ITCR20090043A1 - BIDIRECTIONAL ENGAGEMENT ORGAN WITH TRANSMISSION OF THE MOTORCYCLE SPRING AND FRICTION SPRING - Google Patents

Description

DESCRIPTION

BIDIRECTIONAL ENGAGEMENT WITH HELICAL SPRING MOTION TRANSMISSION MECHANISM AND FRICTION IGNITION

DESCRIPTION

The invention is aimed at the sector of coupling devices for the bidirectional selective transmission of a rotary motion from a drive shaft to a driven shaft and vice versa, particularly suitable for use on mobile operating machines and vehicles in general.

More in detail, the invention relates to a clutch member in which the main motion transmission mechanism is made by means of a substantially cylindrical spring with helical development, arranged astride the two shafts, where friction triggering means can be selectively activated or which can be deactivated with external control means, they cause the two ends of said spring to be dragged which, by wrapping around said shafts, causes their rotation in unison.

From US patent 4,440,280 one of these devices is known for use in photocopying machines. Such a device has limitations and defects that do not make it suitable for use on vehicles and operating machines that have to transfer high power, forces and driving torques between the two shafts and that work in motion, advancing on even very rough terrain.

Patent application No. CR2009A000031 in the name of the same inventor describes a coupling device particularly suitable for use on mobile vehicles and vehicles in general, which makes the use of the machines safe for operators, who do not causes undesired actuation of the driven shaft, which does not generate friction, which is reliable, simple to build and does not require special maintenance interventions.

This grafting member includes:

- a first drum associated with a drive shaft;

- a second drum associated with a driven shaft;

wherein said first and second drum have the same external diameter and said driving and driven shafts are coaxial in the direction of a main axis;

- a helical transmission spring arranged around the two drums, having a first and a second end;

- a first sleeve arranged around said spring;

- a second sleeve rotatably associated with the first sleeve;

- a flange associated with said first drum;

- a control lever acting on said second sleeve to move said first and second sleeve towards said flange which is adapted to act as a shoulder for said first and second sleeve;

where the first end of the helical spring is fixed to the first sleeve and the second end is fixed to the second drum and said first sleeve is slidingly associated with said driven shaft, so that there is no rotation of the spring and of the sleeves when not there is rotation between the two shafts.

The clutch member also comprises an antagonist spring arranged between said second drum and said first sleeve capable of generating a direct force along the axis of said driving and driven shafts, with a direction that opposes the displacement of said first and second sleeve towards said flange, so as to avoid any involuntary actuation of the coupling, if this is of the normally open type.

Despite the numerous advantages that the invention described in the aforesaid application presents, some drawbacks or aspects remain for certain applications which are not addressed and resolved.

The main limitation is that the clutch device can transmit the total torque only in one direction, that is only from the crankshaft to the driven shaft, in practice according to the winding direction of the helical transmission spring. . Usually this limit is not serious if the organ is used on agricultural machinery such as rotary tillers or rotary cultivators with irreversible worm screw final drive. In fact, in such machines it is difficult to produce the â € œengine brakeâ € effect, ie the phenomenon whereby the driving torque acting on the clutch is not directed from the engine to the transmission, but from this to the engine. If, on the other hand, the clutch is used on wheeled transport vehicles or on two-wheel tractors with non-irreversible worm gear final drive, it may happen that, when going downhill and with heavy loads, the latter may have to give torque to the main motor, but since the engagement organ of the aforementioned patent application is not able to work in a bidirectional way, there cannot be transmission of torque contrary to the motor and the operator is necessarily obliged to use the brakes of the means to decelerate the vehicle itself.

The invention aims to overcome these limits, creating a coupling device particularly suitable for use on mobile vehicles and vehicles in general, which makes it possible to reverse the torque, that is, from the shaft driven towards the € ™ crankshaft; that makes the use of the machines safe for the operators; that it does not cause unwanted activation of the driven shaft; that does not generate friction; which is reliable, simple to build and does not require special maintenance.

