Abstract:
A motor vehicle transmission having at least two sub-transmissions, each with at least one input shaft. The input shafts are arranged on an input side on an input axis. The two sub-transmissions have a single output shaft. A countershaft assembly having two countershafts aligned on a countershaft axis. A main shaft arranged on the input axis can be connected, via range groups, to the output shaft. At least one of the input shafts can connect to the output shaft via at least one of a gear plane, a shift element and the main shaft. At least three shift devices are arranged with at most one of the shift devices is arranged on the countershaft axis. The first three shift devices are arranged, relative to torque flow, downstream of the input side of the transmission on the input axis.

Description:
[0001]    This application is a National Stage completion of PCT/EP2013/075879 filed Dec. 9, 2013, which claims priority from German patent application serial no. 10 2013 200 196.7 filed Jan. 9, 2013. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention concerns a transmission, in particular a dual-clutch transmission for a motor vehicle, comprising at least two partial transmissions, wherein each partial transmission has at least one input shaft and wherein the at least two input shafts are arranged on a drive input side along an input shaft axis, an output shaft on a drive output side as the drive output shaft of both partial transmissions, a countershaft assembly, wherein the countershaft assembly comprises at least one countershaft axis with at least two countershafts, at least one main shaft arranged on the input shaft axis and at least one range group, by way of which at least one main shaft can be connected to the drive output shaft, such that at least one of the input shafts can be connected to the drive output shaft by way of at least one wheel plane and/or at least one shifting element and/or at least one main shaft. 
       BACKGROUND OF THE INVENTION 
       [0003]    Transmissions for motor vehicles are designed among others as so-termed dual-clutch transmissions, in which, in each case, an input shaft is associated with a partial transmission and in which the input shafts of the two partial transmissions can be connected by way of a respective powershift element to a drive input, for example an internal combustion engine or an electric machine, wherein the two powershift elements are combined in the form of a dual clutch. The gears that can be obtained by means of such a transmission are then distributed in alternation between the two partial transmissions so that, for example, one partial transmission is used to obtain the even-numbered gears and the corresponding other partial transmission the odd-numbered gears. It is also known to obtain the individual gears by means of one or more wheel stages or wheel planes, each having a different transmission ratio. By means of corresponding shifting elements these can be connected into the force or torque flow between the drive input and the drive output, so that a corresponding, desired transmission ratio between the drive input and the drive output can in each case be obtained. 
         [0004]    By virtue of an alternating distribution of the gears between the two partial transmissions it is possible, when driving in a gear associated with one partial transmission, already to pre-select a subsequent gear by appropriate actuation of the shifting devices so that an eventual shift to the subsequent gear is enabled by opening the powershift element of the one partial transmission and shortly thereafter closing the powershift element of the other partial transmission. In this way the gears or gear steps of the transmission can be powershifted, which improves the accelerating ability of the motor vehicle by virtue of a gearshift that is consequently essentially free from traction force interruption, and which makes for more comfortable shifting processes for a vehicle driver. 
         [0005]    Such dual-clutch transmissions can also be made with a countershaft assembly provided in addition to the drive input and the drive output, such that a more compact structure in the axial direction is made possible. 
         [0006]    From DE 10 2005 044 068 A1 a transmission for a motor vehicle in the form of a dual-clutch transmission is already known. This powershiftable group transmission provides a large number of gears and is particularly suitable for commercial vehicles. A splitter group, a direct gear, a main group and a hollow shaft on a countershaft are provided. Between gears obtained by a change of the input constants within the splitter group without changing the transmission ratio in the main group, gearshifts can be carried out without traction force interruption. In addition, between two adjacent gears obtained by a transmission ratio change in the main group, again gearshifts can be carried out without traction force interruption. 
         [0007]    From DE 10 2010 030 569 A1 a further transmission, particularly one for a motor vehicle with a hybrid drive, has become known. 
       SUMMARY OF THE INVENTION 
       [0008]    An objective of the present invention is therefore to make available a transmission for a motor vehicle, which has good powershifting ability and good hybridizing ability. Moreover, an objective of the present invention is to provide a transmission for a motor vehicle which can be produced more simply and inexpensively and which at the same time enables a reliable transmission of torques between the drive input and the drive output. A further objective of the present invention is to indicate an alternative transmission for a motor vehicle. 
         [0009]    The present invention achieves these objectives with a transmission, in particular a dual-clutch transmission for a motor vehicle, which comprises at least two partial transmissions, wherein each partial transmission has at least one input shaft and wherein the at least two input shafts are arranged on a drive input side on an input shaft axis, an output shaft on a drive output side as the drive output shaft of both partial transmissions, a countershaft assembly wherein the countershaft assembly has at least one countershaft axis with at least two countershafts, at least one main shaft arranged on the input shaft axis, and at least one range group, by way of which at least one main shaft can be connected to the drive output shaft, wherein at least one of the input shafts can be connected to the drive output shaft by way of at least one wheel plane and/or at least one shifting element and/or at least one main shaft, characterized in that there are N shifting devices, at most one of the N shifting devices is arranged on the at least one countershaft axis, and wherein N is an integer larger than or equal to three and the first three shifting devices are arranged in torque flow downstream from the drive input side of the transmission on the input shaft axis. 
         [0010]    The invention also achieves its objective by virtue of a motor vehicle, in particular a passenger or utility vehicle, having a transmission as described below. 
         [0011]    One of the advantages achieved thereby is to multiply the gears and reduce the load on the transmission elements of the transmission by virtue of a lower spread, since no extreme transmission ratios are produced by individual wheel planes. Further advantages are that the transmission has good powershifting ability and good hybridization ability. 
         [0012]    Preferably in the description and particularly in the claims, the term “wheel stage” or “wheel plane” is understood to mean essentially two transmission elements that cooperate with one another for the transmission of torques from one transmission element to the other transmission element, which wheel plane preferably provides a step-down or step-up ratio in particular for the shafts of the transmission that cooperate with the transmission elements. 
         [0013]    Preferably in the description and particularly in the claims, the term “shifting element” is understood to mean a device which has at least an open and a closed condition, such that in the open condition the device transmits no torque and in the closed condition the device can transmit a torque between two devices that cooperate with the device or shifting element. 
         [0014]    Preferably in the description and particularly in the claims, the term “shifting device” is understood to mean at least one shifting element and at least one device for actuating the at least one shifting element. 
         [0015]    Preferably in the description and particularly in the claims, the term “transmission element” is understood to mean a device by which force and/or torque can be transmitted. Transmission elements can preferably be in the form of wheels, preferably gearwheels, in particular spur gears, bevel gears, worm gears or the like. 
