GB2524392A

GB2524392A - A manual transmission

Info

Publication number: GB2524392A
Application number: GB1502555.4A
Authority: GB
Inventors: Olaf Heldmann
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2014-03-10
Filing date: 2015-02-16
Publication date: 2015-09-23
Also published as: CN104913049B; CN104913049A; DE102014003238A1; GB201502555D0

Abstract

A manual dual clutch transmission comprises a first shaft 25, at least one first idler gear 29, 30 and a first selector sleeve 31 movable between a first gear position coupling the first idler gear 30 to the shaft 25 and a neutral position permitting rotation of the idler gear 30 relative to the shaft 25. A first cam follower 58 moves the first selector sleeve 31 along the shaft 25. A first selector shaft 39 is displaceable for displacing the cam follower 58 in the direction of the shaft 25 and carries a first coupling body 41 which is rotatable about a longitudinal axis 40 of the selector shaft 39 between an active position acting on the cam follower 58 and a passive position decoupled from the cam follower 58. Selector shaft 39 is displaced by a grooved cam 67 which is rotated by an actuator 47. The cam 67 moves a pin 44 engaged with a sleeve 56 that is fixed the selector shaft 39. A second selector shaft 38 may displace the cam follower 58 from neutral to a second gear position.

Description

s A manual transmission

Description

The present invention relates to a manual transmission, especially a manual transmission with a twin clutch, as known for example from US2008/O1 3481 9A1.

Manual transmissions comprise several pairs of mutually meshing is gears, wherein at least one gear wheel of each pair is arranged as an idler gear, which can be coupled by means of a selector sleeve in an interlocking fashion to a shaft that carries said gear in order to produce a torque flow by the respective pair of gears between the drive and output of the transmission. In order to provide sev- eral gears in a manual transmission, several pairs of gears and accordingly general- ly also several selector sleeves are required which need to be independently mova- ble from each other. The actuators required for driving the movements of the vari-ous selector sleeves require installation space which makes the transmission bulky in its entirety.

The initially cited document US200B/0134819A1 proposes the control of the movement of two selector sleeves mounted on the same shaft by means of a selector drum. The selector drum carries two control coulisses on its circumference, which cooperate with a cam follower acting on a respective one of the selector sleeves. The ascending gradient of the coulisses relative to the rotational axis of the drum determines the extent and the direction of the movement of the cam followers produced by a rotation of the drum. Different progressions of the coulisses allow different movements of the two cam followers associated therewith. Although a drum is capable of controlling the movements of two selector sleeves, independ-ence of the movements with respect to each other cannot be achieved because the possible movements are fixedly predetermined in each point of the drum and it is only possible to choose the direction of rotation. Since all required combinations of the positions of the selector sleeves need to be reflected in the progression of the coulisses and the ascending gradient of the coulisses must not be excessively large in order to prevent self-inhibition, the need for space of this conventional shifting control mechanism is considerable.

It is an object of the present invention to provide a manual transmis- sion which allows mutually independent control of selector sleeves with a space-saving mechanism.

This object is achieved by an embodiment of the invention in such a way that in a manual transmission with -afirstshaft, -at least one first idler gear carried by the first shaft, -a first selector sleeve which is movable along first shaft between a first gear is position coupling the first idler gear to the first shaft and a neutral position permitting a rotation of the idler gear against the first shaft, -a first cam follower which acts on the first selector sleeve for the movement of the first selector sleeve along first shaft; a first selector shaft is displaceable in the direction of the shaft for the displacement of the first cam follower and carries a first coupling body which is rotatable about a longitudinal axis of the first selector shaft between an active position acting on the first cam follower and a passive position decoupled from the first cam follower.

As will be explained below in closer detail, the possibility is provided by the selective coupling capability of the first cam follower to the first selector shaft that a further cam follower is controlled by means of the first selector shaft without entraining the first cam follower, or that the first cam follower is coupled to a second selector shaft and is thus adjusted without simultaneously forcing a movement of the first selector shaft.

The first selector sleeve can further be movable from the neutral po-sition to a gear position which couples a second idler gear to the shaft.

