A power take-off operable in case of a fault, a vehicle and a method for operating the power take-off

Abstract

A power take-off (100) comprising a support part (7a, 7b), an input part (101 ) which sets in rotation a first part (1) bearing one or more first discs (3), a second part (2) that bears one or more second discs (4) and which sets in rotation an output part (102), a supply line (50) of fluid for moving a piston (5) so as to press together the one or more first discs (3) and the one or more second discs (4) transmitting, or not, torque to the output part (102) and command means for commanding the transmission of torque to connect the input part (101) to the output part (102) in a first faulty operating condition (FO1), in a case of a fault that prevents transmission of torque between the one or more first discs (3) and the one or more second discs (4) by friction.

Description

[0001] A POWER TAKE-OFF OPERABLE IN CASE OF A FAULT, A VEHICLE AND A METHOD FOR OPERATING THE POWER TAKE-OFF

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the technical sector concerning power take-offs, i.e. devices which enable take-off of power from a power engine or from a transmission unit, which are utilised for moving a vehicle, so as to transmit power to a user. In particular, the invention relates to power take-offs comprising a disc clutch unit with a hydraulic or pneumatic piston which owing to a pressurised fluid ensures and / or prevents transmission of torque (also indicated as torque or moment of force and expressed in Nm) via the discs, by friction, thus coupling and / or decoupling the input and output from the power take-off. Further, the present invention relates to the technical sector of vehicles provided with at least a power take-off. In detail, the invention relates to the functioning of the power take-off in a fault condition which prevents the normal functioning of the clutch unit, i.e. the transmission of torque between the discs by friction.

[0004] DESCRIPTION OF THE PRIOR ART

[0005] Power take-offs are known, for vehicles, especially of land vehicles such as for example truck-mounted pumps (typically for concrete), refuse collection trucks, mixer trucks and dumpers, and used for taking off mechanical power coming from the drive shaft, guaranteeing the power for the movement of the vehicle or from a transmission unit destined for the movement of the vehicle downstream of the drive shaft, for example located between the power engine and the wheels. By way of example, a power take-off can take power directly from the power engine, from the secondary shaft of the gearbox, or by being interposed between cardan shafts between the gearbox output and the differential input. These power take-offs have one or more outputs for providing the mechanical power sourced from one or more users being, for example, pumps, compressors, depressors (vacuum pumps) and mixers.

[0006] Document WO / 2006 / 090280 describes a power take-off according to the preamble of claim 1.

[0007] Typically, in power take-offs of this type, the transmission of torque is guaranteed in the case of pressurised fluid arriving into a thrust chamber so as to move the piston into an engaged position of the clutch, i.e. with the piston pushing the discs together so that the discs transmit torque to one another by friction. In the technical jargon a distinction is made between discs, which comprise friction material, and counter-discs, which do notcomprise friction material. However the present invention does not relate to the configuration of the discs and the friction means, and therefore the present description will make general reference to one or more first discs and to one or more second discs. Also it is specified that, in the technical jargon, the parts that exchange torque by friction are indicated both with the term discs and with the term lamellae.

[0008] Numerous fault conditions can arise that prevent this transmission of torque. For example, the pump or compressor that supplies the pressurised fluid can stop functioning, the transmission line can break or be interrupted, the seals can break or become worn so as not to allow reaching a sufficient pressure in the thrust chamber, heat dilations or breakages can prevent the displacement of the piston and the discs may no longer be able to transmit by friction due to wear, a common condition known, in the technical jargon, as disc burnout.

[0009] In any condition of fault preventing the transmission of torque between the input shaft and the output shaft of the clutch of the power take-off, the device, or the devices, connected to one of the outputs or to the output of the power take-off cannot function. Loss of functioning of the device served by the power take-off can lead to serious drawbacks, which may not be limited to the consequences determined by the impossibility of using the device. For example, in the case of a truck-mounted pump, a prolonged period of inactivity during functioning can lead to the hardening of the concrete internally of the suction and delivery conduits, as well as internally of the pump itself, causing damages which may be very serious. If on the one hand the loss of functioning causes drawbacks in the work site, the impossibility of activating the device can lead to damage to the truck-mounted pump. And this is without taking into account that in some situations the loss of functioning of the device can have even more damaging consequences than a downtime in the site, such as in the case of a firefighting truck.

[0010] Thus a need is perceived for using the power take-off and / or to rapidly reset the functioning of the power take-off in order to complete the operation underway in any condition of fault which prevents the normal functioning of the clutch, before proceeding to the repair thereof; this typically takes place after the vehicle has been moved to a workshop.

[0011] SUMMARY OF THE INVENTION

[0012] The present invention intends to obviate one or more drawbacks of the prior-art solutions.A first aim of the present invention is to provide a power take-off which guarantees temporary power transmission including in a fault situation that prevents transmission of torque between the discs by friction or to provide a vehicle comprising the power takeoff.

[0013] A further aim is to provide a power take-off that can operate at rated power even in a case of a fault.

[0014] Further aims of some embodiments are: realising a solution that is compact, especially in relation to the applicational limits on vehicles; a solution that limits the impact on the configuration of the power take-off, for example in terms of positioning and / or type of the supports and bearings; and / or a solution that is simple to use even in a context provided with simple or non-equipped tools, such as one in which the vehicle may be located at the time the fault is revealed.

[0015] These and other aims, which will become clear to the expert in the sector from a reading of the description that follows, are attained by means of a power take-off installable on a vehicle for taking power from a power engine or from a transmission which enable movement of the vehicle and for transmitting or interrupting transmission of power to a device, of a method for operating the power take-off and of a vehicle according to the claims.

[0016] According to the teachings of the present description, the power take-off comprises a support part which is configured to be fixed to a part of a vehicle, an input part, one or more first discs, a first part, an output part, one or more second discs, a second part, a piston and a supply line of a pressurised fluid for moving the piston.

[0017] The input part is rotatable with respect to the support part and is predisposed to be set in rotation and the output part is rotatable with respect to the support part and is predisposed to be set in rotation.

[0018] The first part is rotatable with respect to the support part about a rotation axis, is in one piece with the input part or is connected to the input part so that the rotation of the input part sets in rotation the first part to transmit torque and is in one piece or bears the one or more first discs in such a way that the rotation of the first part sets in rotation the one or more first discs to transmit torque.

[0019] The second part is rotatable with respect to the support part about the rotation axis, is in one piece with the output part or is connected with the output part so that the rotation of the second part sets in rotation the output part to transmit torque and is in one piece or bears the one or more second discs in such a way that the rotation of the one or moresecond discs sets in rotation the second part to transmit torque.

[0020] The piston is movable with respect to the support part in the direction of the rotation axis so as to pass from a first operating condition in which it presses together the one or more first discs and the one or more second discs so that the one or more first discs transmit torque to the one or more second discs by friction, in order to transmit torque to the output part, to a second operating condition in which it does not press together the one or more first discs and the one or more second discs or does not press them sufficiently so that the one or more first discs do not transmit torque to the one or more second discs by friction, in order to interrupt transmission of torque to the output part. The piston is also movable with respect to the support part in the direction of the rotation axis so as to pass from the second operating condition to the first operating condition.

[0021] The power take-off advantageously comprises command means for commanding the transmission of torque which are configured to connect the input part to the output part in a first faulty operating condition, in a case of a fault that prevents transmission of torque between the one or more first discs and the one or more second discs by friction. According to the teachings of the present description, the method comprises successive steps of:

[0022] - detecting a fault which prevents the transmission of torque between the one or more first discs and the one or more second discs by friction in the first operating condition;

[0023] - interrupting the drive of the input part;

[0024] - operating the command means to connect the input part to the output part;

[0025] - reactivating the drive of the input part.

[0026] According to the teachings of the present description, the vehicle comprises a power engine which has a drive shaft for supplying power, a transmission for the movement of the vehicle connected to the drive shaft and to a power take-off according to the present description which is connected to the drive shaft or to the transmission to take off power.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Specific embodiments of the invention will be described in the following part of the present description, according to the contents of the claims and with the aid of the appended figures, in which:

[0029] figure 1 is an axonometric view of an embodiment of a power take-off accordingto the invention, from the side of the power engine and the input part;

[0030] figure 2 is an axonometric view of the embodiment of the figure 1 from the side of the output part;

[0031] figure 3 is a schematic view of an embodiment, as well as a reference to other embodiments of a vehicle of the invention;

[0032] figure 4 is an axonometric view with a cutaway in section of a portion of the embodiment of the figure 1 in a second operating condition, which can correspond to a second faulty operating condition;

[0033] figure 5 is a lateral view of the portion visible in figure 4 with an indication of the trace line of the cutting plane of some of the following figures;

[0034] figure 6 shows a section view of the insert of figure 5 in a first operating condition, with an external support, not illustrated, for facilitating understanding;

[0035] figure 7 shows a section view of the insert of figure 5 in a first faulty operating condition, with the external support, not illustrated, for facilitating understanding;

[0036] figure 8 shows a section view of the insert of figure 5 in the second operating condition, which can correspond to the second faulty operating condition, which illustrates a portion of the supply line, a portion of support part having a box configuration that are not completely visible in figures from 4 to 7 and another support, while in this case too the external support is not illustrated in the interest of facilitating understanding;

[0037] figure 9 is an axonometric view with a cutaway in section entirely alike to that of figure 4 but in the first faulty operating condition;

[0038] figure 10 shows a section view of figure 5 in the second operating condition, which can correspond to the second faulty operating condition, and with the external support, not illustrated, in the interests of facilitating understanding;

[0039] figure 11 is an axonometric view of a coupling part with an indication of a detail; figure 12 is a view in larger scale of the detail of figure 11 ;

[0040] figure 13 is an axonometric view of a first part with an indication of a detail; figure 14 is a view in larger scale of the detail of figure 13;

[0041] figure 15 is a lateral view entirely alike to that of figure 5 indicating the trace of the cutting plane of figure 16 and figure 18;

[0042] figure 16 is a section view of figure 15 relative to a further embodiment of a power take-off according to the invention, in a first faulty operating condition;

[0043] figure 17 is a section view relating to a cutting plane alike to what is illustrated infigure 5 concerning still another embodiment of a power take-off according to the invention, in a first faulty operating condition;

[0044] figure 18 is a section view of figure 15 relative to a further embodiment of a power take-off according to the invention, in a first faulty operating condition;

[0045] figure 19 is a section view of figure 15 relating to the embodiment of figure 18, in a successive step to the first faulty operating condition;

[0046] figure 20 is a schematic section view concerning still another embodiment of a power take-off according to the invention, which has a different configuration with respect to the one of figures from 1 to 19, in a second operating condition, which can correspond to a second faulty operating condition;

[0047] figure 21 is the schematic section view of figure 20 in a first operating condition, of the cutting plane passing through the rotation axis alike to what is illustrated in figures 5 and 15.