         [0016]    Preferably in the description and particularly in the claims, the term “dual shifting element” is understood to mean two shifting elements and two separate shifting element actuating devices, particularly in the form of sliding sleeves, which can be actuated in such manner that at least one of the two shifting elements is closed and the respective other shifting element is at the same time opened. 
         [0017]    Further advantageous embodiments, features and advantages of the invention are described in the subordinate claims. 
         [0018]    Expediently the countershaft assembly comprises two countershaft axes, each with at least two countershafts. By virtue of this arrangement the forces that occur between transmission elements on the input and countershaft axes are reduced. In the case when the transmission elements are gearwheels, this enables the tooth width to be smaller. 
         [0019]    Advantageously, at least two of the input shafts are arranged coaxially with one another and/or at least two of the main shafts are arranged coaxially with one another and/or at least two of the countershafts are arranged coaxially with one another. This reduces the fitting space occupied, for example by the at least two input shafts. Thus, the transmission can also be used in a motor vehicle when space is restricted. 
         [0020]    Expediently, at least one of the input shafts and/or at least one of the countershafts and/or at least one of two main shafts is in the form of a hollow shaft and the respective other shaft is a solid shaft. This makes for a particularly space-saving arrangement, for example of the two input shafts, since the input shaft in the form of a hollow shaft can be arranged coaxially with and parallel to the solid input shaft. With the design as a solid shaft and/or as a hollow shaft, in each case transmission elements that have to be connected fixed to the solid or hollow shaft can be made integrally with the shaft concerned, and therefore inexpensively. Thus, a time-consuming and thus costly fixing of respective transmission elements to the corresponding shafts can be dispensed with. 
         [0021]    Advantageously, the shifting devices comprise one and/or two shifting elements. If the shifting device has only one shifting element the flexibility of the transmission is increased, since each shifting element can be actuated independently of other shifting elements. If the shifting device comprises two shifting elements, these can be actuated together by one shifting element actuating device, which saves space and costs. 
         [0022]    Expediently, at least one gear that can be obtained by the transmission can be bypassed by means of the countershaft assembly to at least the first two of the shifting devices arranged in the torque flow downstream from the drive input side. By virtue of this design measure through-going powershifting of the whole transmission is ensured. 
         [0023]    Advantageously, at least one reverse gear is provided. Thus, the rotational direction of the drive output shaft relative to one of the input shafts can be reversed. By virtue of the at least one reverse gear, the flexibility with regard to using the transmission in a variety of vehicles is substantially increased. 
         [0024]    Expediently, the at least one reverse gear and a first forward gear can be engaged by way of the same powershift element. With this arrangement only one of the powershift elements has to be designed as a starting clutch. Thus, the structure of the transmission as a whole is considerably simplified. 
         [0025]    Advantageously, the at least one reverse gear can be actuated by means of at least one of the N shifting devices, the at least one shifting device being the second shifting device which is arranged in the torque flow downstream from the drive input side. An advantage of this arrangement is that with the transmission the reverse gear can be obtained in a simple manner. 
         [0026]    Expediently, one of the N shifting devices comprises a single shifting element, which is arranged on the input shaft axis after at least the first two, in particular the first three of the N shifting devices in the torque flow downstream from the drive input side. In this way, a further force and torque path for a gear is provided by simple means, so that the flexibility is increased, on the one hand, with regard to obtaining various gears and, on the other hand, with regard to the use of the transmission in different motor vehicles. 
         [0027]    Advantageously, the at least one range group is designed as a planetary gear assembly or as a countershaft assembly. By virtue of the planetary gear assembly, or the range group designed as a countershaft assembly, the number of gear steps of both partial transmissions is doubled so that for a larger number of vehicles a large enough number of gears or gear steps can be provided. 
         [0028]    Expediently, first and second range groups are provided, wherein the first and second range groups are in the form of planetary gear assemblies and/or countershaft assemblies. By virtue of this design measure thanks to a compact structure reliable shifting ability of the transmission is ensured and the number of gear steps is quadrupled. If both the first and second range groups are countershaft assemblies, an essential advantage given by this is that no separate, complex planetary gear assembly has to be provided, and thus is more simple and less costly. 
         [0029]    Preferably the transmission has a sun shaft on the input shaft axis, which on the one hand can be coupled to one of the input shafts and on the other hand is connected to the sun gear of the planetary gear assembly. This further increases the flexibility of the transmission so that numerous gears or gear steps of the transmission can be obtained with the transmission. 
         [0030]    Expediently, the shifting device for actuating the planetary gear assembly comprises at least one shifting element, and by means of the at least one shifting element a ring gear of the planetary gear assembly can be connected to a housing of the transmission. One of the resulting advantages is that the ring gear of the planetary gear assembly can either be rotationally fixed or allowed to rotate freely, which further increases the number of possible gear steps or transmission ratios. Besides, a gear ratio in the fast range is made possible. 
         [0031]    Advantageously, the shifting device for actuating the planetary gear assembly comprises two shifting elements, such that by means of one of the shifting elements the ring gear can be connected to a planetary carrier of the planetary gear assembly. The advantage of this is that it enables block rotation of the planetary gear assembly. 
         [0032]    Expediently, in order to hybridize the transmission an electric machine is arranged on at least one transmission element of a wheel plane and/or on at least one countershaft and/or on at least one of the shafts on the input shaft axis, in particular by means of an additional shifting device and/or a transmission element connected thereto. 
         [0033]    One of the advantages achieved thereby is that the transmission can also be used in hybrid vehicles, in which both an electric machine and an internal combustion engine cooperate with the transmission for the transmission of force and torque to the drive output of the hybrid vehicle. For this, the at least one electric machine can be connected to at least one of the input shafts, to the sun shaft or to the drive output shaft, or to at least one of the countershafts. The electric machine can also be connected to a transmission element of one of the wheel planes which is a loose wheel. The corresponding transmission element can then be coupled to the shaft concerned by means of a shifting element. 
         [0034]    It is also possible to connect the electric machine to a transmission element which is a fixed wheel, i.e. a transmission element connected firmly to one of the shafts of the transmission. In this case it is particularly advantageous for the electric machine to be connected to the transmission by way of at least one shifting element, in particular to a transmission element of a wheel plane. The advantage achieved by this first connection option is that a so-termed static load ability and electric driving without drag losses in the transmission are possible. In this connection explicit reference is made to the disclosure content of DE 10 2010 030 569 A1. 
         [0035]    In this case a first input shaft can be coupled with a powershift element, and a second input shaft, in particular one arranged coaxially with the first input shaft, is connected directly to a rotor of the electric machine for its drive input. For this, two parallel force transmission branches can be coupled with one another on the input side. 
