IT201800002670A1 - TRANSMISSION - Google Patents

Description

DESCRIPTION

of the Italian Patent for Industrial Invention entitled:

"TRANSMISSION"

Field of technique

The present invention relates to a transmission capable of transferring torque from a power unit, for example from an internal combustion engine, to the traction elements of a vehicle, for example to the driving wheels. More particularly, the present invention relates to a transmission adapted to be installed on an agricultural vehicle, for example on a tractor.

State of the art

As is known, most tractors generally comprise an internal combustion engine, at least two driving wheels and a transmission suitable for transferring the torque generated by the internal combustion engine to the driving wheels and possibly to a power take-off suitable for driving the machines. operators that can be connected to the tractor.

In addition to transferring the torque, the transmission must be able to vary the transmission ratio between the angular speed of the crankshaft and the angular speed of the drive wheels, selecting it from time to time from a plurality of available gears.

To allow this speed variation, a conventional type transmission generally comprises an input shaft connected to the crankshaft, for example through a clutch, an output shaft connected to the drive wheels and / or to the power take-off, for example through a differential and / or other transmission members, and a plurality of gears adapted to kinematically connect the input shaft with the output shaft.

Each of these gears normally comprises a first toothed wheel keyed to the input shaft and a second toothed wheel rotatably coupled to the output shaft and meshed with the corresponding first toothed wheel.

The transmission also comprises coupling members, for example synchronizers, which can be operated manually or automatically to selectively engage only one of the second toothed wheels mentioned above, making it integral in rotation with the output shaft and therefore allowing motion transmission through the corresponding gear.

In order to ensure optimal engine operation in any tractor operating condition, for example during agricultural work, during transfers on asphalt or during transfers on land, the transmission nevertheless needs to make available a very large number of different marches.

To meet this requirement with conventional architecture, it is therefore necessary to significantly multiply the number of transmission gears, with the result of obtaining an extremely bulky and heavy transmission that often introduces very significant constructive constraints in the agricultural tractor as a whole.

Presentation of the invention

In light of the foregoing, an object of the present invention is to provide a transmission capable of making numerous different gear available, remaining within the scope of a compact construction solution and therefore of limited size.

Another object of the present invention is to make available a transmission which can be configured or reconfigured in a modular way according to the specific applications for which it is intended, without significantly increasing its overall size.

A further object of the present invention is to make available a transmission which can be coupled not only to an internal combustion engine but also to a hybrid system comprising an internal combustion engine and an electric motor.

Another object of the present invention is finally to achieve the aforementioned objectives within the framework of a simple, rational and relatively low cost solution.

These and other purposes are achieved thanks to the characteristics of the invention which are reported in independent claim 1. The dependent claims outline preferred or particularly advantageous aspects of the invention.

In particular, an embodiment of the present invention makes available a transmission comprising:

- a plurality of rotating shafts having axes of rotation parallel to each other, of which at least a first shaft, a second shaft which can be arranged for example coaxial to the first shaft, a third shaft and a fourth shaft, - a first toothed wheel rotatably coupled to the first tree,

- a first toothed wheel keyed to the fourth shaft and meshing with the first toothed wheel of the first shaft, so as to define a reverse gear,

- a first coupling apparatus adapted to engage (i.e. to make integral in rotation) the first shaft selectively to the first toothed wheel rotatably coupled to it or to the second shaft,

- at least a first and a second toothed wheel keyed to the second shaft,

- at least a first and a second toothed wheel rotatably coupled to the third shaft and singularly meshing respectively with the first and second toothed wheel of the second shaft, so as to define respectively a first and a second gear,

- a second coupling apparatus adapted to engage (i.e. to make integral in rotation) the third shaft selectively to the first or to the second toothed wheel rotatably coupled to it, and

- a second toothed wheel keyed to the fourth shaft and meshing with the first toothed wheel of the third shaft.

Thanks to this solution, an extremely simple, economical and compact transmission is provided, which is effectively able to mechanically supply at least two splitters, of which at least one direct forward splitter (direct) and one reverse gear splitter. , selectable through the first engagement apparatus and, for each of these splitters, at least two different transmission ratios selectable through the second engagement apparatus and which, depending on the specific applications for which the transmission is intended, can be configured as two gears or as two ranges.

In this way, the transmission outlined above can be advantageously used as a basic module both for the development of mechanical or hydraulic-mechanical transmissions with a greater number of gear ratios, and for the realization of CVT (Continuous Variable Transmission) type transmissions. having a wider field of operation than those which are currently known.

According to one aspect of the invention, the center distance between the second shaft and the third shaft can be greater than the interest between the second shaft and the fourth shaft.

In this way it is advantageously possible to optimize the sizing of the parts and, consequently, the overall dimensions, weights and costs of the transmission as a whole.

Substantially for the same reason it is also preferable that the half-plane containing the rotation axes of the second and fourth shaft can be inclined with respect to the half-plane containing the rotation axes of the second and third shaft, for example by an angle of less than 90 ° sexagesimal .

According to another aspect of the present invention, the first engagement apparatus can comprise a synchronizer adapted to engage the first shaft alternatively to the first toothed wheel rotatably coupled thereon or to the second shaft.

Similarly, the second engagement apparatus can comprise a synchronizer adapted to engage the third shaft alternatively with the first or second toothed wheel rotatably coupled thereon.

These solutions have the advantage of being quite economical and not bulky.

In some embodiments, the first engagement apparatus may however comprise two clutches, for example two hydraulic clutches, respectively adapted to engage / disengage the first shaft to / from the second shaft and to engage / disengage the first shaft to / from the first gear wheel rotatably coupled thereon.

Although generally more expensive than the previous one, this second solution has the advantage of being more performing.

According to another aspect of the invention, the transmission can also include:

- a fifth rotating shaft having an axis of rotation parallel to the rotation axes of the other rotating shafts, for example arranged coaxial to the third shaft, and

- a planetary gear set to kinematically connect the fifth shaft to the third shaft.

In this way it is advantageously possible to obtain a significant speed variation between the third and fifth shaft, with a high-performance and compact gearing.

According to a further aspect of the invention, the transmission can also include:

- an additional toothed wheel coupled to the second shaft,

- a further toothed wheel rotatably coupled to the third shaft and meshing with said further toothed wheel of the second shaft, so as to define a further gear, and

- a further coupling apparatus adapted to selectively engage (ie to make integral in rotation) the third shaft to said further toothed wheel rotatably coupled thereto.

Also in this case, the further coupling apparatus may include, for example, a synchronizer able to engage / disengage the third shaft to / from the further toothed wheel rotatably coupled to it.

Thanks to this solution, a further transmission ratio is added to the transmission described above, which can be used both in the forward gear splitter and in the reverse gear splitter, which advantageously increases the field of application of the transmission.

In particular, this type of solution can be useful as a basis for the realization of a CVT transmission.

