DOUBLE GEARBOX

Abstract

A dual transmission with input shafts, output shafts, a transmission case and two separate single transmissions arranged in the transmission case is described. Each single transmission is a two-stage spur gear transmission with three positions for gear centers. A first position is occupied by an input shaft and a second position by an output shaft. A third position is for a middle stationary axle fixed to the transmission case. The three positions define a triangular arrangement having a first side defined by a distance between the first position and the second position, a second side defined by a distance between the first position and the third position, and a third side defined by a distance between the second position and the third position. The second side and the third side form respective angles with the first side. At least one of these angles has a value ranging between 5° and 70°.

Claims

1.-15. (canceled)

16. A dual transmission comprising input shafts, output shafts, a transmission case and two separate single transmissions arranged in the transmission case, wherein the dual transmission is configured for being arranged in a powertrain of a motor vehicle with at least two electric machines for propulsion by being configured to be driven by the two electric machines via the input shafts and by being configured to drive one separate wheel of the motor vehicle by each output shaft, each single transmission providing a speed reduction, wherein each single transmission is a two-stage spur gear transmission with three positions for gear centers, a first position of the three positions being occupied by one of the input shafts and a second position of the three positions being occupied by one of the output shafts, wherein the input shafts and the output shafts are arranged in a middle region of the dual transmission and extend transversely to a case longitudinal direction of the transmission case, wherein an arrangement of the input shafts and output shafts defines a reference plane within the transmission case, wherein a third position of the three positions is for a middle stationary axle fixed to the transmission case and configured to stiffen the transmission case, the middle stationary axle being arranged in angular alignment to the reference plane, wherein the first, second and third position are each at a distance from a transmission case bottom, the distance of the third position being greater than the distance of the first position and the second position, wherein the first, second and third position define a triangular arrangement having a first side defined by a distance between the first position and the second position, a second side defined by a distance between the first position and the third position, and a third side defined by a distance between the second position and the third position, wherein the first side is a longest side of the triangular arrangement and rests on the reference plane, and the second side and the third side form respective angles with the first side and thus with the reference plane, at least one of said angles being selected from a range between 5° and 70°.

17. The dual transmission according to claim 16, wherein upon gear contact, rotation of a driven gear, configured to rotate about the middle stationary axle, occurs in a direction of rotation away from the transmission case bottom of the transmission case in a driving manner following gear contact.

18. The dual transmission according to claim 16, wherein the input shafts and the output shafts are each rotatably arranged in pairs in an aligned manner, at a distance from the transmission case bottom that is lower than a distance of the middle axle from the transmission case bottom.

19. The dual transmission according to claim 16, further comprising stepped gears rotatably mounted on the middle axle.

20. The dual transmission according to claim 16, configured to implement a first speed reduction ratio in a first stage of the two-stage spur gear transmission in a direction away from the transmission case bottom and a second speed reduction ratio in a second stage of the two-stage spur gear transmission in a direction toward the transmission case bottom.

21. The dual transmission according to claim 16, wherein gears mounted on the middle axle are supported by bearings configured to transmit a torque free of transverse forces.

22. The dual transmission according to claim 21, wherein teeth of two adjacent toothings of the gears on the middle axle are formed with a different respective angle of inclination, each gear being a member of a helical gear set.

23. The dual transmission according to claim 16, further comprising a vent channel for venting air from an interior of the dual transmission, the vent channel being arranged i) in a stationary axle of the dual transmission or ii) perpendicular to a gear axle.

24. The dual transmission according to claim 16, wherein the middle axle forms a support for at least two idler wheels.

25. The dual transmission according to claim 23, wherein the vent channel is mounted within a region of the transmission case, said region, in an installed position of the dual transmission, remaining above a maximum level of oil in case tilt angles of the dual transmission are less than 45°.

26. The dual transmission according to claim 16, wherein the input shafts are drive shafts partially nested one inside the other, each input shaft extending towards a connection provided for one of the electric machines, each input shaft having a cantilever end.

27. The dual transmission according to claim 16, wherein the input shafts are embodied as one common dual shaft, which is a coaxial shaft arrangement, the dual shaft being supported at four points within the transmission case of the dual transmission.

28. The dual transmission according to claim 16, wherein the dual transmission comprises first gears arranged directly adjacent to each other with an air gap between respective gear cheeks, each of the first gears being configured to mesh with a gear on one of the input shafts or a gear on one of the output shafts, to form a pair providing a respective speed reduction ratio, wherein each pair comprising one of the first gears is supported for rotation independent of each pair comprising the other first gear.

29. The dual transmission according to claim 16, the dual transmission further comprising a single bearing bracket, wherein the output shafts are supported at their ends by the single bearing bracket, the bearing bracket having a central hole structure for receiving each said end.

30. The dual transmission according to claim 16, wherein the input shafts and the output shafts extend over a shorter range of a distance from one case wall to an opposite case wall of the transmission case.

31. The dual transmission according to claim 19, wherein the stepped gears have a larger, first diameter on a motor drive side and a smaller, second diameter on an output side of the third position.

32. The dual transmission according to claim 21, wherein the gears mounted on the middle axle comprise a first gear with a first diameter and a first inclination angle, and a second gear with a second diameter and a second inclination angle, and wherein the first diameter is larger than the second diameter, and the first inclination angle is larger than the second inclination angle.

33. The dual transmission according to claim 23, wherein the vent channel comprises a sleeve including at least one bore provided in the third position, the sleeve enclosing a cylindrical space passing through the transmission case from a first inner side to either an opposite, second inner side or to a center in the transmission case.

34. A twin transmission for a duo electric machine powertrain with single-wheel drive, to be driven by two electric machines, each for driving a respective road wheel of a motor vehicle, the twin transmission comprising: an input shaft through which the twin transmission is driven as a result of a drive power of one of the two electric machines; a spur gear intermediate bearing, on which at least one gear is located and supported; a middle stationary axle for the spur gear intermediate bearing, the middle stationary axle being fixed to a transmission case and being configured to stiffen the transmission case; and an output shaft configured for being connected with a wheel half-axle, wherein: the input shaft and the output shaft are arranged for torque transfer by rotation through a tooth meshing, a transmission train from the input shaft, via the spur gear intermediate bearing, to the output shaft follows a shape of an inverted or upside down letter V, the input shaft and the output shaft are located horizontally with their shaft centers geometrically defined on an uniform plane, the spur gear intermediate bearing is a deflection stage for a torque, and the spur gear intermediate bearing has at least one freewheel body and at least one gear that is mounted as an idler wheel, so that introduced transverse forces are at least partially compensated by diverting transverse forces on the idler wheel with respect to the middle stationary axle.