         [0036]    A second possible way to connect or couple the electric machine to the transmission is by arranging a planetary gear assembly in the transmission. Then, an internal combustion engine can be coupled to a first input shaft by an appropriate shifting element, particularly in the form of a separator clutch. The electric machine engages on the one hand with a second input shaft and on the other hand with the first input shaft of the transmission by way of a planetary gear assembly. When the separator clutch is actuated, i.e. closed, the internal combustion engine is also coupled by the planetary gear assembly to the second input shaft. The planetary gear assembly, comprising a sun gear, a ring gear, planetary gearwheels and a planetary carrier, is in this case designed such that, and cooperates with the internal combustion engine and the electric machine in such manner that, the planetary carrier engages with the second input shaft. The electric machine is coupled to the sun gear of the planetary gear assembly. Moreover, a further shifting element in the form of a bridging shifting element can be provided, which cooperates with the planetary gear assembly in such manner that when the bridging shifting element is actuated there is a rotationally fixed connection between the electric machine, the first input shaft and the second input shaft, whereas in contrast when the bridging shifting element in not actuated, i.e. open, the rotationally fixed connection between the electric machine and the first and second input shafts does not exist and in particular, therefore, the rotation speeds of the two input shafts are not equal. 
         [0037]    If a further shifting element is arranged between the shifting element that serves to connect the internal combustion engine to the first input shaft and the bridging shifting element, then by means of this further shifting element, in particular in the form of a dual shifting element, both the aforesaid first connection option and the aforesaid second connection option can be implemented by actuating the further shifting element. 
         [0038]    Expediently the N shifting devices, at least six wheel planes and in particular at least nine wheel planes and the at least one range group are so arranged that at least seven forward gears, in particular at least 15 forward gears, and at least two reverse gears can be obtained by the transmission, which in particular are fully powershiftable. An advantage is the high flexibility and reliability of the transmission, so that it is suitable for use in a large number of the most varied motor vehicles. Moreover, by virtue of the large number of forward gears a motor vehicle with this transmission can be better operated in the optimum working range of the internal combustion engine, thereby in particular reducing fuel costs. 
         [0039]    Advantageously, at least one and in particular two drive input constants are provided. An essential advantage is that the drive input constants enable the transmission of force and torque by simply designed means, so the transmission also withstands more severe loading. 
         [0040]    Expediently, at least one of the shifting devices is in the form of a dual shifting element. The use of a dual shifting element has the advantage that the transmission can be built even more compactly and so takes up a minimum of fitting space in the motor vehicle, while at the same time its flexibility compared with shifting devices having two shifting elements is increased since with the two shifting elements respectively different shafts can be engaged. 
         [0041]    Further important features and advantages of the invention emerge from the claims, the drawings and the associated figure descriptions that refer to the drawings. 
         [0042]    It is understood that the features previously mentioned and still to be explained below can be used not only in the combination indicated in each case, but rather, in other combinations as well or in isolation, without going beyond the scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0043]    Preferred designs and embodiments of the present invention are illustrated in the drawings and will be explained in greater detail in the description that follows, wherein the same indexes are used for the same, or similar, or functionally equivalent components or elements. 
           [0044]    The drawings show, in schematic form: 
           [0045]      FIG. 1 : A transmission according to a first embodiment of the present invention; 
           [0046]      FIG. 2 ; A shifting matrix for a transmission according to the first embodiment of the present invention; 
           [0047]      FIG. 3 : A transmission according to a second embodiment of the present invention; 
           [0048]      FIG. 4 : A shifting matrix for a transmission according to the second embodiment of the present invention; 
           [0049]      FIG. 5 : A transmission according to a third embodiment of the present invention; 
           [0050]      FIG. 6 : A shifting matrix for a transmission according to the third embodiment of the present invention; 
           [0051]      FIG. 7 : A transmission according to a fourth embodiment of the present invention; 
           [0052]      FIG. 8 : A transmission according to a fifth embodiment of the present invention; 
           [0053]      FIG. 9 : transmission according to a sixth embodiment of the present invention; 
           [0054]      FIG. 10 : A shifting matrix for a transmission according to the sixth embodiment of the present invention; 
           [0055]      FIG. 11 ; A transmission according to a seventh embodiment of the present invention; 
           [0056]      FIG. 12 : A shifting matrix for a transmission according to the seventh embodiment of the present invention; 
           [0057]      FIG. 13 : A transmission according to a eighth embodiment of the present invention; 
           [0058]      FIG. 14 : A transmission according to a ninth embodiment of the present invention; 
           [0059]      FIG. 15 : A transmission according to a tenth embodiment of the present invention; 
           [0060]      FIG. 16 : A transmission according to a eleventh embodiment of the present invention; 
           [0061]      FIG. 17 : A shifting matrix for a transmission according to the eleventh embodiment of the present invention; 
           [0062]      FIG. 18 : A transmission according to a twelfth embodiment of the present invention; 
           [0063]      FIG. 19 : A shifting matrix for a transmission according to the twelfth embodiment of the present invention; 
           [0064]      FIG. 20 : A transmission according to a thirteenth embodiment of the present invention; 
           [0065]      FIG. 21 : A transmission according to a fourteenth embodiment of the present invention; 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0066]      FIG. 1  shows a transmission according to a first embodiment of the present invention. 
         [0067]    In  FIG. 1  the index  1  denotes a transmission in the form of a dual-clutch transmission. The dual-clutch transmission  1  comprises two powershift elements in the form of clutches K 1 , K 2 . By means of the dual clutches K 1 , K 2 , the drive input side AN can be coupled or connected to the drive output side AB of the transmission  1  for the transmission of force and torques. For this, the first clutch K 1  is connected to a first input shaft EW 1  and the second clutch K 2  is connected to a second input shaft EW 2 . The first input shaft EW 1  is in the form of a solid shaft, while in contrast the second input shaft EW 2  is a hollow shaft H 1 . The two input shafts EW 1 , EW 2  are arranged parallel to and coaxially with one another. A drive input shaft ANW connects the two clutches K 1 , K 2 , for example to a motor. 
         [0068]    In addition the transmission  1  comprises two partial transmissions  2 ,  3 . The first partial transmission  2  can be coupled to the first input shaft EW 1  and the second partial transmission to the second input shaft EW 2 . With the first partial transmission  2  is associated at least the second wheel plane II, while in contrast at least the first wheel plane I is associated with the second partial transmission  3 . 
