Patent Description:
In particular, the present invention relates to a forestry shredder and a radio-controlled vehicle for the maintenance of green areas such as, for example, the mowing of: lands, roadsides, ditches or the like.

Advantageously, the present invention relates to a forestry shredder and a radio-controlled vehicle capable of working in extreme working conditions, i.e. even on slopes with gradients greater than <NUM>°.

It is known that a forestry shredder is an apparatus which is moved by a vehicle such as, for example, a tractor, and which comprises a rotor from which blades capable of shredding grass, shrubs, stumps and logs (up to <NUM> in diameter) protrude.

Advantageously, according to the present invention, the forestry shredder is configured to be moved by a radio-controlled vehicle.

Radio-controlled vehicles of the GREENCLIMBER type manufactured by MDB SRL are known. Such types of radio-controlled vehicles advantageously allow working safely on very steep slopes and with gradients of even <NUM>°. The advantage of using radio-controlled vehicles is that the operator can operate said vehicle remotely and safely.

Other types of radio-controlled vehicles are also known, which install in use forestry shredders; however, the other types of known radio-controlled vehicles are not able to work on extreme gradients (greater than <NUM>°), therefore the shredders installed on the other known radio-controlled vehicles (different from the vehicles of the GREENCLIMBER type) are subjected to stresses that are reduced and different with respect to the object of the present invention.

The known forestry shredders are connected to a radio-controlled vehicle by means of an axle shaft. However, such type of connection has the drawback that the axle shaft can be susceptible to breakage, due to the high stresses that can develop thereon during use.

In addition to what has been described above, the known forestry shredders comprise a rotor from which blades protrude and a door, which covers the front of the area in which the rotor operates. The door can be selectively arranged in an opening position or in a closing position, depending on the conditions of use. In the known forestry shredders, the opening system of the door is created by means of a hydraulic cylinder, which is substantially arranged outside said shredder and in a central position. Such opening system is therefore exposed to the external environment and can be susceptible to breakage.

In addition, the known shredders have the rotor that is connected by permanent (i.e. non-releasable) joints such as, for example, the weld, to the shaft that drives it into rotation. In other words, in order to ensure the correct transmission of the motion, the joining end of the rotor is connected to the shaft in a permanent manner. However, this type of joint has the drawback that, in the event of breakage of the shaft, it is necessary to replace both the rotor and the shaft with a consequent high cost. In order to obviate this, it has been attempted to replace the shaft eliminating the previous weld, for example by means of a cut, and attaching the new shaft making another weld. However, it has been observed that, during the elimination of the previous weld, the connecting end of the rotor as well as the new weld further weakened the rotor since it induced internal thermal tensions that reduced the resistance of the joint and of said rotor. It is further evident that a routine and also an extraordinary maintenance of this type of rotor is very complicated and costly.

From documents <CIT>, <CIT>, <CIT>, <CIT> and <CIT> forestry shredders are known which have a releasable connection between the rotor and the machine body to which it is connected. However, these documents do not disclose a releasable connection between the rotor and the respective shaft.

Document <CIT> discloses a forestry shredder, in which the rotor is connected to the respective shaft via side plates. The rotor is made up of a cylinder provided with a plurality of tool holder pins, which are arranged parallel to the rotation axis of the drum. In document <CIT> it is shown that the bearing is mounted between the shaft and the lateral panel of the main body of the forestry shredder.

In document <CIT> there is disclosed a radio-controlled vehicle comprising a forestry shredder.

Moreover, the known shredders comprise a belt tensioning assembly (also called a belt tensioner) created by means of a tie rod fixed on a retainer by means of two opposite nuts. This tensioning assembly is not easily accessible for an operator, who must necessarily access inside the shredder in order to check that there is no possible slackening of said belt. Moreover, the known tensioning assembly does not allow a simple adjustment of the tension of the drive belt.

The object of the present invention is to provide a forestry shredder capable of overcoming the above-described drawbacks.