[0048] DESCRIPTION OF PREFERRED EMBODIMENTS

[0049] With reference to the appended figures, reference numeral 100 denotes a power takeoff, according to the invention, installable on a vehicle (1000) for taking off power from the power engine (1001) or from the transmission (1003) which enable movement of the vehicle (1000), and for transmitting or interrupting transmission of power to a device (1004).

[0050] The references are included for ease of understanding of the invention, but are not intended to limit the scope of protection.

[0051] An embodiment of the power take-off (100) comprises:

[0052] - a support part (7a, 7b) which is configured to be fixed to a part of a vehicle (1000);

[0053] - an input part (101 ) which is rotatable with respect to the support part (7a, 7b) and which is predisposed to be set in rotation;

[0054] - one or more first discs (3);

[0055] - one or more second discs (4);

[0056] - an output part (102) which is rotatable with respect to the support part (7a, 7b) and which is predisposed to be set in rotation;

[0057] - a first part (1);

[0058] - a second part (2);

[0059] - a piston (5);

[0060] - a supply line (50) of a pressurised fluid for moving the piston (5);- command means for commanding, i.e. governing the transmission of torque. The first part (1) is rotatable with respect to the support part (7a, 7b) about a rotation axis (X), and is one piece with the input part (101) or is connected with the input part (101 ) so that the rotation of the input part (101 ) sets in rotation the first part (1 ). Further, the first part (1) is one piece with or bears the one or more first discs (3) in such a way that the rotation of the first part (1 ) sets in rotation the one or more first discs (3).

[0061] The second part (2) is rotatable with respect to the support part (7a, 7b) about the rotation axis (X), and is one piece with the output part (102) or is connected with the output part (102) so that the rotation of the second part (2) sets in rotation the output part (102). Further, the second part (2) is one piece with or bears the one or more second discs (4) in such a way that the rotation of the one or more second discs (4) sets in rotation the second part (2).

[0062] The piston (5) is movable with respect to the support part (7a, 7b) in the direction of the rotation axis (X) so as to pass from a first operating condition (NO1) to a second operating condition (NO2) and vice versa, i.e. so as to pass from the second operating condition (NO2) to the first operating condition (NO1).

[0063] In the first operating condition (NO1), the piston (5) presses together the one or more first discs (3) and the one or more second discs (4) so that the one or more first discs (3) transmit torque to the one or more second discs (4) by friction, in order to transmit torque to the output part (102).

[0064] In the second operating condition (NO2), the piston (5) does not press together the one or more first discs (3) and the one or more second discs (4) or does not sufficiently press the one or more first discs (3) and the one or more second discs (4) so that the one or more first discs (3) do not transmit torque to the one or more second discs (4) by friction, in order to interrupt transmission of torque to the output part (102).

[0065] The command means are advantageously configured to connect the input part (101) to the output part (102) in a first faulty operating condition (FO1), in a case of a fault that prevents transmission of torque between the one or more first discs (3) and the one or more second discs (4) by friction.

[0066] Owing to the command means, the input part (101) and the output part (102) of the power take-off (100) can be connected to one another so as to transmit power to the device (1004) when the one or more first discs (3) and the one or more second discs (4) are not able to transmit torque by friction due to a fault. The fault might directly involve the one or more first discs (3) and the one or more second discs (4) or one of thecomponents that ensure the pressure of the one or more first discs (3) and the one or more second discs (4) by the piston (5). For example, the one or more first discs (3) and the one or more second discs (4) might be worn or may have been damaged by engaging at an excessive rotation velocity or the supply line (50) might have been interrupted or the supply line (50) might no longer be receiving pressurised fluid or the seals of a thrust chamber (52) of the piston (5) might have deteriorated and have had a negative effect on the internal pressure.

[0067] According to known-type configurations, the support part (7a, 7b) can be fixable to the casing of the power engine (1001 ) or of the transmission (1003) of a vehicle (1000) or to the frame, or to a part solidly constrained to the frame, of the vehicle (1000).

[0068] The appended figures illustrate how the first part (1), the second part (2), the one or more first discs (3), the one or more second discs (4) functionally form a clutch unit which, in constructional terms, is integrated in the power take-off (100). Using a terminology typical of the functioning of a clutch unit, the piston (5) is displaced in the direction of the rotation axis (X) with respect to the support part (7a, 7b) from an engaged position (E), corresponding to the first operating condition (NO1), to a disengaged position (D), corresponding to the second operating condition (NO2).

[0069] The command means preferably comprise a coupling part (61) and in the first faulty operating condition (FO1 ) the coupling part (61 ) engages the first part (1 ), or an element that rotates together with the first part (1), and engages the second part (2), or an element that rotates together with the second part (2), in such a way that the first part (1) sets the second part (2) in rotation in order to transmit torque to the output part (102). In other words, the coupling part (61) is configured to engage with the first part (1), or an element that rotates together with the first part (1), and is configured to engage the second part (2), or an element that rotates together with the second part (2), in such a way that the first part (1) sets the second part (2) in rotation in order to transmit torque to the output part (102) in the first faulty operating condition (FO1).

[0070] The engagement of the coupling part (61) can take place in various positions and can directly involve the parts that bear the one or more first discs (3) and the one or more second discs (4), the one or more first discs (3) and the one or more second discs (4), or other parts that rotate together with the first part (1) or the second part (2). In many solutions of the prior art the piston (5) rotates together with the first part (1) or the second part (2); in a case where the piston (5) is borne by the second part (2) the transmission of torque can be guaranteed with the coupling part (61) coupled to thepiston (5) and to the first part (1 ), or to an element that rotates together with the first part (1).

[0071] Owing to the coupling part (61) the power take-off (100) passes from a functioning in which the torque transmission takes place by friction to a functioning in which the torque transmission takes place by coupling via an interposed body; in some preferred embodiments, described in the following, the interposed body comprises a splined profiled element, i.e. it comprises teeth which determine a tangential engagement with respect to the rotation axis (X) for the transmission of the rotary motion. For example in figures 6, 17, 18 and 20 the coupling part (61) is configured to engage with the first part (1), or an element that rotates together with the first part (1), and the second part (2), or an element that rotates together with the second part (2).

[0072] The teachings of the present description are applied to numerous configurations of power take-offs (100) which, in the first instance, are differentiated from one another due to the installation position thereof on the vehicle (1000) and the modes of integration with the vehicle. This affects the configuration of the support part (7a, 7b). For example, the configuration of figure 20 can be installed downstream of the secondary shaft of the gearbox or integrated into the power engine (1001): typically, in the first case the power take-off (100) comprises a support part (7a, 7b) which is boxshaped, while in the second case the support part (7a, 7b) can simply be a cover (7b) on the side of the output part (102) which is fixed to the casing of the power engine (1001). In this second case the bearing furthest from the support part (7a, 7b) can already be available inside the power engine (1001), before the installation of the power take-off (100).

[0073] The support part (7a, 7b) can comprise one or more main bodies (7a) which together with lids (7b) or caps form a single closure in the normal functioning of the power takeoff (100); for example, from a comparison between figure 7 and figure 8 it can be observed that, at the output part (102), a cover (7b) is reversible fixed to a main body (7a).

[0074] According to an embodiment, the support part (7a, 7b) is box-shaped so as to be able to receive a lubricant, typically oil, to ensure that the internal parts are in an oil bath. Figures 8, 16, 17 and 18, for example, illustrate some holes for the passage of the lubricant, at the position of the one or more first discs (3) and the one or more second discs (4), and enables an appreciation of how the box-configured support part (7a, 7b) contains many parts in an oil bath.The box-configured support part (7a, 7b) preferably houses the one or more first discs (3), the first part (1), the one or more second discs (4), the second part (2), the piston (5) and the command means. In the embodiments of figures from 1 to 21 the box-configured support part (7a, 7b) also houses gears that ensure the transmission of the torque from the input part (101) to the first part (1), although the latter might be in one piece with the input part (101). In an entirely similar way, the box-configured support part (7a, 7b) might accommodate one or more gears between the second part (2) and the output part (102).

[0075] The gears present in the box-configured support part (7a, 7b) ensure a predetermined transmission ratio between the rotation of the input part (101) and the rotation of the output part (102).

[0076] The output part (102) is illustrated as a cardan flange in figures from 1 to 19 but could have other configurations, for example a part of a splined shaft, as shown by way of example in figures 20 and 21.

[0077] As known to the expert in the sector, the transmission of torque by friction can take place by contact between many discs or between two discs, appropriately dimensioned on the basis, in particular, of the torque transmitted. In the case of two discs the configuration of the appended figures might be maintained, or, more likely, one of the two discs might be borne by the piston (5), or might be solidly constrained to the piston (5), with the piston (5) rotating together with the part, between the first part (1) and the second part (2), which does not bear or is solidly constrained to the other disc. Typically, the power take-off (100) according to the invention comprises first discs (3) and second discs (4) as in the embodiments of the appended figures; the clutch unit, thus-realised, is therefore a multi-disc clutch unit. Also known to the technical expert in the sector are numerous constructional variants for connecting the discs to the relative disc carriers; for example figure 13 illustrates a guide part (14) for the one or more first discs (3).

[0078] As known to the expert in the sector and illustrated by way of example in figure 8, the supply line (50) provides pressurised fluid to the thrust chamber (52) so as to engage the clutch, with the piston (5) displacing towards the left in the direction of the rotation axis (X), and the transfer of torque by friction. Further, the spring (9), or appropriate elastic means of known type, causes the disengagement and return into a position that prevents transfer of torque, in a case where the thrust chamber (52) is not commanded in pressure, i.e. in a case where it is below a pressure level.The pressurised fluid is typical air or oil, with the clutch unit being preferably a multi-disc clutch unit that is pneumatic or hydraulic.

[0079] The thrust chamber (52) might be delimited by the first part (1 ), by the second part (2) or by the support part (7a, 7b), with the piston (5) being movable in the direction of the rotation axis (X) with respect to each thereof.

[0080] The support part (7a, 7b) preferably comprises an opening (71) and an outer cap (72) for closing the opening (71) during normal functioning and the command means are configured to be operated or moved through the opening (71), more preferably manually, as will be detailed further in the following. The aim of the opening (71) is to enable access on an internal side of the support part (7a, 7b), i.e. the side opposite the side facing towards the operator, without any need for interventions that are typically carried out in the workshop.