         [0069]    Furthermore, the transmission  1  comprises an input shaft axis  4  on which the two input shafts EW 1 , EW 2  are arranged. In addition, on the input shaft axis  4  in the torque flow downstream from the two input shafts EW 1 , EW 2  is arranged a first main shaft HW 1  in the form of a first sun shaft SW 1 . The first sun shaft SW 1  is also connected to a sun gear  40  of a first planetary gear assembly GP 1 . Finally, the planetary gear assembly PG 1  can be coupled or connected to a drive output shaft AW on the input shaft axis  4 . Furthermore, the planetary gear assembly GP 1  comprises planetary gearwheels  41  mounted to rotate on a planetary carrier  42  or web  42 . Farther outward in the radial direction is arranged a ring gear  43  with which the planetary gearwheels  41  engage, as they also do with the sun gear  40 . The planetary carrier  42  of the planetary gear assembly GP 1  is connected in the torque flow downstream with a planetary carrier shaft PTW in the form of a solid shaft, which is designed to be the drive output shaft AW. Upstream in the flow of torque, the planetary carrier  42  is connected to a planetary carrier shaft PTW in the form of a hollow shaft. The planetary gear assembly GP 1  serves as a first range group RG 1 . 
         [0070]    In the flow of torque- and force, downstream from the drive input side AN of the transmission  1 , starting from the two clutches K 1 , K 2 , the transmission  1  comprises a first wheel plane I, a second wheel plane II, a first shifting element S 11 , a second shifting element S 12 , a third wheel plane III, a fourth wheel plane IV, a third shifting element S 21 , a fourth shifting element S 22 , a sixth wheel plane VI in the form of a reverse gear step, a fifth wheel plane V, a fifth shifting element  31 , and a range group RG 1  in the form of a planetary gear assembly GP 1 , which can be actuated by means of a sixth shifting element  341  and a seventh shifting element S 42 . 
         [0071]    Each of the wheel planes I, II, III, IV, V and VI comprises transmission elements, particularly in the form of gearwheels, in each case connected to a shaft of the transmission  1 . 
         [0072]    In each case, parallel to the input shaft axis  4  are arranged two countershaft axes  5   a ,  5   b  for a countershaft assembly  6 . The countershaft assembly  6  comprises a countershaft VW 1   a  in the form of a solid shaft with a countershaft VW 2   a  in the form of a hollow shaft arranged parallel to and coaxial with it on the first countershaft axis  5   a , and a countershaft VW 1   b  in the form of a solid shaft with a countershaft VW 2   b  in the form of a hollow shaft arranged parallel to and coaxial with it on the second countershaft axis  5   b . Between the input shaft axis  4  and, respectively, each of the countershaft axes  5   a ,  5   b  the sixth wheel plane VI comprises in each case an intermediate wheel ZR 1 , ZR 2  for reversing the rotational direction, so that by means of the drive output shaft AW but with the same rotational direction of the input shafts EW 1 , EW 2 , a reversed rotational direction for obtaining at least one reverse gear can be obtained. Thus, the sixth wheel plane VI is designed as the reverse gear stage. 
         [0073]    Beginning from the drive input side AN, the countershaft axis  5   a ,  5   b  comprises in each case the first wheel plane I, the second wheel plane II, the third wheel plane III, the fourth wheel plane IV, the sixth wheel plane VI in the form of a reverse gear stage, and the fifth wheel plane V. 
         [0074]    Below, the seven shifting elements S 11 , S 12 , S 21 , S 22 , S 31 , S 41  and S 42  will now be described. 
         [0075]    The first shifting element S 11  is arranged on the input shaft axis  4  and connected on the one hand to a second hollow shaft H 2  and on the other hand to the first main shaft HW 1 , in the form of the first sun shaft SW 1 . The second hollow shaft H 2  is arranged coaxially with and parallel to the first input shaft EW 1  and is functionally connected thereto. When actuated, the first shifting element S 11  forms a connection between the second hollow shaft H 2  and the first main shaft HW 1  for the transmission of force and torques. Both with the second hollow shaft H 2  and with the first input shaft EW 1  a transmission element is connected on the input shaft axis  4 , which cooperates with respective transmission elements on the two countershafts VW 2   a , VW 2   b  of the countershaft axes  5   a .  5   b  to form the second wheel plane II. 
         [0076]    The second shifting element S 12  is arranged on the input shaft axis  4  and connected on the one hand to a third hollow shaft H 3  and on the other hand to the first main shaft HW 1  or first sun shaft SW 1 , and when actuated, forms a connection for the transmission of force and torques between the third hollow shaft H 3  and the first main shaft HW 1 . The third hollow shaft H 3  is in this case arranged coaxially with and parallel to the first main shaft HW 1  or first sun shaft SW 1 , radially on the outside thereof. On the third hollow shaft H 3  is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 2   a , VW 2   b  of the countershaft axes  5   a ,  5   b  to form the third wheel plane III. 
         [0077]    The first shifting element S 11  and the second shifting element S 12  are combined together in a first shifting device SE 1  and can be actuated by a common shifting element actuating device SB 1 . 
         [0078]    The third shifting element S 21  is arranged on the input shaft axis  4  and connected on the one hand to the first main shaft HW 1  or first sun shaft SW 1  and on the other hand to a fourth hollow shaft H 4 , and when actuated, forms a connection for the transmission of force and torques between the fourth hollow shaft H 4  and the first main shaft HW 1 . The fourth hollow shaft H 4  is arranged coaxially with and parallel to the first main shaft HW 1 , radially on the outside thereof. On the fourth hollow shaft H 4  is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 1   a , VW 1   b  to form the fourth wheel plane IV. The fourth shifting element S 22  is arranged on the input shaft axis  4  and connected, on the one hand, to the first main shalt HW 1  or first sun shaft SW 1  and, on the other hand, to a fifth hollow shaft H 5 , and when actuated, forms a connection for the transmission of force and torques between the fifth hollow shaft H 5  and the first main shaft HW 1 . The fifth hollow shaft H 5  is arranged coaxially with and parallel to the first main shaft HW 1 , radially on the outside thereof. On the fifth hollow shaft H 5  is arranged a transmission element, which cooperates with respective intermediate wheels ZR 1 , ZR 2  between the input shaft axis  4  and in each case one of the two countershaft axes  5   a ,  5   b  and a respective transmission element on the two countershafts VW 1   a , VW 1   b , to form the sixth wheel plane VI in the form of the reverse gear stage. 
         [0079]    The third shifting element S 21  and the fourth shifting element S 22  are combined in a second shifting device SE 2  and can be actuated by means of a common shifting element actuating device SB 2 . 
         [0080]    The fifth shifting element S 31  is arranged on the input shaft axis  4  and enables a connection between a sixth hollow shaft H 6  and a seventh hollow shaft H 7 . The seventh hollow shaft H 7  is in the form of a planetary carrier shaft PTW and is also connected to the planetary carrier  42  of the planetary gear assembly GP. When actuated, the fifth shifting element S 31  forms a connection for the transmission of force and torque between the sixth hollow shaft H 6  and the planetary carrier shaft PTW. The fifth shifting element S 31  is arranged in a third shifting device SE 3  and can be actuated by means of a third shifting element actuating device SB 3 . The sixth hollow shaft H 6  and the planetary carrier shaft PTW are at least partially arranged coaxially with and parallel to the first sun shaft SW 1 , radially on the outside thereof. 