These purposes are achieved with a bidirectional clutch member with a helical spring motion transmission mechanism and friction initiation, comprising primary means for transmitting motion from a drive shaft to a driven shaft, where said primary means comprise:

- a first drum associated with a drive shaft;

- a second drum associated with a driven shaft;

wherein said first and second drum have the same external diameter and said driving and driven shafts are coaxial in the direction of a main axis;

- a main transmission helical spring, arranged around said first and second drums, having first and second ends,

where said main helical spring is wound in such a way as to be able to cling to said shafts when it has to transmit a direct torque from the driving shaft to the driven shaft;

- a first sleeve arranged around said spring;

- a second sleeve rotatably associated with the first sleeve;

- a flange associated with said first drum;

- a control lever acting on said second sleeve to move said first and second sleeve towards said flange which is adapted to act as a shoulder for said first and second sleeve;

where the first end of the main helical spring is fixed to the first sleeve and the second end is fixed to the second drum and said first sleeve is slidingly associated with said driven shaft, characterized by the fact that said member comprises secondary motion transmission means from the driven shaft towards the driving shaft, arranged between said driving and driven shafts, able to activate automatically when a direct torque is generated from the driven shaft towards the driving shaft.

According to a first aspect of the invention, said secondary means for transmitting motion from the driven shaft towards the drive shaft comprise a secondary helical spring, arranged astride a third drum associated with said drive shaft and a fourth drum associated with said driven shaft, in which said third and fourth drums have the same diameter, said spring has an internal diameter slightly smaller than that of said third and fourth drums and is wound in the opposite direction to that of the main transmission helical spring.

Preferably the diameter of said third and fourth drums is smaller than that of said first and second drums.

According to a further aspect of the invention, said secondary means for transmitting motion from the driven shaft to the drive shaft comprise a one-way ratchet.

According to a preferred variant, said unidirectional ratchet mechanism comprises a free wheel bearing.

According to an even more preferred variant of the invention, the secondary helical spring comprises a first end fixed to the third drum and a second end fixed to a third sleeve rotatably associated with the fourth drum and said first sleeve comprises a pad with a ring coaxial to said fourth drum, where the displacement of said first sleeve determined by the control lever acting on said second sleeve causes the same displacement of said ring pad which consequently rests on said third sleeve.

According to a further aspect of the invention, said third sleeve comprises a pad made of a material with a high coefficient of friction able to cooperate with said ring pad.

According to another aspect, the connecting means between said first sleeve and said ring plug comprise a plurality of adjusting screw pins adapted to allow adjustment of the distance between said ring plug and said third sleeve.

The invention has numerous advantages:

- since the main transmission helical spring is capable of transmitting only direct torques from the drive shaft to the driven shaft, thanks to the secondary transmission means of direct torques from the driven shaft to the drive shaft, the The clutch can operate in a bidirectional way, allowing the machine in which it is inserted to exploit the â € œengine brakeâ € to absorb such torques contrary to the main drive ones;

- thanks to the fact that the secondary transmission means are activated automatically when a direct torque is generated from the driven shaft to the driving shaft, the user does not have to perform any action to control them;

- thanks to the fact that said secondary transmission means are exclusively of the mechanical type, there is no need for auxiliary electrical command and control systems;

- thanks to the fact that, in a preferred variant of the invention, said secondary transmission means can be selectively deactivated by the operator by acting on the control lever, the transmission of the torque from the driven shaft to the crankshaft can be interrupted or temporarily suspended, for example to prevent the engine from stopping or to allow gear changes;

- thanks to the two distinct mechanisms that transmit the drive torque and the braking torque, it is possible to calibrate, in relation to the constructive characteristics, the two pairs, making them different from the other, with significant benefits in every respect, for example to develop a braking torque greater than the driving torque, etc .;

- thanks to the independence of the two drive and braking torque transmission mechanisms, it would also be possible to delegate the transmission of the main motion, from the drive shaft to the driven shaft, to the secondary spring and vice versa.

The advantages of the invention will be more evident in the following, in which preferred manufacturing methods are described, by way of non-limiting example, and with the help of the figures, where: Figs. 1 and 2 show, in section according to a longitudinal plane, a bidirectional clutch member with a helical spring motion transmission mechanism and friction trigger according to the invention, shown respectively in the opening and closing conditions of the main transmission, but always in conditions of torque transmission from the driven shaft to the crankshaft;

Fig. 3 represents, in section according to a longitudinal plane, a variant of the invention in which the driving and driven shafts are connected by a free wheel bearing;

Fig. 4 shows, in partial cross section, an internal detail of the free wheel bearing of Fig. 3;

Fig. 5 represents, in partial section along a longitudinal plane, a more complex variant of the bidirectional clutch member, illustrated in conditions of non-transmission of motion between the two shafts.

All the figures show a variant of the bidirectional clutch member of the normally closed type.