The object of the present invention is to provide a forestry shredder that can be installed on board a radio-controlled vehicle that generally works on very steep lands and in the presence of many irregularities. In other words, the object of the present invention is to provide a forestry shredder that is configured to ensure the resistance and the correct functioning especially in extreme working conditions, in particular at high gradients (even greater than <NUM>°).

According to the present invention, a forestry shredder is provided as claimed in the appended claims.

The invention will now be described with reference to the accompanying drawings, which illustrate non-limiting example embodiments thereof, wherein:.

<FIG> illustrates during use a radio-controlled vehicle <NUM> and a forestry shredder <NUM> according to the present invention.

It is noted that the forestry shredder <NUM> according to the present invention can be installed on board any vehicle equipped with a system compatible to be fixed to the forestry shredder <NUM>. Advantageously, the forestry shredder <NUM> according to the present invention is configured to be installed on board a radio-controlled vehicle <NUM> capable of working on extreme gradients.

The radio-controlled vehicle <NUM> comprises rolling bodies <NUM> and is configured to be able to move on a supporting plane π1, which can have a gradient α (i.e. is inclined by an angle α) even greater than <NUM>°, with respect to a horizontal plane n0. Preferably, the radio-controlled vehicle <NUM> is a highly performing vehicle and of the type manufactured by the company MDB S. under the trade name "GREEN CLIMBER".

According to what illustrated in <FIG>, the radio-controlled vehicle <NUM> respectively has:.

It is noted that the axes identified for the radio-controlled vehicle <NUM> can also be identified for the forestry shredder <NUM>, which therefore also has axes X, Y and Z as defined above.

Hereafter and in <FIG>, the suffixes I and II are used for indicating the right side and the left side, respectively. The terms such as front, rear, top, bottom or the like are used with reference to the normal operation in the forward direction v of the radio-controlled vehicle <NUM>.

The radio-controlled vehicle <NUM> comprises a front coupling <NUM> to which the forestry shredder <NUM> is connected, as will be better illustrated in the following. In particular, the front coupling <NUM> is a plate, generally known as tool-holder plate, which protrudes from the front of the radio-controlled vehicle <NUM> and is substantially perpendicular to the longitudinal axis X.

With no loss of generality and purely by way of example, the figures schematically illustrate a rotor <NUM> with work tools <NUM>, generally known as blades, which cut the plant material during the rotation of the rotor <NUM>.

The forestry shredder <NUM> comprises a drive assembly <NUM> (schematically illustrated in <FIG> and with some details removed for the sake of clarity), which will be described in detail in the following and which, in use, makes the rotor <NUM> rotate around the transverse axis Y1.

Advantageously, the main machine body <NUM> is configured to ensure both rigidity and resistance. The main machine body <NUM> further comprises two support sides <NUM>, hereafter and in <FIG> and <FIG> are used to respectively identify the right support side <NUM> and the left support side <NUM>, of the forestry shredder <NUM>.

According to the embodiment illustrated in the accompanying figures, each support side <NUM> is a box-shaped body with a housing <NUM>, which is preferably arranged laterally to the shredding chamber <NUM>.

According to an alternative embodiment (not illustrated), each support side <NUM> is defined by a single wall, i.e. is not a box-shaped body.

The main machine body <NUM> comprises a structure <NUM>, which connects the support sides <NUM> to one another, delimits and covers, at the top, the shredding chamber <NUM>. The structure <NUM> has a front edge <NUM> substantially parallel to the transverse axis Y1.

The forestry shredder <NUM> further comprises a door <NUM> which allows accessing the rotor <NUM>. The door <NUM> is connected, in particular hinged, to the structure <NUM> in the area of the front edge <NUM>. As illustrated in <FIG>, the front edge <NUM> is effectively arranged in the area of a side of the forestry shredder <NUM> which is opposite the side to which the radio-controlled vehicle <NUM> is connected in use. The door <NUM> is arranged crosswise, in particular perpendicularly, to the support sides <NUM>. In other words, the door <NUM> substantially extends in a direction parallel to the transverse axis Y1 of the rotor <NUM>.