The first coupling body can be a finger which is rigidly connected to the first selector shaft and is therefore jointly rotatable therewith about the longitudi-nal axis of the first selector shaft.

In order to enable a movement of the first coupling body between ac-tive and passive position and to allow the additional axial adjustment of the first coupling body, the first selector shaft can be rotatably mounted in a sleeve and be retained axially in a non-movable manner against the sleeve.

A coulisse and a cam engaging in the coulisse can be distributed on the sleeve and a drum surrounding the sleeve in order to convert a rotation of the drum into a displacement of the first selector shaft and to thus adjust the first selec-tor shaft between neutral position and first gear position.

For the purpose of displacing the selector shaft, the coulisse should comprise at least one section extending on a helical trajectory.

In particular, a section extending on such a helical trajectory can co- operate with the cam when the selector sleeve is situated between the neutral posi-tion and the gear position.

A position of the cam in which the selector sleeve is situated in the neutral position can be situated in the middle of section extending on the helical trajectory. In this case, the rotation of coulisse and cam relative to each other allows a displacement of the selector sleeve from the neutral position to two mutually op-posite gear positions.

Alternatively, the neutral position of the sleeve can also correspond to a position of the cam at an end of the section extending on the helical trajectory. A coulisse section which is adjacent to this end and extends in the circumferential direction allows a relative rotation of coulisse and cam which leaves the selector sleeve in the neutral position.

The cam can also be situated in a section of the coulisse extending in the circumferential direction when the selector sleeve assumes the gear position.

This reduces the requirements placed on the precision of the control of a rotation of the coulisse on the one hand since the gear position will also be reached exactly when the rotation of the coulisse is not controlled precisely. On the other hand, the section extending in the circumferential direction allows a drive of the coulisse to continue to run even after reaching the gear position. As a result, a single servomo-tor can both drive the relative rotation of cam and coulisse as well as an opening and closing movement of a friction dutch when the selector sleeve is in the gear position.

According to a further development, the manual transmission com-prises a second selector shaft which is displaceable for the displacement of the first cam follower in the direction of the shaft and carries a second coupling body which is rotatable about a long itudinal axis of the second selector shaft between an active position acting on the first cam follower and a passive position which is decoupled from the first cam follower. Such a further development is especially appropriate in the case of a twin-clutch transmission in order to enable the coupling of the move-ment of the first cam follower in a selective manner by means of the first selector shaft to a first friction clutch or by means of the second selector shaft to a second friction clutch.

The two selector shafts can respectively be displaceable from the neutral positions in two opposite directions without obstructing each other.

In the case of such a twin-clutch transmission, the first friction clutch can connect a first main shaft to a drive shaft and a second friction clutch can con-nect a second main shaft to the drive shaft, and the first main shaft is coupled to an output shaft in the first gear position, whereas the second main shaft is coupled to the output shaft in the second gear rosiion.

Since each gear can generally only be realized via one of the two main shafts in a twin-clutch transmission, the freedom of movement of the second selector shaft can be dimensioned in order to displace the first cam follower be-tween the neutral position and the second gear position, whereas the freedom of movement of the first selector shaft is dimensioned in order to displace the first cam follower between the neutral position and the first gear position.

Although the selector shafts should be axially movable relative to each other in order to enable the respective control of the positions of the cam fol-lowers independently from each other. At the same time, they can be connected in a torsion-proof manner to each other in order to ensure that both coupling bodies are not simultaneously in engagement with a cam follower and can exert opposite actuating forces on said cam follower.

On the other hand, there can be at least one shifting position in which s both coupling bodies are in engagement with different cam followers. As a result, a change of load can occur from one main shaft to the other without having to twist the selector shafts for this purpose. In the case of a six-gear transmission such a change of load can especially correspond to the transition between the third and fourth gear.

A further shifting position in which both coupling bodies are in en-gagement with different cam followers can correspond to the first and the sixth In a compact and simultaneously sturdy embodiment of the transmis-sion, the first selector shaft is hollow and the second selector shaft engages in the first selector shaft. It is thus ensured in a simple manner that the two selector shafts are aligned coaxially.

