Abstract:
A multi-group transmission of a motor vehicle which includes at least two transmission groups arranged in a drivetrain and a way for supporting traction force during gearshifts such that traction-force gearshifts are maintained with improved shifting comfort at comparatively low cost, little design effort and compact installation space demands. At least one electromagnetic clutch is a change-under-load unit by which, bypassing the force flow of at least one main group made as a gear-change transmission, an active connection can be formed between a driveshaft and a main transmission shaft or a transmission output shaft. During a gearshift operation, an active connection is temporarily made between a driveshaft and a main transmission shaft or a transmission output shaft by way of at least one electromagnetic clutch designed as a change-under-load unit.

Description:
[0001]    This application claims priority from German patent application serial no. 10 2008 001 537.7 filed May 5, 2008. 
       FIELD OF THE INVENTION 
       [0002]    The invention concerns a multi-group transmission of a motor vehicle and a method for operating a multi-group transmission of a motor vehicle. 
       BACKGROUND OF THE INVENTION 
       [0003]    Multi-group transmissions consist of two or more transmission groups, usually arranged in series, by combining which a large number of gears can be produced. Increasingly, they are designed as automated gearshift transmissions consisting, for example of an input group, a main group and a downstream range group. Such transmissions are used in particular in utility vehicles since they provide an especially fine gradation of gears, for example with 12 or 16 gears, and are highly efficient. For a smaller number of gears configurations with only a main group and an input group or a main group and a range group are also possible. Furthermore, compared with manual gearshift transmissions they are characterized by high operating comfort and, compared with automatic transmissions, their production and operating costs are particularly economical. 
         [0004]    By virtue of their structure conventional multi-group gearshift transmissions, like all manual or automated gearshift transmissions not shifted under load, undergo a traction force interruption during gearshifts since the flow of force from the drive motor is always interrupted by disengaging a clutch in order to disengage the engaged gear without load, to synchronize the transmission and the drive motor in a neutral position to a connection speed, and then to engage the target gear. Since the vehicle is rolling during the traction force interruption, undesired speed increases or speed decreases can occur. In addition the fuel consumption can increase. Whereas with passenger motor vehicles the traction force interruption, which affects the driving dynamics, is as a rule perceived only as annoying, for example during upshifts in a driving style of sporty orientation, in the case of medium-weight or heavy utility vehicles the driving speed can be reduced to the point where an upshift is made impossible and, on uphill stretches, undesired downshifts, creep-driving or even additional starting operations may be necessary. 
         [0005]    From DE 10 2006 024 370 A1 by the present applicant a traction-force-supported automated multi-group transmission with a splitter group as its input transmission, a main group as its basic transmission and a range group as its output or downstream transmission is known. The structure of this known multi-group transmission with its input group and the main group enables a direct gear to be engaged as an intermediate gear during a gear change. For this, a direct connection is temporarily formed between an input shaft of the input transmission and a main shaft of the main transmission by means of a change-under-load clutch. This renders the main transmission and the splitter group free from load, so that the engaged gear can be disengaged, the transmission synchronized and the target gear engaged, during all of which the starting clutch remains engaged. The change-under-load clutch transmits the motor torque to the transmission output, and a dynamic torque that is released during a speed reduction between the original and target gears is used to a large extent to compensate the traction force interruption. The change-under-load clutch can be positioned between the input transmission and the main transmission or between the starting clutch and the input transmission. The gear ratio of the intermediate gear is determined by the direct connection of the input shaft to the main shaft. A shift in the range group is not necessarily traction-force-supported without adopting other measures. 