With reference in particular to Figs. 1-2, a bidirectional clutch member with a helical spring motion transmission mechanism and friction initiation is shown, respectively in the opening and closing conditions of the main transmission system, comprising a first drum 1 associated with a drive shaft 2 and a second drum 3 associated with a driven shaft 4, in which said first and second drums have the same external diameter and said drive and driven shafts are coaxial, that is, they are arranged along the same axis X.

The bidirectional clutch member comprises a main transmission mechanism of a drive torque Cm between the drive shaft 2 and the driven shaft 4, where said main transmission mechanism comprises a helical spring 5 arranged around the two drums 1 and 3, a first sleeve 6 arranged around said spring 5, slidingly associated with said driven shaft 4, a second sleeve 7 rotatably associated with the first sleeve 6, a flange 8 associated with said first drum 1, a control lever 9 acting on said second sleeve 7 to move said first and second sleeves towards said flange 8, in contrast to a resistant elastic force generated by an antagonist spring 18.

The helical spring 5 is made of substantially square section wire and comprises a first end 10 fixed to said first sleeve 6 and a second end 11 fixed to said second drum 3.

The main spring 5 is wound according to the direction of rotation of the crankshaft and is therefore able to tighten by wrapping itself on the drums 1 and 3 when the torque Cm must pass from the crankshaft 2 to the driven shaft 4 Conversely, the spring 5 releases, widening its diameter and moving away from the drums 1 and 3, when a braking torque Cb must pass from the driven shaft 4 to the motor shaft 2.

The first sleeve 6 is rotatably associated with the first drum 1 by effect of a ball bearing 12 interposed between them. Said ball bearing 12 can be omitted if contact is not foreseen between the first sleeve 6 and the first drum 1.

The second sleeve 7 is rotatably associated with the first sleeve 6 by effect of a ball bearing 13 interposed between them.

The flange 8 comprises a shoulder plane 14, to which a pad 15 of material with a high friction coefficient, for example rubber, can be applied, able to cooperate by sliding with a corresponding contact plane 16, facing it, belonging to the first sleeve 6. The planes 14 and 16 form an angle with the X axis which can be approximately 90 °, as illustrated, or of a different amplitude.

Alternatively, the pad 15 can be applied to the contact plane 16.

The control lever 9 is rotatably associated with a fixed pin 17 and is pushed by elastic means 38, so as to be able to transmit a force on the second sleeve 7 directed along the X axis and in a direction such as to cause the displacement of the sleeves 6 and 7 towards flange 8, so as to make the coupling member normally closed. Actuation means 37, contrary to the force exerted by the spring 38, on which the operator can act at his discretion, allow the clutch to be opened.

An antagonist spring 18 is interposed between the second drum 3 and the first sleeve 6, capable of generating said resilient elastic force which opposes the displacement of said first and second sleeve towards said flange 8.

A bearing 19 is interposed between the first drum 1 and the second drum 3, designed to ensure the centering of the components along the main axis X and to allow reciprocal rotation without sliding between the two members when the transmission is open.

The bidirectional clutch member also comprises a secondary transmission mechanism of a braking torque Cb between the driven shaft 4 and the driving shaft 2, where said secondary transmission mechanism comprises, with reference to Figs. 1 and 2, a secondary helical spring 20, a third drum 21 associated with said drive shaft and a fourth drum 22 associated with said driven shaft 4, where said drums 21 and 22 have the same diameter, which is smaller than that of the drums 2 and 3 and are coaxial to them.

The secondary helical spring 20 is arranged astride said drums 21 and 22, has an internal diameter slightly smaller than that of said drums and is therefore always closed on them, but not tightened. Said spring is wound in the opposite direction to that of the main spring 5.

With reference to Figs. 3 and 4, an even more simplified variant of the bidirectional transmission component is illustrated, in which the secondary transmission mechanism comprises mechanical means with unidirectional ratchet mechanism arranged between the driving shaft and the driven shaft.

In the example illustrated, said unidirectional ratchet mechanical means comprise a freewheel bearing 23, replacing the ball bearing 19 arranged between the first drum 1 of the drive shaft 2 and the second drum 3 of the driven shaft 4 , provided with pawls 24 integral with the driven shaft 4 able to cooperate, when the torque Cb passes from the driven shaft 4 to the driving shaft 2, with the teeth of a toothed crown 25 associated with said driving shaft 2.