The first cam follower can comprise a first passage in which the first coupling body acts in an active position, and a second passage in which the second coupling body acts in its active position. The two engagement contours can be es-pecially spaced in the axial direction of the selector shafts in order to prevent any Impairment in the freedom of movement of one of the selector shafts by the en-gagement of the other selector shaft on the first cam follower.

At least the first coupling body can further comprise a second active position in which it acts on a second cam follower. The coupling body can thus be used according to its position in order to engage different gears of the transmission.

Further features and advantages of the invention are provided in the following description of embodiments by reference to the enclosed drawings, where-in: Fig. 1 shows a schematic view of a manual transmission ac-cording to a first embodiment of the invention in the neutral position; Fig. 2 shows a selector shaft control mechanism of the man-ual transmission of Fig. 1 in a perspective view; Fig. 3 shows the selector shaft control mechanism of Fig. 2 in an axial sectional view; Fig. 4 shows a selector shaft control mechanism of the man-ual transmission of Fig. 1 in the neutral position with preselected first gear; Fig. 5 shows the control mechanism with engaged first gear; Fig. 6 shows the control mechanism with engaged first and preselected second gear; Fig. 7 shows The control mechanism after the engagement of the second gear, with still preselected first gear: Fig. 8 shows the control mechanism with engaged second gear, after cancelling the preselection of the first gear: Fig. 9 shows a preparatory step for the engagement of the third gear; Fig. 10 shows the control mechanism with preselected third gear; Fig. 11 shows the control mechanism in disengaging the sec-ond gear; Fig. 12 shows the control mechanism with engaged third gear; Fig. 13 shows the control mechanism with engaged third and preselected fourth gear; Fig. 14 shows the control mechanism with engaged fourth and still preselected third gear; Fig. 15 shows the control mechanism with engaged fourth gear and no longer preselected third gear; Fig. 16 shows the control mechanism with engaged fifth and still preselected fourth gear; to Fig. 17 shows the control mechanism after the cancellation of the preselection of the fourth gear; Fig. 18 shows the control mechanism with engaged sixth gear, and Fig. 19 shows the control mechanism prepared for engaging the reverse gear.

Fig. I shows a schematic view of a manual transmission according to a first embodiment of the invention. A drive shaft 1 carries two hollow shafts 2, 3 which are equipped with gear wheels 4, 5 and 6, 7. The hollow shafts 2, 3 can re-spectively be coupled by a friction clutch 8 and 9 in a friction-locked manner to the drive shaft 1. A selector shaft 10 and 11 is respectively mounted in a torsion-proof and axially adjustable manner on the two hollow shafts 2, 3. The selector sleeves 10, 11 which rotate with the hollow shafts 2, 3 are respectively surrounded by a ring 12, which is torsion-proof with respect to a housing (not shown) but axially movable.

The ring 12 is surrounded on its part by a gear wheel 13 which is coaxial to the drive shaft 1. The gear wheel 13 is rotatable about the ring 12 and engages by means of a pin 14 in a groove of the ring 12. Balls 15 are retained in boreholes of the gear wheel 13. The balls 15 respectively touch a ramp 16 fixed to the housing of the manual transmission on the one hard and an axially movable ring 17 on the other hand which extends about a respective one of the hollow shafts 2, 3 and which is supported via a roller bearing 18 on plates 19 of the friction clutch 8 or 9 on the side of the hollow shafts.

Fig. 1 shows the gear wheel 13 in a neutral position, from which it is adjustable in opposite directions. During each rotation of the gear wheel 13 from the neutral position, it passes an angular interval at first in which the balls 15 are not deflected from the ramp 16 in the axial direction. When leaving this angular interval, the balls 15 are pressed by the ramp 16 against the plates 19 and push them in frictionally engaged contact with plates 20 of the friction clutches 8 and 9 on the side of the drive shaft.