In fact, an embodiment of the present invention provides that the transmission may also include:

- a hydraulic motor having a drive shaft kinematically connected to a crown gear of the planetary gear so as to be able to rotate it, and

- a hydraulic pump having a drive shaft kinematically connected to the first shaft and hydraulically connected to the hydraulic motor.

In this way, a CVT transmission is obtained in which, for each split and range available mechanically, it is possible to continuously vary the transmission ratio between the first shaft and the fifth shaft thanks to the rotating drive of the gear wheel. planetary, remaining within the scope of an extremely simple and compact solution.

In accordance with another embodiment of the present invention, the transmission may include:

- a sixth rotating shaft having an axis of rotation parallel to the rotation axes of the other rotating shafts,

- at least a first and a second toothed wheel rotatably coupled to the sixth shaft and singularly meshing with the first and second toothed wheel of the second shaft respectively, so as to define respectively a third and a fourth gear,

- a third coupling apparatus adapted to selectively engage (i.e. to make integral in rotation) the sixth shaft to the first or to the second toothed wheel rotatably coupled to it, and

- a fifth gear adapted to kinematically connect the sixth shaft to the third shaft.

Thanks to this solution, an extremely compact transmission is made available which, mechanically, is effectively able to supply at least four gears for each splitter.

Also in this case, the third engagement apparatus can comprise a simple synchronizer adapted to engage (ie to make integral in rotation) the sixth shaft alternatively to the first or to the second toothed wheel rotatably coupled thereon.

To optimize the sizing of the parts and, consequently, the overall dimensions, weights and costs of the transmission, it is preferable that the distance between the second shaft and the sixth shaft is less than the interest between the second shaft and the third shaft. .

For example, the center distance between the second shaft and the sixth shaft can have a value between that of the interest between the second shaft and the fourth shaft and that of the center distance between the second shaft and the third shaft.

It is also a preferred aspect of the invention that the half-plane containing the rotation axes of the second and sixth shaft can be inclined with respect to the half-plane containing the rotation axes of the second and third shaft, for example by an angle of less than 90. ° sexagesimal and, for example, higher than the angle formed between the half-plane containing the rotation axes of the second and fourth shaft and the half-plane containing the rotation axes of the second and third shaft.

According to an aspect of this embodiment, the aforementioned fifth gear can comprise a third and a fourth toothed wheel rotatably coupled to the second shaft and integral in rotation with each other, a third toothed wheel keyed to the third shaft and meshing with the third wheel of the second shaft, a third toothed wheel keyed to the sixth shaft and meshing with the fourth toothed wheel of the second shaft, and a fourth engagement apparatus to selectively engage (i.e. make integral in rotation) the second shaft to the third and fourth toothed wheel rotatably coupled on it.

Also in this case, the fourth engagement apparatus can comprise a synchronizer adapted to engage / disengage the second shaft to / from the third gear wheel rotatably coupled thereto.

In this way, it is advantageously possible to add to the transmission also a fifth gear for each available splitter, consequently increasing the field of application of the transmission without significantly modifying its overall dimensions.

The third and fourth sprockets of the second shaft preferably have the same number of teeth but may possibly have toothings with a different profile, for example by applying different corrections relating to the displacement factor of the profile and the correction factor addendum.

In this way, it is advantageously possible to optimize the tensions that are discharged on the toothed wheels during the various operating phases, consequently optimizing their sizing and therefore the dimensions, the weights and the connected costs.

Returning to the relative position of the shafts, we want to highlight here that the distance between the second and sixth shafts, as well as the angle formed between the half-plane containing the rotation axes of the second and sixth shaft and the half-plane containing the axes of rotation of the second and third shaft, can be uniquely determined according to the maximum transverse dimensions of the transmission (which can be a fixed design parameter) and the number of teeth of the wheels that mesh between the second and sixth shaft. In other words, once the transversal dimensions and the number of teeth have been fixed, the angle formed between the half-planes and the center distance are determined univocally, therefore it could happen that they are different from those previously indicated, for example that the angle between the half-planes is greater than 90 °.

According to another aspect of the invention, the transmission can also comprise a fifth coupling apparatus adapted to selectively engage (ie to make integral in rotation) the fifth shaft with a satellite carrier of the planetary gear or directly with the third shaft.

Thanks to this solution it is advantageously possible to add two ranges to the transmission, selectable through the fifth engagement device, which allow to multiply the number of transmission ratios that can be obtained with the transmission.

According to a further aspect of the invention, the transmission can also include:

- a sixth coupling apparatus adapted to selectively engage (i.e. to make integral in rotation) a first portion of the third shaft, to which the respective first, second and third toothed wheels are coupled, to a second portion of the third shaft,

- a fifth toothed wheel rotatably coupled to the second shaft and integral in rotation to the third and fourth toothed wheel of said second shaft,

- a fourth toothed wheel rotatably coupled to the second portion of the third shaft and meshing with the fifth toothed wheel of the second shaft, and

- a seventh clutch device adapted to selectively engage said second portion of the third shaft to the fourth toothed wheel rotatably coupled thereon.

This solution allows two further ranges to be added to the transmission, selectable through the sixth and seventh gearbox, which further multiply the number of available transmission ratios. For example, it is possible to obtain four ranges, including a creeper, a mini-creeper, a medium and a high.

In this case, the sixth engagement apparatus may comprise a reconfigurable joint adapted to selectively engage / disengage the first portion of the third shaft to / from the second portion.

The seventh clutch device may in turn comprise a further reconfigurable joint adapted to selectively engage / disengage the second portion of the third shaft to / from the fourth gear wheel rotatably coupled thereon. A further embodiment of the present invention provides that the transmission may also include:

- a second toothed wheel keyed on the first shaft,

- a seventh rotating shaft having an axis of rotation parallel to the rotation axes of the other rotating shafts,

- at least one first toothed wheel rotatably coupled to the seventh shaft and meshing with the second toothed wheel of the first shaft,

- a second toothed wheel keyed on the seventh shaft and meshing with the second toothed wheel keyed on the second shaft, and

- an eighth coupling apparatus adapted to selectively engage (ie to make the seventh shaft integral in rotation) to the first toothed wheel rotatably coupled to it.

In this way it is advantageously possible to add an additional splitter to the transmission, in addition to the direct forward and reverse one, for example a forward low speed splitter.

The eighth engagement apparatus may comprise a clutch, for example a hydraulic clutch, designed to engage / disengage the seventh shaft to / from the first toothed wheel rotatably coupled to it.

To optimize the sizing of the parts and, consequently, the overall dimensions, weights and costs of the transmission, it is preferable that the distance between the second shaft and the seventh shaft is substantially equal to or (slightly) greater than the interest between the second tree and third tree.