In particular, the toothed crown 25 is fixed to an extension 26 of the first drum 1 by means of a key 27 and the pawls 24 are hinged on a ring 28, in turn fixed inside the second drum 3 by means of a key 29.

With reference to Fig. 5, a more complex variant of the bidirectional transmission component is shown, which allows to interrupt the torque passage between the driven shaft and the crankshaft.

This variant comprises, in addition to the components already illustrated by describing Figs. 1 and 2, a third sleeve 30 rotatably associated with the fourth drum 22 and a ring pad 31 fixed to the first sleeve 6 and slidingly associated with the fourth drum 22. The secondary spring 20 comprises a first end 32 stably associated with the third drum 21 and a second end 33 stably associated with the third sleeve 30.

The third sleeve 30 comprises a pad 34 made of a material with a high friction coefficient, facing said ring pad 31 and able to cooperate with it to be driven in rotation.

Alternatively, the pad 34 can be associated with the ring pad 31.

The ring plug 31 is associated with the first sleeve 6 by means of a plurality of screw pins 35, which slide freely in corresponding holes 36 present on the drum 3.

These screw pins 35 also act as a register to allow to adjust the distance S between said ring pad 31 and said pad 34, so that it is equal to the distance S between the surfaces that must come into contact with the pad 15 and the surface 16 .

The correct adjustment of the distance S allows that, with a single movement of the second sleeve 7 by means of the control lever 9, simultaneous contact is caused between the pad 15 and the contact plane 16 and between the ring pad 31 and the pad 34 .

In the case of a bidirectional coupling member with a helical spring motion transmission mechanism and friction trigger, of the normally closed type, such as the one illustrated, in addition to including all the components already described above and with the same functions, a mechanism comprising a closing spring 38 acting continuously on the control lever 9, with a force greater than that given by the sum between the force exerted by the antagonist spring 18 and the minimum necessary to trigger the organ itself, so to keep the flange 8 and the first sleeve 6 in constant contact with each other, ensuring a continuous grip to the transmission member itself.

The operator can act with external means 37, for example of the pedal type, so as to transmit on the lever 9 a traction force which, opposing the force generated by the closing spring 38, can cause the separation between the flange 8 and the first sleeve 6, and the consequent disengagement of the transmission member.

Also in this variant of the invention the external force to be applied to defuse the transmission element can be very small and in practice independent of the force transmitted between the two shafts. The operation of the grafting organ is as follows.

Reference will first be made to the variants illustrated in Figs. 1 and 2.

In the case of normally open engagement and transmission of the torque Cm from the crankshaft 2 to the driven shaft 4, when the engine is started, the drum 1, connected to the crankshaft 2, starts rotating together with the flange 8, while the drum 3, the driven shaft 4, the spring 5, the first sleeve 6, the second sleeve 7 and the components connected thereto remain stationary. The helical spring 20, closed on the drums 21 and 22, crawls thereon, but without clinging to them, due to the winding direction of the selected coils. When a suitable force is exerted on the second sleeve 7 with the control lever 9, parallel to the direction of the rotation axis X, i.e. such as to overcome the resisting force represented by the elastic force developed by the antagonist spring 18, a axial displacement of the first sleeve 6 until the contact plane 16 touches the plug 15 possibly associated with the shoulder plane 14 of the flange 8.

Since the flange 8 is in continuous rotation together with the motor shaft 2, it tends to drag the first sleeve 6 into rotation due to the friction force generated between the plug 15 and the thrust plane 16. The rotation of the first sleeve 6 causes the rotation of the first end 10 of the helical spring 5, which consequently closes by tightening between its coils the two drums of the same external diameter 1 and 3, since the winding direction of the spring 5 is in agreement with the direction of rotation of the crankshaft 2.

The closure thus obtained makes the drive shaft 2 and the driven shaft 4 integral and forces them to rotate with the same angular speed, in a transitory time that depends on the load acting on the driven shaft 4 and on the geometric characteristics and of the materials of the spring 5, of the drums 1 and 3, of the pad 15, of the thrust surface 16, etc.

At the end of the transitional period, also the spring 20 will rotate in unison with the two shafts 2 and 4, no longer crawling on the drums 21 and 22.

The freewheel bearing 23 of the variant illustrated in Figs behaves in the same way. 3 and 4. In the initial transitory the harpoons 24 will jump on the teeth of the ring gear 25, then they will rotate in unison with it.