35. A dual transmission for a powertrain of a motor vehicle, comprising two input shafts being configured to be driven by two electric machines of the motor vehicle, and two separate single transmissions, each single transmission configured for being connected with a separate wheel of the motor vehicle and to provide a respective speed reduction, wherein each single transmission is a two-stage spur gear transmission with three positions for gear centers in a common transmission case, a first position of the three positions being occupied by an input shaft and a second position of the three positions being occupied by an output gear, wherein an input shaft center and an output gear center are arranged in a middle region of the dual transmission and the input shaft of each single transmission extends transversely to a case longitudinal direction of the transmission case, wherein an arrangement of the input shaft center and the output gear center defines a horizontal reference plane within the transmission case at a first distance from a transmission case bottom, when the dual transmission is in a mounting orientation corresponding to a mounted position of the dual transmission in the motor vehicle, wherein a third position of the three positions is for a center of a middle stationary axle, the middle stationary axle being fixed to the transmission case and configured to stiffen the transmission case, the middle stationary axle being arranged parallel to the horizontal reference plane at a second distance from the transmission case bottom greater than the first distance, wherein the first position, the second position and the third position define connecting lines between the third position and the first position and between the third position and the second position, said lines forming respective angles with the horizontal reference plane, each said respective angle being selected from a range between 10° and 50°.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0160] The present invention can be understood even better if reference is made to the accompanying figures which show particularly advantageous design possibilities by way of example, without limiting the present invention thereto, wherein

[0161] FIG. 1 shows a vehicle system in a schematic illustration,

[0162] FIG. 2 shows another example of a vehicle system in a schematic illustration,

[0163] FIG. 3 shows a schematically illustrated transmission in a longitudinal section,

[0164] FIG. 4 shows a schematically illustrated transmission in an open side view,

[0165] FIG. 5 shows a schematically illustrated transmission according to FIG. 4 in a state of rotation,

[0166] FIG. 6 shows a schematic illustration of another example of a transmission in a longitudinal section,

[0167] FIG. 7 shows an isolated detail from the transmission of FIG. 6 with an alternative embodiment of a stiffening pipe used for venting,

[0168] FIG. 8 shows a variant of an advantageous transmission with a vent, in a schematic illustration, and

[0169] FIG. 9 shows a further development of a dual input shaft for a transmission, by which a transmission according to FIG. 3 or a transmission according to FIG. 6 can advantageously be further developed.

DESCRIPTION OF THE FIGURES

[0170] FIG. 1 and FIG. 2 schematically show a motor vehicle 500 or 500.sup.I which, in addition to the space for the driver, which is identifiable by the steering wheel 514 and can also be referred to as the drivers cab or passenger compartment, has a rear 526 and a trunk region 528, identifiable by the marked direction of travel 502. Located in the front part of the passenger compartment, as usual, is the steering wheel 514, which can transmit a driver's steering movements to two wheels as road wheels 510, 512 via a steering linkage 516 consisting of a steering shaft, a steering transmission, track rods and wheel steering levers. Two further road wheels 506, 508 are mounted on a second axle, the vehicle rear axle 518. A wheel or road wheel can also be referred to as a vehicle wheel because it serves to move the motor vehicle 500 or 500.sup.I. The road wheels 506, 508 are driven via half-axles 520, 522, the universal (joint) drive shafts. The half-axles 520, 522 are attached to the output side of a dual transmission 1 or 1.sup.III. A first electric machine 5 or 5.sup.II and a second electric machine 7 or 7.sup.II are attached to the drive side of the dual transmission 1 or 1111. The electric machines 5, 7 or 5.sup.II, 7.sup.II and the half-axles 520, 522 are each attached in pairs to opposite sides of the transmission 1 or 1.sup.III. Torque from the electric machine 5 or 5.sup.II is applied to an input shaft 33 (see FIG. 3) of the dual transmission 1 or 1.sup.III via a respective side, and the first half-axle 520, and thus the output to the first road wheel 506, is attached on the same side of the dual transmission 1 or 1.sup.III. In the same way, torque from the electric machine 7 or 7.sup.II is applied to an input shaft 35 (see FIG. 3) of the dual transmission 1 or 1.sup.III, and the second half-axle 522, and thus the output to the second road wheel 508, is arranged on the same side of the dual transmission 1 or 1.sup.III.

[0171] A particularly advantageous motor vehicle body exists if the electric machines 5, 7, which in FIG. 1 are mounted in front of the half-axles 520, 522 in the direction of travel 502, are mounted behind the half-axles 520, 522 as shown on the basis of the electric machines 5.sup.II, 7.sup.II in FIG. 2, for example in that the symmetrically constructed dual transmission 1 is rotated through 180° in the illustrated plane of the vehicle floor 504 of FIG. 1 and in particular mounting points for the dual transmission 1 and the electric machines 5, 7 are provided underneath the trunk 528. As shown in FIG. 2, however, a powertrain 3.sup.I comprising a dual transmission 1.sup.III can also be constructed in a motor vehicle 500.sup.I, the gears (see FIG. 3) of said transmission being designed to transmit power in an arrangement of the electric machines 5.sup.II, 7.sup.II behind a rear axle 518.sup.I.

[0172] According to FIG. 1 and according to FIG. 2, an electric accumulator 9 is located in the region of the vehicle floor 504, which accumulator, via electrical leads 11, 13, can provide electrical energy to the electric machines 5, 7 or 5.sup.II, 7.sup.II and the motor controls thereof (not shown). The powertrain 3 or 3.sup.I thus extends from the accumulator 9, via the electrical leads 11, 13, via the electric machines 5, 7 or 5.sup.II, 7.sup.II and the motor controls thereof, via the dual transmission 1 or 1.sup.III, and via the half-axles 520, 522, to the road wheels 506, 508. One electric machine 5, 7 or 5.sup.II, 7.sup.II thus drives one road wheel 506, 508. This is a single-wheel drive.

[0173] The transmission 1 or 1.sup.III is arranged on the vehicle longitudinal axis 524. One electric machine 5 or 5.sup.II and one half-axle 520 are located on one side of the vehicle longitudinal axis 524, while the other electric machine 7 and the other half-axle 522 are arranged on the other side of the longitudinal axis 524. The electric machine 5 or 7, which according to FIG. 1 is arranged close to the center and rotates transversely to the vehicle longitudinal axis 524, rotates the transmission 1 so that, on the output side, an output shaft 37, 39 (see FIG. 3) can apply a torque to a wheel 506 or 508 likewise transversely to the vehicle longitudinal axis 524. The electric machine 5.sup.II or 7.sup.II, which according to FIG. 2 is arranged close to the trunk and rotates transversely to the vehicle longitudinal axis 534, rotates the transmission 1.sup.III so that, on the output side, an output shaft 37, 39 (see FIG. 3) can apply a torque to a wheel 506 or 508 likewise transversely to the vehicle longitudinal axis 524. As shown in FIG. 1 or FIG. 2, for such a drive connection, the electric machine 5, 7 or 5.sup.II, 7.sup.II is attached to the input shaft 33, 35 (shown in FIG. 3) by a coupling 532, 534. The transmission 1 or 1.sup.III and the electric machines 5, 7 or 5.sup.II, 7.sup.II are coupled.