The groove of the ring 12 extends in the circumferential direction in a first direction of rotation starting from a neutral position, so that the frictional clutch 8 and 9 will close upon rotation of the gear wheel 13 in said first direction after leaving the aforementioned angular interval, without the ring 12 and the selector sleeve 10 or 11 which is controlled by said ring moving axially. In the opposite second direc-tion of rotation, the groove extends at first in a helical manner, so that the selector sleeve 10 and 11 is axially displaced by a rotation of the ring 12 from the neutral position in said second direction. In a manner that is known from conventional lock-ing synchromesh devices, the selector sleeve 10 and 11 strikes a synchronized disc 21 at first and brings the same into frictional contact with a gear wheel 22 and 23 in order to engage in a selector toothing 24 of the gear wheel 22, 23 when it is syn- chronized with the hollow shaft 2 and 3 and to thus couple it in a torsion-proof man-ner to the hollow shaft 2 and 3. Once the selector sleeve 10 or 11 has engaged in the selector toothing 24, the pin reaches a further section of the groove extending in the circumferential direction, so that the selector sleeve 10 or 11 is no longer dis-placed any further when the baIls 15 reach the ascending section of the ramp 16 and begin to deflect the plates 19.

The transmission comprises two auxiliary shafts 25, 26. The auxiliary shaft 25 carries a fixed gear 27 which meshes with the gear wheel 22, a fixed gear 28 which meshes with the gear wheel 23, and idler gear 29 which meshes with the gear wheel 5, and an idler gear 30 which meshes with the gear wheel 7, a selector sleeve 31 which is displaceable in opposite directions from its neutral position shown in Fig. 1 in order to respectively couple the idler gear 29 and the idler gear in a torsion-proof manner to the auxiliary shaft 25, and an output pinion 32. The auxiliary shaft 26 carries an idler gear 33 which meshes with the gear wheel 4, and an idler gear 34 which meshes with the gear wheel 6, a selector sleeve 35 which is displaceable in opposite directions from the neutral position shown in Fig. 1 in order to respectively couple one of the idler gears 33, 34 in a torsion-proof manner to the auxiliary shaft 26, and an output pinion 36. Both output pinions 32, 36 mesh with a differential gear (not shown in Fig. 1).

S A control mechanism 37 is highlighted in Fig. 1 from the aforemen-tioned components of the manual transmission for better clarity of the illustration and is shown in Fig. 2 in a perspective view. The control mechanism 37 comprises two selector shafts 38, 39 which are aligned along the same longitudinal axis 40 parallel to the shaft 1, 25, 26 and which are rotatably mounted about the axis 40.

Fig. 3 shows the control mechanism 37 in a sectional view along the axis 40.

In the case of the embodiment that is considered here by way of ex-ample, the selector shaft 39 is a hollow shaft which extends in the direction of axis only over a part of the control mechanism 37 and in which the selector shaft 38 formed as a solid shaft is accommodated. Alternatively, the two selector shafts can also be over-mounted on one side, or two hollow shaft can be concerned which are slid onto a common carrier.

Each selector shaft 38, 39 carries one or two radially protruding cou-pling bodies which are designated here as selector fingers 41, 42, 43. In Fig. 1, a selector finger 41 of the selector shaft 38 is shown in engagement with a cam fol-lower 58, which is rigidly connected to a selector fork 62 acting on the selector sleeve 31. A second cam follower 52 is connected to a selector fork 57 acting on the selector sleeve 35.

The selector shafts 38, 39 are not twistable relative to each other, but are movable relative to each other along the axis 40. For this purpose, a pin an-chored on the selector shaft 39 can engage in a longitudinal groove of the selector shaft 38.

The cam followers 52, 58 are substantially plate-shaped with a nar- row side facing the axis 40, in which two sections 53 are formed, i.e. one for ac-commodating the selector fingers 41, 42 of the selector shaft 38 and the other for accommodating the selector finger 43 of the selector shaft 39. A further cam follow-er 54 with a single section 53 can be arranged in order to also accommodate the selector finger 43.

The two selector fingers 41, 42 span a different angle with respect to the axis 40 than the selector forks 52, 58, so that the two never engage simultane-ously in the selector forks 52, 58.

