <NUM> which is arranged transversely to the axis X of the rotor and on which a tool holder <NUM> is fixed, preferably in a removable manner for potential replacement.

Each tool holder <NUM> is arranged to mount two or more tools <NUM> which are preferably identical to each other so as to be interchangeable, as explained more clearly below.

As illustrated in the embodiment of <FIG>, the tools <NUM> each comprise a shank <NUM> and a blade <NUM> which are integral with each other or in any case joined to form a unitary structure.

It may be noted that, in this context, the term "shank" is preferably intended to be understood to be an end portion of the tool <NUM> which is or can be fixed to the tool holder.

In some embodiments, the shank <NUM> has a through-hole <NUM> which can be used, for example, to suspend the tool <NUM> when it is not in use.

Preferably, the shank <NUM> extends in a removal direction Y of the tool <NUM> from the tool holder <NUM>.

With reference to the plane of the blade <NUM>, the shank <NUM> (more particularly, removal direction Y) and the blade <NUM> together form an angle A, preferably an acute angle. In a preferred embodiment, the angle A is between <NUM>° and <NUM>° and even more preferably it is between <NUM>° and <NUM>°. It will be understood that, in some embodiments, the angle A can be zero or a right-angle.

Advantageously, both the shank <NUM> and the blade <NUM> do not have bent portions about a longitudinal axis so that each tool <NUM> can be mounted in any of the two positions provided on the tool holder <NUM>. Furthermore, advantageously, the blade <NUM> at least and preferably also the shank <NUM> are symmetrical with respect to a plane which contains the axis X of the rotor.

According to another advantageous aspect, the blade <NUM> starting from the shank <NUM> tapers towards the free end <NUM> thereof and has a decreasing cross-section, preferably with a tapering with an approximately trapezoidal shape, preferably isosceles-shaped, with the small side <NUM> facing the axis X of the rotor so as to terminate at a point with a substantially triangular cross-section. Preferably, when the tools <NUM> are installed in an operating position on the tool holder <NUM>, the two blades <NUM> are substantially parallel with the axis X of the rotor or slightly divergent towards the free ends <NUM> thereof.

In some embodiments, the shank <NUM> is mounted on the rotor <NUM> in a seat <NUM>, preferably in the form of a pocket. Still in a preferable manner, the seat <NUM> extends in the removal direction Y of the tool <NUM> from the seat itself.

The seat <NUM> can be delimited between two walls <NUM>, <NUM>. Preferably, the first wall <NUM> is integrally fixed to the tool holder <NUM> and, in one aspect, defines a pocket with two edges <NUM> which are preferably parallel and extend in the same direction and which are in any case formed so as to conform to the shape of the shank <NUM>.

Preferably, the shank <NUM> has two opposing sides <NUM> which extend in the removal direction Y of the tool <NUM> from the seat <NUM>. The sides <NUM> of the shank are advantageously configured to abut respective edges <NUM> of the seat <NUM>. Furthermore, the shank <NUM> may comprise a pair of opposing faces <NUM> which preferably represent the large sides of the shank. According to embodiments, the sides <NUM> connect the faces <NUM> to each other.

The first wall <NUM> can be constructed by forging, generating more robust zones where needed. Preferably, an end deformation <NUM> is provided on at least one of the edges <NUM> in order to prevent the contact of the shank <NUM> with the corner of the pocket. In this manner, the concentration of the working load of the tool <NUM> is moved further away from the corner.

The second wall <NUM> is preferably formed in a plate-like manner and closes the seat <NUM> by clamping the shank <NUM> between the edges <NUM>.

In one possible embodiment, the two walls <NUM>, <NUM> are fixedly joined to each other, for example, by means of welding or mechanical connection with interference, in such a manner that the seat <NUM> is substantially in the form of a downwardly open pocket or in any case at the opposite side to the tool holder <NUM>.