It is also preferable that the half-plane containing the rotation axes of the second and seventh shaft can form, with the half-plane containing the rotation axes of the second and fourth shaft, an angle substantially equal to 180 ° sexagesimal.

In other words, it is preferable that the rotation axes of the second, fourth and seventh shaft can lie in a common plane, in which the rotation axis of the second shaft is interposed between the rotation axes of the fourth and seventh shaft.

According to one aspect of this embodiment, the transmission can also comprise:

- a third toothed wheel keyed on the first shaft,

- a third toothed wheel rotatably coupled to the seventh shaft and meshing with the third toothed wheel of the first shaft, and

- a ninth coupling apparatus adapted to selectively engage (ie to make integral in rotation) the seventh shaft with the third toothed wheel rotatably coupled thereto.

This ninth engagement apparatus can also comprise a clutch, for example a clutch of the hydraulic type, adapted to engage / disengage the seventh shaft to / from the third gear wheel rotatably coupled thereto.

Thanks to this solution, an additional splitter is advantageously added, for example a high speed forward gear splitter, further multiplying the number of available gear ratios.

Brief description of the drawings

Further features and advantages of the invention will become evident from reading the following description provided by way of non-limiting example, with the aid of the figures illustrated in the attached tables.

Figure 1 is the diagram of a transmission according to a basic embodiment of the present invention.

Figure 2 is the view A indicated in Figure 1 showing only the arrangement of the rotating shafts.

Figure 3 is the diagram of a transmission according to a second embodiment of the present invention.

Figure 4 is the diagram of a transmission according to a third embodiment of the present invention.

Figure 5 is the view A indicated in Figure 4 showing only the arrangement of the rotating shafts.

Figure 6 is the diagram of a transmission according to a fourth embodiment of the present invention.

Figure 7 is the diagram of a transmission according to a fifth embodiment of the present invention.

Figure 8 is the view A indicated in Figure 7 which shows only the arrangement of the rotating shafts.

Figure 9 is the diagram of a transmission according to a sixth embodiment of the present invention.

Detailed description

With the aid of the aforementioned figures, many embodiments of a transmission 100 are now described which is generally adapted to transfer torque from a power unit to one or more members to be operated.

For example, the transmission 100 can be installed on board a motor vehicle, typically but not exclusively on board an agricultural vehicle such as a tractor, in order to transfer the torque generated by the power unit to the traction elements of the vehicle, for example to the driving wheels, and possibly to an operating machine that can be installed on the vehicle itself or connected to it, for example through a power take-off.

The power unit for which the transmission 100 is intended can be any device capable of generating torque. For example, the power unit can simply comprise an internal combustion engine, such as a Diesel engine, or it can be a hybrid power unit, comprising both an internal combustion engine and an electric motor connected to a battery.

According to a basic embodiment, illustrated in Figure 1, the transmission 100 can comprise a plurality of rotating shafts having mutually parallel rotation axes, of which at least a first shaft 105, a second shaft 110, a third shaft 115, a fourth shaft 120 and a fifth shaft 125.

The first shaft 105 is adapted to be connected to the power unit, so as to receive the torque and be rotated by it. For example, the first shaft 105 can be directly connected to the drive shaft of the internal combustion engine and / or the electric motor.

The fifth shaft 125 is adapted to be connected to the members to be operated, for example to the driving wheels of the vehicle, so as to transmit to them the torque generated by the power unit and set them in rotation.

For example, the fifth shaft 125 can be connected to the members to be driven through one or more transmission systems, including for example a bevel gear 130 and / or a planetary gear 135.

The second, third and fourth shaft 110, 115 and 120 of the transmission 100 are kinematically interposed between the first shaft 105 and the fifth shaft 125, in such a way as to transmit the motion from one to the other.

Preferably, the second, third and fourth shaft 110, 115 and 120 are mutually parallel and mutually spaced, with the second shaft 110 which can be arranged coaxial to the first shaft 105 and the third shaft 115 which can be arranged coaxial to the fifth shaft 125.

As illustrated in figure 2, for reasons of constructive compactness and optimization of efforts and masses, the center distances between the second, third and fourth shafts 110, 115 and 120 may be different and their rotation axes may not be perfectly coplanar.

For example, the center distance D3 between the second shaft 110 and the third shaft 115 may be greater than the interest D4 between the second shaft 110 and the fourth shaft 120.

Furthermore, the half-plane S4 containing the rotation axes of the second and fourth shaft 110 and 120 can be inclined with respect to the half-plane S3 containing the rotation axes of the second and third shaft 110 and 115, for example by an acute angle of less than 90 ° sexagesimal and preferably between 60 ° and 70 ° sexagesimal.

Returning to Figure 1, the transmission 100 can comprise a first toothed wheel 140 rotatably coupled to the first shaft 105 and meshing with a first toothed wheel 145 keyed on the fourth shaft 120, so as to define a reverse gear.

It should be emphasized here that, in the context of the present description, the wording "rotatably coupled" indicates that the toothed wheel is coaxially inserted and supported on the relative shaft, with respect to which it is however free to rotate around the common axis, while with the the word "keyed" generally indicates that the toothed wheel is integral in rotation with the relative shaft, regardless of whether the connection between these two components is obtained by keying or any other known system.

The reverse gear defined by wheels 140 and 145 can be configured to define a slight multiplication of speed between the first shaft 105 and the fourth shaft 120.

For example, the first wheel 145 of the fourth shaft 120 can have 23 teeth and the corresponding first wheel 140 of the first shaft 105 can have 28 teeth, defining a transmission ratio of about 0.82.

The transmission 100 may further comprise a first engagement apparatus, which is adapted to engage the first shaft 105 selectively to the first toothed wheel 140 or directly to the second shaft 110.

In the context of this discussion, even the wording "graft" is to be understood generically as the ability of a grafting apparatus to make two components integral with each other in rotation, regardless of the specific methods used to obtain this effect.

In the example illustrated in Figure 1, the first engagement apparatus comprises two clutches, for example two hydraulic clutches, of which a clutch 150 adapted to engage / disengage the first shaft 105 to / from the second shaft 110, and a clutch 155 adapted to engage / disengage the first shaft 105 to / from the first toothed wheel 140.

In other embodiments, such as for example the one illustrated in Figure 4, the first input apparatus could however comprise a synchronizer 160 adapted to engage the first shaft 105 alternatively to the first toothed wheel 140 or to the second shaft 110.

For example, the synchronizer 160 can comprise a movable member, typically axially sliding along the first shaft 105, between a first engagement position in which it engages the first shaft 105 to the toothed wheel 140 and a second engagement position in which it engages the first shaft 105 directly to the second shaft 110, passing through an intermediate or neutral position, in which the first shaft 105 is rotatably released both from the toothed wheel 140 and from the second shaft 110. The displacement and locking of this movable member in the three positions outlined above can be obtained by means of special mechanical members, for example forks and levers, which can be operated manually or in an automated way.