The selector shafts 38, 39 are respectively surrounded by shift sleeves 55 and 56, which are arranged in a torsion-proof manner with respect to a housing of the transmission (not shown). In order to prevent rotation of the shift sleeves 55, 56, but to simultaneously allow a translators' motion along the axis 40, the shift sleeves 55, 56 are respectively provided with one longitudinal groove 61 (only shown for the shift sleeve 56 in Fig. 2) into which a finger 63 engages which is fixedly attached to the housing. Several fingers 64 of the shift sleeves 55, 56, which fingers are directed radially to the inside, engage in a circumferential groove 65 of the selector shaft 38 and 39 (see Fig. 1) in order to transmit a translators' motion of the shift sleeves 55, 56 onto the selector shafts 38. 39, but to simultaneously permit a rotation of the selector shafts 38, 39 about the axis 40.

A coulisse 46, which is attached to the shifi sleeves 55, 56 and is al-so arranged in this case as a groove respectively comprises a helical section 51 and, on both ends of the helical section 51, sections 49, 50 extending in the circum-ferential direction around the axis 40. In Fig. 2, the coulisses 46 are mostly hidden in the drums 66 and 67, which respectively carry a cam 44 which cooperates in an interlocking fashion with the coulisse 46. The drums 66, 67 are axially immobile, but are rotatable about the axis 40 by engagement of a respective one of a threaded screw 48 driven by a servomotor 47 on a gear wheel 45 which is connected in a torsion-proof manner to the drum 66 and 67. The side walls of the drums 66, 67 are cut out over a large area in order to allow the finger 63 to pass through without im-pairing the rotation of the drums 66, 67.

In the illustration of Fig. 1, the transmission is idling, and the hollow shafts 2, 3 are twistable against the drive shaft I and the idler gears 29, 30 and 33, 34 are twistable against the auxiliary shafts 25 and 26. In order to engage a first gear in the transmission, a torque flow must be produced from the drive shaft 1 to the differential gear via the gears 5, 29. The left servomotor 47 is actuated for this purpose in a first step in order to twist the left gear wheel 45 that meshes therewith in such a way that the cam 44 on the left drum 66 passes through the helical section 51 of the coulisse 46 and displaces the selector shaft 38 along the axis 40 to the left. The selector finger 41 entrains the selector sleeve 31 via the cam follower 58 and thus couples the idler gear 29 to the auxiliary shaft 25. Fig. 4 shows the result-ing configuration of the control mechanism 37 partly in a top view in the direction of the two cams 44 (wherein the portion of the drums 66, 67 that carries the cams 44 is cut away in order to show the coulisse 46), and partly in a sectional view in the plains of the cam followers 52, 58.

The selector sleeve 31 and the coupling of the idler gear 29 to the auxiliary shaft 25 produced by the displacement of said sleeve are not shown in Fig. 4 because they are based on the locking synchromesh principle which is known to the person skilled in the art. A synchronized disc 21 conventionally blocks the ad- vancement of the selector sleeve 31 for such a time until the idler gear 29 is syn- chronized by friction with the auxiliary shaft 25. The cam 44 can advance to the p0-Is sition shown in Fig. 4 only when the synchronized disc 21 releases the path to the selector sleeve 31 in order to latch into the idler gear 29.

The left gear wheel 13 is also twisted out of its neutral position to-gether with the left gear wheel 45, but not to such an extent that there is an axial displacement of the balls 15 caught in the gear wheel 13. The friction clutch 8 is therefore still open. Although the selector sleeve 31 is latched into the idler gear 29 in an interlocking manner, no torque is yet transmitted.

As a result of a further rotation of the left servomotor 47, the cam 44 (as shown in Fig. 5) reaches the section 50 of the coulisse 46. While the cam 44 passes through the section 50, the left gear wheel 13 also continues to rotate, and its balls 15 are axially deflected on the ramp 16. As a result, the plates 19, 20 of the left friction clutch 8 are gradually pressed against each other, the friction clutch 8 closes, and the torque flow in the first gear is established. The contact of the plates 19, 20 defines a stop position shortly before the cam 44 reaches the end of the sec-tion 50, beyond which the cam 44 cannot advance.