With reference to the embodiment of <FIG>, the location plane of the seat <NUM> and in particular of the walls <NUM>, <NUM> forms, with respect to the axis X of the rotor, an angle B which, in the present embodiment, is substantially equal to the angle A which the shank <NUM> forms with respect to the plane of the blade <NUM>.

For some applications, in particular of the harrow type, it is preferable for the angle B to be acute. For example, the angle B may be between <NUM>° and <NUM>° and more particularly between <NUM>° and <NUM>°.

This angle has the effect that, advantageously, when the shank <NUM> is inserted in the respective seat <NUM>, the shank is radially inside the area which is travelled by the blade <NUM> during the rotation of the rotor <NUM> about the axis X thereof. In particular, the shank <NUM> extends from an end of the blade <NUM> towards the axis X of the rotor. In this manner, the shank is less exposed to wear during the processing of the soil.

It will be understood that, in some embodiments, the angle B may also be substantially zero because the seat <NUM> extends in a plane which is approximately parallel with the axis X.

For other applications, particularly of the lawn-cutting type, it is preferable for the angle B to be substantially a right-angle or in any case between <NUM>° and <NUM>° and more particularly between <NUM>° and <NUM>°.

As illustrated in the embodiments of <FIG> and <FIG>, there are provided rapid fixing means between the seat <NUM> and the respective tool <NUM> in order to secure the shank <NUM> of the tool in the respective seat <NUM>.

These rapid fixing means comprise at least one respective spring-mounted tooth <NUM>, in particular spring-mounted by means of a spring <NUM>, for example, of the leaf spring type, which is mounted on a flank <NUM> of the seat <NUM> or the walls <NUM>, <NUM> so as to project into the seat <NUM> so as to interfere with the shank <NUM> when it is inserted in the seat <NUM> in order to retain it there.

Naturally, the spring <NUM> may be replaced by a more general resilient element <NUM>. Therefore, it will be appreciated that, although there will be described below preferred features in relation to embodiments in which the resilient element <NUM> is a spring, these features may equally well also be used in the case of a resilient element <NUM> which is structurally different from the spring but functionally similar. In a preferable manner, the spring <NUM> extends longitudinally between an end 11a thereof which is fixed to the tooth <NUM> and an opposite end 11b thereof which is mounted on the flank <NUM> of the respective seat <NUM>.

It may be noted that, in this context, the term "flank" of the seat <NUM> (or of the walls <NUM>, <NUM>) is preferably intended to be understood to be a flank which does not face the axis X of the rotor or which is directed towards the ground. In this manner, the flank is also readily accessible to an operator who is located at the side of the harrow or the lawnmower.

Advantageously, the rapid fixing means and the shank <NUM> are formed so as to urge the tooth <NUM> out of the seat <NUM> counter to the spring <NUM> by interference between the tooth and the shank when the shank is inserted in the seat <NUM> and to release the tooth <NUM> in order to engage with a recess <NUM> of the shank <NUM> in order to retain the shank in the respective seat <NUM> when the tooth <NUM> and recess <NUM> are located in a mutually corresponding position.

With reference to the embodiments of <FIG>, the tooth <NUM> is formed in a catch-like manner, with a wedge-like profile which is substantially triangular, the vertex <NUM> of which is directed towards the seat <NUM>. Preferably, the profile is in the form of a right triangle with an oblique side <NUM> which forms a sliding plane for a surface <NUM> which has an inclined plane or which is otherwise formed (for example, rounded) of the shank <NUM> so as to press the tooth <NUM> counter to the spring <NUM> out of the seat <NUM> when the shank is inserted therein.

Therefore, it is preferable for at least at one of the opposing sides <NUM> of the shank <NUM>, preferably at the opposite side to the blade <NUM>, there to be provided a respective surface <NUM> which has an inclined plane or which is rounded and which is able to interfere with the tooth <NUM> in order to urge it counter to the spring <NUM> when the shank <NUM> is inserted in the seat <NUM>.

In some embodiments, a respective surface <NUM> with an inclined plane affects both the opposite sides <NUM> of the shank <NUM> and is preferably directed at the opposite side to the respective blade <NUM>.