[0081] The outer cap (72) preferably engages sealedly in the opening (71), and the seal especially prevents leakage of lubricants, typically oil.

[0082] The expert in the sector is aware of various solutions to this end. For example, in a first solution the cover (7b), in the appended figures from 1 to 19, or the main body (7a), in figures 20 and 21, comprises a first gasket (74) which is configured to be interposed between the outer cap (72) and the opening (71). Still by way of example, the first gasket (74) can be an axial gasket housed in the outer cap (72) or a washer made of a different material, for example copper, or can be a of a type known as bonded seal. In other solutions the outer cap (72) has a cladding to guarantee seal or is made of a material the also ensures the seal, or the respective seat of the outer cap (72) is made in such a way as to guarantee the seal, for example by counterboring.

[0083] Like considerations are valid for the seal of the hole (1a, 21) and the through-hole (51) described in the following. In other words, both to guarantee the seal of the outer cap (72), and to guarantee the seal of the cap (81), described in the following, and to guarantee the seal of the command part (65) in the through-hole (51), as described in the following, the power take-off (100) preferably comprises seal means; the seal means preferably comprise seals, gaskets, claddings and / or composites.

[0084] In the sector, gaskets or cladding or composites are often used, comprising technopolymers, for example fluoroelastomers. These, as well as guaranteeing the seal, resist well and over time at operating temperatures typical of power take-offs, which can exceed 350 K, typically also 370 K. Like fluorelastomers are often indicated by the trade name Viton, falling within the FPM group of the ISO 1629:2013 standard.The first gasket (74) can be of a type known in the technical jargon as a bonded seal, for example a washer with a sealing part made of fluoroelastomer.

[0085] The command means are also preferably configured to disconnect the input part (101) from the output part (102) so as to pass from the first faulty operating condition (FO1) to a second faulty operating condition (FO2). In this way the transmission of power to the device (1004) can be terminated as soon as the operation has concluded during which the fault occurred, thus enabling the vehicle (1000) to reach a workshop or an assistance centre with the device disconnected (1004). This possibility therefore assumes special relevance not only for reducing consumption but especially in all those applications where the operativity of the power take-off (100) would cause problems, or create risks.

[0086] As can be observed in figures 4 and 10 the second operating condition (NO2) and the second faulty operating condition (FO2) are substantially alike as they involve the absence of transmission of torque between the input part (101) and the output part (102), however in the case of the second faulty operating condition (FO2) the torque transmission between the one or more first discs (3) and the one or more second discs (4) by friction is not possible.

[0087] The expert in the sector is aware of numerous configurations of power take-offs which might be applied to the power take-offs (100) according to the invention.

[0088] In the configurations illustrated in figures from 1 to 21 the output part (102) is at the end of a shaft (102a) which is rotationally connected to the support part (7a, 7b) according to a rotation axis (X). The first part (1) and the second part (2) are borne by the shaft (102a) but, while the first part (1) is free to rotate with respect to the shaft (102a), in this case, with the interposing of a roller bearing, the second part (2) rotates together with the shaft (102a), in this case due to the engagement of profiles indicated with a dotted line in figures from 1 to 19 and with a normal portion in figures 20 and 21.

[0089] The expert in the sector is aware of many solutions that enable two parts to rotate together; some of these still allow the displacement in the axial direction, while others fix the two parts to one another also in the axial direction, or, possibly, the parts might be fixed to one another axially in the overall configuration of the power take-off (100). Among the solutions typically used are any combination of projection / s and recess / es arranged axially, for example splined profiles, or the use of one or more tabs or a keying by interference.

[0090] Likewise, the expert in the sector is aware of several solutions which enable two parts tobe rotatable with respect to one another; in the sector of power take-offs roller bearings are typically used, for example roller bearings as visible in the appended figures.

[0091] With reference to figures from 1 to 19 the second part (2) sets the piston (5) in rotation as it comprises a guide (22) which is engaged by the first engagement part (54), in this case realised with splined profiles.

[0092] The configuration illustrated above also functions with an opposite direction of torque transmission, i.e. with reference to figures 6, 16, 17, 19 and 20 the right side becomes the input part (101) and the left side is connected to the output part (102). For this reason the present description offers, at various points, the alternative of the first part (1) or the second part (2): for example, with reference to figures 6, 16, 17 and 19, the hole (1a, 21) which in the appended figures is made on the second part (2) would be made on the first part (1 ) in the case of an opposite direction of the torque transmission. Further in the configuration visible in figures 6, 16, 17 and 19, but the same is valid also for figures 20 and 21, the second part (2), in accordance with one of the constructional modalities known to the expert in the sector, comprises a disc guide part (24) and is engaged by an abutment part (25) stopped by means of an elastic ring (26). The elastic ring (26) limits the movement, in the direction of the rotation axis (X) of the abutment part (25) which opposes the advancement of the first discs (3) and the second discs (4) caused by the piston (5). The disc guide part (24) has a function that is entirely alike to that of the guide (14) in relation to the one or more first discs (3), enabling translation only of the one or more second discs (4) in the direction of the rotation axis (X).

[0093] In a case where the torque is transmitted in an opposite direction, as just described for the second part (2) with respect to figures 6, 16, 17 and 19 it could be applied to the first part (1).

[0094] Notwithstanding the fact that the embodiments of the appended figures share the general characteristics described in the foregoing and have other common characteristics, they have some specific features that will be more fully described in the following with the help of the appended figures.

[0095] - Embodiments with special reference to figures from 4 to 14, from 17 to 19 and from 20 to 21. - The coupling part (61) is preferably movable in the direction of the rotation axis (X), more preferably according to the rotation axis (X), between at least a rest position (P) and a first position (P1 ).

[0096] In the rest position (P) the coupling part (61) is configured to engage with the first part(1 ), or the element that rotates together with the first part (1 ), and the second part (2), or an element that rotates together with the second part (2). In this way the piston (5) can operate in the normal functioning way and, possibly, enabling the interruption of the transmission of power downstream of the first faulty operating condition (FO1 ).

[0097] In the first position (P1) the coupling part (61) is configured to engage with the first part (1), or an element that rotates together with the first part (1), and engages the second part (2), or the element that rotates together with the second part (2).

[0098] Further, the support part (7a, 7b) comprises an opening (71), the first part (1) or the second part (2) comprises a hole (1a, 21) and the operation of the coupling part (61) to displace the coupling part (61) into the first position (P1) takes place through the opening (71) and the hole (1a, 21).

[0099] In this way an operator can activate the first faulty operating condition (FO1 ) through the opening (71) and the hole (1a, 21) in a case of a fault that does not allow transmission of torque between the one or more first discs (3) and the one or more second discs (4) by friction.

[0100] The drive is preferably manual, i.e. an operator acts through the opening (71) to displace the coupling part (61) or a command part (65) introduced in the following.

[0101] The presence of an opening (71), preferably though not necessarily on a portion of support part (7a, 7b) facing the same direction as the output part (102), and of a hole (1a, 21), facilitate the operation of the command means so as to move the coupling part (61) in the direction of the rotation axis (X). A coupling part (61) which is movable in the direction of the rotation axis (X) facilitates the realisation of couplings between parts which ensure the transmission of significant torques, thus also enabling the power takeoff (100) to operate at the rated power even in a condition of fault (FO1 ).

[0102] For what is expressed in the foregoing, it is preferable for the command means to be manually operable, i.e. the command means can be moved by using tools commonly available on-board the vehicle (1000) such as, for example, screwdrivers, or hex keys. In particular, it is preferable that both the drive that brings the coupling part (61) into the first position (P1) and the possible drive bringing the coupling part (61) into a rest position (P) are manually achievable.

[0103] In greater detail, in the example embodiments of figures 6, 17, 18 and 20 the opening (71) enables the operation and, possibly, the introduction and / or extraction of a command part (65), described in the following.

[0104] The command means are preferably configured to maintain the coupling part (61) in arest position (P) in the first operating condition (NO1) and in the second operating condition (NO2).

[0105] The command means thus avoid interfering with the engagement and the disengagement determined by the piston (5) during normal functioning. Further, the presence of the coupling part (61) internally of the box-configured support part (7a, 7b) or, in any case, on the side of the support part (7a, 7b), destined to be the inner side prevents or reduces the introduction of elements from outside with the main advantage of reducing the risk that the command means are not together with the power take-off (100) when the fault occurs.

[0106] In the comparison between figure 6 and figure 7 it can be observed how the coupling part (61) is movable with respect to the first part (1), i.e. the part not engaged in the rest position (P), according to the rotation axis (X). The coupling part (61) is typically movable with respect to the first part (1), the second part (2) and the support part (7a, 7b).

[0107] To ensure normal functioning it is very important that the coupling part (61) remains in a rest position (P) in the first operating condition (NO1) and in the second operating condition (NO2).

[0108] In the case illustrated in figures 6 and 7 the coupling part (61) can assume several rest positions (P) with respect to the first part (1), the second part (2) and the support part (7a, 7b) being borne by the piston (5), i.e. by an element that rotates together with the second part (2) but which is in turn movable with respect to the second part (2) in the direction of the rotation axis (X).

[0109] In the case illustrated in figure 20 a single rest position (P) of the coupling part (61) is included, also due to the presence of an abutment.

[0110] Several options are possible both for maintaining the coupling part (61) in at least a rest position (P) and for moving it into the first position (P1), as will be shown by examples illustrated in the following.

[0111] As the power of the power take-off (100) is transferred through the coupling part (61) it is important for the couplings to be configured so as to guarantee the transfer of the torque, preferably at least of the torque corresponding to the rated power of the power take-off (100) or at least the one corresponding to the rated power of the output part (102), in cases where there is a plurality of outputs. Further, it is preferable for the couplings to be configured to prevent the undesired disengagement in the first faulty operating condition (FO1).For these reasons the coupling part (61) preferably comprises a splined profiled element. The use of splined profiles, and like guide solutions which enable placing two rotating bodies together and enable the axial movement of a body with respect to another, is known to the expert in the sector. For example, in figures 6, 16, 17 and 18 it can be observed how the second part (2) engages the shaft (102a) and the piston (5) engages the second part (2) by means of splined profiles and, in figure 20, the second part (2) engages the shaft (102a) by means of a splined profiled element. In all the cases referred to in the foregoing, the axial mobility of the second part (2) is opposed by a spring (9). As known to the expert in the sector, the second part (2) might be keyed on the shaft (102a), i.e be coupled by interference.