In other words, the front edge <NUM> is arranged in the area of the front portion of the forestry shredder <NUM>. The door <NUM> is hinged to the structure <NUM> so as to be able to be selectively arranged in a closing position C (illustrated in <FIG>) or in an opening position O (illustrated in <FIG>).

Specifically, in the closing position C the door <NUM> prevents the access to the rotor <NUM> from the outside, whereas in the opening position O the door <NUM> is raised, allowing the access to the rotor <NUM> and exposing it to the outside through a window.

The forestry shredder <NUM> further comprises an opening system <NUM> for the door <NUM> which moves it from the closing position C to the opening position O, and vice versa.

Advantageously, the opening system <NUM> is lateral, i.e. is configured to interact with a respective longitudinal end of the door <NUM>. In other words, the opening system <NUM> is not arranged in the middle (or in a substantially central position) of the door <NUM> (along the transverse axis Y1).

According to what illustrated in Figures from <NUM> to <NUM>, wherein some parts have been removed for the sake of clarity, the opening system <NUM> is installed in the area of a support side <NUM>, in particular of the support side <NUM>.

In particular, the opening system <NUM> is installed inside the main machine body <NUM>. The support side <NUM>, therefore, protects the opening system <NUM>.

In other words, the opening system <NUM> is connected to the main machine body <NUM> in the area of at least one of the support sides <NUM>.

Preferably, the opening system <NUM> is connected to the main machine body <NUM> in the area of one single support side <NUM>.

Advantageously, as illustrated in Figures from <NUM> to <NUM>, if the support side <NUM> is a box-shaped body and is thus provided with the housing <NUM>, then the opening system <NUM> is arranged therein. In other words, if the main machine body <NUM> is provided with the housing <NUM> which is arranged laterally to the shredding chamber <NUM>, then the opening system <NUM> is arranged inside said housing <NUM>.

According to a possible embodiment (not illustrated), the support side <NUM> is not a box-shaped body and the opening system <NUM> is arranged inside the main machine body <NUM>, in particular inside the shredding chamber <NUM>.

As illustrated in <FIG>, the opening system <NUM> comprises an operating means <NUM> and motion transmission means <NUM>. The operating means <NUM> comprises an end <NUM>, which is connected to the main machine body <NUM> and another end <NUM>, which is opposite the end <NUM>, which is instead connected to the motion transmission means <NUM>.

Advantageously, the operating means <NUM> is a linear actuator such as, for example, a linear motor, and/or a hydraulic cylinder and/or a pneumatic cylinder.

Advantageously, the motion transmission means <NUM> comprise a rocker arm <NUM> and a pin <NUM> around which the door <NUM> rotates. The rocker arm <NUM> is interposed between the operating means <NUM> (in particular, it is connected to its end <NUM>) and the pin <NUM>. The pin <NUM> is substantially parallel to the axis Y1 of the rotor <NUM> and defines the hinge around which the door <NUM> rotates. The rocker arm <NUM> and the pin <NUM> are connected to one another, so as to rotate in an integral manner.

The rocker arm <NUM> is configured to oscillate between a first angular position (illustrated in <FIG>), in which the operating means <NUM> is in a retracted position and the door <NUM> is in the closing position C, and a second angular position (illustrated in <FIG>), in which the operating means <NUM> is in an extended position and the door <NUM> is in the opening position O, and vice versa. The oscillation of the rocker arm <NUM> is comprised between <NUM> and <NUM>°, in particular between <NUM> and <NUM>°. In other words, between the first angular position and the second angular position, the rocker arm <NUM> executes a rotation that is less than <NUM>°, in particular is equal to <NUM>°.

As illustrated in Figures from <NUM> to <NUM>, the main machine body <NUM> further comprises a connection plate <NUM>, which is configured, in use, to connect the forestry shredder <NUM> to a front coupling <NUM> of a radio-controlled vehicle <NUM>. The connection plate <NUM> is provided with one or more slots <NUM> and a reference axis Z1.