[0174] The vehicle 500 or 500.sup.I shown in FIG. 1 or FIG. 2 is driven via its vehicle rear axle 518 or 518.sup.I. This is an electric rear axle drive using the dual transmission 1 or 1.sup.III. The dual transmission 1 or 1.sup.III is arranged in the region of the rear compartment 526 or in the region of the trunk 528, and in each case in the region of the vehicle floor 504.

[0175] It is particularly advantageous if FIGS. 3 and 4 are considered jointly.

[0176] An advantageous exemplary embodiment will be explained below primarily on the basis of FIG. 3. FIG. 4 and FIG. 5 are to be included in addition to what is stated below.

[0177] The transmission 1 is shown in a sectional view in FIG. 3, and the transmission 1.sup.I is shown in a sectional view in FIG. 6, the section being made in each case through the individual gear centers 25, 27, 29. When describing FIG. 6, particular emphasis will be placed on the differences compared to FIG. 3. For reference signs used jointly in FIG. 3 and FIG. 6, reference can be made to the description of FIG. 3 when considering FIG. 6. The transmission 1.sup.III of FIG. 2 can be designed in the manner of a transmission 1 according to FIG. 3 or in the manner of a transmission 1.sup.I according to FIG. 6 or in the manner of a transmission 1.sup.II according to FIG. 8, the transmission case in each case having attachment points for mounting it in the vicinity of the trunk (not shown).

[0178] As FIG. 3 and FIG. 6 show, the dual transmission 1 or 1.sup.I has two single transmissions 15, 17, each single transmission 15, 17 being formed as a two-stage spur gear transmission. Each spur gear transmission has three positions 19, 21, 23 for gear centers 25, 27, 29 in a single, common transmission case 31. The drive torque 5.sup.I, 7.sup.I is applied by the electric machines 5, 7 (see FIG. 1) to the respective input shaft 33, 35. The input shafts 33, 35 connected to the respective electric machines 5 and 7 (see FIG. 1) and the output shafts 37 and 39 connected to the respective half-axles 520 and 522 are arranged at the same height in a middle region M in relation to a transverse extension, i.e. in particular a relatively short distance from one case wall 41 to an opposite case wall 43 of the transmission case 31. The position of the input shafts 33, 35 and of the output shafts 37, 39, which define the gear centers 25 and 29, describes a reference plane B within the transmission case 31. A middle axle 45, which describes a middle gear center 27 or middle position of an axially mounted gear 49, 49.sup.I, 50, 50.sup.I, is in a parallel and elevated position relative the reference plane B and forms a position of the gear center 27 at a distance from the transmission case bottom.

[0179] The two input shafts 33, 35 are combined to form a dual input shaft 32. They are mechanically connected to form the dual input shaft 32. The two input shafts 33, 35 extend along the axis 44 and in this way form the dual input shaft 32. The two coaxially arranged input shafts 33, 35 are connected to each other in such a way as to be rotatable relative to each other.

[0180] As can be seen even better on the basis of FIG. 4 and FIG. 5, the middle axle 45 is located at a corner of a triangle 47 spanned by the gear centers 25, 27 and 29.

[0181] The middle axle 45 can be intersected by a straight line g connecting the gear center 25 or 29 and the middle axle 45, namely in an angle range of around 5° to 70°.

[0182] As can be seen particularly well in FIG. 4, it may be advantageous to locate the gear centers 25, 27, 29 on two planes so that a straight line g extending from one plane to the next is at an angle α to one of the two planes, namely the plane B, the angle being taken from an angle range of 10° to 50° or even only an angle range of 15° to 48°.

[0183] As can likewise be seen from FIG. 3 or FIG. 6, the way in which the gear centers 25, 27, 29 are to be located depends on the on the gears 75, 75.sup.I of the input shafts 33, 35, the gears 77, 77.sup.I of the output shafts 37, 39 and the gears 49, 49.sup.I, 50, 50.sup.I of the toothing geometries selected on the middle axle 45, as well as on the powers to be transmitted. The gears 75, 75.sup.I on the input side have a diameter d.sub.1 that is smaller than a diameter d.sub.4 of the gears 77, 77.sup.I on the output side of the dual transmission 1. On account of being driven by the drive torques 5.sup.I, 7.sup.I, the gears 75, 75.sup.I are the first gears in the flow of torque through the transmission 1.

[0184] The respective gear 75, 75.sup.I on the input shaft side of each single transmission 15, 17 drives a respective gear 49, 49.sup.I on the middle axle 45, wherein, in the exemplary embodiments shown, the directions of rotation of the electric machines 5, 7 (see FIG. 1) in the traction mode of the vehicle are selected in such a way that the gear 49, 49.sup.I has a direction of rotation rotating away from the case bottom 51 of the transmission case 31 following gear contact in a driving manner.

[0185] The direction of rotation arrow in FIG. 5 illustrates this specification of the directions and of the direction of rotation. The dual transmission can also be operated in the reverse direction of the direction of rotation arrows, particularly for driving in reverse.

[0186] If, in a manner differing from the advantageous motor vehicle body shown in FIG. 1 and described in this connection, a motor vehicle body is realized with a transmission arrangement as in FIG. 2, in which the transmission arrangement is turned through 180° in comparison to the transmission arrangement in FIG. 1, then a direction of rotation rotating toward the case bottom 51 of the transmission case would likewise be set for the gear 49, 49.sup.I following gear contact, but the direction of rotation of the electric machines must be adapted to the installation position.

[0187] As illustrated in particular in FIG. 3 or FIG. 6, the axle 45 defining the middle position or the middle gear center 27 is designed as a stationary axle that is fixed to the case. This makes it possible to stiffen the transmission case 31 without the need for additional components. The respective driven gear 49, 49.sup.I on the axle 45 and the driving gear 50, 50.sup.I are borne on the axle 45 via in each case two needle bearings 61, 63, 61.sup.I, 63.sup.I in order to avoid any tilting of the gears 49, 50 or 49.sup.I, 50.sup.I, which are moreover preferably formed in pairs as a one-piece stepped gear.

[0188] In contrast, the input shafts 33, 35 and the output shafts 37, 39 are mounted by way of rolling bearings 65, 67, 69 and 71 in outer walls of the transmission case 31. Furthermore, the input shafts 33, 35 are mounted by means of ball bearings, or a separate ball bearing per single transmission 15, 17, in the vicinity of a case partition wall 73 that has apertures for the joint lubrication of the single transmissions 15 and 17. The output shafts 37 and 39 are mounted in a second case partition wall 73.sup.I, more precisely a spectacles-type bearing bracket, by means of needle bearings (without reference signs) or one needle bearing per single transmission 15, 17.

[0189] As can be seen particularly well from looking at FIG. 4 and FIG. 5, the input shafts 33, 35 and the output shafts 37, 39 are arranged lower than the axle 45 in relation to the case bottom 51 of the transmission case 31.

[0190] The stepped gears 79, 79.sup.I (see FIG. 6) on the axle 45 have a first, larger diameter d.sub.2 on the drive side and a smaller, second diameter d.sub.3 on the output side (see FIG. 3). There is a step-down ratio toward the output side. It can also be said that the two gears 49, 50 or 49.sup.I, 50.sup.I are joined together or welded together to form a stepped gear 79 or 79.sup.I.