In order to shift to the second gear! the right servomotor 47 is acti-vated. It twists the right gear wheel 45, so that the cam 44 of the drum 67 passes through the section 49 of the coulisse 46. Since the section 49 extends in the cir- cumferential direction, the actuating rod 39 is not moved by the rotation. In the posi- tion as shown in Fig. 6, the rotation of the co-rotating right gear wheel 13 has pro-gressed to such an extent that its balls 15 are slightly axially deflected and the plates 191 20 of the friction clutch 9 begin to touch each other.

While the right gear wheel 45 is twisted beyond the position as shown in Fig. 6 until the cam 44 reaches a stop close to the end of the section 49 and closes the clutch 9, the left gear wheel 45 is simultaneously rotated in the opposite direction, so that the cam 44 of the drum 66 returns to the boundary between the sections 50, 51. In this state shown in Fig. 7, the torque flows in the second gear via the gear wheel 23 and the fixed wheel 28, and the clutch 8 is open again. The first gear is still preselected.

If the left gear wheel 45 (as shown in Fig. 8) is twisted further back, the cam 44 passes through the section 51 again, the selector shaft 38 returns to its is position shown in Fig. 1, and the selector sleeve 31 is situated in its neutral position again between the idler gears 29, 30. The preselection of the first gear is thus can-celled. The position of the right gear wheel 45 does not change in the meantime so that the second gear is still engaged in Fig. 8.

In Fig. 9, the selector shafts 38, 39 are twisted about the axis 40, so that the selector finger 41 engages at nothing and instead the selector finger 43 of the selector shaft 39 engages in the cam follower 58 and the selector finger 42 of the selector shaft 38 engages in the cam follower 52.

A renewed forward rotation of the left gear wheel 45 in which the cam 44 (as shown in Fig. 10) passes through the helical section 51 again produces an axial displacement of the left selector shaft 38, but in this case the cam follower 52 and the selector sleeve 35 which is coupled thereto via the selector fork 57 are en-trained on the auxitiary shaft 26 and brought into interlocking engagement on the idler gear 33. The third gear is thus preselected. It has not yet been engaged since the friction clutch 9 is still closed and the friction clutch 8 is still open.

In order to engage the third gear (as shown in Fig. 11), the right gear wheel 45 is twisted back to the initial position already shown in Fig. 1 in which the right friction clutch 9 is open, while simultaneously the left friction clutch 8 is closed by twisting of the left gear wheel 45 up to the stop position close to the end of the section 50.

The position of the left gear wheel 45 is unchanged in Fig. 12, so that the friction clutch 8 remains closed and the third gear is engaged. The cam 44 is again situated at the boundary between the sections 49, 51 on the right gear wheel 45.

The cam 44 is moved;through the section 51 in Fig. 13 by further ro-tation of the right gear wheel 45, and the selector shaft 39 is deflected to the right.

The cam follower 58 which is coupled thereto by the selector finger 43 is deflected to the right with said shaft, and the selector sleeve 31 is in interlocking engagement with the gear wheel 30.

In order to engage the fourth gear, the friction clutch 9 needs to be is closed and the friction clutch 8 needs to be opened. This occurs again by twisting of the mutually coupled gear wheels 45, 13 on the left and right side of the transmis-sion, so that (as shown in Fig. 14) the right cam 44 reaches the stop position close to the end of section 50, while the left cam 44 is situated on the boundary between the sections 50, 51.

In Fig. 15, the left gear wheel 45 is further twisted back, so that the left cam 44 is situated between the sections 49, 51 again and the cam follower 52 coupled to the left selector shaft 38 is situated in the neutral position again. The fourth gear is engaged and the preselection of the third gear is cancelled.

Fig. 16 shows the right gear wheel 45 rotated to a position again in which the friction clutch 9 is open, while the cam 44 is situated on the left gear wheel 45 on a limit stop close to an end of the section 49. The friction clutch 8 is closed in this position and the selector sleeve 10 couples the hollow shaft 2 to the gear wheel 22 so that a fifth gear is engaged in which the torque flow extends via the gear wheel 22 to the fixed gear 27 of the auxiliary shaft 25.