When the control lever 9 no longer exerts any thrust force on the second sleeve 7, the thrust surface 16 detaches from the pad 15, thanks also to the elastic return force generated by the antagonist spring 18, the helical spring 5 tends to widen again and thus making the rotation of the drive shaft 2 independent from the driven shaft 4, which will stop in a short time only when there is no longer any braking torque Cb, when the secondary spring 20 will be able to release the drums 21 again and 22. The peculiarity of the clutch member lies in the fact that the tangential force T0 necessary to close the spring 20 around the two drums 21 and 22, that is, the one necessary to cause the activation of the secondary transmission mechanism, It is very low and the friction between the spring 20 and the drum 22 is sufficient to generate it.

The force T0 to be exerted at the first end of the spring 20, which is equal to the trigger force, is expressed by the following formula:

T = Ï „M

where:

T0Ã is the trigger force;

TMÃ is the maximum force acting on the central coil of the spring 20; f is the friction coefficient between the internal surface of the spring 20 and the external surface of the drum 22 (if both are made of iron, it is approximately 0.2);

n is the number of coils counted by the central one.

Observing the formula, it is evident that the more coils separate the central coil of the spring 20 from its periphery, the less force will be required to operate the secondary clutch transmission mechanism, because the value of the forces acting on the individual coils decreases. from the center towards the periphery with exponential law, and this force To can be enormously lower than that TM which determines the value of the torque Cb to be transmitted.

In the case of a normally closed clutch, such as that illustrated in Figs. 1-5, the organ acts like any clutch of a mechanical transmission between rotating shafts, in which the driven shaft is always rotating in unison with the crankshaft.

If the two shafts must be disconnected, for example to stop the vehicle, or to change gear, or to cut power from the work tools, it is sufficient to exert adequate force on the control lever 9, through the external actuation means 37. to overcome the opposite elastic forces of the elastic means 38, so as to cause the detachment of the first sleeve 6 from the flange 8 and the consequent disengagement of the clutch member.

In the case of open or closed engagement and transmission of a braking torque Cbd from the driven shaft 4 to the motor shaft 2, in the initial transient the driven shaft 4 tends to rotate with an angular speed greater than that of the motor shaft 2. This circumstance causes the onset of a friction force To on the end of the secondary spring 20 associated with the drum 22 which determines the tightening of the spring itself on the drums 22 and 23 allowing, at the end of the transitory, the rotation to the € ™ unison of trees 4 and 2 and the transfer of the couple Cb between them. Thanks to the opposite winding of the spring 20 with respect to the main spring 5, the same transient which allows the spring 20 to entangle the drums 21 and 22, allows the spring 5 to open, releasing the members belonging to the main transmission mechanism.

Similarly, in the variant illustrated in Figs. 3 and 4, the free wheel bearing 23, during the initial transient transfer of the braking torque Cb, immediately engages thanks to the pawls 24 which engage the teeth of the toothed wheel 25, allowing the immediate transfer of the torque.

Referring now to the variant illustrated in Fig. 5, the operation is as follows.

When starting the crankshaft everything works as already described for the other variants of the invention.

In the case of normally open transmission, not shown, when the operator acts on the control lever 9 to determine the closure of the clutch, in addition to the movement of the transmission components connected to the main spring 5, it also causes contact between the ring buffer 31 and the buffer 34 associated with the third sleeve 30, preparing the secondary spring 20 to intervene, should a braking torque Cb be transferred between the driven shaft 4 and the drive shaft 2.

In particular, due to the effect of the connections between the ends 32 and 33 of the secondary spring 20 with the third drum 21 and the third sleeve 30, the spring itself rotates in unison with the same angular speed as the drive shaft.

In summary, the rotation of the drive shaft 2 also drives the secondary spring 20 into rotation, which in turn drives the third sleeve 30 into rotation.

When the ring pad 31 which is initially stationary, joins the friction pad 34 which rotates like the crankshaft 2, the secondary spring 20 is triggered and remains adherent, but only adherent, to the third drum 21 of the drive shaft 2 and to the fourth drum 22 of the driven shaft 4.

This occurs simultaneously with the tightening of the main spring 5 on the first drum 1 and on the second drum 3, which therefore causes the transmission of motion and rotation at the same angular speed of the drive shaft 2 and of the driven shaft 4, but also of the whole group associated with the secondary spring 20.

As long as the motor transmits torque to the driven shaft, the main spring 5 works and the secondary spring 20 - it does not transmit any torque, but when the direction of the torque is reversed, that is, it passes from the driven shaft to the Crankshaft, then the secondary spring tightens on the third and fourth drums, causing the transmission of a torque from the driven shaft to the crankshaft (engine brake).