[0191] If FIG. 3 and FIG. 6 and respectively FIG. 4 and FIG. 5 are considered simultaneously, it can be seen that the larger diameter d.sub.2 is located toward the inside, while the smaller diameter d.sub.3 (in comparison thereto) is located closer to the case 31. It is thus possible to direct the torques introduced into the transmission 1 toward the output shaft 37, 39 in an outward direction. Owing to the planes of the transmission 1, in which the gear centers 25, 27, 29 are located, and owing to the arrangement of the stages 53, 55, the torques follow a course in the shape of a double V (on the one hand with regard to heights in relation to a base, in particular the case bottom 51, of the transmission 1, and on the other with regard to a divergence away from a vehicle longitudinal axis 524 (see FIG. 1)).

[0192] As shown in FIG. 5, about the gear center 25, the gear 75 of the input shaft 35 has a first direction of rotation 85 that is directed toward the case bottom 51. About the second gear center 27, the larger gear 49 of the stepped gear 79, which is driven by the input shaft 35, has a second direction of rotation 87 that on the drive side is directed away from the case bottom 51. The driven gear 77 is rotated about the third gear center 29, said driven gear meshing with the smaller gear 50 of the stepped gear 79 and being driven thereby in a third direction of rotation 89 towards the case bottom 51. Owing to a spacing of the second gear center 27 from the reference plane “B”, the first gear center 27 and the third gear center 29 are closer to each other than in the case of a linear arrangement of three gear centers, the gears of which have the same dimensions as the gears 75, 77, 79. The transmission case 31 is thus shortened in a direction of the base of the triangle 47, which lies in the reference plane “B”. In other words, as shown in FIG. 5, the transmission 1 is particularly compact and efficient in terms of installation space.

[0193] In FIG. 5, the case 31 is shown schematically in an open state on the basis of the first sub-case 95. The first sub-case 95 can be connected to a shell-like second sub-case (not shown) at a flat sealing surface 91. The connection of the identically curved sub-case, such as the sub-case 95, takes place by means of bolts, which can be screwed into bolt threads 93 of the first sub-case 95. The sealing surface 91 extends parallel to the triangular area spanned by the positions 19, 21, 23. In other words, the sealing surface lies in a plane parallel to the gears 75, 77, 79. It can also be said that the input shaft 35 is arranged perpendicular to the sealing surface 91 or perpendicular to the sub-case connection surface 91 in the transmission case 31. This facilitates assembly of the transmission 31.

[0194] In an installed state of the transmission case in a motor vehicle (see motor vehicle 500 or 500.sup.I in FIG. 1 or FIG. 2), the case longitudinal direction 190 shown in FIG. 6 is oriented parallel to the vehicle longitudinal axis (see vehicle longitudinal axis 524 in FIG. 1 or FIG. 2). The transmission case 31 has a larger extension in its case longitudinal direction 190 than in its width 106.

[0195] In the dual transmission 1 according to the invention, a first gear stage 53 or first ratio 53 is created, which forms a ratio turning away from the case bottom 51 of the transmission case 31, as well as a second gear stage 55 or the second ratio 55, which forms a ratio turning toward the case bottom 51. On the other hand, the gear pairing consisting of the first two gears 75.sup.I, 49.sup.I in the flow of torque in the transmission 1 creates the ratio 53.sup.I. The gear pairing consisting of the subsequent two gears 50.sup.I, 77.sup.I creates the ratio 55.sup.I.

[0196] As shown in particular by FIG. 3 or FIG. 6 in a schematic longitudinal section through the dual transmission 1 or 1.sup.I, the middle gears 49, 50 or 49.sup.I, 50.sup.I, which are formed in one piece with each other, are designed to transmit a torque in a manner free of transverse forces due to the fact that the teeth 57 and 59 or 57.sup.I and 59.sup.I of two adjacent gears 49, 50 or 49.sup.I, 50.sup.I have different angles of inclination for each row of teeth, such as the angles of inclination β.sub.1 and β.sub.2. To aid comprehension, the angles of inclination β.sub.1, β.sub.2 are indicated only schematically in the illustrated section plane of FIG. 3 or FIG. 6. The teeth 57, 59 of the sub-transmission 17 as well as adjacent teeth of the respective rows of teeth (without reference signs) extend with respective tooth directions in a parallel manner through the section plane of FIG. 3 or FIG. 6. In relation to a specified or selected direction of the middle axle 45, the teeth 57, 59 or the running surfaces thereof extend with a tooth direction laterally toward the other sub-transmission 15 or away from the other sub-transmission 15, wherein a deviation, expressible by vectors, of the tooth directions of the teeth 57, 59 from the direction of the middle axle 45 in each case has the same sign for their vector values (identical sign in the angles of inclination).

[0197] The gears 49, 50 or 49.sup.I, 50.sup.I are free of axial forces, at least in the traction mode of the vehicle.

[0198] For the gears 49.sup.I, 50.sup.I and the teeth 57.sup.I, 59.sup.I of the other single transmission 15, the same applies on account of an identical design of transmission parts, i.e. the sub-transmission 15, which is constructed in a manner identical to the sub-transmission 17, has adjacent gears 49.sup.I, 50.sup.I which are designed with a corresponding inclination of the teeth 57.sup.I, 59.sup.I. In other words, what has been described above correspondingly applies to the gears 49.sup.I, 50.sup.I and the teeth 57.sup.I, 59.sup.I of the other single transmission 15 due to an identical design of transmission parts.

[0199] It may be advantageous to provide thrust washers to support the gears 49, 50 or 49.sup.I, 50.sup.I on the transmission case 31.

[0200] Furthermore, in order to vent the transmission case 31, it may be advantageous to provide a sleeve instead of the middle axle 45 or additionally on the middle axle 45, which sleeve makes it possible to equalize the pressure in the transmission case 31.

[0201] The gears 49, 49.sup.I, 50, 50.sup.I, 75, 75.sup.I, 77 and 77.sup.I are formed as disk wheels on account of the high torques to be transmitted. As shown in FIG. 3 or FIG. 6, the gears 77 on the output shaft side are formed by a disk that has a thickness smaller than the width of their gear rim. In addition, the respective disk of the gears 77, 77.sup.I is at an angle to the respective output shaft 37, 39. In other words, it may be formed at a non-perpendicular angle to the respective output shaft 37, 39. The disk has a base with an end face that extends radially from the output shaft 37, 39 or merges into the output shaft 37, 39 and in particular bounds a running surface of a needle bearing in an axial direction.

[0202] All the gears, axles and shafts installed in the transmission case 31 are lubricated via a common sump. Each single transmission 15, 17 has a step-down ratio of, for example, 8.5:1 or even 12:1.