         [0081]    The sixth shifting element S 41  is arranged on the input shaft axis  4  and is connected, on the one hand, to the ring gear  43  of the planetary gear assembly GP 1  and, on the other hand, to the housing G of the transmission  1 , and when actuated, rotationally fixes the ring gear  43  of the transmission  1  relative to the housing G of the transmission  1 , The seventh shifting element  842  is connected, on the one hand, to the ring gear  43  of the planetary gear assembly GP 1  and, on the other hand, to the planetary carrier  42  or web of the planetary gear assembly GP 1 , and when actuated, forms a rotationally fixed connection between the ring gear  43  and the planetary carrier  42  of the planetary gear assembly GP 1 . 
         [0082]    The sixth shifting element  841  and the seventh shifting element  842  are arranged in a common, fourth shifting device SE 4  and can be actuated by means of a common fourth shifting element actuating device SB 4 . 
         [0083]    In all, the transmission  1  according to  FIG. 1  comprises two input shafts EW 1 , EW 2  on the input shaft axis  4 , the first input shaft EW 1  being in the form of a solid shaft and the second input shaft EW 2  being in the form of a hollow shaft and being arranged coaxially with and parallel to the first one. On the countershaft axes  5   a ,  5   b  parallel to the input shaft axis  4  there are respective countershafts VW 1   a , VW 1   b  made as solid shafts, and in each case parallel to and coaxial with these, respective countershafts VW 2   a , VW 2   b  in the form of hollow shafts. On the input shaft axis  4 , in the direction toward the drive output shaft AW, besides the two input shafts EW 1 , EW 2  there is arranged a first main shaft HW 1  in the form of a first sun shaft SW 1 , which is connected to a sun gear  40  of a planetary gear assembly GP 1 . In addition the planetary gear assembly GP 1  is connected to the drive output shaft AW, which is also arranged on the input shaft axis  4 . In this case a planetary carrier shaft PTW connected to a planetary carrier  42  forms the drive output shaft AW. 
         [0084]    The transmission according to  FIG. 1  comprises six wheel planes I, II, III, IV, V and VI, the sixth wheel plane forming the reverse gear stage. All the wheel planes I to VI are in particular spur gear stages with discrete transmission ratios. Each wheel plane I, II, III, IV, V and VI comprises three transmission elements, in particular in the form of gearwheels, Between the input shaft axis  4  and the two countershaft axes  5   a ,  5   b  the reverse gear stage VI comprises respective intermediate wheels ZR 1 , ZR 2 . Thus, in total 20 transmission elements, in particular in the form of gearwheels are provided for the wheel planes. Furthermore, between the first sun shaft SW 1  and the drive output shaft AW there is arranged a range group RG 1  in the form of a planetary gear assembly GP 1 . 
         [0085]    In addition, in  FIG. 1  the transmission ratios of the individual wheel planes I, II, III, IV, V and VI and that of the planetary gear assembly are shown. The first wheel plane has a transmission ratio i 1  of 1.2. The second wheel plane II has a transmission ratio i 2  of 1.2, The third wheel plane III has a transmission ratio i 3  of 1.5. The fourth wheel plane IV has a transmission ratio i 4  of 1.12. The sixth wheel plane VI has a transmission ratio i 5  of −1.5. The fifth wheel plane V has a transmission ratio i 6  of 2.0. The planetary gear assembly GP has a transmission ratio i 07  of −2.2. 
         [0086]      FIG. 2  shows a shifting matrix for a transmission according to the first embodiment of the present invention. 
         [0087]    In  FIG. 2  a shifting matrix for a transmission  1  according to  FIG. 1  is shown. Horizontally columns are shown, each for a shifting element S 11 , S 12 , S 21 , S 22 , S 31 , S 41  and S 42  and for the two clutches K 1  and K 2 . In addition the absolute transmission ratio i_ of the individual gear steps and the relative transmission ratio phi between the next-lower gear and the current gear is shown. Perpendicular to this and downward, the seven forward gears denoted by the indexes V 1  to V 7  are shown, as well as two reverse gears denoted by R 1  and R 2 . The cells in the shifting matrix left empty, for example, in the forward gear V 1 , the shifting elements S 11 , S 21 , S 22 , S 31  and S 42 , and the clutch K 2 , indicate that the corresponding shifting elements and the corresponding clutch are open, i.e. that the shifting elements and clutch in those cases transmit no forces or torque between the respective shafts linked or connected to the shifting element or clutch concerned. A cell filled with an X in the shifting matrix denotes a correspondingly actuated or closed shifting element or clutch; for example in the shifting matrix, to obtain the forward gear V 1 , the clutch K 1  and the shifting elements S 12  and S 41  are closed. 
         [0088]    Unless otherwise stated in what follows, all the clutches K 1 , K 2  and all the shifting elements S 11 , S 12 , S 21 , S 22 , S 31 , S 41  and S 42  are in each case open. 
         [0089]    To obtain the first forward gear V 1 , by means of the transmission  1 , according to  FIG. 2 , the clutch K 1  and the shifting elements S 12  and S 41  are closed. To obtain the second forward gear V 2 , the clutch K 2  and the shifting elements S 21  and S 41  are closed. To obtain the third forward gear V 3 , the clutch K 1  and the shifting elements S 11  and S 41  are closed. To obtain the fourth forward gear V 4 , the second clutch K 2  and the shifting element S 31  are closed. To obtain the fifth forward gear V 5 , the first clutch K 1  and the shifting elements S 12  and S 42  are closed, To obtain the sixth forward gear V 6 , the clutch K 2  and the shifting elements S 21  and S 42  are closed. To obtain the seventh forward gear V 7 , the first clutch K 1  and the shifting elements S 11  and S 42  are closed. To obtain the first reverse gear R 1 , the clutch K 2  and the shifting elements S 22  and S 41  are closed, To obtain the second reverse gear R 2 , the clutch K 2  and the shifting elements S 22  and S 42  are closed. 
         [0090]    The absolute transmission ratio i_ of the first forward gear V 1  is 5.76. The absolute transmission ratio i_ of the second forward gear V 2  is 4.30 and the relative transmission ratio phi between the first forward gear V 1  and the second forward gear V 2  is 1.34. 
         [0091]    The absolute transmission ratio i_ of the third forward gear V 3  is 3.20 and the relative transmission ratio phi between the second V 2  and the third V 3  forward gears is 1.34. The absolute transmission ratio i_ of the fourth forward gear V 4  is 2.40 and the relative transmission ratio phi between the third V 3  and the fourth V 4  forward gears is 1.34. 