In Fig. 17, the left gear wheel 45 continues to remain in the stop posi-tion in which the friction clutch 8 is closed, while the cam 44 is again situated on the right gear wheel 45 between the sections 49, 51 and the cam follower 58 holds the selector sleeve 31 in its neutral position so that the preselection of the fourth gear is cancelled.

In order to engage the sixth gear, the selector shafts 38, 39 are s twisted at first again about the longitudinal axis 40, so that the selector finger 41 on the cam follower 58 and the selector finger 43 on the cam follower 52 engage again. The state shown in Fig. 18 in which the sixth gear is engaged is subsequent-ly reached by the rotation of the right gear wheel 45 until the cam 44 reaches the stop of the section 50 with simultaneously opening of the friction clutch 8. The torque flow extends via the gear wheels 6 and 34 to the auxiliary shaft 26.

In Fig. 19, the selector shafts 38. 39 are twisted in such a way that the selector finger 43 engages in a third cam follower 54. The selector forks 52, 58 are empty. As is shown in Fig. 1, the cam follower 54 controls a selector sleeve 74 engaging in reverse gear. This selector sleeve 70 (as shown in Fig. 1) can be ar-ranged on a further auxiliary shaft 71, which carries an idler gear 72 to be coupled by the selector sleeve 70 and a further output pinion 73 meshing with the differential gear. The idler gear 72 meshes with an idler gear 74 on the auxiliary shaft 26, and the idler gear 72 meshes on its part with the gear wheel 7 on the hollow shaft 3. The selector sleeve 70 is pulled from its neutral position to the right by a rotation of the right drum 67 until the cam 44 is situated at the transition point between the sec-tions 50, 51 of the coulisse 46, and the idler gear 72 is coupled to the auxiliary shaft so that the reverse gear is preselected. The friction clutch 9 is closed by further rotation of the coulisse 46 until the cam 44 is situated at the end of the section 50, and the torque flow runs via the hollow shaft 3 and the gear wheel 7, the idler gear 74, the idler gear 72, the auxiliary shaft 71 and the output pinion 73.

It is understood that the above detailed description and drawings rep- resent specific exemplary embodiments of the invention, but that they are only in- tended for illustration and shall not be construed as limiting the scope of the inven- tion. Various modifications of the described embodiments are possible without de- parting from the scope of the following claims and their equivalent range. In particu- lar, this description and the drawings also provide embodiments which are not men-tioned in the claims. Such features can also occur in combinations other than those specifically disclosed herein. The fact that several such features are mentioned in the same sentence or in any other manner of textual context does not justify the conclusion that they can only occur in the specifically disclosed combination. In-stead1 it must be assumed in principle that individual features can be omitted or modified in the case of several such features in so far as the functionality of the invention is thus not placed in doubt.

List of reference numerals 1 Drive shaft 2 l-1oIIoW shaft 3 Hollow shaft 4 Gear wheel Gear wheel 6 Gear wheel 7 Gear wheel s Friction clutch 9 Friction clutch io selector sleeve Selector sleeve 12 Ring 13 Gearwheel 14 Pin Ball 16 Ramp 17 Ring is Roller bearing 19 Plate on the side of the hollow shaft Plate on the side of the drive shaft 21 SynchroniZed disc 22 Gear wheel 23 Gear wheel 24 Selector toothing Auxiliary shaft 26 Auxiliary shaft 27 Fixed gear 28 Fixed year as Idler gear so Idler gear si selector sleeve 32 Output pinion 33 Idler gear 34 Idler gear Selector sleeve 36 Output pinion 37 Control mechanism 38 Selector shaft 39 Selector shaft Axis 41 Selector finger 42 Selector finger 43 Selector finger 44 Cam Gear wheel 46 Coulisse 47 Servomotor 48 Threaded screw 49 Section of the coulisse Section of the coulisse 51 Section of the coulisse 52 Cam follower 53 Section 54 Cam follower Shift sleeve 56 Shift sleeve 57 Selector fork 58 Cam follower 59 Longitudinal groove Finger 61 Longitudinal groove 62 Selector fork 63 Finger 64 Finger Groove 66 Drum 67 Drum Selector sleeve 71 Auxiliary shaft 72 Idler gear 73 Output pinion 74 Idler gear