         [0006]    Moreover, from DE 198 44 783 C1 a method for shifting a gear-change transmission with interlock-type gearwheel clutches is known in which, by means of a gear-synchronizing transmission integrated in the speed-change transmission, optionally by means of a gear stage with ratio i&gt;1 or a gear stage with ratio i&lt;1 a drive connection can be formed between a transmission input shaft and a transmission output shaft. A respective friction clutch is associated with each of the gear stages, which are used during a gearshift operation to adapt the speed of the input shaft to the respective synchronous speed. By controlling the frictional connection between the input and output shafts and/or the drive motor, the speed of the input shaft and the torque variation at the output shaft during the gear change are influenced. A frictional starting element arranged between the drive motor and the input shaft remains engaged during the gearshift operation. Thus, the gearshift is comparable to a change-under-load. The method can be used, by virtue of a suitable alternating use of the frictional connections via one or the other gear stage of the synchronizing transmission, for upshifts or downshifts in traction and thrust operation. 
         [0007]    From EP 1 096 172 A2 an automated change-under-load transmission with unsynchronized gearshift clutches is known. Again, two friction clutches are provided for synchronization. A common flywheel is arranged as a clutch input component between a crankshaft of the drive motor and a transmission input shaft. One synchronization clutch is coupled to the lowest gear stage and used for thrust gearshifts and as a starting element. The other synchronization clutch is coupled to the highest gear stage and used for traction gearshifts. The synchronization clutches are connected on one side via the thrust or traction gears to a transmission output shaft and on the other side via the clutch input component to the transmission input shaft. Synchronization during a gearshift operation, i.e. equalization of the speed of the transmission input shaft with the speed of the gearset of the target gear, takes place by engaging or disengaging the thrust or traction synchronization clutch. During a traction shift the synchronization clutches and the gearshift clutches are actuated in a shift sequence which ensures the transmission of a drive torque to the transmission output shaft, so that the gearshift takes place with no interruption of the traction force. In contrast to the known, traction-force-supported, sequentially shifted double clutch transmissions, this transmission also enables shifts with gear intervals over more than one step to be carried out. 
         [0008]    The two last-mentioned publications each describe a change-speed transmission with change-under-load characteristics. The synchronization clutches described therein, which maintain a torque flow to the drive output, are respectively coupled to the lowest and highest gear stage of the change-speed transmission. However, this solution cannot be easily transferred to a multi-group transmission with a number of transmission groups arranged one after another in the flow of force, and its shift sequence. 
       SUMMARY OF THE INVENTION 
       [0009]    Against this background the purpose of the present invention is to indicate a multi-group transmission and a method for operating a multi-group transmission which, with comparatively small demands in terms of cost, design and construction effort, and structural space, enable traction-force-maintaining gearshifts to be carried out with further improved shifting comfort. 
         [0010]    The invention is based on the recognition that with the help of electromagnetic clutches, gears, gear constants and/or gear ranges of individual groups of an automated multi-group transmission can be shifted under load or bridged by means of additional gearsets through power-branched intermediate gears in the force flow, in order to compensate or avoid traction force interruptions in shift operations of these groups, so that with such a transmission greater operational comfort is achieved without actuating a starting element during the gear change or even when a separate starting element is omitted entirely. 
         [0011]    Accordingly, the invention starts from a multi-group transmission of a motor vehicle, with at least two transmission groups arranged in the drivetrain, in which means are provided for supporting the traction force during gearshift operations. To achieve the stated objective the invention also provides that at least one electromagnetic clutch made as a change-under-load means is provided, by virtue of which, while bypassing the force flow of at least a main group made as a gear-change transmission, an active connection can be formed between a driveshaft and a main transmission shaft or a transmission output shaft. 
         [0012]    A gearshift is understood to mean a shift operation in which an original gear is disengaged and a target gear is engaged, including also the special case in which the target gear is the same as the original gear so that no gear ratio change takes place. An electromagnetic clutch is understood to be a clutch that can be actuated by the magnetic force of an electromagnet. 
         [0013]    In addition the invention starts from a method for operating a multi-group transmission of a motor vehicle, with at least two transmission groups arranged in a drivetrain, in which traction force supporting means are activated during a gearshift operation. In relation to the method, the stated objective is achieved in that at least by means of an electromagnetic clutch made as a change-under-load means, an active connection can be temporarily formed or maintained between a driveshaft and a main transmission shaft or a transmission output shaft. 