         [0092]    The absolute transmission ratio i_ of the fifth forward gear V 5  is 1.80 and the relative transmission ratio phi between the fourth V 4  and the fifth V 5  forward gears is 1.34. The absolute transmission ratio i_ of the sixth forward gear V 6  is 1.34 and the relative transmission ratio phi between the fifth V 5  and the sixth V 6  forward gears is 1.34. 
         [0093]    The absolute transmission ratio i_ of the seventh forward gear V 7  is 1.00 and the relative transmission ratio phi between the sixth V 6  and seventh V 7  forward gears is 1.34. The absolute transmission ratio i_ of the first reverse gear R 1  is −5.76. The absolute transmission ratio i_ of the second reverse gear R 2  is −1.80. 
         [0094]      FIG. 3  shows a transmission according to a second embodiment of the present invention. 
         [0095]      FIG. 3  shows a transmission substantially according to  FIG. 1 . The difference from the transmission  1  according to  FIG. 1  is that in the transmission  1  according to  FIG. 3  the reverse gear stage VI is arranged between the third wheel plane III and the fourth wheel plane IV. For this purpose the corresponding transmission element is arranged on the fourth hollow shaft H 4 , which element cooperates respectively with the intermediate wheel ZR 1 , ZR 2  between the input shaft axis  4  and one of the two countershaft axes  5   a ,  5   b  and the corresponding transmission elements on the two countershafts VW 2   a , VW 2   b , to form the sixth wheel plane VI in the form of the reverse gear stage. Furthermore, the countershafts VW 2   a , VW 2   b  extend in the axial direction from the second wheel plane II through the third wheel plane III as far as the sixth wheel plane VI. The reverse gear stage VI can be engaged by means of the third shifting element S 21 . 
         [0096]    Furthermore,  FIG. 3  shows the transmission ratios of the individual wheel planes I, II, III, IV, V and VI and that of the planetary gear assembly GP. The first wheel plane I has a transmission ratio i 1  of 1.2. The second wheel plane II has a transmission ratio i 2  of 1.2. The third wheel plane III has a transmission ratio i 3  of 1.5. The sixth wheel plane VI has a transmission ratio i 5  of −1.5. The fourth wheel plane IV has a transmission ratio i 4  of 1.12. The fifth wheel plane V has a transmission ratio i 6  of 2.0. The planetary gear assembly GP has a transmission ratio i 07  of −2.2. 
         [0097]      FIG. 4  shows a shifting matrix for a transmission according to the second embodiment of the present invention. 
         [0098]    Unless otherwise stated below, all the clutches K 1 , K 2  and all the shifting elements S 11 , S 12 , S 21 , S 22 , S 31 , S 41  and S 42  are in each case open. 
         [0099]      FIG. 4  shows a shifting matrix for a transmission according to  FIG. 3 . Unless expressly stated in what follows, the clutches K 1 , K 2  and all the shifting elements S 11 , S 12 , S 21 , S 22 , S 31 , S 41  and S 42  are open. 
         [0100]    The manner of obtaining the forward gears V 1  to V 7  is the same as how the gears V 1  to V 7  are obtained according to  FIG. 2 . To avoid repetition, reference should be made to the description relating to  FIG. 2 . 
         [0101]    To obtain the first reverse gear R 1  the clutch K 1  and the shifting elements S 22  and S 41  are closed. To obtain the second reverse gear R 2  the clutch K 1  and the shifting elements S 22  and S 42  are closed. 
         [0102]    The absolute transmission ratio i_ of the first forward gear V 1  is 5.76. The absolute transmission ratio i_ of the second forward gear V 2  is 4.30 and the relative transmission ratio phi between the first forward gear V 1  and the second forward gear V 2  is 1.34. 
         [0103]    The absolute transmission ratio i_ of the third forward gear V 3  is 3.20 and the relative transmission ratio phi between the second forward gear V 2  and the third forward gear V 3  is 1.34, The absolute transmission ratio i_ of the fourth forward gear V 4  is 2.40 and the relative transmission ratio phi between the third forward gear V 3  and the fourth forward gear V 4  is 1.34. 
         [0104]    The absolute transmission ratio i_ of the fifth forward gear V 5  is 1.80 and the relative transmission ratio phi between the fourth forward gear V 4  and the fifth forward gear V 5  is 1.34. The absolute transmission ratio i_ of the sixth forward gear V 6  is 1.34 and the relative transmission ratio phi between the fifth forward gear V 5  and the sixth forward gear V 6  is 1.34. 
         [0105]    The absolute transmission ratio i_ of the seventh forward gear V 7  is 1.00 and the relative transmission ratio phi between the sixth forward gear V 6  and the seventh forward gear V 7  is 1.34. The absolute transmission ratio i_ of the first reverse gear R 1  is −5.76. The absolute transmission ratio i_ of the second reverse gear R 2  is −1.80. 
         [0106]      FIG. 5  shows a transmission according to a third embodiment of the present invention. 
         [0107]      FIG. 5  shows a transmission substantially according to  FIG. 1 . The difference from the transmission  1  according to  FIG. 1  is that in the transmission  1  according to  FIG. 5 , a second range group RG 2  in the form of a second planetary gear assembly GP 2  is provided. The planetary carrier or web  42  of the first planetary gear assembly GP 1  is connected to a second sun shaft SW 2 . This is connected to a sun gear  40 ′ of the second planetary gear assembly GP 2 . The second sun shaft SW 2  is a solid shaft and is arranged on the main shaft axis  4 . In contrast to the transmission  1  according to  FIG. 1 , in the transmission  1  according to  FIG. 5  fourteen gears can now be obtained by virtue of the second range group RG 2  in the form of a planetary gear assembly GP 2 . 
         [0108]    The second planetary gear assembly GP 2  has an eighth shifting element S 51  and a ninth shifting element S 52 . The eighth shifting element S 51  is arranged on the input shaft axis  4  and connected, on the one hand, to the ring gear  43 ′ of the second planetary gear assembly GP 2  and on the other hand to the housing G of the transmission  1 , and when actuated, forms a rotationally fixed connection between the ring gear  43 ′ of the transmission  1  and the housing G of the transmission  1 . The ninth shifting element S 52  is connected on the one hand to the ring gear  43 ′ of the second planetary gear assembly GP 2  and on the other hand to the planetary carrier  42 ′ or web of the second planetary gear assembly GP 2 , and when actuated, forms a rotationally fixed connection between the ring gear  43 ′ and the planetary carrier  42 ′ of the second planetary gear assembly GP 2 . 
         [0109]    The eighth shifting element S 51  and the ninth shifting element S 52  are arranged in a common, fifth shifting device SE 5  and can be actuated by means of a common, fifth shifting element actuating device SB 5 . 