The reference axis Z1 is parallel to the vertical axis Z, is coplanar to the connection plate <NUM> and is transverse, in use, to the supporting plane π1 of the ground.

The forestry shredder <NUM> further comprises a connection unit <NUM>, which is interposed between the connection plate <NUM> and the front coupling <NUM>. The connection unit <NUM> comprises a connection flange <NUM> which is provided with through openings <NUM> which in particular are holes. The connection flange <NUM> is configured to be respectively connected to both the connection plate <NUM> and the front coupling <NUM> by means of connection means <NUM> which engage the respective through opening <NUM> of the connection flange <NUM> and allow the relative inclination (i.e. a different inclination) between the connection flange <NUM> with respect to the connection plate <NUM>.

In addition, each connection means <NUM> is configured also to engage, i.e. slide in, the respective slot <NUM> of the connection plate <NUM> and thus to allow a relative inclination between the forestry shredder <NUM> and the radio-controlled vehicle <NUM>. In other words, each connection means <NUM> engages the respective through opening <NUM> and the slot <NUM> for connecting the connection flange <NUM> to the connection plate <NUM> and thus allow the inclination of the forestry shredder <NUM> between an inclined position (illustrated in <FIG>) with respect to the radio-controlled vehicle <NUM> and an aligned position, i.e. substantially with the same inclination as the radio-controlled vehicle <NUM> (illustrated in <FIG>). It is noted that the relative inclination between the connection plate <NUM> and the connection flange <NUM> thus allows adapting the orientation of the forestry shredder <NUM> to the slope below, in particular to the supporting plane π1.

The connection means <NUM> connect the connection plate <NUM> to the connection flange <NUM>; whereas, they do not connect the connection flange <NUM> to the front coupling <NUM>.

Advantageously, the connection flange <NUM> is connected to the front coupling <NUM> by means of clamps <NUM>; whereas, the connection means <NUM> that connect the connection plate <NUM> and the connection flange <NUM> are releasable connection means that comprise bolts.

Advantageously, the connection plate <NUM> and the connection flange <NUM> are hinged to one another by means of a pin <NUM>, which is provided with a central axis X1 and which is arranged centrally in the area of an upper end <NUM> of the connection plate <NUM>, the pin <NUM> acts as a centre of rotation of the connection flange <NUM> with respect to the connection plate <NUM>.

According to what illustrated in Figures from <NUM> to <NUM>, the connection plate <NUM> is provided with two slots <NUM> which are made on opposite sides of the axis Z1 of the connection plate <NUM>. In particular, the reference axis Z1 is an axis of symmetry of the connection plate <NUM> and is incident with the central axis X1 of the pin <NUM>. Therefore, the slots <NUM> are identical and specular to one another.

Advantageously, each slot <NUM> is curved, in particular convex, towards the inside of the connection plate <NUM>. In other words, each slot <NUM> comprises an arc of a circle having the centre in the area of the pin <NUM>, i.e. of the central axis X1.

The connection unit <NUM> further comprises spring-back means <NUM> which connect a respective upper peripheral end <NUM> of the connection plate <NUM> with the main machine body <NUM>. In particular, each spring-back means <NUM> is connected at one of its ends to the main machine body <NUM> in the area of a respective coupling <NUM> which is arranged in a lower position in proximity of the support side <NUM> and at its opposite end in the area of an upper peripheral end <NUM> of the connection flange <NUM>.

Advantageously, the spring-back means <NUM> are compression springs which are configured to bring the forestry shredder <NUM> from the inclined position (illustrated in <FIG>) back to the aligned position (illustrated in <FIG>).

It is highlighted that the connection unit <NUM> of the forestry shredder <NUM> according to the present invention is devoid of a connecting axle shaft. In other words, the forestry shredder <NUM> is not connected to the radio-controlled vehicle <NUM> by means of an axle shaft.