The transmission 100 illustrated in Figure 1 further comprises at least a first and a second toothed wheel, indicated respectively with 165 and 170, which are keyed onto the second shaft 110.

The first toothed wheel 165 is meshed with a corresponding first toothed wheel 175 rotatably coupled to the third shaft 115, so as to form a first gear.

Similarly, the second toothed wheel 170 is meshed with a corresponding second toothed wheel 180 rotatably coupled to the third shaft 115, so as to form a second gear.

A second clutching apparatus is provided to selectively engage the third shaft 115 to the first or second sprocket 175 or 180, such that the second and third shafts 110 and 115 are kinematically coupled by the first or second gear.

In the illustrated example, this second engagement apparatus may comprise a synchronizer 185 adapted to engage the third shaft 115 alternatively to the first toothed wheel 175 or to the second toothed wheel 180.

For example, the synchronizer 185 can comprise a movable member, typically axially sliding along the third shaft 115, between a first engagement position in which it engages the third shaft 115 with the first toothed wheel 175 and a second engagement position in which it engages the third shaft 115 to the second toothed wheel 180, passing through an intermediate or neutral position, in which the third shaft 115 is rotatably released both from the first toothed wheel 175 and from the second toothed wheel 180. The displacement and locking of this movable member in the three positions outlined above can be obtained by means of suitable mechanical members, for example forks and levers, which can be operated manually or in an automated way.

The first and second gears mentioned above can be configured so as to both define a speed reduction between the second shaft 110 and the third shaft 115 but with a different transmission ratio, for example higher for the first gear and lower for the second. gear.

For example, the first wheel 175 of the third shaft 115 can have 47 teeth and the corresponding first wheel 165 of the second shaft 110 can have 23 teeth, defining a transmission ratio of approximately 2.04.

The second wheel 180 of the third shaft 115 can have 35 teeth and the corresponding second wheel 170 of the second shaft 110 can have 34 teeth, defining a transmission ratio of approximately 1.03.

The transmission 100 also includes a second toothed wheel 190 keyed to the fourth shaft 120 and also meshing with the first toothed wheel 175 of the third shaft 115, so that the reverse gear can rotate the second shaft 110.

It should be noted here that in Figure 1, although the toothed wheel 175 is represented as a thin body, in reality it has an axial extension (i.e. a thickness) sufficient to mesh with both the toothed wheel 190 and the toothed wheel 165, despite the latter are mutually offset axially.

The number of teeth of the second toothed wheel 190 is preferably chosen so that the overall transmission ratio between the first shaft 105 and the second shaft 110, when the reverse gear is engaged, is substantially equal to 1.

For example, the number of teeth of the second sprocket 190 can be equal to 19.

The transmission 100 according to the embodiment illustrated in Figure 1 may finally comprise a planetary gear, generally indicated with 195, which is able to kinematically connect the third shaft 115 with the fifth shaft 125. Preferably, the epicyclic gear mechanism 195 is configured to obtain a reduction in speed between the third shaft 115 to the fifth shaft 125.

This planetary gear 195 can comprise a sun gear 200 keyed to the third shaft 115, a gear wheel 205 with internal toothing, a plurality of planet gear wheels 210 individually meshing with the sun gear 200 and with the gear ring 205, and a -satellites 215 associated with the fifth tree 125.

In the example shown in Figure 1, the ring gear 205 is fixed and the satellite carrier 215 is keyed to the fifth shaft 125, so that the epicyclic gearing defines a constant transmission ratio between the third shaft 115 and the fifth shaft 125.

To increase the freedom of variation of the transmission ratio, other embodiments, some of which will be described below, however, provide that the ring gear 205 can be driven in rotation about its own axis and / or that the fifth shaft 125 can be engaged selectively to the satellite carrier 215 or directly to the third shaft 115.

Thanks to the construction architecture described above, the transmission 100 according to the embodiment of Figure 1 is capable of providing two splitters mechanically, of which at least one direct forward (direct) splitter and one reverse (reverse) splitter.

The direct forward splitter is configured when the first shaft 105 is directly engaged with the second shaft 110, for example by closing the clutch 150 and opening the clutch 155.

The reverse gear splitter, on the other hand, is configured when the first shaft 105 is engaged with the first sprocket 140, for example by opening the clutch 150 and closing the clutch 155.

In this second case, the rotation of the first shaft 105 is transmitted to the fourth shaft 120 through the reverse gear and from there to the second shaft 110 through the sprockets 190, 175 and 165, so that the second shaft 110 rotates in the opposite direction with respect to to the first tree 105.

For each of these splitters, the transmission 100 of figure 1 then makes available two different transmission ratios between the first shaft 105 and the fifth shaft 125, which depend on whether the third shaft 115 is engaged to the gear wheel 175 or to the wheel. toothed 180.

Starting from this basic configuration, the transmission 100 can be developed in different ways, significantly increasing the number of gear ratios available and the field of application, while always remaining within the scope of a compact and relatively economical solution.

A possible development is shown for example in Figure 3, in which the transmission 100 can be configured as a CVT (Continuous Variable Transmission) type transmission.

In addition to what has already been described in relation to the basic embodiment, the transmission 100 according to this second embodiment can comprise a further toothed wheel 220 keyed to the second shaft 110, which is meshed with a further toothed wheel 225 rotatably coupled to the third shaft 115, so as to define a further gear.

This further gear can be configured to define a speed multiplication between the second shaft 110 and the third shaft 115.

For example, the further toothed wheel 225 can have 18 teeth and the corresponding toothed wheel 220 can have 37 teeth, defining a transmission ratio of approximately 0.49.

A further engagement apparatus is provided to engage the third shaft 115 selectively to the further toothed wheel 225 or to leave it rotatably idle.

In the illustrated example, this further engagement apparatus can comprise a synchronizer 230, which can comprise for example a movable member, typically axially sliding along the third shaft 115, between an engagement position in which it engages the third shaft 115 to the further wheel 225 and a neutral position, in which the third shaft 115 is rotatably released from the further toothed wheel 225. The displacement and locking of this movable member in the two positions outlined above can be obtained by means of special mechanical members, for example forks and levers, which can be operated manually or automatically.

In this way, for each forward and reverse gear splitter, the transmission 100 also makes available mechanically a further transmission ratio, in addition to the two described with reference to the first embodiment, which is obtained when the synchronizer 185 it is in the neutral position while the synchronizer 230 is in the engagement position.

These three gear ratios can be configured as three different operating ranges of the transmission 100, in which the gear ratio defined by the wheels 165 and 175 can represent a low speed range, the gear ratio defined by the two wheels 170 and 180 can represent a medium speed range, and the gear ratio defined by wheels 220 and 225 can represent a high speed range.