         [0014]    According to the invention, particularly in automated multi-group transmissions with a splitter group having two gear constants as the upstream transmission, a three- or four-gear main group as a basic transmission of countershaft design and a range group of planetary structure as its downstream transmission, for example in a heavy utility vehicle, electromagnetic clutches can be used to good advantage for supporting the traction force. They are noted in particular for their accurate controllability, quick response time and compact structure. Furthermore no additional or large-size oil pump, as sometimes needed with hydraulic clutches for supporting the traction force, is required for actuating the clutch. 
         [0015]    Preferably a transmission of this type is designed with two countershafts, so that in the embodiments described below—when “one” or “at least one” countershaft is mentioned—the sense of this should be extended to two countershafts. Correspondingly, the power is branched via two countershafts. 
         [0016]    According to the invention, during a gearshift an electromagnetic clutch can engage an additional gearset as an intermediate gear, this intermediate-gear gearset being driven by at least one countershaft. In this case the electromagnetic clutch advantageously comprises a pot-like rotor on the drive input side, which encloses an axially displaceable, disk-shaped armature on the drive output side and an electric energizing magnet, such that the rotor mounted to rotate on a shaft on the drive output side is connected in a rotationally fixed manner at its outer wall to a loose wheel of the intermediate-gear gearset and has frictional means on its inner wall on the clutch input side. 
         [0017]    The armature and clutch output side frictional means are arranged fixed on the drive output shaft and the frictional means can move axially relative to one another, so that depending on the current in the energizing magnet or an embedded energizing coil, axial displacement of the armature under the action of magnetic force can bring the frictional means into active contact with one another so that the electromagnetic clutch can transfer torque in a slipping or in a friction-locked mode. An end face of the energizing magnet can function as a pressure plate of the clutch packet, and in that case to increase the contact pressure force a ball ramp device known per se can advantageously be provided. In principle, other electromagnetically actuated clutch structures are also possible. 
         [0018]    The intermediate-gear gearset with the electromagnetic clutch can be arranged downstream from the main group, and a fixed wheel fitted in a rotationally fixed manner on the countershaft is in that case engaged with a loose wheel mounted to rotate on a main transmission shaft, such that the loose wheel can be connected in a rotationally fixed manner by means of the electromagnetic clutch to the said main transmission shaft on the drive output side of the main group. This arrangement is structurally particularly compact. 
         [0019]    Also advantageous is an arrangement in which, by virtue of axially extended countershafts, the intermediate-gear gearset with the electromagnetic clutch are arranged downstream from the range group, and in that case a fixed wheel mounted rotationally fixed on the countershaft is engaged with a loose wheel mounted to rotate on the transmission output shaft, the said wheel being able to be connected rotationally fixed to the transmission output shaft by means of the electromagnetic clutch. In this case the traction force support also includes a shifting of the range group during the gear change, regardless of whether or not the range group is designed to be able to change under load or whether or not the main transmission shaft is directly connected to the transmission output shaft. 
         [0020]    Furthermore it can be provided that the splitter group has two gear constants, a further respective electromagnetic clutch being associated with each gear constant, by means of which the gear constants can be shifted under load. The electromagnetic clutches replace the usual synchronized shift mechanisms for engaging the gear constants. In this way, on the one hand a traction force interruption while shifting between the gear constants is avoided. On the other hand the electromagnetic clutches of the splitter group can also be used as starting elements so that a separate, conventional starting element can be omitted, this additionally having a cost, space and weight saving effect. 