[0203] As can be seen from FIG. 4, the positions 19, 21, 23 of the gear centers 25, 27, 29 are located in a middle region M within the case walls 41, 43. As a stepped gear, the gear 49 with its teeth, such as the tooth 57, and the gear 50 with its teeth, such as the tooth 59, is the gear arranged furthest from the case bottom 51 in the upward direction. In traction mode, such a stepped gear, as formed from the gears 49, 50, is driven by an input shaft 35, which is part of the dual input shaft 32 (see FIG. 3).

[0204] It can be seen particularly well in FIG. 6 that, between the input shafts 33, 35, in the region of the gears 75, 75.sup.I thereof, an air gap 83 separates the (sub-)input shafts 33, 35 and thus the gears 75, 75.sup.I. Each gear 75, 75.sup.I is designed as a gear rim 58 formed in one piece with the dual input shaft 32. The gear rim 58 is part of the input shaft 35. The input shafts 33, 35 are separated from each other by an air gap 83 in the region of their gears 75, 75.sup.I. Arranged adjacent to the gears 75, 75.sup.I are ball bearings 81, 81.sup.I, via which the dual input shaft 32 is supported against the case 31, in particular via the bearing-carrying case partition wall 73.

[0205] As shown in particular in FIG. 5, each sub-transmission 15, 17 extends in its own sub-transmission chamber 97, which in each case is formed at least in parts by the transmission pan or case pan 95.

[0206] In a regular filling state, the transmission case 31 is filled with a transmission oil, but not completely filled with oil; instead, part of the interior, i.e. part of the internal volume 108 (see FIG. 6) of the transmission case 31 is filled with air.

[0207] By way of its internal cavity, the transmission 1.sup.I shown in FIG. 6 with its transmission case 31 creates an internal volume 108 that extends from the first inner side 102 thereof to the second inner side 104 thereof. However, the volume-reducing components are arranged in the internal volume 108. The internal volume 108 is partly reduced by the gears, such as the gears 49, 49.sup.I, 50, 50.sup.I, 75, 75.sup.I, 77, 77.sup.I, by shafts, such as the shafts 33, 35, 37, 39, and by other components, such as needle bearings 61, 61.sup.I, 63, 63.sup.I and rolling bearings, as well as by a sleeve 116. The free internal volume 108 is reduced by the installed components. The remaining internal volume 108 is filled to a certain level with a transmission fluid, such as a transmission oil, for operating the transmission 1.sup.I. Air remains in the rest of the internal volume 108.

[0208] For air that is to pass outward via a bore 118 in a sleeve 116 to a breather cap 130 in order to be discharged, a vent structure is incorporated in the transmission 1.sup.I.

[0209] The sleeve 116, which is hollow due to a bore 118, is located in the region of the gear axle 114 among the gear pairs 49, 50 or 49.sup.I, 50.sup.I designed as stepped gears 79 or 79.sup.I. The cavity created by the bore 118 in the interior of the sleeve 116 has connections to the rest of the internal volume 108 of the transmission 1.sup.I or of the transmission case 31 via further bores 118.sup.I, 118.sup.II. The further bores 118.sup.I, 118.sup.II extend transversely, in particular orthogonally, to the bore 118.

[0210] The sleeve 116 extends from one inner side 102 to the opposite inner side 104 of the transmission case 31. The sleeve 116 is a transverse strut that stiffens the case 31. An (internal) width 106 of the transmission case 31 is completely spanned by the sleeve 116. The sleeve 116 therefore extends from a first case wall 41 to a second case wall 43.

[0211] Advantageously, the sleeve 116 is located in a middle region M of the transmission 1.sup.I. The middle region M of the transmission 1.sup.I is used by the second, middle position 21 to center gears 49, 49.sup.I, 50, 50.sup.I.

[0212] Via the (feed) bores 118.sup.I, 118.sup.II, air from the internal volume 108, namely from anywhere therein so long as it is somehow distributed over the width 106, can enter the centrally arranged bore 118 of the sleeve 116, which in particular spans the width 106 of the case 31. The air then passes to the breather cap 130. The case wall 41, 43 may contain further bores (not shown), which extend partially along the case wall 41, 43 and via which air enters the bore 118 that spans the width 106 of the case 31. Such bores in the case wall also serve to supply oil to the needle bearings of the gears 49, 49.sup.I, 50, 50.sup.I.

[0213] As can be seen from a joint consideration of FIGS. 6 and 7, a narrower portion 136 is connected to the thicker portion 134 outside of a center 110 of the transmission 1.sup.I. The narrower portion 136 of the vent extends over less than half the distance of the sleeve 116.

[0214] FIG. 7 shows an enlarged view of a detail from a sleeve 116.sup.I that is designed in an alternative manner compared to the sleeve 116 of FIG. 6, together with a detail from the case wall 43 and the gears 49, 49.sup.I, 50, 75, 77, which are also shown in FIG. 6. The needle bearings 61, 63 are also visible below the gears 49, 50.

[0215] The sleeve 116.sup.I shown in FIG. 7 offers more functions than the sleeve 116 according to FIG. 6. In terms of dimensions, however, the sleeves 116, 116.sup.I are identical.

[0216] For exchange with the surrounding environment, the vent according to FIG. 7 provides a breather cap 130, which is connected to the breather tube 132, plugged onto a nozzle 131. The nozzle 131 is connected to the breather tube 132 in the form of an extension that enlarges a flow cross-section. A venting point, in particular at a distance from a surface of the transmission (see transmission 1.sup.I in FIG. 6), can be defined by means of a nozzle length, a nozzle curvature or a nozzle outlet angle. The vent channel 124 has multiple portions 134, 136. The portions 134, 136 can also be referred to as vent channel segments. The vent channel 124 is divided into multiple portions 134, 136, some of which extend parallel to each other and some of which extend perpendicular to another portion. The portions 134, 136 have different diameters. This creates possible ways of influencing the flow behavior of the air in a transmission, such as the transmission 1.sup.I (see FIG. 6). The vent channel 124 has a portion 134 that is deemed to be the actual vent channel 124 owing to the fact that it has a diameter 126 that is larger than the other portions, such as the portion 136.

[0217] The enlarged detail of one end of the sleeve 116.sup.I, which is shown in FIG. 7, shows the vent structure inserted in the case wall 43, said vent structure including the breather tube 132 with the breather cap 130 as well as the multi-deflected channel routing with its portions 134, 136 and its transition regions, such as the transition region 138. The thickest portion 134 is the vent channel 124 that has the largest cross-section 126. Bores 118.sup.I, 118.sup.III and lubrication passages, such as the lubrication passage 152, branch off from the vent channel 124. Advantageously, the vent channel 124 itself is a bore 118. In simplified terms, this can be referred to as the bore 118 when denoting elongate channels of uniform cross-section 126 that extend in particular over the width 106 of the case (see FIG. 6), such as the vent channel 124. In its central region, therefore, the sleeve 116.sup.I provides a space 122 that may optionally contain an air-oil mixture, for example in the form of an aerosol. By means of transverse bores, such as the transverse bore 140, and lubrication passages, such as the lubrication passage 152, the oil or the oil-air mixture or the oil-air mist can be used to lubricate the bearings 144, 146. Such bearings may be designed as needle bearings 61, 63. The sleeve 116.sup.I thus serves not only to provide the venting space 122, but also as a bearing 144, 146 for idler wheels, such as the idler wheel 148. The gears 49, 49.sup.I, 50, which rotate about the sleeve 116 and mesh with other gears, in particular the gears 75, 77, form spur gear ratio stages, such as the spur gear ratio stage 150.