[0112] Preferably:

[0113] - the coupling part (61) comprises first engaging means and second engaging means; - a part between the first part (1), or the element that rotates together with the first part (1), and the second part (2), or the element that rotates together with the second part (2), comprises engaging means and the other part comprises respective engaging means;

[0114] - the first engaging means are configured to engage the engaging means in the first position (P1) so as to transmit torque and the second engaging means are configured to engage the respective engaging means in the first position (P1) so as to transmit torque.

[0115] In other words, the first engaging means, the second engaging means, the engaging means and the respective engaging means guarantee the tangential engagement between parts with respect to the rotation axis (X). To obtain a tangential engagement other known solutions in the mechanical sector might be used, among which axial engagement pins and any combination of projection / s and recess / es, for example a single protuberance which engages an axial channel.

[0116] Here and throughout the rest of the document, the terms first, second, respective and the absence of a specification serve to identify the specific engaging means in question. The first engaging means preferably comprise a first splined engagement profile (63) and the engaging means comprise a first splined profile (11) which is engaged with the first splined engagement profile (63) in the first position (P1).

[0117] The first splined engagement profile (63) and the first splined profile (11) enable a transfer of the torque that is more homogeneous, and reduce the local stresses; further, they can enable a more fluid coupling and / or can ensure maintenance of the coupling,as described in the following.

[0118] Figures 7, 9, 17, 18 and 21 illustrate how the first splined engagement profile (63) engages a first splined profile (11 ) made on the first part (1 ).

[0119] The first splined profile (11) and / or the first splined engagement profile (63) is preferably configured in such a way as to determine forces that prevent the disengagement of the coupling part (61) in the first faulty operating condition (FO1), i.e. with the first part in rotation. For example in figures 6, 17 and 18 the first splined profile (11) determines the forces on the coupling part (61) and the first splined engagement profile (63) determines the forces on the first part (1 ) that prevent the disengagement of the coupling part (61 ). Figures from 11 to 14 show examples of how the first splined profile (11) and the first splined engagement profile (63) can comprise respective profiled parts (13, 63b) configured in such a way as to oppose the disengagement of the coupling part (61) during the course of the rotation about the rotation axis (X) of the first part (1) in a first direction, or of the second part (2) in other embodiments.

[0120] Figure 12 illustrates how the teeth are tapered, i.e. the profiled parts (63b) of the first splined engagement profile (63) are inclined so that the width of the tooth reduces as it moves away from the end configured to be facing towards the teeth of the first splined profile (11). In the technical jargon like gearings are known as bevel gears; the use of bevel gears in the place of straight teeth gears avoids the drawbacks in the use of the power take-off (100) in the first faulty operating condition (FO1 ).

[0121] Figure 14 illustrates how the teeth are tapered, i.e. the profiled parts (13) of the first splined profile (11) are inclined so that the width of the tooth reduces as it moves away from the end configured to be facing towards the teeth of the first splined engagement profile (63). In the technical jargon like gearings are known as bevel gears; the use of bevel gears in the place of straight teeth gears avoids the drawbacks in the use of the power take-off (100) in the first faulty operating condition (FO1 ).

[0122] The first splined profile (11) preferably comprises lead-ins (12) for facilitating the meshing of the first splined engagement profile (63) and / or the first splined engagement profile (63) comprises lead-ins (63a) for facilitating the meshing. The lead-ins (12, 63a) facilitate the use of command means and ease the passage to the first faulty operating condition (FO1). Figures 12 and 14 show an example of one of the pointed shapes of the ends of the teeth.

[0123] The second engaging means preferably comprise a second splined engagement profile (64) and the engaging means comprise a second splined profile (53, 22’) which isengaged with the second splined engagement profile (64), at least in the first position (P1).

[0124] In the example embodiments of figures 6, 17 and 18 and 20 the second splined engagement profile (64) is engaged in the second splined profile (53, 22’) in the at least a rest position (P), i.e in the second operating condition (NO2) and, possibly, in the second faulty operating condition (FO2). The use of a splined profiled element therefore guarantees a guide for the coupling part (61) in the displacement in the direction of the rotation axis (X); consequently the second splined engagement profile (64) and the second splined profile (53, 22’) are configured to remain engaged in the axial displacement of the coupling part (61). In more general terms, the means, between the engaging means and the respective engaging means, are configured to engage respectively the first engaging means or the second engaging means so as to guide the displacement of the coupling part (61 ) in the direction of the rotation axis (X).

[0125] Figure 11 is also an example of how, preferably, the coupling part (61) comprises a second splined engagement profile (64) which enables the coupling part to rotate together with the first part (1), or together with an element that rotates together with the first part (1 ) or the second part (2), or together with an element that rotates together with the second part (2). With reference to figure 7, the piston (5) comprises a second splined profile (53) and the second splined engagement profile (64) is engaged in the second splined profile (53) so that the coupling part (61) transmits the rotation from the first part (1), after the splined profiles have allowed the displacement in the direction of the rotation axis (X) deriving from the comparison between figure 7 and figure 6.

[0126] With reference to figure 21, the shaft (102a) comprises a second splined profile (22’) and the second splined engagement profile (64) is engaged in the second splined profile (22’) so that the coupling part (61) transmits the rotation from the first part (1), after the splined profiles have allowed the displacement in the direction of the rotation axis (X) deriving from the comparison between figure 21 and figure 20.

[0127] The first splined engagement profile (63) is preferably radially external and the first splined profile (11) is radially internal, so that the coupling part (61) can occupy a more central zone, tending to reduce the volume. More preferably the second splined profile (53, 22’) is radially external and the second splined engagement profile (64) is radially internal.

[0128] The embodiments of figures 6 and 17 show a single command part (65) while the embodiment of figure 19 has several command parts (65), however also theembodiments of figures 6 and 17 might have several command parts (65) which operate on a same coupling part (61), appropriately modified in line with what is described in the present description. In other words, in the case of several command parts (65) these behave substantially as a single command part (65) though they might not be operated together but in succession or in alternation. The embodiment of figure 20 is also shown, by way of example, with several command parts (65), but it could also operate with a single command part (65).

[0129] In some cases, for example in the case of using threaded connections for displacing the coupling part (61), it might be less easy to use several command parts (65), so that it might be preferable to have a single command part (65). With a single command part (65), the pins (82) represented in some of the appended figures absolve a relevant function.

[0130] The power take-off (100) preferably comprises one or more pins (82) arranged in the direction of the rotation axis (X), preferably parallel to the rotation axis (X), for guiding the coupling part (61) in the movement along the direction of the rotation axis (X) and, possibly, vice versa.

[0131] The one or more pins (82), possibly arranged circumferentially with respect to the rotation axis (X), are particularly useful for reducing the number of command parts (65), down to a single command part and / or for reducing the number of openings (71) and holes (1a, 21) for the command means as they facilitate the displacement along the direction of the rotation axis (X), more preferably parallel to the rotation axis (X), of the coupling part (61). As will be detailed in the description of the method, in the first faulty operating condition (FO1) and in the second faulty operating condition (FO2) it is sometimes possible to operate also only with the outer cap (72) for the closure towards the external environment.

[0132] In the case where the command means are used to pass to the second faulty operating condition (FO2), the drive of the coupling part (61) to displace the coupling part (61) from the first position (P1) to a rest position (P) preferably takes place through the opening (71) and the hole (1a, 21).

[0133] - Embodiments with special reference to figures from 4 to 14, from and from 17 to 19. - The coupling part (61) preferably occupies a volume (V) which is between the piston (5) and the one or more first discs (3) and the one or more second discs (4).

[0134] This enables reducing or eliminating the impact of the introduction of the commandmeans on the volume of the power take-off (100) in some configurations which are widely available on the market, or facilitating the introduction thereof internally of the power take-off (100). For example the volume (V) that can be observed on the left of the piston (5) in figures 6 and 7 is already available in the power take-off today on the market which does not have the command means. In a further example, the volume (V) might be easily obtained by modifying the extension of the piston (5) in the direction of the rotation axis (X) starting from a more compact configuration of the power take-off (100).

[0135] Further, the positioning of the coupling part (61) in the volume (V) facilitates the conservation of the existing configuration of the supports, for example by not impacting on the arrangement and / or type of the bearings used in a configuration not having the command means.

[0136] Once more, this positioning enables maximising or not reducing the thrust area of the piston (5) and / or facilitates the provision of pressurised fluid to the thrust chamber (52). Further, the rotational connection between the first part (1) and the second part (2) for the transmission of torque is facilitated in the volume (V).

[0137] Preferably:

[0138] - the piston (5) comprises a through-hole (51);

[0139] - the command means comprise a command part (65);

[0140] - in the first operating condition (NO1) and in the second operating condition (NO2) the command part (65) engages the through-hole (51) and the coupling part (61) so as to retain the coupling part (61) in a rest position (P).

[0141] For motives relating to size, effectiveness of the clutch and / or overall configuration of the power take-off (100) the piston (5) typically acts at least on a radially external portion of the discs, so that to occupy the volume (V) without negatively affecting these aspects it is preferable for the piston (5) to comprise a through-hole (51 ).

[0142] Further, the through-hole (51) facilitates the axis drive and limits the impacts on the transmission of the drive and the torque during normal functioning.

[0143] Owing to the engagement of the command part (65) in the through-hole (51) it is possible to ensure the normal functioning and, at the same time, activate the first faulty operating condition (FO1) through the opening (71) and the hole (1a, 21).

[0144] Typically, as already anticipated in the foregoing, the command part (65) engages the through-hole (51) sealedly to prevent leakage, primarily pressurised fluid but also lubricant.Preferably:

[0145] the first part (1) or the second part (2) comprises a bell-shaped part (23) and bears the piston (5) in such a way as to rotate together with the piston (5);

[0146] - the bell-shaped part (23) delimits with the piston (5) a thrust chamber (52) which is connected to the supply line (50) in order to receive pressurised fluid;

[0147] -the hole (1a, 21) is realised in the bell-shaped part (23);

[0148] - the through-hole (51) and the hole (1a, 21) are located in a same axis parallel to the rotation axis (X).

[0149] Owing to the bell-shaped part (23), the rotation in unison of the part of the piston (5) and the corresponding position of the through-hole (51) and the hole (1a, 21), it is possible to provide a power take-off (100) that is compact and / or reliable and with command means easily operable in a case of fault. In fact, the thrust chamber (52) can be easily delimited, for example in figure 6 gaskets can be seen that ensure the seal between the bell-shaped part (23), the piston (5) and the shaft (102a). Further, the through-hole (51) and the hole (1a, 21) are easily alignable to the opening (71), for example by a rotation of the output part (102).