As described in the foregoing, the forestry shredder <NUM> is further provided with a drive assembly <NUM> (schematically illustrated in <FIG> and with some details removed for the sake of clarity), which drives the rotor <NUM> into rotation. The drive assembly <NUM>, illustrated in Figures from <NUM> to <NUM>, comprises a drive (not illustrated), a drive belt <NUM> which transmits the motion from the drive to the rotor <NUM>, a drive pulley <NUM> and a driven pulley <NUM>. In particular, the drive belt <NUM> is respectively fitted on the drive pulley <NUM> and a driven pulley <NUM> which are properly spaced apart from one another.

In particular, the drive belt <NUM> transfers the motion from the drive pulley <NUM> driven into rotation by the drive to the driven pulley <NUM> which drives into rotation a shaft <NUM> and thus the rotor <NUM>. The drive assembly <NUM> is provided with a tensioning assembly <NUM> of the drive belt <NUM> in order to ensure the correct tensioning of the drive belt <NUM> and, thus, the correct transmission of the motion.

The drive assembly <NUM> is provided with an adjustment flange <NUM>, which is arranged in the area of one of the pulleys <NUM> and <NUM>, in particular of the drive pulley <NUM>. The adjustment flange <NUM> is connected to the pulley <NUM> or <NUM>, in particular to the drive pulley <NUM> of the drive belt <NUM>, in order to adjust the tension of the drive belt <NUM> through the rotation of the adjustment flange <NUM>. The adjustment flange <NUM> is provided with a slot <NUM> (illustrated in <FIG> and <FIG>), in which a connection means <NUM> slides. In other words, the slot <NUM> is configured to allow a rotation of the adjustment flange <NUM> by an angle comprised between <NUM> and <NUM>°, in particular between <NUM> and <NUM>°. The tensioning assembly <NUM> is thus configured to perform a fine adjustment of the rotation of the adjustment flange <NUM>, i.e. an adjustment by an angle less than <NUM>°, in particular at <NUM>°.

The tensioning assembly <NUM> further comprises a tie rod <NUM> provided with a threaded end <NUM> and a spring <NUM>, in particular a compression spring, preferably a coil spring, fitted around the tie rod <NUM>. The spring <NUM> is arranged in particular between a stop <NUM> (which in particular is fixed) and a nut <NUM>, which is screwed onto the threaded end <NUM> of the tie rod <NUM> in order to vary the preload of the spring <NUM>. In other words, by screwing the nut <NUM> it is possible to compress the spring <NUM> more (i.e. reduce its length) and thus vary its preload. By varying the preload of the spring <NUM> it is possible to perform an adjustment of the orientation of the adjustment flange <NUM> and thus adjust the tension of the drive belt <NUM>. The preload of the spring <NUM> and consequently the tension of the drive belt <NUM> vary according to the level, i.e. degree, of screwing of the nut <NUM> on the threaded end <NUM>. In particular, the tensioning of the drive belt <NUM> is directly proportional to the preload of the spring <NUM>. Advantageously, by increasing the preload of the spring <NUM> also the tensioning of the drive belt <NUM> increases.

As illustrated in the accompanying figures, the tensioning assembly <NUM> protrudes at least partially (preferably completely) from the main machine body <NUM>. In other words, the tensioning assembly <NUM> is arranged at least partially (preferably completely) outside the main machine body <NUM>. In particular, at least one portion of the tie rod <NUM> and of the nut <NUM> protrude outwards from the main machine body <NUM>. In other words, at least one portion of the tie rod <NUM> and of the nut <NUM> is arranged outside the main machine body <NUM>.

In particular, as illustrated in the accompanying figures, the tensioning assembly <NUM> is arranged on an outer surface of a side <NUM>, i.e. the tensioning assembly <NUM>, and is connected to the outside of the main machine body <NUM> in the area of one of the support sides <NUM>.

Alternatively, if the support side <NUM> is made as a box-shaped body and has the housing <NUM>, then the tensioning assembly <NUM> can be arranged at least partially inside the housing <NUM>, so as to have at least one portion protruding outward from the housing <NUM>.