[0218] The special deflections starting from a vent feed line 128, via which oil is held back by means of narrower portions, such as the portion 136, are integrated in the edge region 120 of the sleeve 116.sup.I. In addition to the gears 49, 50, the sleeve 116.sup.I serves as a bearing for other gears, such as the gear 49.sup.I.

[0219] Via transverse bores, such as the transverse bore 118.sup.I, an oil-air mist can enter the channel 124, which forms part of the vent structure. The lubrication passages, such as the lubrication passage 152, are arranged in the sleeve 116.sup.I in order to route oil back to the bearings 144, 146. Air from the air-oil mixture can flow via the vent feed line 128 to the breather cap 130 in order to be discharged from the transmission, such as the transmission 1.sup.I according to FIG. 6 for example, to the surrounding environment when overpressure occurs, for example in relation to an ambient pressure of the surrounding environment. It is particularly advantageous that, by means of a flow deflection through the channels arranged at an angle to each other, such as the channels 134, 136, the flow is directed toward walls in order thus to improve an oil separation, so that air that is almost free of oil is discharged into the environment.

[0220] FIG. 8 shows another exemplary embodiment of a transmission 1.sup.II in a sectional view.

[0221] The transmission 1.sup.II according to FIG. 8 has a center 110.sup.I. The spectacles-type bearing bracket 73.sup.II is arranged in the case 31.sup.I with its central hole structure 154 in the region of the center 110.sup.I of the transmission 1.sup.II or of the case 31.sup.I. From the bearing 146.sup.I of the output gear 77.sup.II, a sleeve 116.sup.II provided with a bore 118.sup.Iv extends along a stationary axis 112, as a result of which air can be discharged via the breather element 130.sup.I. The bore 118.sup.Iv in the sleeve 116.sup.II forms the connecting channel or vent channel 124.sup.I from the center 110.sup.I or from an inner region of the central hole structure 154 of the spectacles-type bearing bracket 73.sup.II to the breather element 130.sup.I.

[0222] The spectacles-type bearing bracket 73.sup.II has a single hole structure, namely the central hole structure 154, which serves to accommodate two bearings 144.sup.I, 146.sup.I. Of these two bearings 144.sup.I, 146.sup.I, only the bearing 146.sup.I arranged behind the vent channel 124.sup.I can be seen in the sectional illustration of FIG. 8. The other bearing 144.sup.I, indicated in dashed line, would sit congruently in front of the illustrated bearing 146.sup.I. In other words, the vent channel opens into an air space 156 between two bearings 144.sup.I, 146.sup.I The air space 156 is annularly surrounded by the spectacles-type bearing bracket 73.sup.II. The air space 156 is part of the internal volume 108.sup.I or belongs to the internal volume 108.sup.I. A spectacles-type bearing bracket attachment 158 is surrounded by the internal volume 108.sup.I of the case 31.sup.I, which can also be referred to as the transmission case 31.sup.I. The spectacles-type bearing bracket attachment 158 is designed as a four-point attachment. In other embodiments, two-point attachments or three-point attachments or other torsion-proof attachments can be used. The spectacles-type bearing bracket attachment 158 comprises two spectacles-type bearing bracket forks, such as the spectacles-type bearing bracket fork 159, each of which, in the manner of a lever arm, directs tangential forces or transverse forces that may act on the bearings 144.sup.I, 146.sup.I into the transmission case 31.sup.I. Via the spectacles-type bearing bracket attachment 158, the spectacles-type bearing bracket is connected to a spectacles-type bearing bracket support structure 155 in the interior of the case 31.sup.I. The two sub-cases of the case 31.sup.I can be connected to each other in a fluid-tight manner via a flat sub-case connection surface 157, for example with the interposition of a seal or a sealant (not shown).

[0223] With regard to the venting assemblies, therefore, FIG. 8 shows another variant of a transmission 1.sup.II, this time with two vent channels 124, 124.sup.I that operate independently of each other. The transmission 1.sup.II has multiple spur gear ratio stages 150.sup.I, 150.sup.II. The transmission 1.sup.II has a stepped gear 79.sup.I. The spur gear ratio stages 150.sup.I, 150.sup.II are borne in different ways, for example by a spectacles-type bearing bracket 73.sup.II. As a result, the transmission 1.sup.II provides multiple centers 110.sup.I, 110.sup.II that can advantageously be used for venting via vent channels 124, 124.sup.I. The channels 124, 124.sup.I are routed in sleeves, such as the sleeve 116.sup.II for example.

[0224] The sleeve 116.sup.II extends along the axis 112, which is arranged transversely to the axis of rotation of the gear 77.sup.II. The gear 77.sup.II is rotatably mounted on the spectacles-type bearing bracket 73.sup.II via a bearing 146.sup.I. There is additionally a further bearing 144.sup.I, which is offset relative to the first-mentioned (more accurately the second) bearing 146.sup.I. By means of a transverse bore 142 in the spectacles-type bearing bracket 73.sup.II, a vent channel 124.sup.I is routed between the two bearings 144.sup.I, 146.sup.I to the transmission case 31.sup.I, more precisely out of the transmission case 31.sup.I. The transmission case 31.sup.I has a width 106.sup.I. Because the vent channel 124.sup.I starts only from the region of the bearings 144.sup.I, 146.sup.I and extends as far as the case 31.sup.I, the vent channel 124.sup.I is (only approximately) half as long as the width 106.sup.I of the transmission 1.sup.II.

[0225] The vent channel 124.sup.I extends along the axis 112, which extends transversely to the axis of rotation. The vent channel 124.sup.I opens into the breather element 130.sup.I. The breather element 130.sup.I is located outside the transmission case 31.sup.I.

[0226] The vent channel 124.sup.I has been formed by a bore 118.sup.Iv in the sleeve 116.sup.II, said bore extending transversely to the axis of rotation.

[0227] The sleeve (without a reference sign) arranged for venting purposes between the spur gear ratios 150.sup.I, 150.sup.II has an elongate vent hole, created by a bore (without a reference sign). The bore extends in the interior of the sleeve, see sleeve 116, bore 118 in FIG. 6).

[0228] As can be seen from FIG. 8, air in the interior of the transmission case 31.sup.I is routed via the bore 118.sup.IV to the breather element 130.sup.I.

[0229] FIG. 9 shows a further development of a dual input shaft 32.sup.I which is advantageous for a dual transmission.

[0230] The dual input shaft 32.sup.I has two gears 75.sup.II, 75.sup.III each of which is formed as a gear rim 58.sup.I or 58.sup.II between two ball bearings 177, 179. The two gears 75.sup.II, 75.sup.III are located between the ball bearings 177, 179.