         [0110]    Furthermore, in  FIG. 5  the transmission ratios of the individual wheel planes I, II, III, IV, V and VI and those of the planetary gear assemblies GP 1 , GP 2  are shown. The first wheel plane I has a transmission ratio i 1  of 1.12. The second wheel plane II has a transmission ratio i 2  of 1.12. 
         [0111]    The third wheel plane III has a transmission ratio i 3  of 1.4. The fourth wheel plane IV has a transmission ratio i 4  of 1.12. The sixth wheel plane VI has a transmission ratio  15  of −1.4. 
         [0112]    The fifth wheel plane V has a transmission ratio  15  of 1.75. The first planetary gear assembly GP 1  has a transmission ratio i 07  of −1.45. The second planetary gear assembly GP 2  has a transmission ratio i 08  of −3.8. 
         [0113]      FIG. 6  shows a shifting matrix for a transmission according to the third embodiment of the present invention. 
         [0114]      FIG. 6  shows a shifting matrix for a transmission  1  according to  FIG. 5 . Unless expressly stated in what follows, the clutches K 1 , K 2  and the shifting elements S 11  S 12 , S 21 , S 22 , S 31 , S 41 , S 42 , S 51  and S 52  are open. 
         [0115]    To obtain the first forward gear V 1 , the clutch K 1  and the shifting elements S 12 , S 41  and S 51  are closed. To obtain the second forward gear V 2 , the second clutch K 2  and the shifting elements S 21 , S 41  and S 51  are closed. To obtain the third forward gear V 3 , the first clutch K 1  and the shifting elements S 11 , S 41  and S 51  are closed. To obtain the fourth forward gear V 4 , the clutch K 2  and the shifting elements S 31  and S 51  are closed. To obtain the fifth forward gear V 5 , the clutch K 1  and the shifting elements S 12 , S 42  and S 51  are closed. To obtain the sixth forward gear V 6 , the clutch K 2  and the shifting elements S 21 , S 42  and S 51  are closed. To obtain the seventh forward gear V 7 , the clutch K 1  and the shifting elements S 11  S 42  and S 51  are closed. To obtain the eighth forward gear V 8 , the clutch K 1  and the shifting elements S 12 , S 41  and S 52  are closed. To obtain the ninth forward gear V 9 , the second clutch K 2  and the shifting elements S 21 , S 41  and S 52  are closed. To obtain the tenth forward gear V 10 , the clutch K 1  and the shifting elements S 11 , S 41  and S 52  are closed, To obtain the eleventh forward gear V 11 , the clutch K 2  and the shifting elements S 31  and S 52  are closed. To obtain the twelfth forward gear V 12 , the clutch K 1  and the shifting elements S 12 , S 42  and S 52  are closed. To obtain the thirteenth forward gear V 13 , the clutch K 2  and the shifting elements S 21 , S 42  and S 52  are closed. To obtain the fourteenth forward gear V 14 , the clutch K 1  and the shifting elements S 11 , S 42  and S 52  are closed. 
         [0116]    To obtain the first reverse gear R 1 , the clutch K 2  and the shifting elements S 22 , S 41  and S 51  are closed. To obtain the second reverse gear R 2 , the clutch K 2  and the shifting elements S 22 , S 42  and S 51  are closed. 
         [0117]    The absolute transmission ratio i_ of the first forward gear V 1  is 18.4, The absolute transmission ratio i_ of the second forward gear V 2  is 14.8, and the relative transmission ratio phi between the first V 1  and second V 2  forward gears is 1.25. 
         [0118]    The absolute transmission ratio i_ of the third forward gear V 3  is 11.8 and the relative transmission ratio phi between the second V 2  and third V 3  forward gears is 1.25. The absolute transmission ratio i_ of the fourth forward gear V 4  is 9.41 and the relative transmission ratio phi between the third V 3  and fourth V 4  forward gears is 1.25. 
         [0119]    The absolute transmission ratio i_ of the fifth forward gear V 5  is 7.53 and the relative transmission ratio phi between the fourth V 4  and fifth V 5  forward gears is 1.25. The absolute transmission ratio i_ of the sixth forward gear V 6  is 6.02 and the relative transmission ratio phi between the fifth V 5  and sixth V 6  forward gears is 1.25. 
         [0120]    The absolute transmission ratio i_ of the seventh forward gear V 7  is 4.80 and the relative transmission ratio phi between the sixth V 6  and seventh V 7  forward gears is 1.25. The absolute transmission ratio i_ of the eighth forward gear V 8  is 3.84 and the relative transmission ratio phi between the seventh V 7  and eighth V 8  forward gears is 1.25. 
         [0121]    The absolute transmission ratio i_ of the ninth forward gear V 9  is 3.07 and the relative transmission ratio phi between the eighth V 8  and ninth V 9  forward gears is 1.25. The absolute transmission ratio i_ of the tenth forward gear V 10  is 2.45 and the relative transmission ratio phi between the ninth V 9  and tenth V 10  forward gears is 1.25. 
         [0122]    The absolute transmission ratio i_ of the eleventh forward gear V 11  is 1.96 and the relative transmission ratio phi between the tenth V 10  and eleventh V 11  forward gears is 1.25. The absolute transmission ratio i_ of the twelfth forward gear V 12  is 1.57 and the relative transmission ratio phi between the eleventh V 11  and twelfth V 12  forward gears is 1.25. 
         [0123]    The absolute transmission ratio i_ of the thirteenth forward gear V 13  is −1.25 and the relative transmission ratio phi between the twelfth V 12  and thirteenth V 13  forward gears is 1.25. The absolute transmission ratio i_ of the fourteenth forward gear V 14  is 1.00 and the relative transmission ratio phi between the thirteenth V 13  and fourteenth V 14  forward gears is 1.25. 
         [0124]    The absolute transmission ratio i_ of the first reverse gear R 1  is −18.4. The absolute transmission ratio i_ of the second reverse gear R 2  is −7.53. 
         [0125]      FIG. 7  shows a transmission according to a fourth embodiment of the present invention. 
         [0126]      FIG. 7  shows a transmission substantially according to  FIG. 5 . The difference from the transmission  1  according to  FIG. 5  is that the first range group RG 1  is not a planetary gear assembly, but instead a countershaft assembly. Owing to this, two further wheel planes V and VI are additionally provided. The wheel planes I to III and VI and the first main shaft HW 1  and the second sun shaft SW 2  from  FIG. 5  correspond to the wheel planes I to III and VIII and the first main shaft HW 1  and the second sun shaft SW 2  of  FIG. 7 . The second range group RG 2  of  FIG. 5  corresponds to the second range group RG 2  of  FIG. 7 . The first main shaft HW 1  is connected to the second sun shaft SW 2  by means of the seventh shifting element S 42 . 