If the control lever 9 ceases to act on the second sleeve 7, everything stops and the two springs 5 and 20 are again released from their respective drums, no longer transmitting any torque in any direction.

Similar considerations, mutatis mutandis, are valid in the case of normally closed coupling and transmission, just like the case illustrated in Fig. 5.

As is evident to those skilled in the art, the invention has been described with reference, by way of example, to operating machines and moving vehicles, but it can be used in all those applications where a normally open clutch member is required. or normally closed, easy to operate, always achieving the advantages highlighted above.

Naturally, the details of construction and the embodiments may be widely varied with respect to what has been described and illustrated, without thereby departing from the scope of the present invention, as described,

Claims (10)

CLAIMS 1. Bidirectional clutch member with helical spring motion transmission mechanism and friction initiation, comprising primary means for transmitting motion from a drive shaft to a driven shaft, where said primary means comprise: - a first drum (1) associated with a drive shaft (2); - a second drum (3) associated with a driven shaft (4); in which said first and said second drum (1, 3) have the same external diameter and said drive shafts (2) and driven (4) are coaxial in the direction of a main axis (X); - a main helical transmission spring (5), arranged around said first and second drums (1, 3), having first and second ends (10, 11), where said main helical spring (5) is wound in such a way as to be able to cling to said shafts when it has to transmit a torque Cmdirect from the motor shaft (2) to the driven shaft (4); - a first sleeve (6) arranged around said spring (5); - a second sleeve (7) rotatably associated with the first sleeve (6); - a flange (8) associated with said first drum (1); - a control lever (9) acting on said second sleeve (7) to move said first and second sleeves (6, 7) towards said flange (8) which is adapted to act as a shoulder for said first and second sleeves (6 , 7); where the first end (10) of the main helical spring (5) is fixed to the first sleeve (6) and the second end (11) is fixed to the second drum (3) and said first sleeve (6) is slidingly associated to said driven shaft (4), characterized in that said member comprises secondary means (20, 23) for transmitting motion from the driven shaft (4) to the drive shaft (2), arranged between said drive shafts ( 2) and driven shaft (4), able to activate automatically when a direct torque is generated from the driven shaft (4) towards the motor shaft (2). 2. Clutch member according to claim 1, characterized in that said secondary means for transmitting motion from the driven shaft (4) towards the drive shaft (2) comprise a secondary helical spring (20), arranged astride between a third drum (21) associated with said drive shaft (2) and a fourth drum (22) associated with said driven shaft (4), in which said third and fourth drums (21, 22) have the same diameter, said spring (20) has an internal diameter slightly smaller than that of said third and fourth drums and is wound in the opposite direction to that of the main transmission helical spring (5). 3. Clutch member according to claim 2, characterized in that the diameter of said third and fourth drums (21, 22) is smaller than that of said first and second drums (1, 3). 4. Clutch member according to claim 1, characterized in that said secondary means for transmitting motion from the driven shaft (4) towards the drive shaft (2) comprise a unidirectional ratchet. 5. Clutch member according to claim 4, characterized in that said unidirectional ratchet comprises a freewheel bearing (23). 6. Clutch member according to claim 5, characterized in that said freewheel bearing (23) comprises pawls (24) associated with the driven shaft (4) and a toothed wheel (25) associated with the crankshaft ( 2). 7. Clutch member according to claim 2, characterized in that the secondary coil spring (20) comprises a first end (32) fixed to the third drum (21) and a second end (33) fixed to a third sleeve (30) rotatably associated with the fourth drum (22) and said first sleeve (6) comprises a ring pad (31) coaxial to said fourth drum (22), where the movement of said first sleeve (6) is determined by the control lever (9) which acts on said second sleeve (7) causes the same displacement of said ring plug (31) which consequently rests on said third sleeve (30). 8. Coupling member according to claim 7, characterized in that said third sleeve (30) comprises a pad (34) made of a material with a high friction coefficient, adapted to cooperate with said ring pad (31). 9. Coupling member according to claim 7, characterized in that the connection between said first sleeve (6) and said ring plug (31) comprises a plurality of screw pins (35) acting as adjusting means suitable for allowing the adjusting the distance between said ring pad (31) and said third sleeve (30). 10. Machine characterized in that it comprises a bidirectional clutch member according to at least one of the preceding claims.