[0231] The dual input shaft 32.sup.I has two drive connections 117, 119. Each drive connection 117, 119 is provided on a stub 165, 167 of the dual input shaft 32.sup.I, said dual input shaft being formed by stub shafts 161, 163. A drive connection 117, 119 serves to be surrounded by a connector (not shown) in such a way as to enable transmission of a rotational force. The drive connection 117, 119 comprises a splined shaft profile 105, 107 in a shaft casing 109, 111. The shaft casing 109, 111 starts at the end of a shaft end face 113, 115. Owing to the splined shaft profile 105, 107 in the shaft casing 109, 111, the stub shaft 161, 163 offers a good form-fitting and/or force-fitting connection to the electric machine 5, 7 or 5.sup.II, 7.sup.II (see FIG. 1 or FIG. 2).

[0232] The two stub shafts 161, 163, which together are essential parts of the dual input shaft 32.sup.I, are designed as stepped shafts 169, 171. The largest step in the stepped shaft 169, 171 is the step of the integrated gear rim 58.sup.I or 58.sup.II. The gear rim 58.sup.I, 58.sup.II is designed as a gear 75.sup.II, 75.sup.III having a gear cheek 101, 103. Each gear cheek 101, 103 belongs to a separate gear 75.sup.II, 75.sup.III. An air gap 83.sup.I is located between the gear cheeks 101, 103, said air gap being defined by the spacing between the gears 75.sup.II, 75.sup.III. The air gap 83.sup.I enables the gear cheeks 101, 103 to rotate next to each other, particularly at different speeds, in an almost friction-free manner.

[0233] The stepped shafts 169, 171 each have a separate bearing pair 173, 175 to support them against the case 31.sup.I, which is shown only schematically. Each bearing pair 173, 175 is composed of one deep groove ball bearing 177, 179 and one cylindrical roller bearing 181, 183.

[0234] The two stepped shafts 169, 171 mesh with each other in such a way as to be rotatable on the axle 44 via two shaft bearings 145, 147. Advantageous examples of shaft bearings 145, 147, which are shown only in very abstract form, are plain bearings or needle bearings. The shaft bearings 145, 147 have different diameters. The shaft bearings 145, 147 run in grooves on the first, inner stepped shaft 169, in particular the journal region 162 thereof, and are supported against the second stub shaft 171, in particular in the journal receptacle region 164 thereof, said second stub shaft coaxially surrounding the first stub shaft 169 in the journal region 162 of the latter. Between the journal region 162 and the journal receptacle region 164, an air gap 83.sup.II is provided next to the shaft bearings 145, 147 and between the shaft bearings 145, 147.

[0235] The stepped shaft 169 can therefore be regarded as a shaft that is stepped differently in two directions, said shaft having the largest diameter and carrying the gear 75″. Starting from the largest diameter below or next to the gear 75.sup.III, the second stepped shaft 171 is a shaft that tapers in a stepped manner, which runs out into the splined shaft profile 107 as the smallest diameter of the stepped shaft 171.

[0236] The second stepped shaft 171 is a shaft that is hollow in part. The first stepped shaft 169 is a shaft that is solid throughout. At the point where the drive torque is introduced into the second stepped shaft 171, namely on the second shaft casing 111, the stepped shaft 171 is likewise a solid stepped shaft. Only in the region of the shaft bearings 145, 147 or in the gear rim 58.sup.I with the gear 75.sup.III is the stepped shaft 171 hollow in some steps. The journal region 162 of the other stepped shaft 169 is received in the cavity, as a result of which the journal region extends away from the gear 75.sup.II and below the gear 75.sup.III of the partially hollow stepped shaft 171.

[0237] The narrower shaft bearing 147, which can also be referred to as the shaft bearing that has a smaller diameter, is located in the interior of the bearing pair 175. The smaller shaft bearing 147 is located in an aligned manner between the bearings 179, 183 of the second bearing pair 175. The other shaft bearing 145 is located below the gear 75.sup.III. In other words, the second shaft bearing 147 lies opposite the bearing pair 175 in a plane perpendicular to the axis of the input shafts 44. The first shaft bearing 145 is assigned to the gear cheeks 101, 103.

[0238] The two stepped shafts 169, 171 are connected to each other via shaft bearings 145, 147. Each stepped shaft 169, 171 is supported against a case part by a combination of a deep groove ball bearing 177, 179 and a cylindrical roller bearing 181, 183.

[0239] As suitable shaft bearings 145, 147, consideration is particularly preferably given to plain bearings and needle bearings. Depending on the application, a plain bearing or a needle bearing is installed either at one point or at another point.

[0240] Owing to the solid design of the stub shafts 161, 163 and the extremely short design thanks to the piloted dual input shaft 32.sup.I, rapidly rotating electric machines 5, 7 or 5.sup.II, 7.sup.II that drive at high torque (see FIG. 1 or FIG. 2) can be connected to the input side of the transmission 1.

[0241] It is sufficient if the stepped shafts 169, 171 are designed as stub shafts 161, 163. For instance, it is possible to use stepped shafts 169, 171 having a length that is less than ten times the width at the gear rim 58.sup.I.

[0242] The design possibilities shown in the individual figures can also be combined with each other in any form.

[0243] For instance, it is possible to make the partition walls 73, 73.sup.I longer or shorter and yet still leave a total, contiguous oil space in the transmission case 31.

[0244] At the location where a breather cap 130 is provided, a breather element 130.sup.I can of course also be used instead of the cap, for example in order to improve a flow distribution.

[0245] A twin transmission, which is designed in a similar way to the transmissions 1, 1.sup.I, 1.sup.II, 1.sup.III, may be equipped with one, two or more than two vents of the types described above. In other words, various stationary axles are available, on each of which a vent can be arranged. Choosing which of the axles to use for one, two or more than two vents is a design task for a transmission designer.

[0246] In addition, a person skilled in the art understands that the rear-axle drive variant of a motor vehicle 500 or 500.sup.I, which is shown by way of example in FIG. 1 or FIG. 2, can also be accordingly reconfigured for a front-axle drive variant of a vehicle with front-axle drive. In this case, not only does the steering movement from the steering wheel 514 act, by way of the steering linkage 516, on the road wheels 510, 512 and the angle position thereof, but also the powertrain 3 opens into the road wheels 510, 512.

[0247] The transmission can also be briefly summarized as follows. A dual transmission 1 for a powertrain 3 of a motor vehicle 500 comprising two electric machines 5, 7 is equipped with two single transmissions 15, 17. The single transmissions 15, 17 are two-stage spur gear transmissions with three positions 19, 21, 23 for gear centers 25, 27, 29. Two positions are occupied by input shafts 35 and by output shafts 39 and establish a reference plane B. The position 21 for a middle axle 45 as one of the gear centers 27 forms a corner of a triangle 47 that rests with its longest side on the reference plane B. A straight line g can be drawn from one of the other gear centers 25, 29 to the middle axle 45, thereby forming an angle α in an angle range between 5° and 70°. As a result, a power and/or a torque is transmitted by means of the transmission 1 between one of the input shafts 35 and one of the output shafts 39 via a spur gear intermediate bearing 61, 63 by means of a meshing of teeth. As a result, any introduced transverse forces can be at least partially compensated by diverting transverse forces with the idler wheel of the middle axle 45.