The transmission 100 according to this second embodiment can further comprise a hydraulic motor 235 and a hydraulic pump 240 hydraulically connected to the hydraulic motor 235.

The hydraulic pump 240 comprises a drive shaft 245, which is able to be rotated to allow the operation of the hydraulic pump 240 and, therefore, the pumping under pressure of an operating fluid (typically oil) towards the hydraulic motor 235.

To allow rotation of the drive shaft 245, the latter can be kinematically connected to the first shaft 105, for example through a toothed wheel 250 keyed onto the drive shaft 245 and meshed with a toothed wheel 255 keyed directly onto the first tree 105.

On the other hand, the hydraulic motor 235 includes a drive shaft 260 and uses the pressure of the operating fluid coming from the hydraulic pump 240 to rotate the aforementioned drive shaft 260.

The drive shaft 260 can be kinematically connected to the ring gear 205 of the planetary gear 195 which, in this embodiment, is not fixed but is free to rotate around its own axis, coinciding with the axis of the third shaft 115 and of the fifth shaft 125.

This kinematic connection can be obtained by means of a toothed wheel 265 keyed on the motor shaft 260 and meshing, for example, with an external toothing directly obtained in the toothed crown 205.

Thanks to this solution, for each splitter (forward and reverse) and for each operating range (low, medium and high) set mechanically, the hydraulic motor 235, driven by the pressure of the operating fluid pumped by the hydraulic pump 240, is adapted to rotate the ring gear 205 at different speeds, continuously varying the transmission ratio generated by the planetary gear 195 and therefore the speed of the fifth shaft 125 with respect to the speed of the first shaft 105.

A different development of the basic transmission described above is illustrated in Figure 4.

In addition to what has already been described in relation to the basic embodiment, the transmission 100 according to this third embodiment comprises a sixth rotary shaft 270 having a rotation axis parallel to the rotation axes of the other shafts.

As shown in Figure 5, the center distance D6 between the second shaft 110 and the sixth shaft 270 may be less than the interest D3 between the second shaft 110 and the third shaft 115.

For example, the D6 center distance can have a value between that of the D3 interest and that of the D4 center distance.

Furthermore, the half-plane S6 containing the rotation axes of the second and sixth shafts 110 and 270 can be inclined with respect to the half-plane S3, for example by an acute angle of less than 90 ° sexagesimal.

Preferably, the angle of inclination of the half-plane S6 with respect to the half-plane S3 can be higher than the angle of inclination between the half-plane S4 and the half-plane S3, for example between 75 ° and 85 ° sexagesimal.

Returning to Figure 4, at least a first and a second toothed wheel, indicated respectively with 275 and 280, are rotatably coupled to the sixth shaft 270, which are engaged respectively with the first and second toothed wheel 165 and 170 of the second shaft 110 , in order to define a third and a fourth gear.

The third gear (wheels 165 and 275) can be configured to define a speed reduction between the second shaft 110 and the sixth shaft 270, preferably with a transmission ratio between that defined by the first gear (wheels 165 and 175) and that defined by the second gear (wheels 170 and 180) connecting the second and third shafts 110 and 115.

For example, the first toothed wheel 275 of the sixth shaft 270 can have 33 teeth, defining a transmission ratio of approximately 1.43 with the first wheel 165 of the second shaft 110.

Otherwise, the fourth gear (wheels 170 and 280) can be configured to define a speed multiplication between the second shaft 110 and the sixth shaft 270.

For example, the second toothed wheel 280 of the sixth shaft 270 can have 24 teeth, defining a transmission ratio of approximately 0.71 with the second wheel 170 of the second shaft 110.

The transmission 100 may further comprise a third clutching apparatus for engaging the sixth shaft 270 selectively to the first or second sprocket 275 or 280.

In the illustrated example, this third engagement apparatus may comprise a synchronizer 285 adapted to engage the sixth shaft 270 alternatively to the first toothed wheel 275 or to the second toothed wheel 280.

For example, the synchronizer 285 can comprise a movable member, typically axially sliding along the sixth shaft 270, between a first engagement position in which it engages the sixth shaft 270 to the first toothed wheel 275 and a second engagement position in which it engages the sixth shaft 270 to the second toothed wheel 280, passing through an intermediate or neutral position, in which the sixth shaft 270 is rotatably released both from the first toothed wheel 275 and from the second toothed wheel 280. The displacement and locking of this movable member in the three positions outlined above can be obtained by means of suitable mechanical members, for example forks and levers, which can be operated manually or in an automated way.

According to this third embodiment, the transmission 100 can further comprise a fifth gear adapted to kinematically connect the sixth shaft 270 to the third shaft 115, preferably so as to define a unitary transmission ratio between these two shafts.

This fifth gear can comprise a third and a fourth toothed wheel, indicated respectively with 290 and 295, which are rotatably coupled to the second shaft 110 and are integral in rotation with each other.

For example, the toothed wheels 290 and 295 can be made in a single body or in separate bodies but joined together.

The third toothed wheel 290 is meshed with a third toothed wheel 300 keyed to the third shaft 115, while the fourth toothed wheel 295 is meshed with a third toothed wheel 305 keyed to the sixth shaft 270.

To obtain a unitary transmission ratio between the sixth shaft 270 and the third shaft 115, the toothed wheel 290 can have the same number of teeth as the toothed wheel 295, while the toothed wheel 300 can have the same number of teeth as the toothed wheel 305 .

A fourth clutching apparatus is also provided to engage the second shaft 110 selectively to the third and fourth sprockets 290 and 295 or to leave them rotatably idle.

In the illustrated example, this fourth engagement apparatus can comprise a synchronizer 310, which can comprise for example a movable member, typically axially sliding along the second shaft 110, between an engagement position in which it engages the second shaft 110 to the toothed wheels 290 and 295 and a neutral position, in which the second shaft 110 is rotatably released from the toothed wheels 290 and 295. The displacement and locking of this movable member in the two positions outlined above can be obtained by means of suitable mechanical members, for example forks and levers, which can be operated manually or automatically.

When the sprockets 290 and 295 are engaged on the second shaft 110, the latter is kinematically connected to the third shaft 115 through the meshing of the wheels 290 and 300, which are preferably configured in such a way as to provide a multiplication of speeds, for example with a lower transmission ratio than that defined by the wheels 170 and 280.

By way of example, the toothed wheel 300 can have 18 teeth and the corresponding toothed wheel 290 can have 37 teeth, defining a transmission ratio of approximately 0.49.

According to this third embodiment, the transmission 100 can also comprise a fifth clutch apparatus adapted to engage the fifth shaft 125 selectively with the satellite carrier 215 of the planetary gear 195 or directly with the third shaft 115.

This fifth coupling apparatus can comprise for example a coupling 315, which can be modified between a first configuration, in which it engages the fifth shaft 125 directly to the third shaft 115, for example with front coupling, and a second configuration, in which it engages the fifth shaft 125 to satellite carrier 215.