Claims

CLAIMS: 1. A manual transmission, comprising -a first shaft (25), -at least one first idler gear (29, 30) carried by the first shaft (25), -a first selector sleeve (31) which is movable along the first shaft (25) between a first gear position coupling the first idler gear (30) to the first shaft (25) and a neutral position permitting a rotation of the idler gear (30) relative to the first shaft (25), -a first cam follower (58) which ads on the first selector sleeve (31) for moving the first selector sleeve (31) along the first shaft (25); -a first selector shaft (39), which is displaceable for displacing the first cam follower (58) in the direction of the shaft (25) and carries a first coupling body which is rotatable about a longitudinal axis (40) of the first selector shaft (39) between an active position acting on the first cam follower (58) and a passive position decoupled from the first cam follower (58).
2. A manual transmission according to claim 1, wherein the first selector sleeve (31) can further be moved from the neutral position to a second gear posi-tion coupling a second idler gear (29) to the shaft (25).
3. A manual transmission according to claim 1 or 2, wherein the coupling body is a selector finger (43) which is rigidly connected to the first selector shaft (39).
4. A manual transmission according to one of the preceding claims, wherein the first selector shaft (39) is rotatably mounted in a sleeve (56) and Is axially non-movable against the sleeve (56).
5. A manual transmission according to claim 4, wherein a coulisse (46) and a cam (44) engaging in the coulisse (46) are distributed on the sleeve (56) and a drum (67) surrounding a sleeve (56) in order to convert a rotation of the drum (67) into a displacement of the first selector shaft (39).
6. A manual transmission according to claim 5, wherein the coulisse (46) com-prises a section (51) extending on a helical trajectory with which the cam (44) interacts at least when the selector sleeve (31) is situated between the neutral position and the gear position, and comprises at least one section (51) extending in the circumferential direction with which the cam (44) inter-acts when the selector sleeve (31) is in the gear position.
7. A manual transmission according to claim 6, wherein the coulisse (46) com-prises a section (49) with which the cam (44) interacts when the selector sleeve (31) is in the neutral position.
8. A manual transmission according to claim 6 or 7, wherein a single servomo-tor (47) drives the rotation of the coulisse (46) and the cam (44) against each other and an opening and closing movement of a first friction clutch (8, 9).
9. A manual transmission according to one of the preceding claims, further comprising -a second selector shaft (30), which is displaceable for displacing the first cam follower (58) in the direction of the shaft (25) and carries a second coupling body which is rotatable about a longitudinal axis (40) of the second selector shaft (38) between an active position acting on the first cam follower (58) and a passive position decoupled from the first cam follower (58).
10. A manual transmission according to claim 9, wherein a first friction clutch (9) connects a first main shaft (3) to a drive shaft (1), a second friction clutch (8) connects a second main shaft (2) to the drive shaft (1), in which in the first gear position the first main shaft (3) is coupled to an output shaft and in the second gear position the second main shaft (2) coupled to the output shaft.
11. A manual transmission according to claim 9 or 10, in so far as referring back to claim 2, wherein the freedom of movement of the second selector shaft (38) is dimensioned in order to displace the first cam follower (58) between the neutral position and the second gear position, and the freedom of movement of the first selector shaft (39) is dimensioned in order to displace the first cam follower (58) between the neutral position and first gear posi-tion.
12. A manual transmission according to one of the claims 9 to 11, wherein the selector shafts (38, 39) are connected to each other in a torsion-proof man-ner and are axially movable against each other.
13. A manual transmission according to one of the claims 9 to 12, wherein the first selector shaft (39) is hollow and the second selector shaft (38) engages in the first selector shaft (39).
14. A manual transmission according to one of the claims 9 to 13, wherein the first cam follower (58) comprises a first passage (53) in which the first cou-pling body acts in its active position and a second passage (53) in which the is second coupling body acts in its active position.
15. A manual transmission according to one of the claims 9 to 14, characterized in that the first coupling body further comprises a second active position in which it acts on a second cam follower (52).