As already mentioned, in at least one side, but preferably in both opposing sides <NUM> of the shank <NUM>, there is formed, preferably with a symmetrical arrangement, a respective recess <NUM> which can receive the tooth <NUM> when the position of the shank coincides with the position for correct assembly of the tool <NUM> in the tool holder <NUM>.

Preferably, when the shank <NUM> is inserted in the respective seat <NUM>, the flank <NUM> of the seat faces the at least one of the opposing sides <NUM> of the shank in which the recess <NUM> is formed.

In one aspect, the recess <NUM> is completely a blind recess and preferably defines an undercut. It is further preferable for at least one wall <NUM> of the recess <NUM> to be located in a plane which is substantially perpendicular or in any case transverse to the removal direction Y of the shank <NUM> from the respective seat <NUM> so that the tooth <NUM> interferes with the wall <NUM> when the shank <NUM> is inserted in the respective seat in order to retain it there.

Advantageously, the tools <NUM> are axially symmetrical, which allows them to be inserted in any of the two (or more) seats <NUM> in an interchangeable manner. In this case, the tool <NUM> also preferably does not have any bent portions. In order to replace the tools of a rotary harrow or a lawnmower which is equipped in this manner, it is simply necessary to grip the spring <NUM> so as to remove the tooth <NUM> from the recess <NUM>. In this case, the shank <NUM> of the tooth is pulled out from the seat <NUM>. Conversely, during the insertion of the shank <NUM> in the seat <NUM>, the simple fact of inserting the shank in the seat involves the automatic removal of the tooth <NUM> counter to the spring <NUM> and the resilient return thereof in order to engage with the recess <NUM> when the tooth and recess are mutually aligned.

In order to further facilitate the removal of the tooth <NUM> from the recess <NUM>, in some embodiments it is possible to grip an extension piece <NUM> of the spring which projects from the flank <NUM> of the respective seat outwards. In a preferred embodiment, the extension piece <NUM> is opposite the tooth <NUM>.

It must be observed that the removal of the tooth <NUM> does not require any work in the lower portion of the harrow or the lawnmower because the spring <NUM> or the potential extension piece <NUM> thereof are readily able to be gripped by the flank <NUM> of the respective seat which is also clearly visible and directly accessible to an operator who is located at the side of the harrow or lawnmower.

Claim 1:
An agricultural machine comprising at least one rotor (<NUM>) which is rotatably supported about an axis (X), the at least one rotor (<NUM>) including a tool holder (<NUM>) which extends transversely relative to the axis (X) of the rotor (<NUM>) and at least one tool (<NUM>) which is removably secured to the tool holder (<NUM>), each tool (<NUM>) including a blade (<NUM>) and a shank (<NUM>), with which the blade (<NUM>) is fixed in a respective seat (<NUM>) of the tool holder (<NUM>), the shank (<NUM>) being an end portion of the tool (<NUM>), rapid fixing means being provided between the seat (<NUM>) and the respective tool (<NUM>) in order to secure the shank (<NUM>) of the tool in the respective seat (<NUM>), characterized in that the rapid fixing means include at least one respective spring-mounted tooth which comprises a tooth (<NUM>) and a resilient element (<NUM>) which are mounted on the seat (<NUM>) so as to interfere with the shank (<NUM>) when it is inserted in the seat (<NUM>) in order to retain it there, whereby the rapid fixing means and the shank (<NUM>) are formed so as to urge the tooth (<NUM>) out of the seat (<NUM>) counter to the resilient element (<NUM>) by means of interference between the tooth (<NUM>) and shank (<NUM>) when the shank (<NUM>) is inserted in the seat (<NUM>) and to release the tooth (<NUM>) to engage with a recess (<NUM>) of the shank (<NUM>) in order to retain the shank (<NUM>) in the respective seat (<NUM>) when the tooth (<NUM>) and recess (<NUM>) are located in a mutually corresponding position.