In this way, when the joint 315 is in the first configuration, the fifth shaft 125 is integral in rotation with the third shaft 115 and is therefore forced to rotate with it at the same speed, while when the joint 315 is in the second configuration, between the third shaft 115 and the fifth shaft 125 introduces a defined speed reduction of the transmission ratio of the planetary gear 195.

In this case, the ring gear 205 of the epicyclic gearing 195 is preferably kept fixed.

Thanks to this constructive architecture, the transmission 100 according to the third embodiment of figure 4 is able to provide the two forward and reverse gear splitters, selectable, as for the basic embodiment, through the first engagement apparatus , in this case through the synchronizer 160.

For each of these splitters, the transmission 100 of figure 4 also provides two ranges, which can be selected through the fifth coupling device, in this case through the joint 315, of which for example a faster range (high), obtainable when the fifth shaft 125 is directly coupled to the third shaft 115, and a slower range (e.g. medium), obtainable when the fifth shaft 125 is connected to the third shaft 115 through the epicyclic gearing 195.

For each splitter and each range, the transmission 100 of Figure 4 also provides five gears mechanically, defined by the five gears which connect the second, third and sixth shafts 110, 115 and 270 together.

In particular, a first gear is obtained when the second engagement apparatus, in this case the synchronizer 185, is in the position in which it engages the third shaft 115 with the toothed wheel 175, while the third engagement apparatus and the fourth engagement apparatus, in this case the synchronizers 285 and 310 are both in neutral position. In this way, the rotation of the second shaft 110 (both forward and reverse) is transmitted to the third shaft 115, and from there to the fifth shaft 125, through the sprockets 165 and 175.

A second gear is obtained when the third engagement apparatus, in this case the synchronizer 285, is in the position in which it engages the sixth shaft 270 with the toothed wheel 275, while the second and fourth engagement apparatus, in this case the synchronizers 185 and 310, are both in neutral position. In this way, the rotation of the second shaft 110 (both forward and reverse) is first transmitted to the sixth shaft 270 through the sprockets 165 and 275, and subsequently from the sixth shaft 270 to the third shaft 115, and from here to fifth shaft 125, through the sprockets 305, 295, 290 and 300.

A third macia is obtained when the second engagement apparatus, in this case the synchronizer 185, is in the position in which it engages the third shaft 115 to the toothed wheel 180, while the third engagement apparatus and the fourth engagement apparatus, in this case the synchronizers 285 and 310, are both in neutral position. In this way, the rotation of the second shaft 110 (both forward and reverse) is transmitted to the third shaft 115, and from there to the fifth shaft 125, through the sprockets 170 and 180.

A fourth gear is obtained when the third engagement apparatus, in this case the synchronizer 285, is in the position in which it engages the sixth shaft 270 with the toothed wheel 280, while the second and fourth engagement apparatus, in this case the synchronizers 185 and 310, are both in neutral position. In this way, the rotation of the second shaft 110 (both forward and reverse) is first transmitted to the sixth shaft 270 through the sprockets 170 and 280, and subsequently from the sixth shaft 270 to the third shaft 115, and from here to fifth shaft 125, through the sprockets 305, 295, 290 and 300.

Finally, a fifth gear is obtained when the fourth engagement apparatus, in this case the synchronizer 310, is in the position in which the second shaft 110 engages directly to the wheels 290 and 295, while the second and third engagement apparatus, in this case the synchronizers 185 and 285 are both in the neutral position. In this way, the rotation of the second shaft 110 (both forward and reverse) is transmitted to the third shaft 115, and from there to the fifth shaft 125, through the sprockets 290 and 300.

Thanks to this solution, therefore, a transmission 100 is obtained which is able to mechanically supply two ranges and five gears for each range, for a total of ten speed ratios for both the forward and reverse splitter.

A further variant of the transmission 100 is illustrated in Figure 6 and is entirely similar to the one described above, with the exception of the aspects that will be described below.

The transmission 100 according to this fourth embodiment provides that the third shaft 115 is divided into two mutually coaxial but independent portions, indicated respectively with 115A and 115B.

These two portions 115A and 115B can be made integral in rotation to each other selectively through a sixth coupling apparatus, for example through a joint 320 which can be arranged alternatively in an engagement configuration, in which it makes the two portions 115A and 115B integral with each other, and a disengagement configuration, in which the two portions 115A and 115B are free to rotate independently.

The toothed wheels 175, 180 and 300 are coupled to the first portion 115A, according to the methods already described above for the third embodiment of Figure 4.

A fourth toothed wheel 325 is rotatably coupled to the second portion 115B, which is meshed with a fifth toothed wheel 330 rotatably coupled to the second shaft 110, so as to define a further gear.

This further gear can be configured to achieve a speed reduction between the second shaft 110 and the second portion 115B of the third shaft 115.

For example, the toothed wheel 325 can have 44 teeth while the toothed wheel 330 can have 14 teeth, defining a transmission ratio of approximately 3.14.

The toothed wheel 330 is preferably integral in rotation to the toothed wheels 290 and 295, for example it can be formed in a single body with them or in separate bodies but connected to each other.

A seventh clutch apparatus is also present for selectively connecting the second portion 115B of the third shaft 115 to the fourth gear wheel 325 rotatably coupled thereon.

In the illustrated example, this seventh clutch apparatus may comprise a coupling 335, which can be arranged in an engaging configuration in which it engages the second portion 115B to the sprocket 325 and in a disengagement configuration, in which the second portion 115B it is rotatably released from the toothed wheel 325.

Thanks to these modifications, a 100 transmission is provided which, in addition to the usual two forward and reverse splitters, is able to make available, for each of these splitters, four ranges, selectable through the fifth, sixth and seventh gear. grafting.

In particular, a first and faster range (eg high) can be obtained when the fifth engagement apparatus, in this case the joint 315, is configured so as to directly engage the fifth shaft 125 to the second portion 115B of the third shaft 115; the sixth engagement apparatus, in this case the joint 320, is configured to engage the first and second portions 115A and 115B of the third shaft 115 together; and the seventh coupling apparatus, in this case the joint 335, is in the disengagement configuration.

A second range (e.g. medium), slower than the previous one, can be obtained when the fifth coupling apparatus, in this case the coupling 315, is configured in such a way as to engage the fifth shaft 125 to the second portion 115B of the third shaft 115 through the epicyclic gearing 195; the sixth engagement apparatus, in this case the joint 320, is again configured to engage the first and second portions 115A and 115B of the third shaft 115 together; and the seventh coupling apparatus, in this case the joint 335, is still in the disengagement configuration.