[0150] These advantages are still more evident should it be the second part (2) that comprises a bell-shaped part (23) and that bears the piston (5), as shown by way of example in appended figures from 1 to 19. In fact, in many applications the input part (101) is connected to the drive shaft (1002) of the vehicle (1000) without interposing a clutch with the consequence that it is very much easier to set in the rotation the output part (102) that can be free or connected to the device (1004).

[0151] By rotating the output part (102) it is possible to align the through-hole (51) and the hole (1a, 21) to the opening (71), so as to enable the operation of the command means and, possibly, enable the coupling part (61) to engage the first splined profile (11), as described in the foregoing, in a case where the two parts are not correctly aligned. This latter engagement can however also be obtained on the start-up of the power engine (1001), as soon as the first part (1) starts rotating if the elastic means (68) described in the following are present.

[0152] Especially in a case where the output part (102) is connected to the device (1004), a wrench seat (103) facilitates the setting in rotation so as to align the through-hole (51) and the hole (1a, 21) to the opening (71). The wrench seat (103) is also useful for the same reasons in the embodiment of figure 16.

[0153] Incidentally, it is specified that the piston (5) of appended figures from 1 to 19 is made intwo bodies, conjoined using seals, but this is not strictly necessary.

[0154] The power take-off (100) typically comprises a shaft (102a) which is rotatable about the rotation axis (X) with respect to a part, between the first part (1) and the second part (2), and which is connected to the other part, between the first part (1) and the second part (2), so as to rotate together or so as to be unitary therewith. In this configuration it is preferable that the thrust chamber (52) is delimited by the shaft (102a) and the coupling part (61) engages the piston (5) so as to rotate together with the piston (5). Several advantages are attained in this way.

[0155] A first advantage concerns the thrust area of the piston (5), which can extend radially from the shaft (102a), thus reducing the pressure demanded in the thrust chamber (52) to obtain the same effect.

[0156] A second advantage regards the simplicity with which the thrust chamber (52) can be supplied, with the supply line (50) crossing the shaft (102a) and which can directly face onto the thrust chamber via a hatch on the lateral surface of the shaft (102a).

[0157] A third advantage is the relative simplicity with which the seals between the components can be obtained.

[0158] A fourth advantage consists in facilitating the transmission of the transmittable torque, for example the rated torque, internally of the typical configuration of a clutch of a power take-off (100). In particular, the coupling of the piston (5) and the shape of the components can be exploited to transmit high torques without generating excessive stresses. These advantages are also correlated to the position of the coupling part (61) in the volume (V) and to the presence of the through-hole (51 ).

[0159] This is without considering that the coupling between the first part (1) and the second part (2), or between one of these and an element that rotates together with the other, can take place in more restricted spaces and / or more easily. With reference to the embodiments shown in figures 6, 17 and 18, the coupling part (61) is interposed between the piston (5) and the first part (1). With reference to the embodiment given by way of example in figure 20 the coupling part (61 ) is interposed between the first part (1 ) and the shaft (102a), the latter being made solid to the second part (2) by a spline and a spring (9). In the embodiments of figures 6, 17 and 18 the position of the coupling part (61) avoids limits or complications in the transmittable torque, as the latter is transmitted by means of the use of splined profiles, or the like, as described in the foregoing.

[0160] The second part (2) preferably comprises a bell-shaped part (23) and bears the piston (5) in such a way as to rotate together with the piston (5). The position of the through-hole (51) on the output side (102) facilitates the operation of the command means as is also evidenced in other parts of the description and as clearly illustrated in figures from 1 to 19.

[0161] The power take-off (100) preferably comprises a cap (81) which is configured to sealingly engage the hole (1a, 21) so as to be sealingly engaged in the hole (1a, 21) in the first operating condition (NO1) and in the second operating condition (NO2) and so as to guarantee the pressurised fluid seal coming from the supply line (50) in the first operating condition (NO1) and in the second operating condition (NO2).

[0162] The command part (65) is preferably engaged sealedly in the through-hole (51) in the first operating condition (NO1) and in the second operating condition (NO2) to guarantee the seal of the pressurised fluid in arrival from the supply line (50).

[0163] Some of the solutions for guaranteeing the seal have already been discussed in the foregoing. In the embodiments of figures from 1 to 19, by way of example, the cap (81) engages a respective seat that is realised by counterboring so as to guarantee the seal. In the embodiments of figures from 1 to 19, by way of example, the piston (5) comprises a gasket (55) which is configured to be placed between the seat (5a) and the command part (65) to guarantee the seal.

[0164] Some detailed explanation is now given of some of the options shown by way of example in appended figures 6, 10, 17, 18 and 19 for displacing from the at least one rest position (P) and / or for retaining the coupling part (61) from the at least a rest position (P) and, possibly, for displacing the coupling part (61) to the at least a rest position (P) and / or for retaining the coupling part in the first position (P1).

[0165] The command means preferably comprise elastic means (68) which are configured to exert a force on the coupling part (61) so as to move the coupling part (61) from the at least a rest position (P) to the first position (P1) when the command part (65) disengages the coupling part (61).

[0166] In the embodiments of figures from 4 to 14 the elastic means (68) comprise springs arranged circumferentially (see in particular la figure 9), but might comprise a single spring, for example configured in a similar way to the spring (9), or known elements which perform the same function.

[0167] The use of the elastic means (68) is particularly convenient to guarantee the engagement of the coupling part (61) and, possibly, to prevent the disengagement thereof before the activation of the power take-off (100). As already mentioned in the foregoing, the elastic means (68) can enable the coupling of the coupling part at thestart of the movement of the input part (101), after the operation of the command means.

[0168] The command part (65) can engage the coupling part (61) in several ways, for example the command part (65) can comprise an engagement configured to engage a hollow in the coupling part (61) or the command part (65) can engage with the coupling part (61) by means of a threaded connection.

[0169] According to a preferred embodiment, shown by way of example in figures 6, 10, 17 and 19, the command part (65) comprises threading (66), the coupling part (61) comprises a threaded part (62) and the threading (66) engages the threaded part (62) so as to be able to retain the coupling part (61) in at least a rest position (P). For this purpose it is sufficient for the threaded part (62) to allow the engagement between the command part (61) and the coupling part (65) and it therefore does not necessarily have to be crossable by the command part (65) as illustrated in the appended figures; this characteristic can however facilitate the displacement of the coupling part (61) from the first position (P1), as described in the following.

[0170] Notwithstanding the above it is preferable that the command part (65) comprises a head (65a) and that the piston (5) has a seat (5a) that accommodates the head (65a) in the first operating condition (NO1) and in the second operating condition (NO2) in such a way that the piston (5) is interposed between the head (65a) and the coupling part (61) so as to retain the coupling part (61) in a rest position (P).

[0171] It is further preferable for the command part (65) to extend from the head (65a) so that, with the head (65a) in the seat (5a), the coupling part (61) is engageable by the command part (65), in particular so that, with the head (65a) in the seat (5a), the coupling part (61) is engaged by the command part (65) in the first position (P1).

[0172] In this way the command means can command the passage from a first faulty operating condition (FO1) to a second faulty operating condition (FO2) since after the engagement with the coupling part (61) the command part can be utilised to displace the coupling part (61) into at least a rest position (P).

[0173] For example the threaded part (62) can be crossable by the command part (65), being realised at a hole position, which is a through-hole, and the rotation of the command part (65) can recall the coupling part into a rest position (P). Figure 6 illustrates this option, with the command part (65) able to be re-inserted through the opening (71), the hole (1a, 21) and the through-hole (51) into the volume (V) so as to recall the coupling part (61 ) towards the seat (5a) where the head (65a) is engaged.Likewise, in the embodiment of figure 17 it is possible to pass from the first faulty operating condition (FO1) to the second faulty operating condition (FO2) by recalling the coupling part (61 ) with the threading (66) of the command part (65).

[0174] However, the embodiment of figure 17 differs from the one of figure 6 inasmuch as the coupling part is displaced into the first position (P1), no longer by means of the elastic means (68), but owing to the rotation of the command part (65) so as to move the coupling part (61) away from the head (65a) and ensuring the engagement of the head (65a) in the seat (5a) by means of the cap (81 ) in the hole (1a, 21 ).

[0175] The embodiment of figures 18 and 19 differs from the one of figure 6 and from that of figure 17 as the command means comprise a command part (65) which ensures the return into a rest position (P), alike to what is described in the foregoing, while a second command part (65’) is used to push the coupling part (61) into the first position (P) and, possibly, to secure it. The command means also comprise a second command part (65’) which, in the example embodiment of figures 18 and 19, is not internal of the box-configured support part (7a, 7b) or on the inner side of the support part (7a, 7b) during normal functioning, i.e. in the first operating condition (NO1) and in the second operating condition (NO2).

[0176] By way of example, figure 18 illustrates the second command part (65’) engaging the through-hole (51) in the place of the command part (65) so as to be able to displace the coupling part (61) into the first position (P1). It can be observed how the coupling part (61) has an engagement seat for the second command part (65’) at the position of the through-hole where the threaded part (62) is positioned.

[0177] Figure 19 illustrates the moment when the command part (65) collects the coupling part (61), i.e. due to the threading (66) (visible only in a first portion) and to the threaded part (62) displaces the coupling part (61) towards a rest position (P). In this step the outer cap (72), illustrated, is not present while both the outer cap (72) and the cap (81) of the hole (1a, 21) will be inserted during normal operation.

[0178] The cap (81) can further be used for ensuring the engagement of the coupling part (61) before the activation of the power take-off (100), opposing the displacement of the second coupling part (65). In the example of figure 18 the second coupling part (65’) maintains the coupling part (61) in the first position (P1) by means of a threaded connection with the piston (5).

[0179] - Embodiments with special reference to figures 20 and 21. - Figure 20 is a schematic section view of a portion of a power take-off (100) on the basisof the example of the sections visible in the preceding figures. Visible at the top left is an interruption line, as the support part (7a, 7b) continues, and also a gear which engages the first part (1) is not illustrated.

[0180] Figure 20 illustrates how the teachings of the invention are applicable to other configurations of power take-offs and clarifies some alternatives indicated in the description, for example in relation to the fact that the hole (1a, 21) can be made on the first part (1 ) or on the second part (2).