         [0021]    The shift-under-load function and the starting function can advantageously be obtained if the electromagnetic clutch of the first gear constant on the motor side, has an armature arranged so that it can be axially displaced on the driveshaft and a rotor surrounding the armature, which is connected in a rotationally fixed manner to a loose wheel of the first gear constant and arranged together with the wheel to rotate on the driveshaft, and an energizing magnet, while the electromagnetic clutch of the second gear constant, on the transmission side, has an axially displaceable armature arranged on the driveshaft and a rotor surrounding the armature, which is connected in a rotationally fixed manner to a loose wheel of the second gear constant and arranged together with the wheel to rotate on the driveshaft, and an energizing magnet, such that on the driveshaft respective frictional means arranged on the clutch input side, and on the rotors respective frictional means arranged on the clutch output side, can be brought into mutual frictional engagement, so that the loose wheels can be connected, selectively and alternately, in a rotationally fixed manner to the driveshaft. For this, the electromagnetic clutches can be engaged or disengaged one after the other or with an overlap. 
         [0022]    In a preferred embodiment of the method according to the invention it is provided that in a gearshift involving a shift operation within the main group, the intermediate-gear gearset is engaged as an intermediate gear by means of the associated electromagnetic clutch, whereby the intermediate gear, bypassing the force flow of the main group, forms an active connection between the driveshaft and the main transmission shaft or the transmission output shaft. This enables traction upshifts or downshifts to be carried out with no interruption of the traction force. By engaging the intermediate gear the main transmission is rendered free from load and can therefore be shifted. The gearshift clutch of the original gear in the main transmission preferably remains engaged until the shift to the target gear has been made. Rather, the electromagnetic clutch on the additional, intermediate-gear gearset supports the motor torque at the drive output in its slipping condition, while the motor speed is adapted to the target gear selected. 
         [0023]    Since by means of an appropriate intermediate gear the rotating masses to be synchronized can be braked, the transmission brake usually provided for braking those masses during upshift processes can be omitted, whereby further costs, space and weight are saved. Only for a shift process is the gearshift clutch of the original gear engaged in the main transmission disengaged, and the desired target gear is engaged when the synchronous speed has been reached. Thereafter the electromagnetic clutch is disengaged again and the force flow is then transmitted via the new gear. 
         [0024]    Such traction-force-supported gear changes are also possible with gear intervals covering two or more gear steps. Since the drivetrain remains under load throughout the gear change by virtue of the intermediate gear, fluctuations and jerky shifts are also reduced, which results in an additional improvement of the shifting comfort. 
         [0025]    In further preferred version of the method according to the invention it is provided that during a gear change involving a shift operation within the splitter group, a shift is carried out by means of the associated electromagnetic clutches between the gear constants, such that an active connection is preserved between the driveshaft and the main transmission shaft or the transmission output shaft. Accordingly, gear changes in which shifting only occurs between the gear constants are carried out directly under load by means of the electromagnetic clutches of the splitter group, so that in this case an engagement of an intermediate gear can be omitted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    To clarify the invention the description of a drawing with two example embodiments is attached. The drawings show: 
           [0027]      FIG. 1 : Transmission layout of a multi-group transmission of a motor vehicle with electromagnetic clutches for traction-force-supported shift operations 
           [0028]      FIG. 2 : A second embodiment of a multi-group transmission with electromagnetic clutches 
           [0029]      FIG. 3 : Schematic representation of an electromagnetic clutch for engaging an intermediate gear, drawn on a larger scale, and 
           [0030]      FIG. 4 : Two more electromagnetic clutches for shifting a splitter transmission, drawn on a larger scale. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]      FIG. 1  shows an automated multi-group transmission designed as a dual-countershaft transmission  1 , with two parallel rotating countershafts  8 ,  9  and three transmission groups  2 ,  3  and  4  arranged one after another, as can be provided for example in the drivetrain of a truck. Such a transmission, as such, i.e. without traction force support, is known in particular from the ZF-AS Tronic series, and with traction-force-supporting direct gear engagement from DE 10 2006 024 370 A1 by the present applicant, mentioned earlier. 
         [0032]    The first transmission group  2 , located on the motor side, is formed as a two-gear splitter group. The second, central transmission group  3  consists of a three-gear main or basic transmission. The third, output-side transmission group  4  is a two-gear range group arranged on the downstream side. 