A third range (e.g. mini-creeper), slower than both the previous ones, can be obtained when the fifth engagement apparatus, in this case the coupling 315, is configured in such a way as to engage the fifth shaft 125 directly to the second portion 115B of the third shaft 115; the sixth coupling apparatus, in this case the coupling 320, is in a decoupling configuration to release the first and second portions 115A and 115B of the third shaft 115; and the seventh engagement apparatus, in this case the joint 335, is in the configuration in which it engages the second portion 115B of the third shaft 115 to the toothed wheel 325.

A fourth range (e.g. creeper), slower than all the previous ones, can finally be obtained when the fifth engagement apparatus, in this case the coupling 315, is configured in such a way as to engage the fifth shaft 125 to the second portion 115B of the third shaft 115 through the planetary gear 195; the sixth engagement apparatus, in this case the joint 320, is still in the decoupling configuration to release the first and second portions 115A and 115B of the third shaft 115 from each other; and the seventh coupling apparatus, in this case the joint 335, is still in the position in which it engages the second portion 115B of the third shaft 115 to the toothed wheel 325.

For each splitter and for each of these four ranges, the transmission 100 conforming to this fourth embodiment also makes available the five mechanical gears which are selectable through the second, third and fourth engagement apparatus, as already described with reference to the third embodiment.

However, it is worth highlighting that, while the operation of transmission 100 in the first two ranges mentioned above (high and medium) is completely analogous to that described with reference to the third embodiment, in the other two ranges (mini-creeper and creeper ) torque transmission occurs in a different way.

In fact, in each of these last two ranges (mini-creeper and creeper), the first portion 115A of the third shaft 115 rotates independently with respect to the second portion 115B, which is integral with the wheel 325.

Therefore, when the first gear is engaged, according to the methods described above, the rotation of the second shaft 110 is transmitted first to the first portion 115A of the third shaft 115 through the wheels 165 and 175, and subsequently to the second portion 115B and then to the fifth shaft 125 through the wheels 300, 290, 330 and 325.

When the second gear is engaged, again in the manner described above, the rotation of the second shaft 110 is transmitted first to the sixth shaft 270 through the wheels 165 and 275, and subsequently to the second portion 115B of the third shaft 115 and then to the fifth shaft 125 through wheels 305, 295, 330 and 325.

When the third gear is engaged, again in the manner described above, the rotation of the second shaft 110 is transmitted first to the first portion 115A of the third shaft 115 through the wheels 170 and 180, and subsequently to the second portion 115B and then to the fifth shaft 125 through the wheels 300, 290, 330 and 325.

When the fourth gear is engaged, again in the manner described above, the rotation of the second shaft 110 is transmitted first to the sixth shaft 270 through the wheels 170 and 280, and subsequently to the second portion 115B of the third shaft 115 and then to the fifth shaft 125 through wheels 305, 295, 330 and 325.

When the fifth gear is finally engaged, again in the manner described above, the rotation of the second shaft 110 is transmitted directly to the second portion 115B of the third shaft 115 and then to the fifth shaft 125 through the wheels 330 and 325.

Thanks to this solution, therefore, a transmission 100 is obtained which is able to mechanically supply four ranges and five gears for each range, for a total of twenty speed ratios for both the forward and reverse splitter.

A further variant of the transmission 100 is illustrated in Figure 7 and is completely similar to the fourth variant just described, with the exception of the aspects that will be illustrated below.

A first aspect of diversity consists in the fact that the first clutch apparatus can comprise the two clutches 150 and 155 already described in relation to the basic embodiment shown in Figure 1.

A second, more important aspect of diversity, consists instead in the fact that the transmission 100 can comprise a seventh rotating shaft 340 having a rotation axis parallel to the rotation axes of the other rotating shafts.

As shown in Figure 8, the center distance D7 between this seventh shaft 340 and the second shaft 110 can be substantially equal to or (slightly) higher than the interest D6 between the second shaft 110 and the sixth shaft 270.

Furthermore, the seventh shaft 340 can be arranged so that the half plane S7 containing the rotation axes of the second and seventh shafts 110 and 340 can form, with the half plane S4 containing the rotation axes of the second and fourth shafts 110 and 120 , an angle substantially equal to 180 ° sessage simali. In other words, the axes of rotation of the second, fourth and seventh shafts 110, 120 and 340 can lie in a common plane, in which the second shaft 110 is interposed between the fourth and seventh shafts 120 and 340.

Returning to Figure 7, a first toothed wheel 345 can be rotatably coupled to the seventh shaft 340, which is meshed with a second toothed wheel 350 directly keyed onto the first shaft 105.

The gear defined by the two toothed wheels 345 and 350 can be configured to achieve a speed reduction between the first shaft 105 and the seventh shaft 340.

For example, the toothed wheel 345 can have 44 teeth while the toothed wheel 350 can have 31 teeth, defining a transmission ratio of about 1.42.

An eighth clutching apparatus is provided for engaging the seventh shaft 340 selectively to the first toothed wheel 345 or for leaving it rotatably idle with respect thereto.

In the illustrated example, this further engagement apparatus may comprise a clutch 355, for example a hydraulic clutch, which is adapted to engage / disengage the gear wheel 345 to / from the seventh shaft 340.

A second toothed wheel 360 can also be keyed to the seventh shaft 340 which is meshed with the second toothed wheel 170 which is keyed onto the second shaft 110.

It should be noted here that in figure 7 the toothed wheel 360 is shown offset with respect to the toothed wheel 170 only for reasons of clarity, since these two wheels actually lie on the same transverse plane and can mesh with each other without interfering with the toothed wheel 280 , thanks to the fact that the sixth and seventh shafts 270 and 340 are angularly out of phase with respect to the second shaft 110 as illustrated in Figure 8.

The number of teeth of the toothed wheel 360 is preferably chosen in such a way as to define a (slight) multiplication of speeds between the seventh shaft 340 and the second shaft 110, but in any case such that the overall transmission ratio between the first shaft 105 and the second shaft 110 is greater than 1. For example, the toothed wheel 360 may have 40 teeth.

Thanks to these modifications, the transmission 100 according to the embodiment illustrated in Figure 7 comprises three splitters, of which the direct forward gear splitter, which is configured when the first shaft 105 is directly engaged with the second shaft 110, for example thanks to the closing of the clutch 150 and simultaneous opening of the clutches 155 and 355, a reverse splitter, which is configured when the first shaft 105 is connected to the second shaft 110 through the fourth shaft 120, for example thanks to the closing of the clutch 155 and the simultaneous opening of the clutches 150 and 355, and finally a slow forward (low) splitter, which is configured when the first shaft 105 is connected to the second shaft 110 through the seventh shaft 340, for example thanks to the closure of the clutch 355 and the simultaneous opening of the clutches 150 and 155.

For each of these three splitters, the transmission 100 then makes available the four ranges and the five marches already described with reference to the fourth embodiment.