[0181] The main difference of the configuration of the power take-off (100) of figure 20 with respect to that of the preceding figures consists in a reduction of the free spaces radially on the output side to realise an axial drive. In fact, the type of output part (102), the arrangement and the type of bearings on the output side, the small radial extension of the piston (5) and the presence of a spring (9) which engages a substantial part of the volume (V) make insertion difficult of a coupling part (61) that is movable in the direction of the rotation axis (X) and preferably drivable by the output side (102).

[0182] As already discussed above and given by way of example in figure 20, the coupling part (61) is borne by the shaft (102a) which rotates together with the second part (2), as the latter is constrained angularly on the shaft (102a) and blocked in translation along the axis by the spring (9). The coupling part (61) is movable in the direction of the rotation axis (X) with respect to the shaft (102a) and the first part (1), as well as to the support part (7a, 7b).

[0183] With reference to the embodiment given by way of example in figure 20 the coupling part (61) is interposed between the first part (1) and the shaft (102a); the position of the coupling part (61) avoids limits or complications in the transmittable torque, as the latter is transmitted by means of the use of splined profiles, or the like, as described in the foregoing.

[0184] The command means preferably comprise a command part (65) which engages or is engageable in the hole (1a, 21) to displace the coupling part (61) in the direction of the rotation axis (X), more preferably along the rotation axis (X). In other words, the command part (65) engages the hole (1a, 21) to displace the coupling part (61) in the direction of the rotation axis (X), more preferably along the rotation axis (X).

[0185] The presence of a command part (65) facilitates the displacement of the coupling part (61) by the operator.

[0186] The command means preferably comprise first elastic means (69) configured to oppose the displacement of the coupling part (61) to the first position (P1) in the first operatingcondition (NO1) and in the second operating condition (NO2) and the command part (65) is movable according to an axis that is transversal to the rotation axis (X) in such a way that in the advancement towards the rotation axis (X) displaces the coupling part (61) from a rest position (P) to the first position (P1) opposing the first elastic means (69).

[0187] In the example embodiment of figures 20 and 21 the first elastic means (69) comprise springs arranged circumferentially, but might comprise a single spring, for example configured in a similar way to the spring (9), or known elements which perform the same function.

[0188] In the example embodiment of figures 20 and 21 the command part (65) is introduced only in a case of a fault through the opening (71); possibly, the power take-off (100), in the present case the first part (1), might be configured to retain the engagement part in the hole (1a, 21) also during normal functioning, i.e. in the first operating condition (NO1) and in the second operating condition (NO2).

[0189] Thus a power take-off (100) is obtained in which the first elastic means (69) guarantee normal functioning, with no interference of the coupling part (61) and at the same time allow easy operation of the command means by the operator.

[0190] So as to pass from the first faulty operating condition (FO1) to a second faulty operating condition (FO2), the command part (65) is preferably movable according to an axis that is transversal to the rotation axis (X), more preferably perpendicular thereto, in such a way that during retraction away from the rotation axis (X) it allows the return of the coupling part (61) into the rest position (P).

[0191] In this way the power take-off (100) is configured to pass to a second faulty operating condition (FO2) i.e: the command means are also configured to disconnect the input part (101) from the output part (102) so as to pass from the first faulty operating condition (FO1) to a second faulty operating condition (FO2), i.e. so as to terminate the transmission of torque.

[0192] The command part (65) preferably comprises an inclined end or a conical tip (67) and is movable according to an axis that is orthogonal to the rotation axis (X).

[0193] The operation in radial direction of the command part (65) enables the introduction of the command means also in a configuration that makes an axial solution difficult such as the one illustrated in figures from 4 to 19. While it is theoretically possible to displace the coupling part (61) with the command part (65) which forms, with the rotation axis (X), and angle of less than TT / 2 rad, it is preferable for the command part (65) to beappropriately conformed and to be introduced orthogonally to the rotation axis (X). In particular, it is easier to bring the hole (1a, 21) into the clear passage of the opening (71). In this regard note that it would be preferable to change the torque transmission direction with respect to that indicated in figure 20 so as to have the hole (1a, 21) on the second part (2), more easily manoeuvrable by the operator.

[0194] The inclined end or the conical tip (67) is configured in such a way as to displace the coupling part (61 ) towards the spline of the first part (1 ) so as to engage it.

[0195] In the example of figure 20 the coupling part (61) comprises a first splined engagement profile (63) and a second splined engagement profile (64) to engage respectively a first splined profile (11) on the first part (1) and a second splined profile (53, 22’) on the shaft (102a) in the first faulty operating condition (FO1 ).

[0196] The outer cap (72) ensures the seal to the lubricant in normal functioning and might possibly not be present in the first faulty operating condition (FO1).

[0197] The comparison between figure 21 and figure 20 shows the advancement of the command part (65) by means of the rotation imparted by a hexagonal key (not shown) due to a threaded connection between the first part (1) and the command part (65). In the example embodiment the command part (65) is introduced on the inner side of the support part (7a, 7b) through the opening (71) only in a case of a fault; also visible is a second command part which acts on the coupling part (61) in an opposite position, although it would also be possible to provide several command parts (65) in a different arrangement for example arranged at 120 degrees to one another.

[0198] - Embodiments with special reference to figure 16. - The example embodiment of figure 16 shows how, even in a case where the coupling part (61) is introduced and therefore does not have at least a rest position (P), it is preferable that:

[0199] the coupling part (61) is movable in the direction of the rotation axis (X) up to a first position (P1) in which it engages the first part (1), or the element that rotates together with the first part (1), and engages the second part (2), or the element that rotates together with the second part (2);

[0200] -the support part (7a, 7b) comprises an opening (71);

[0201] - the first part (1 ) or the second part (2) comprises a hole (1 a, 21 );

[0202] - the command means are operable through the opening (71) and the hole (1a, 21) to displace the coupling part (61) into the first position (P1).

[0203] Alike to what is described above, it is preferable for the command means to be manuallyoperable, possibly also in the extraction of the coupling part (61).

[0204] Preferably:

[0205] - the one or more first discs (3) comprise at least a first disc (31 ) which has a respective first hole (32);

[0206] - the one or more second discs (4) comprise at least a second disc (41) which has a respective second hole (42);

[0207] - in at least a disc, between the at least a first disc (31) and the at least a second disc (41), the respective first hole (32) or the respective second hole (42) is a through-hole; - in the first faulty operating condition (FO1) the coupling part (61) engages at least a first hole (32) and at least a second hole (42) so that at least a first disc (31) sets at least a second disc (41) in rotation.

[0208] As can be observed in figure 16 the coupling between the first part (1) and the second part (2) can occur via an element that rotates together with the first part (1 ), the first disc (31), and with an element that rotates together with the second part (2), the second disc (41).

[0209] In this way the coupling part (61) can be inserted into the power take-off (100), through the opening (71) and the hole (1a, 21), only after a fault has occurred, with a potential lesser impact on the normal functioning of the power take-off (100) although this can correspond to a greater difficulty in driving the command means by the operator.

[0210] Though it is preferable for the coupling part (61) to operate on a plurality of first discs (3), with an appropriate dimensioning it can operate only on a first disc (31) and a second disc (41) obviously arranged on the side on which the coupling part (61) is introduced. The disc that is second to be engaged does not necessary have to have a through-hole as a blind hole also guarantees engagement.

[0211] Also possible are intermediate solutions between the use of two discs and all the discs, with the final hole being engaged not being necessarily a through-hole, unless that is required for engaging the abutment part (25) as described in the following.

[0212] The embodiments described with reference to the example of figure 16 might advantageously replicate the axial arrangement, the arrangement of the holes and many other specifications illustrated in the foregoing.

[0213] The command means can also comprise several coupling parts as shown by way of example in figure 16 in order to reduce the local tensions and / or to improve the functioning of the power take-off (100) in the first faulty operating condition (FO1 ). In this case too, alike to what is discussed above in relation to the plurality of command parts(65), the plurality of coupling parts (61) replicate the functioning described herein as they would not have to be inserted or de-inserted simultaneously, but in succession, or driven alternatingly to facilitate the alignment between the first holes (32) and the second holes (42).

[0214] In a case where the first discs (3) and second discs (4) provided with respective first holes (32) and second holes (42) the presence of the guide part (14) and the disc guide part (24) described above is practically essential to guarantee the alignment between the first holes (32) and the second holes (42) and, thus, to enable the alignment between the first holes (32) and the second holes (42) in order to engage the coupling part (61).

[0215] The support part (7a, 7b) preferably comprises an opening (71), the first part (1) or the second part (2) comprises a hole (1a, 21) and wherein the coupling part (61) is configured to be introduced manually through the opening (71) and the hole (1a, 21) in the direction of the rotation axis (X), more preferably parallel to the rotation axis (X), until reaching a first position (P1) in which it engages at least a first hole (32) and at least a second hole (42).

[0216] For the above-described reasons, the command means are more easily drivable with respect to other arrangements.

[0217] The piston (5) preferably comprises a through-hole (51) and in the first faulty operating condition (FO1) the coupling part (61) engages the through-hole (51).

[0218] In this case too the crossing of the thrust chamber (52) facilitates the operation of the command means in some preferred configurations of the power take-off (100).

[0219] In the normal functioning of the power take-off (100) it is necessary for the through-hole (51) to be sealedly closed, for example with another cap in an entirely similar way to what was described for the cap (81 ).

[0220] Preferably, in the first faulty operating condition (FO1) the coupling part (61) engages the through-hole (51) so as to maintain the engagement in at least a first hole (32) and in at least a second hole (42), for example via a threaded connection, as illustrated by way of example in figure 16.

[0221] In the first faulty operating condition (FO1) the extraction of the coupling part (61) can be avoided in other ways, for example, as already described above for the command part (65), thanks to an element that limits the axial displacement, for example by engaging the cap (81) in the hole (1a, 21). Also, the coupling part (61) might engage the hole (1a, 21) so as to maintain the engagement in at least a first hole (32) and in at leasta second hole (42). For example, a threaded connection can be included between the coupling part (61) and the part, between the first part (1) and the second part (2), with the hole (1a, 21). The coupling part (61) might be engaged in the abutment part (25), for example by a threaded connection, or according to an embodiment which appears more complex in a first hole (32) or a second hole (42), for example by a threaded connection.

[0222] The coupling part (61) is preferably configured to be extracted manually from the first position (P1) through the opening (71) and the hole (1a, 21) so as to disconnect the at least a first hole (32) from the at least a second hole (42), thereby passing from a first faulty operating condition (FO1) to a second faulty operating condition (FO2).

[0223] In this way the power take-off (100) is configured to pass to a second faulty operating condition (FO2) i.e: the command means are also configured to disconnect the input part (101) from the output part (102) so as to pass from the first faulty operating condition (FO1) to a second faulty operating condition (FO2).