         [0033]    The splitter group  2  has two gear constants i k1 , i k2 , each comprising a fixed wheel  10 ,  12  or  13 ,  15  respectively arranged rotationally fixed on the first countershaft  8  and on the second countershaft  9 , these wheels meshing with a respective loose wheel  11  or  14 . To engage the gear constants i k1 , i k2 , in each case an electromagnetic clutch  5  or  7 , to be described in detail later, is provided, by means of which the loose wheels can optionally be connected rotationally fixed to a driveshaft  6  of a drive motor (not shown). By means of these electromagnetic clutches  5 ,  7  the splitter group can be shifted under load, i.e. the gear constants i k1 , i k2  can be switched between without interruption of the drive input. The electromagnetic clutches can also be used as starting elements and are therefore correspondingly sized. 
         [0034]    The main transmission  3  has three forward gears i 1 , i 2  and i 3  and a reverse gear i R . The 1 st  and 2 nd  gears each have two fixed wheels  18 ,  20  or  21 ,  23  and a loose wheel  19  or  22 . The 3 rd  gear is produced in combination with the second gear constant i k2 , of the splitter transmission  2 . The reverse gear comprises two fixed wheels  24 ,  28 , a loose wheel  26  and two rotating intermediate wheels,  25 ,  27  for reversing the rotation direction, which mesh on one side with the respective associated fixed wheel  24  or  28  and on the other side with the loose wheel  26 . To engage the 1 st  gear and the reverse gear a shift device  29  with shifting claws is provided, by means of which the associated loose wheel  19  or  26  can selectively be connected rotationally fixed to a main transmission shaft  30 . To engage the 2 nd  gear and the 3 rd  gear a claw-type shift device  31  is provided, by means of which the respective associated loose wheel  14  or  22  can selectively be coupled rotationally fixed to the main transmission shaft  30 . 
         [0035]    The downstream range transmission  4  is made as a planetary transmission. 
         [0036]    In it, a planetary gearset  32  is guided by a planetary gear carrier  33 . The planetary gearwheels mesh on one side with a central sun gear  34  and on the other side with an outer ring gear  35 . The sun gear  34  is connected to the main transmission shaft  30  and the planetary gear carrier  33  to a transmission output shaft  36 . To shift the range transmission  4  a shifting device  37 , preferably with synchronization, is provided. In a first shift position this shifting device  37  connects the ring gear  35  to a housing  38 , so that the planetary gears rotate between the ring gear  35  and the sun gear  34  and, in accordance with the gear ratio, the transmission output shaft  36  is driven by the planetary gear carrier  33  in the same direction as the main transmission shaft  30 . In a second shift position the ring gear  35  is locked to the planetary gear carrier  33 , so that the planetary transmission  4  and hence the transmission output shaft  36  rotate directly at the same speed as the main transmission shaft  30 . 
         [0037]    The combination of the transmission groups  2 ,  3  and  4  shown in the transmission layout illustrated gives a total of 2×3×2=12 gears. The force flow of the transmission  1  branches according to a shift sequence in which, beginning with the 1 st  gear in the main transmission  3 , first the splitter transmission  2  and the main transmission  3  are shifted through in alternation so that, in succession, 2×3=6 gears of a lower gear range “1 st  to 6 th  gears” are engaged. When the 6 th  gear is reached the range transmission  4  is shifted over, and the main transmission  3  and splitter transmission  2  are again shifted through in alternation so that, again 2×3=6 gears, but this time in an upper gear range. “7 th  to 12 th  gears” are engaged. The upstream splitter group  2  also engages the reverse gear ratio i R  in alternation, so that in addition two reverse gears are available. 
         [0038]    Between the main transmission  3  and the range transmission  4  is arranged an additional gearset  17  as an intermediate gear, which can be engaged by means of an electromagnetic clutch  16 . The intermediate-gear gearset  17  comprises two fixed wheels  39  and  41  mounted on the countershafts  8  and  9 , which are engaged with a loose wheel  40  on the main transmission shaft  30 . The loose wheel  40  is connected to the electromagnetic clutch  16  by which it can be connected in a rotationally fixed manner to the main transmission shaft  30 . 