A last variant of the transmission 100 is illustrated in Figure 9. This last embodiment is entirely analogous to the previous one, with the difference that it comprises a third toothed wheel 365 rotatably coupled to the seventh shaft 340, which is meshed with a third toothed wheel 370 keyed on the first shaft 105.

The gear defined by the two toothed wheels 365 and 370 can be configured to achieve a speed multiplication between the first shaft 105 and the seventh shaft 340.

For example, the toothed wheel 365 can have 37 teeth while the toothed wheel 370 can have 38 teeth, defining a transmission ratio of approximately 0.97.

A ninth engagement apparatus is provided for engaging the seventh shaft 340 selectively to the third sprocket 365 or for leaving it rotatably idle with respect thereto.

In the example illustrated, this further engagement apparatus may comprise a clutch 375, for example a hydraulic clutch, which is adapted to engage / disengage the gear wheel 365 to / from the seventh shaft 340.

Thanks to this expedient, the transmission 100 is provided with a fourth splitter, in addition to those already described with reference to the previous embodiment.

This fourth splitter can be a fast forward (high) splitter and is configured when clutch 375 is closed, while clutches 150, 155 and 355 are all left open, so that the rotation of the first shaft 105 is transmitted to the second shaft 110 through the wheels 370, 365, 360 and 170.

Also in this case, for each of these four splitters, the transmission 100 then makes available the four ranges and the five gears already described with reference to the fourth embodiment, for a total of eighty transmission ratios globally available.

Obviously, a technician in the field can make numerous changes of a technical-applicative nature to the transmissions 100 described above, without thereby departing from the scope of the invention as claimed below.

Claims (10)

CLAIMS 1. A transmission (100) comprising: - a plurality of rotating shafts having axes of rotation parallel to each other, of which at least a first shaft (105), a second shaft (110), a third shaft (115) and a fourth shaft (120), - a first toothed wheel (140) rotatably coupled to the first shaft (105), - a first toothed wheel (145) keyed to the fourth shaft (120) and meshing with the first toothed wheel (140) of the first shaft (105), so as to define a reverse gear, - a first coupling apparatus adapted to engage the first shaft (105) selectively to the first toothed wheel (140) rotatably coupled to it or to the second shaft (110), - at least a first and a second toothed wheel (165, 170) keyed to the second shaft (110), - at least a first and a second toothed wheel (175, 180) rotatably coupled to the third shaft (115) and individually meshing respectively with the first and second toothed wheel (165, 170) of the second shaft (110), so as to define respectively a first and a second gear, - a second coupling apparatus adapted to engage the third shaft (115) selectively with the first or second toothed wheel (175, 180) rotatably coupled thereto, and - a second toothed wheel (190) keyed to the fourth shaft (120) and meshing with the first toothed wheel (175) of the third shaft (115). A transmission (100) according to claim 1, comprising; - a fifth rotating shaft (125) having a rotation axis parallel to the rotation axes of the other rotating shafts, and - a planetary gear (195) placed to kinematically connect the fifth shaft (125) to the third shaft (115). A transmission (100) according to claim 1 or 2, comprising: - a further toothed wheel (220) coupled to the second shaft (110), - a further toothed wheel (225) rotatably coupled to the third shaft (115) and meshing with said further toothed wheel (220) of the second shaft (110), so as to define a further gear, and - a further coupling apparatus adapted to selectively engage the third shaft (115) to said further toothed wheel (225) rotatably coupled thereto. A transmission (100) according to claim 2 or 3, comprising: - a hydraulic motor (235) having a driving shaft (260) kinematically connected to a ring gear (205) of the planetary gear (195) so as to be able to rotate it, and - a hydraulic pump (240) having a drive shaft (245) kinematically connected to the first shaft (105) and hydraulically connected to the hydraulic motor (235). A transmission (100) according to any one of the preceding claims, comprising: - a sixth rotating shaft (270) having an axis of rotation parallel to the rotation axes of the other rotating shafts, - at least a first and a second toothed wheel (275, 280) rotatably coupled to the sixth shaft (270) and individually meshing respectively with the first and second toothed wheel (165, 170) of the second shaft (110), so as to define respectively a third and a fourth gear, - a third coupling apparatus adapted to selectively engage the sixth shaft (270) with the first or second toothed wheel (275, 280) rotatably coupled thereto, and - a fifth gear adapted to kinematically connect the sixth shaft (270) to the third shaft (115). A transmission (100) according to claim 5, wherein said fifth gear can comprise a third and a fourth toothed wheel (290, 295) rotatably coupled to the second shaft (110) and integral in rotation with each other, a third toothed wheel (300) keyed to the third shaft (115) and meshing with the third wheel (290) of the second shaft (110), a third toothed wheel (305) keyed to the sixth shaft (270) and meshing with the fourth toothed wheel (295) of the second shaft (110), and a fourth coupling apparatus for selectively coupling the second shaft (110) to the third and fourth gear wheels (290, 295) rotatably coupled thereon. A transmission (100) according to any one of claims 2 to 6, comprising a fifth engagement apparatus adapted to selectively engage the fifth shaft (125) with a planet carrier (215) of the planetary gear (195) or directly with the third shaft (115). A transmission (100) according to claim 6 or 7, comprising: - a sixth engagement apparatus adapted to selectively engage a first portion (115A) of the third shaft (115), to which the respective first, second and third toothed wheels (175, 180, 300) are coupled, to a second portion (115B ) of the third shaft (115), - a fifth toothed wheel (330) rotatably coupled to the second shaft (110) and integral in rotation to the third and fourth toothed wheel (290, 295) of said second shaft (110), - a fourth toothed wheel (325) rotatably coupled to the second portion (115B) of the third shaft (115) and meshing with the fifth toothed wheel (330) of the second shaft (110), and - a seventh clutch apparatus adapted to selectively engage said second portion (115B) of the third shaft (115) to the fourth toothed wheel (325) rotatably coupled thereon. A transmission (100) according to any one of the preceding claims, comprising: - a second toothed wheel (350) keyed on the first shaft (105), - a seventh rotating shaft (340) having an axis of rotation parallel to the rotation axes of the other rotating shafts, - at least one first toothed wheel (345) rotatably coupled to the seventh shaft (340) and meshing with the second toothed wheel (350) of the first shaft (105), - a second toothed wheel (360) keyed on the seventh shaft (340) and meshing with the second toothed wheel (170) keyed on the second shaft (110), and - an eighth coupling apparatus adapted to selectively engage the seventh shaft (340) to the first toothed wheel (345) rotatably coupled thereto. A transmission (100) according to claim 8, comprising: - a third toothed wheel (370) keyed on the first shaft (105), - a third toothed wheel (365) rotatably coupled to the seventh shaft (340) and meshing with the third toothed wheel (370) of the first shaft (105), and - a ninth engagement apparatus adapted to selectively engage the seventh shaft (340) with the third toothed wheel (365) rotatably coupled thereto.