LIST OF REFERENCE SIGNS

[0248] Reference sign Meaning [0249] 1, 1.sup.I, 1.sup.II, 1.sup.III dual transmission or twin transmission, in particular reduction transmission embodied in duplicate [0250] 3, 3.sup.I powertrain, in particular duo electric machine powertrain [0251] 5, 5.sup.II first electric machine [0252] 5.sup.I first drive torque [0253] 7, 7.sup.II second electric machine [0254] 7.sup.I second drive torque [0255] 9 energy store, in particular electrical accumulator [0256] 11 first electrical lead [0257] 13 second electrical lead [0258] 15 single transmission, in particular first single transmission or sub-transmission [0259] 17 single transmission, in particular second single transmission or sub-transmission [0260] 19 position, first [0261] 21 position, second, middle [0262] 23 position, third [0263] 25 gear center, in particular first gear center [0264] 27 gear center, in particular second gear center [0265] 29 gear center, in particular third gear center [0266] 31, 31.sup.I transmission case [0267] 32, 32.sup.I dual input shaft [0268] 33 input shaft [0269] 35 input shaft [0270] 37 output shaft [0271] 39 output shaft [0272] 41 case wall [0273] 43 case wall [0274] 44 axle, in particular of the input shafts [0275] 45 axle, middle [0276] 47 triangle [0277] 49, 49.sup.I gear [0278] 50, 50.sup.I gear [0279] 51 case bottom [0280] 53 stage, first [0281] 55 stage, second [0282] 57, 57.sup.I tooth [0283] 58, 58.sup.I, 58.sup.II gear rim [0284] 59, 59.sup.I tooth [0285] 61, 61.sup.I needle bearing [0286] 63, 63.sup.I needle bearing [0287] 65 rolling bearing [0288] 67 rolling bearing [0289] 69 rolling bearing [0290] 71 rolling bearing [0291] 73, 73.sup.I case wall, in particular case partition wall, such as a spectacles-type bearing bracket [0292] 75, 75.sup.I, 75.sup.II, 75.sup.III gear, in particular of the input shaft [0293] 77, 77.sup.I, 77.sup.II gear, in particular of the output shaft [0294] 79, 79.sup.I stepped gear [0295] 81, 81.sup.I ball bearing [0296] 83, 83.sup.I, 83.sup.II air gap [0297] 85 first direction of rotation, such as direction of rotation at the first position, in particular direction of rotation of input shaft [0298] 87 second direction of rotation, such as direction of rotation at the second position, in particular direction of rotation of stepped gear [0299] 89 third direction of rotation, such as direction of rotation at the third position, in particular direction of rotation of output shaft [0300] 91 sealing surface, in particular sub-case connection surface [0301] 93 bolt thread [0302] 95 sub-case, in particular first case shell [0303] 97 sub-transmission chamber [0304] 101 first gear cheek [0305] 102 inner side, first inner side [0306] 103 second gear cheek [0307] 104 inner side, second inner side [0308] 105 first splined shaft profile [0309] 106, 106.sup.I width [0310] 107 second splined shaft profile [0311] 108, 108.sup.I internal volume [0312] 109 first shaft casing [0313] 110 center, in particular of the case, or central region of the case [0314] 110.sup.I center, in particular center of a bearing opening in a spectacles-type bearing bracket [0315] 110.sup.II center, in particular center of a shaft, such as a hollow sleeve, in the case [0316] 111 second shaft casing [0317] 112 axis, in particular stationary axis extending transversely to an axis of rotation [0318] 113 first shaft end face [0319] 114 gear axle, in particular stationary hollow gear axle [0320] 115 second shaft end face [0321] 116, 116.sup.I, 116.sup.II sleeve [0322] 117 first drive connection [0323] 118, 118.sup.I, 118.sup.II, bore [0324] 118.sup.III, 118.sup.IV [0325] 119 second drive connection [0326] 124, 124.sup.I vent channel [0327] 126 cross-section, in particular diameter [0328] 128 vent feed line [0329] 130, 130.sup.I breather cap or breather element [0330] 131 nozzle [0331] 132 breather tube [0332] 134 first portion, in particular thicker portion [0333] 136 second portion, in particular narrower portion [0334] 138 transition region [0335] 140 transverse bore, in particular first transverse bore [0336] 142 transverse bore, in particular second transverse bore [0337] 144, 144.sup.I bearing, in particular first floating bearing [0338] 145 first shaft bearing [0339] 146, 146.sup.I bearing, in particular second floating bearing [0340] 147 second shaft bearing [0341] 148 idler wheel [0342] 150, 150.sup.I, 150.sup.II spur gear ratio stage [0343] 152 lubrication passage [0344] 154 central hole structure [0345] 155 spectacles-type bearing bracket support structure [0346] 156 air space [0347] 157 sub-case connection surface [0348] 158 spectacles-type bearing bracket attachment [0349] 159 spectacles-type bearing bracket fork [0350] 161 first stub shaft [0351] 162 journal region, in particular journal of the first stub shaft [0352] 163 second stub shaft [0353] 164 journal receptacle, in particular of the second stub shaft [0354] 165 first stub [0355] 167 second stub [0356] 169 first stepped shaft [0357] 171 second stepped shaft [0358] 173 first bearing, in particular bearing pair [0359] 175 second bearing, in particular bearing pair [0360] 177 first ball bearing, in particular deep groove ball bearing [0361] 179 second ball bearing, in particular deep groove ball bearing [0362] 181 first cylindrical roller bearing [0363] 183 second cylindrical roller bearing [0364] 190 case longitudinal direction [0365] 500, 500.sup.I motor vehicle [0366] 502 direction of travel [0367] 504 vehicle floor [0368] 506 first road wheel [0369] 508 second road wheel [0370] 510 third road wheel [0371] 512 fourth road wheel [0372] 514 steering wheel [0373] 516 steering linkage [0374] 518, 518.sup.I vehicle rear axle [0375] 520 first half-axle [0376] 522 second half-axle [0377] 524 vehicle longitudinal axis [0378] 526 rear compartment [0379] 528 trunk region [0380] 532 coupling [0381] 534 coupling [0382] M region, in particular middle region [0383] B reference plane [0384] g straight line [0385] d.sub.1 diameter of a gear 75, 75.sup.I of the input shaft [0386] d.sub.2 diameter of a gear of the stepped gear 49, 49.sup.I [0387] d.sub.3 diameter of a gear of the stepped gear 50, 50.sup.I [0388] d.sub.4 diameter of a gear 77, 77.sup.I of the output shaft [0389] β.sub.1 angle of inclination [0390] β.sub.2 angle of inclination [0391] α angle, in particular deviation from the reference plane B