         [0039]      FIG. 2  shows a comparable dual-countershaft transmission  1 ′ with an intermediate-gear gearset  17 ′ and an electromagnetic clutch  16 ′, which are arranged behind the range group  4 , i.e. directly on the transmission output. In addition the countershafts  8 ′,  9 ′, are extended axially beyond the range group  4 . The intermediate-gear gearset  17 ′ comprises two fixed wheels  39 ′,  41 ′ mounted on the countershafts  8 ′,  9 ′, which engage with a loose wheel  40 ′ on the transmission output shaft  36 . The loose wheel  40 ′ is connected to the electromagnetic clutch  16 ′ by means of which it can be connected in a rotationally fixed manner to the transmission output shaft  36 . 
         [0040]      FIGS. 3 and 4  show the electromagnetic clutches  5 ,  7 ,  16 ,  16 ′ in detail.  FIG. 3  shows the electromagnetic clutch  16 ,  16 ′ of the intermediate-gear gearset  17 ,  17 ′. The clutch drive, i.e. its input side, is formed as a pot-like rotor  42  connected in a rotationally fixed manner to the loose wheel  40 ,  40 ′ of the intermediate-gear gearset  17 ,  17 ′. On its inside the rotor  42  has an annular friction disk  43 . The clutch output, i.e. the output side, is made as a disk-shaped armature  44  mounted in a rotationally fixed manner but able to move axially on the main transmission shaft  30  or the transmission output shaft  36 . In addition, two friction disks  45 ,  46 , are arranged so that they axially enclose the input-side friction disk  43 . The corresponding friction disks  43 ,  45 ,  46  can move axially relative to one another. 
         [0041]    Coaxially thereto is arranged a cup-shaped energizing magnet  47  with an energizing coil (not shown), with a ball ramp device  48  arranged in front of one end to increase the contact pressure. The rotor  42 , armature  44 , frictional means  43 ,  45 ,  46  and energizing magnet  47  together form a clutch packet, so that when current flows in the energizing magnet  47  a correspondingly strong magnetic field produces an engaged condition in which the frictional means  43 ,  45 ,  46  are locked together frictionally or, depending on the degree of engagement, they act in a slipping mode, and in the disengaged condition when the magnetic field is switched off, they are separated from one another by restoring means (not shown). 
         [0042]      FIG. 4  shows the electromagnetic clutches  5 ,  7  of the splitter group  2 . These are arranged in diametrically mirrored positions on the driveshaft  6  so that one clutch  5  is associated with the first gear constant i k1  and the other clutch  7  with the second gear constant i k2 . The structure of the two splitter group clutches  5 ,  7  is comparable to that of the intermediate gear clutch  16 ,  16 ′, although the input and output sides are reversed, i.e. the drive input is from the driveshaft  6  and the drive output takes place via the respective loose wheel  11  or  14  of the gear constant i k1  or i k2 . 
         [0043]    The clutch  5  associated with the first gear constant i k1  comprises a rotor  49  with output-side friction means  50  on the outside, which is connected in a rotationally fixed manner to the associated loose wheel  11 , an armature  51  with associated, input-side frictional means  52 ,  53  and an energizing magnet  54  with a ball ramp device  55 . 
         [0044]    The clutch  7  associated with the second gear constant i k2  comprises a rotor  56  with friction means  57  on the outside, which is connected in a rotationally fixed manner to the associated loose wheel  14 , an armature  58  with associated, input-side frictional means  59 ,  60  and an energizing magnet  61  with a ball ramp device  62 . On the output-side end face facing toward the main group  3  the rotor  56  is connected to the shifting device  31  of the 2 nd  and 3 rd  gears of the main group  3  (see  FIG. 1 ). 