According to what illustrated in <FIG>, the forestry shredder <NUM> comprises two connection assemblies <NUM> (in particular, <NUM> and <NUM>), which respectively connect an end <NUM> or 261II of the rotor <NUM> to the shaft <NUM> or to a shaft <NUM>. In particular, the connection assembly <NUM> connects the end <NUM> of the rotor <NUM> to the shaft <NUM>; whereas, the connection assembly 260II connects the end 261II (which is opposite the end <NUM>) of the rotor <NUM> to the shaft <NUM>. The two shafts <NUM> and <NUM> are made as shafts separate from one another and are coaxial to the transverse axis Y1.

Each connection assembly <NUM> comprises releasable connection means <NUM> and a closing flange <NUM>.

The connection means <NUM> connect the rotor <NUM> (i.e. its ends <NUM>) to the shaft <NUM> or <NUM>. In particular, the connection means <NUM> engage through openings <NUM> which are made in the area of a shoulder of the shaft <NUM> or <NUM>.

Each closing flange <NUM> is provided with a through opening <NUM> which houses the respective shaft <NUM> or <NUM>. In particular, as illustrated in <FIG>, the shaft <NUM> protrudes from the closing flange 265II, in order to be connected to the drive assembly <NUM> (in particular the driven pulley <NUM>) which drives the rotor <NUM> into rotation, as described in the foregoing. Whereas, the shaft <NUM> does not protrude from the closing flange <NUM>.

Each closing flange <NUM> closes the respective end <NUM> of the rotor <NUM> and is connected to the respective support side <NUM> by means of connection means <NUM> (illustrated in <FIG> and <FIG>) which engage the through openings <NUM> and <NUM>. The through openings <NUM> are obtained in the area of the closing flange (<FIG>); whereas, the through openings <NUM> are obtained in the area of the support sides <NUM> (<FIG>).

Therefore, in use when the rotor <NUM> rotates, the closing flange <NUM> does not rotate and is integral with the support side <NUM>.

The term "releasable connection means <NUM> or <NUM>" has the meaning of connection means that allow connecting two elements in a removable manner, such as, for example, bolts. The term "releasable connection means <NUM> or <NUM>" does not have the meaning of permanent connection means such as, for example, welds.

Advantageously, as can be seen from the section illustrated in <FIG>, the rotor <NUM> has a cylindrical body <NUM> on whose outer surface the work tools <NUM> are arranged and has reaction elements <NUM> arranged inside the cylindrical body <NUM> and which are connected thereto. In particular, the two elements <NUM> are arranged spaced apart from the respective ends <NUM> of the rotor <NUM>. Each shaft <NUM> or <NUM> (in particular its shoulder provided with through openings <NUM>) is arranged at least partially in abutment against the reaction element <NUM> and is connected to the same by the connection means <NUM>. In other words, at least one portion of the shaft <NUM> or <NUM> is arranged in abutment against the respective reaction element <NUM> and is connected to said reaction element <NUM> by means of the connection means <NUM>.

Advantageously, the reaction element <NUM> is connected to the inner surface of the cylindrical body <NUM>, in particular by welding.

Each connection assembly <NUM> comprises a bearing <NUM> arranged between the respective shaft <NUM>, <NUM> and the respective closing flange <NUM>. In particular, the bearing abuts on one side against a shoulder of the shaft <NUM> or <NUM> and on the other side it is locked by locking means <NUM> which can comprise, for example, a Seeger ring and a ring nut.

According to a possible alternative (not illustrated), the bearing <NUM> is replaced by a bushing.

Advantageously, the present invention also concerns the radio-controlled vehicle <NUM> comprising a forestry shredder <NUM> as described up to here.

The forestry shredder <NUM> described up to here has a plurality of advantages.

Firstly, by making the opening system <NUM> in accordance with the present invention, a precise and reliable opening of the door <NUM> is made possible.