[0224] Each of the first discs (31 ) preferably has a respective first hole (32), each of the second discs (41) has a respective second hole (42) and in the first faulty operating condition (FO1) the coupling part (61) engages the first through-holes (32) and the second through-holes (42) so that the one or more first discs (3) set in rotation the one or more second discs (4). Further, the first holes (32) and the second holes (42) are preferably all through-holes, and possibly one whereof might not be.

[0225] The risk of damaging the one or more first discs (3) and / or the one or more second discs (4) is thus reduced in the first faulty operating condition (FO1).

[0226] The invention also relates to a method for operating the power take-off (100) according to the present description.

[0227] An embodiment of the method comprises successive steps of:

[0228] - detecting a fault which prevents the transmission of torque between the one or more first discs (3) and the one or more second discs (4) by friction in the first operating condition (NO1);

[0229] - interrupting the drive of the input part (101 );

[0230] - operating, preferably manually, the command means to connect the input part (101 ) to the output part (102);

[0231] - reactivating the drive of the input part (101 ).

[0232] With the operation of the command means it is possible to pass from a transmission of the torque by friction to a transmission of the torque for coupling between parts, asillustrated by way of example in the foregoing.

[0233] The step of detecting a fault can include the use of sensors but, in a more obvious way, the operator might notice that the device (1004) is not operating or that an outside shaft downstream of the output part (102) is not rotating, or rotating slowly notwithstanding the fact that the input part (101) is rotating normally.

[0234] Preferably, in the step of operating the command means, the coupling part (61) is displaced up to a first position (P1), according to the above-described embodiments, from at least a rest position (P); in the first position (P1) the coupling part (61) engages the first part (1), or an element that rotates together with the first part (1), and engages the second part (2), or an element that rotates together with the second part (2), in such a way that the first part (1 ) sets the second part (2) in rotation in order to transmit torque to the output part (102).

[0235] Should the command means also be configured to disconnect the input part (101) at the output part (102), so as to pass from the first faulty operating condition (FO1) to a second faulty operating condition (FO2), the method preferably comprises successive steps of:

[0236] - again interrupting the drive of the input part (101);

[0237] - again operating the command means to disconnect the input part (101) from the output part (102);

[0238] - again reactivating the drive of the input part (101 ).

[0239] In some embodiments, with particular reference to figure 16, in the step of again operating the command means the coupling part (61) is displaced into a position in which the coupling part (61), or the coupling parts (61), if multiple, is extracted from the support part (7a, 7b).

[0240] In other embodiments, with particular reference to figures 6, 17, 18 and 20, in the step of again operating the command means the coupling part (61) is displaced into a rest position (P) in which it engages only one from among the first part (1), or the element that rotates together with the first part (1), and the second part (2), or the element that rotates together with the second part (2).

[0241] In greater detail, with particular reference to figures 6, 17 and 18, in the step of again operating the command means the command part (65), or the command parts (65), is displaced in the direction of the rotation axis (X), preferably parallel thereto, or, with particular reference to figure 20, transversally to the rotation axis (X) in such a way that during the moving away retraction from the rotation axis (X) it allows the return of thecoupling part (61) into a rest position (P).

[0242] In a case where the piston (5) has a through-hole (51) and the first part (1) or the second part (2) comprises a hole (1a, 21), and the through-hole (51) and the hole (1a, 21) are located in a same axis parallel to the rotation axis (X), the step of again operating the command means preferably comprises steps of:

[0243] - bringing the hole (1a, 21) into the clear passage of the opening (71) setting in rotation the input part (101 ) or the output part (102).

[0244] More preferably the second part (2) comprises a hole (1a, 21) and in the step of bringing the hole (1a, 21) into the clear passage of the opening (71) the output part (102) is set in rotation, preferably via the wrench seat (103).

[0245] As already expressed, the movement of the output part (102) is generally easier and typically simpler, especially in a case where the power take-off (100) is not downstream of a clutch.

[0246] In the above described modalities, especially in the case of movement on the side of the output part (102), the operation of the command means is particularly simple particularly because the operator is immediately aware of the positioning of the command means internally of the box-configured support part (7a, 7b) or on the inner side of the support part (7a, 7b) and because the operation of the command means can occur in a parallel direction to the rotation axis (X).

[0247] The removal of the outer cap (72) from the opening (71 ) can take place before or during the step of operating the command means. The removal of the cap (81) from the hole (1a, 21), on the other hand, takes place after bringing the hole (1a, 21) into the clear passage of the opening (71).

[0248] Before the step of reactivating the drive, according to the characteristics of the power take-off (100), it may be necessary to engage, in the hole (1a, 21), the cap (81) again, or it might be sufficient to engage only the outer cap (72) in the opening (71) again. Among other things, the power take-off (100) in the first faulty operating condition (FO1) might in theory even operate without the outer cap (72).

[0249] With reference to the embodiments shown in figures 6 and 7 the operation sequence of the command means includes the removal of the outer cap (72) and the cap (81), the rotation of the command part (65) with a hexagonal key with the purpose of freeing the coupling part (61 ) and the possible closing of the opening (71 ) with the outer cap (72). As mentioned in the foregoing, the method can comprise a step of rotating the input part (101) or the output part (102), preferably the output part (102), so as to ensure themeshing of the first splined engagement profile (63) in the first splined profile (11), before the step of reactivating the drive of the input part (101 ).

[0250] With reference to the embodiments shown in figure 17, in this case it might be preferable to engage the cap (81) again or a special cap to replace the outer cap (72) in such a way that the special cap (81) prevents a displacement of the command part (65) that would disengage the first splined engagement profile (63) from the first splined profile (11).

[0251] With reference to the embodiments shown in figures 18 and 19, typically only the outer cap (72) is engaged again, unless the second command part (65’) is not retained in a way alike to what has been described for the command part (65) of figure 17.

[0252] The method preferably comprises a step of providing a vehicle (1000) according to the present description.

[0253] More preferably, the step of interrupting the activation and, possibly, the step of again interrupting the activation is done by shutting down the power engine (1001); this is in particular necessary when the power take-off (100) has the input part (101) coupled to the drive shaft (1002) and is not downstream of a clutch as in the case shown by way of example in figure 1. The example case of figure 20, possibly with the necessary modifications to the support part (7a, 7b), can instead be installed both on the power engine (1001) and, for example, on the secondary shaft of a manual or robotised gearbox. Typically:

[0254] - when the power take-off (100) in the configuration shown in figure 20 by way of example is installed on the power engine (1001), the second part (2) is on the side of the power engine (1001), in other words the output part (102) on the right corresponds to the input part (101);

[0255] - when the power take-off (100) in the configuration shown in figure 20 by way of example is connected to a secondary shaft of a gearbox, the second part (2) is on the side of the device (1004), as indicated in figure 20.

[0256] The invention also relates to a vehicle (1000); an embodiment of the vehicle (1000) comprises a power engine (1001) which has a drive shaft (1002) for supplying power, a transmission (1003) for the movement of the vehicle (1000) connected to the drive shaft (1002) and a power take-off (100) according to the present description which is connected to the drive shaft (1002) or to the transmission (1003) to take off power.

[0257] The power engine (1001) can transform one or more energy sources, for example it can be a motor that is alternative to internal combustion, an electric motor or a hybrid motoror even a turbine.

[0258] Figure 3 allows an appreciation of how the installation of the power take-off (100) on the vehicle may be achieved in various ways. Figures 1 and 2 illustrate a power take-off (100) of the type applicable to the flywheel of the power engine (1001) for taking off power directly from the drive shaft (1002) in a zone in which the transmission of power does not depend on a clutch. Figure 3 illustrates the positioning of a like power take-off (100) between the power engine (1001) and the transmission (1003). In figure 3 dotted lines denote other installation positions of the power take-offs (100) commonly used by the expert in the sector, starting from the left: on the gearbox, branching off from the gearbox, between two parts of the transmission shaft and on the differential. These indications are not however exhaustive; for example the power take-off (100) might be between the differential and the wheel.

[0259] The power take-off (100) can be predisposed to drive a device (1004) external of the vehicle (1000) or, preferably, the vehicle (1000) comprises a device (1004) and the power take-off (100) transmits or interrupts the transmission of power to the device (1004) as shown schematically in figure 3.

[0260] More preferably, the device (1004) is a pump, a compressor, a depressor or a mixer. The above is understood to have been described by way of non-limiting example, and any constructional variants are understood to fall withing the protective ambit of the present technical solution, as claimed in the following.