         [0045]    A method according to the invention for operating the multi-group transmission described is based essentially on the engagement of an intermediate gear, by which the traction force of the vehicle is maintained while the main group  3  is in neutral during a gearshift operation. According to this, for example in an upshift with a shift operation in the main group  3 , to engage an intermediate gear the electromagnetic clutch  16 ,  16 ′ of the intermediate-gear gearset  17 ,  17 ′ is controlled so as to operate in slipping mode. This transmits the motor torque to the main transmission shaft  30  or directly to the transmission output shaft  36 . 
         [0046]    Consequently, the main transmission  3  is freed from load. During this torque transmission by the slipping electromagnetic clutch  16 ,  16 ′ of the intermediate-gear the motor speed is reduced to a synchronous speed of a target gear. The torque released by this speed reduction is used for maintaining the traction force. The shift from the original gear to the target gear then takes place, and finally the electromagnetic clutch  16 ,  16 ′ is disengaged. 
         [0047]    If the splitter group  2  is not involved in the gearshift operation, drive input takes place via the engaged gear constant, i k1 , i k2  and the countershafts,  8 ,  8 ′,  9 ,  9 ′ bypassing the main group  3 , to the intermediate-gear gearset  17 ,  17 ′. If, however, the shift operation involves a shift in the splitter group  2 , then this takes place under load by virtue of the associated electromagnetic clutches  5 ,  7 , i.e. in a change between the gear constants i k1 , i k2  the torque connection to the drive motor is maintained in any case. 
         [0048]    In the case of an intermediate-gear gearset  17 ′ arranged downstream from the range group  4  a shift of the gear range is automatically traction-force-supported. 
         [0049]    On the other hand, if the intermediate-gear gearset  17  is upstream from the range group  4 , additional measures may sometimes be needed for traction force support. 
       List of indexes 
       [0000]    
       
           1 ,  1 ′ Two-countershaft transmission, multi-group transmission 
           2  Splitter transmission 
           3  Main transmission 
           4  Range transmission 
           5  Electromagnetic clutch 
         Driveshaft 
           7  Electromagnetic clutch 
           8 ,  8 ′ Countershaft 
           9 ,  9 ′ Countershaft 
           10  Fixed wheel 
           11  Loose wheel 
           12  Fixed wheel 
           13  Fixed wheel 
           14  Loose wheel 
           15  Fixed wheel 
           16 ,  16 ′ Electromagnetic clutch 
           17 ,  17 ′ Intermediate-gear gearset 
           18  Fixed wheel 
           19  Loose wheel 
           20  Fixed wheel 
           21  Fixed wheel 
           22  Loose wheel 
           23  Fixed wheel 
           24  Fixed wheel 
           25  Intermediate wheel 
           26  Loose wheel 
           27  Intermediate wheel 
           28  Fixed wheel 
           29  Shift device 
           30  Main transmission shaft 
           31  Shift device 
           32  Planetary gearset 
           33  Planetary gear carrier 
           34  Sun gear 
           35  Ring gear 
           36  Transmission output shaft 
           37  Shift device 
           38  Housing 
           39 ,  39 ′ Fixed wheel 
           40 ,  40 ′ Loose wheel 
           41 ,  41 ′ Fixed wheel 
           42  Rotor 
           43  Friction means 
           44  Armature 
           45  Friction means 
           46  Friction means 
           47  Energizing magnet 
           48  Ball ramp device 
           49  Rotor 
           50  Friction means 
           51  Armature 
           52  Friction means 
           53  Friction means 
           54  Energizing magnet 
           55  Ball ramp device 
           56  Rotor 
           57  Friction means 
           58  Armature 
           59  Friction means 
           60  Friction means 
           61  Energizing magnet 
           62  Ball ramp device 
         i k1  Splitter group gear constant 
         i k2  Splitter group gear constant 
         i 1  Main transmission gear 
         i 2  Main transmission gear 
         i 3  Main transmission gear 
         i R  Main transmission reverse gear