Moreover, by arranging the opening system <NUM> inside the shredding chamber <NUM> or inside the support side <NUM>, it is protected from potential external impacts, therefore the opening system <NUM> is less exposed to damage and to being dirtied during the working phases.

Moreover, by arranging the opening system <NUM> laterally, the main machine body <NUM> is made of a smooth and intact component that prevents dirt or small pieces of mowing, which typically settle on the main machine body <NUM>, from unintentionally locking the opening system <NUM>.

A further advantage of the forestry shredder <NUM> object of the present invention is the presence of a connection unit <NUM>, devoid of axle shafts, which allows improving the connection of the radio-controlled vehicle <NUM> to the forestry shredder <NUM> and makes it more reliable. In fact, as the connection unit <NUM> is devoid of the axle shaft, the risk that the axle shaft could break and potentially fall down the slope of the forestry shredder <NUM> is averted.

The connection unit <NUM> according to the present invention is made of elements that are connected to one another by releasable connection means. Therefore, in the event of a breakdown, a quicker and easier replacement of the component can be performed. Moreover, as the connection unit <NUM> is connected to the connection plate <NUM> by means of the connection means <NUM> which are symmetrically spaced apart from the axis Z1, a better distribution of the forces and of the torques acting on said forestry shredder <NUM> is achieved.

The forestry shredder <NUM> provided with the tensioning assembly <NUM> manufactured in accordance with the present invention, which thus protrudes at least partially outward from the main machine body <NUM>, immediately allows knowing, without requiring any disassembling of components of the forestry shredder <NUM>, whether the drive belt <NUM> has an unsuitable tensioning. In fact, as the tensioning of the drive belt <NUM> is proportional to the preload of the spring <NUM>, it is possible to check whether it is necessary to increase or reduce the tension of the drive belt <NUM> as a function of the compression of the spring <NUM> and thus of the degree of screwing of the nut <NUM> (easily detectable by the operator). Checking the correct tensioning of the drive belt <NUM> is of fundamental importance since, if it is tensioned less than necessary, the drive belt <NUM> slides on the pulleys <NUM> and <NUM> and is thus unable to be properly dragged; whereas, if the drive belt <NUM> is tensioned more than necessary, it will tend to break due to the tractive forces to which it is subjected. Moreover, as the spring <NUM> has a fixed stop <NUM> (i.e. its position does not vary over time), the preload of the spring <NUM> is generated by the simple rotation of the nut <NUM>. Therefore, it is clear that the tensioning assembly <NUM> allows an easy adjustment of the tensioning of the drive belt <NUM>.

Claim 1:
An improved forestry shredder (<NUM>) comprising:
a main machine body (<NUM>), which delimits a shredding chamber (<NUM>) and is provided with two support sides (<NUM>, <NUM>, 204II), which laterally delimit the shredding chamber (<NUM>); and
a rotor (<NUM>), which is arranged inside the shredding chamber (<NUM>), is rotatable around a transverse axis (Y1) arranged crosswise to the support sides (<NUM>, <NUM>, 204II) and is provided with work tools (<NUM>), which are configured to cut plant material during the rotation of the rotor (<NUM>); the rotor (<NUM>) is connected, in the area of two ends (<NUM>, <NUM>, 261II) of its, to a respective shaft (<NUM>, <NUM>) by means of a connection assembly (<NUM>, <NUM>, <NUM>), which comprises first releasable connection means (<NUM>);
each connection assembly (<NUM>, <NUM>, 260II) comprises a closing flange (<NUM>, <NUM>, 265II), which closes the respective end (<NUM>, <NUM>, 261II) of the rotor (<NUM>) and is connected to the respective support side (<NUM>, <NUM>, 204II) by means of second connection means (<NUM>) of the releasable type; each closing flange (<NUM>, <NUM>, 265II) is provided with a through opening (<NUM>), which houses the respective shaft (<NUM>, <NUM>);
and each connection assembly (<NUM>) comprises a bearing (<NUM>) or a bushing arranged between the respective shaft (<NUM>, <NUM>) and the respective closing flange (<NUM>).