Claims

CLAIMS1) A power take-off (100) installable on a vehicle (1000) for taking off power from a power engine (1001) or from a transmission (1003) which enable movement of the vehicle (1000) and for transmitting or interrupting transmission of power to a device (1004), comprising:- a support part (7a, 7b) which is configured to be fixed to a part of a vehicle (1000);- an input part (101 ) which is rotatable with respect to the support part (7a, 7b) and which is predisposed to be set in rotation;- one or more first discs (3);- a first part (1) which is rotatable with respect to the support part (7a, 7b) about a rotation axis (X), which is one piece with the input part (101) or which is connected with the input part (101 ) so that the rotation of the input part (101 ) sets in rotation the first part (1) and which is one piece with or bears the one or more first discs (3) in such a way that the rotation of the first part (1 ) sets in rotation the one or more first discs (3);- an output part (102) which is rotatable with respect to the support part (7a, 7b) and which is predisposed to be set in rotation;- one or more second discs (4);- a second part (2) which is rotatable with respect to the support part (7a, 7b) about a rotation axis (X), which is one piece with the output part (102) or which is connected to the output part (102) so that the rotation of the second part (2) sets in rotation the output part (102) and which is one piece with or bears the one or more second discs (4) in such a way that the rotation of the one or more second discs (4) sets in rotation the second part (2);- a piston (5) which is movable with respect to the support part (7a, 7b) in the direction of the rotation axis (X) so as to pass from a first operating condition (NO1) in which it presses together the one or more first discs (3) and the one or more second discs (4) so that the one or more first discs (3) transmit torque to the one or more second discs (4) by friction, in order to transmit torque to the output part (102), to a second operating condition (NO2) in which it does not press together the one or more first discs (3) and the one or more second discs (4), or does not press them sufficiently so that the one or more first discs (3) do not transmit torque to the one or more second discs (4) by friction, in order tointerrupt transmission of torque to the output part (102), and vice versa so as to pass from the second operating condition (NO2) to the first operating condition (NO1);- a supply line (50) of a pressurised fluid for moving the piston (5);characterised in that it comprises command means for commanding the transmission of torque which are configured to connect the input part (101) to the output part (102) in a first faulty operating condition (FO1), in a case of a fault that prevents transmission of torque between the one or more first discs (3) and the one or more second discs (4) by friction.2) The power take-off (100) of claim 1, wherein the command means comprise a coupling part (61) and the coupling part (61) is configured to engage the first part (1), or an element that rotates together with the first part (1), and is configured to engage the second part (2), or an element that rotates together with the second part (2), in such a way that the first part (1) sets the second part (2) in rotation in order to transmit torque to the output part (102) in the first faulty operating condition (FO1).3) The power take-off (100) of claim 2, wherein:- the coupling part (61) is movable in the direction of the rotation axis (X) between at least a rest position (P) in which it engages only one between the first part (1), or the element that rotates together with the first part (1), and the second part (2), or the element that rotates together with the second part (2), and a first position (P1) in which it engages the first part (1), or the element that rotates together with the first part (1), and engages the second part (2), or the element that rotates together with the second part (2);-the support part (7a, 7b) comprises an opening (71);- the first part (1 ) or the second part (2) comprises a hole (1 a, 21 );- the command means are operable through the opening (71) and the hole (1a, 21) to displace the coupling part (61) into the first position (P1).4) The power take-off (100) of claim 3, wherein the command means are configured to maintain the coupling part (61) in a rest position (P) in the first operating condition (NO1) and in the second operating condition (NO2).5) The power take-off (100) of claim 4, wherein the coupling part (61) occupies a volume (V) which is between the piston (5) and the one or more first discs (3) and the one or more second discs (4).6) The power take-off (100) of claim 5, wherein:- the piston (5) comprises a through-hole (51);- the command means comprise a command part (65);- in the first operating condition (NO1) and in the second operating condition (NO2) the command part (65) engages the through-hole (51) and the coupling part (61) so as to retain the coupling part (61) in a rest position (P).7) The power take-off (100) of claim 6, whereinthe first part (1) or the second part (2) comprises a bell-shaped part (23) and bears the piston (5) in such a way as to rotate together with the piston (5);- the bell-shaped part (23) delimits with the piston (5) a thrust chamber (52) which is connected to the supply line (50) in order to receive pressurised fluid;-the hole (1a, 21) is realised in the bell-shaped part (23);- the through-hole (51) and the hole (1a, 21) are located in a same axis parallel to the rotation axis (X).8) The power take-off (100) of claim 7, comprising a shaft (102a), wherein:- the shaft (102a) is rotatable about the rotation axis (X) with respect to a part, between the first part (1) and the second part (2), and is connected to the other part, between the first part (1) and the second part (2), so as to rotate together or so as to be unitary therewith;- the thrust chamber (52) is also delimited by the shaft (102a);- the coupling part (61) engages the piston (5) so as to rotate together with the piston (5).9) The power take-off (100) of claim 7 or 8, wherein the second part (2) comprises a bell-shaped part (23) and bears the piston (5) in such a way as to rotate together with the piston (5).10) The power take-off (100) of any one of claims from 6 to 9, wherein the command means comprise elastic means (68) which are configured to exert a force on the coupling part (61) so as to move the coupling part (61) from the at least a rest position (P) to the first position (P1) when the command part (65) disengages the coupling part (61).11) The power take-off (100) of any one of claims from 6 to 10, wherein the command part (65) comprises a head (65a) and the piston (5) has a seat (5a) which accommodates the head (65a) in the first operating condition (NO1) and in the second operating condition (NO2) in such a way that the piston (5) is interposed between the head (65a) and the coupling part (61) so as to retain the coupling part (61) in a restposition (P) and wherein the command part (65) extends from the head (65a) in such a way that, with the head (65a) in the housing (5a), the coupling part (61) is engaged by the command part (65) in the first position (P1).12) The power take-off (100) of one of claims 6 to 11 , comprising a cap (81) which is configured to sealingly engage the hole (1a, 21) to guarantee the seal of the pressurised fluid in arrival from the supply line (50) in the first operating condition (NO1) and in the second operating condition (NO2).13) The power take-off (100) of any one of claims 2 to 12, wherein:- the coupling part (61) comprises first engaging means and second engaging means; - a part between the first part (1), or the element that rotates together with the first part (1), and the second part (2), or the element that rotates together with the second part (2), comprises engaging means and the other part comprises respective engaging means;- the first engaging means are configured to engage the engaging means and the second engaging means are configured to engage the respective engaging means, in the first position (P1 ) so as to transmit torque.14) The power take-off (100) of claim 13, wherein the first engaging means comprise a first splined engagement profile (63) and the engaging means comprise a first splined profile (11) which is engaged with the first splined engagement profile (63) in the first position (P1).15) The power take-off (100) of claim 14, wherein the first splined profile (11) and / or the first splined engagement profile (63) is configured in such a way as to determine forces that prevent the disengagement of the coupling part (61) in the first faulty operating condition (FO1).16) The power take-off (100) of one of claims 3 to 15, comprising one or more pins (82) arranged in the direction of the rotation axis (X) for guiding the coupling part (61) in the movement along the direction of the rotation axis (X).17) The power take-off (100) of any one of the preceding claims, wherein the command means are also configured to disconnect the input part (101) from the output part (102) so as to terminate transmission of torque, thereby passing from the first faulty operating condition (FO1) to a second faulty operating condition (FO2).18) The power take-off (100) of claim 3 or any preceding claim depending on claim 3 wherein the operation of the coupling part (61) to displace the coupling part (61) from the first position (P1) to a rest position (P) takes place through the opening (71) and thehole (1a, 21).19) The power take-off (100) of claim 4, wherein the command means comprise a command part (65) which engages the hole (1a, 21) to displace the coupling part (61) in the direction of the rotation axis (X).20) The power take-off (100) of claim 19, wherein the command means comprise first elastic means (69) configured to oppose the displacement of the coupling part (61) to the first position (P1) in the first operating condition (NO1) and in the second operating condition (NO2) and wherein the command part (65) is movable according to an axis that is transversal to the rotation axis (X) in such a way that in the advancement towards the rotation axis (X) displaces the coupling part (61) from a rest position (P) to the first position (P1) opposing the first elastic means (69).21) The power take-off (100) of claim 19 or 20, wherein the command part (65) is movable according to an axis that is transversal to the rotation axis (X) in such a way that during retraction away from the rotation axis (X) it allows the return of the coupling part (61) into the rest position (P).22) The power take-off (100) of any one of claims from 19 to 21, wherein the command part (65) comprises an inclined end or a conical tip (67) and is movable according to an axis that is perpendicular to the rotation axis (X).23) The power take-off (100) of claim 2, wherein:- the one or more first discs (3) comprise at least a first disc (31 ) which has a respective first hole (32);- the one or more second discs (4) comprise at least a second disc (41) which has a respective second hole (42);- in at least a disc, between the at least a first disc (31) and the at least a second disc (41), the respective first hole (32) or the respective second hole (42) is a through-hole; - in the first faulty operating condition (FO1) the coupling part (61) engages at least a first hole (32) and at least a second hole (42) so that at least a first disc (31) sets at least a second disc (41) in rotation.24) The power take-off (100) of claim 23, wherein the support part (7a, 7b) comprises an opening (71), wherein the first part (1) or the second part (2) comprises a hole (1a, 21) and wherein the coupling part (61) is configured to be introduced manually through the opening (71) and the hole (1a, 21) in the direction of the rotation axis (X) until reaching a first position (P1) in which it engages at least a first hole (32) and at least a second hole (42).25) The power take-off (100) of claim 24, wherein the piston (5) comprises a through-hole (51) and in the first faulty operating condition (FO1) the coupling part (61) engages the through-hole (51).26) The power take-off (100) of claim 25, wherein in the first faulty operating condition (FO1) the coupling part (61) engages the through-hole (51) so as to maintain the engagement in at least a first hole (32) and in at least a second hole (42).27) The power take-off (100) of any one of claims from 24 to 26, wherein the coupling part (61) is configured to be extracted manually from the first position (P1) through the opening (71) and the hole (1a, 21) so as to disconnect the at least a first hole (32) from the at least a second hole (42), thereby passing from a first faulty operating condition (FO1) to a second faulty operating condition (FO2).28) The power take-off (100) of any one of claims from 23 to 27, wherein each of the first discs (31) has a respective first hole (32), wherein each of the second discs (41) has a respective second hole (42), wherein in the first faulty operating condition (FO1) the coupling part (61) engages the first through-holes (32) and the second through-holes (42) so that the one or more first discs (3) set in rotation the one or more second discs (4) and wherein the first holes (32) and the second holes (42) are all through-holes except, at most, one thereof.29) A method for operating the power take-off (100) of one of claims 1 to 28, comprising successive steps of:- detecting a fault which prevents the transmission of torque between the one or more first discs (3) and the one or more second discs (4) by friction in the first operating condition (NO1);- interrupting the drive of the input part (101 );- operating the command means to connect the input part (101) to the output part (102);- reactivating the drive of the input part (101 ).30) The method of claim 29, wherein the power take-off (100) is according to claim 17 and wherein, after the step of reactivating the drive of the input part (101), the method comprises successive steps of:- again interrupting the drive of the input part (101);- again operating the command means to disconnect the input part (101) from the output part (102);- again reactivating the drive of the input part (101 ).31)The method of claim 29, wherein the power take-off (100) is according to claim 21 and wherein, after the step of reactivating the drive of the input part (101), the method comprises successive steps of:- again interrupting the drive of the input part (101);- again operating the command means to disconnect the input part (101) from the output part (102);- again reactivating the drive of the input part (101 ).32) The method of claim 29, wherein the power take-off (100) is according to claim 27 and wherein, after the step of reactivating the drive of the input part (101), the method comprises successive steps of:- again interrupting the drive of the input part (101 );- again operating the command means to disconnect the input part (101) from the output part (102);- again reactivating the drive of the input part (101 ).33) A vehicle (1000) comprising a power engine (1001) which has a drive shaft (1002) for supplying power, a transmission (1003) for the movement of the vehicle (1000) connected to the drive shaft (1002) and a power take-off (100) according to one of claims from 1 to 28 which is connected to the drive shaft (1002) or to the transmission (1003) to take off power.34) The vehicle (1000) of claim 33 comprising a device (1004), wherein the power take-off (100) transmits or interrupts the transmission of power to the device (1004) and wherein the device (1004) is a pump, a compressor, a depressor or a mixer.

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