         [0127]    The seventh wheel plane VII in  FIG. 7  corresponds to the fifth wheel plane V of  FIG. 5 . The fifth shifting element S 31  is arranged on the input shaft axis  4  and is connected, on the one hand, to a sixth hollow shaft H 6  and, on the other hand, to the second sun shaft SW 2 , and when actuated, forms a connection for the transmission of force and torques between the sixth hollow shaft H 6  and the second sun shaft SW 2 . The sixth hollow shaft H 6  is arranged coaxially with and parallel to the second sun shaft SW 2 , radially on the outside thereof. Arranged on the sixth hollow shaft H 6  there is a transmission element, which cooperates with respective transmission elements on the two countershafts VW 3   a , VW 3   b  of the countershaft axes  5   a ,  5   b  to form the seventh wheel plane VII. 
         [0128]    The seventh shifting element S 42  is arranged on the input shaft axis  4  and is connected, on the one hand, to a seventh hollow shaft H 7  and, on the other hand, to the second sun shaft SW 2 . The seventh hollow shaft H 7  is arranged coaxially with the first main shaft HW 1  and is functionally connected thereto. When actuated, the seventh shifting element S 42  forms a force- and torque-transmitting connection between the seventh hollow shaft H 7  and the second sun shaft SW 2 . A transmission element on the input shaft axis  4  is connected to both the seventh hollow shaft H 7  and the first main shaft HW 1 , which element cooperates with respective transmission elements on the two countershafts VW 3   a , VW 3   b  of the countershaft axes  5   a ,  5   b  to form the fifth wheel plane V. The countershafts VW 3   a , VW 3   b , which are in the form of hollow shafts, extend in the axial direction from the fifth wheel plane V to the sixth wheel plane VI. 
         [0129]    The sixth shifting element S 41  is arranged on the input shaft axis  4  and is connected, on the one hand, to an eighth hollow shaft H 8  and, on the other hand, to the second sun shaft SW 2 , and when actuated, forms a force- and torques-transmitting connection between the eighth hollow shaft H 8  and the second sun shaft SW 2 . The eighth hollow shaft H 8  is arranged coaxially with and parallel to the second sun shaft SW 2 , radially on the outside thereof. On the eighth hollow shaft H 8  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 3   a , VW 3   b  of the countershaft axes  5   a ,  5   b  to form the sixth wheel plane VI. 
         [0130]    Furthermore,  FIG. 7  shows the transmission ratios of the individual wheel planes and the planetary gear assembly. The first wheel plane I has a transmission ratio i 1  of 1.12. The second wheel plane II has a transmission ratio i 2  of 1.12. The third wheel plane III has a transmission ratio i 3  of 1.4. The fourth wheel plane IV has a transmission ratio i 4  of 1.12. The eighth wheel plane VIII has a transmission ratio i 5  of −1.4. The fifth wheel plane V has a transmission ratio i 7  of 1.56. The sixth wheel plane VI has a transmission ratio i 8  of 1.57. The seventh wheel plane VII has a transmission ratio i 6  of 1.75. The planetary gear assembly GP 2  has a transmission ratio i 08  of −3.8. 
         [0131]    A shifting matrix for a transmission  1  according to  FIG. 7  corresponds to the shifting matrix shown in  FIG. 6 . 
         [0132]      FIG. 8  shows a transmission according to a fifth embodiment of the present invention. 
         [0133]      FIG. 8  shows a transmission substantially according to that of  FIG. 7 . The difference from the transmission  1  according to  FIG. 7  is now that the second range group RG 2  is made not as a planetary gear assembly, but as a countershaft assembly. Thereby, two further wheel planes VIII and IX are provided. The wheel planes I to IV and VI from  FIG. 7  are identical in  FIG. 8 . The wheel plane VIII in  FIG. 7  corresponds to the wheel plane X in  FIG. 8 . The first range group RG 1  in  FIG. 7  corresponds to the first range group RG 1  in  FIG. 8 . The second main shaft HW 2  is provided in place of the second sun shaft SW 2  and is connected by means of the ninth shifting element S 52  to the drive output shaft AW. The first main shaft HW 1  is connected to the second main shaft HW 2  by means of the seventh shifting element S 42 . 
         [0134]    The ninth shifting element S 52  is arranged on the input shaft axis  4  and connected, on the one hand, to a ninth hollow shaft H 9  and, on the other hand, to the drive output shaft AW. The ninth hollow shaft H 9  is arranged coaxially with the second main shaft HW 2  and is functionally connected thereto. When actuated, the ninth shifting element S 52  forms a force- and torque-transmitting connection between the ninth hollow shaft H 9  and the drive output shaft AW. Both with the ninth hollow shaft H 9  and with the second main shaft HW 2 , there is connected a transmission element on the input shaft axis  4 , which cooperates with respective transmission elements on the two countershafts VW 4   a , VW 4   b  of the countershaft axes  5   a ,  5   b  to form the eighth wheel plane VIII. 
         [0135]    The eighth shifting element S 51  is arranged on the input shaft axis  4  and is connected, on the one hand, to a tenth hollow shaft H 10  and, on the other hand, to the drive output shaft AW, and when actuated, forms a force- and torque transmitting connection between the tenth hollow shaft H 10  and the drive output shaft AW. The tenth hollow shaft H 10  is arranged coaxially with and parallel to the drive output shaft AW, radially on the outside thereof. On the tenth hollow shaft H 10  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 4   a , VW 4   b  of the countershaft axes  5   a ,  5   b  to form the ninth wheel plane IX. 
         [0136]    In addition,  FIG. 8  shows the transmission ratios of the individual wheel planes. The first wheel plane I has a transmission ratio i 1  of 1.12. The second wheel plane II has a transmission ratio i 2  of 1.12. 
         [0137]    The third wheel plane III has a transmission ratio i 3  of 1.4, The fourth wheel plane IV has a transmission ratio i 4  of 1.12. The tenth wheel plane X has a transmission ratio i 5  of −1.4. The fifth wheel plane V has a transmission ratio i 7  of 1.56. The sixth wheel plane VI has a transmission ratio i 8  of 1.57. The seventh wheel plane VII has a transmission ratio i 6  of 1.75. The eighth wheel plane VIII has a transmission ratio i 12  of 2.19. The ninth wheel plane IX has a transmission ratio i 13  of 2.19. 
         [0138]    A shifting matrix for a transmission  1  according to  FIG. 8  corresponds to the shifting matrix shown in  FIG. 6 . 
         [0139]      FIG. 9  shows a transmission according to a sixth embodiment of the present invention. 
         [0140]      FIG. 9  shows a transmission substantially according to  FIG. 7 . The difference from the transmission  1  according to  FIG. 7  is that a tenth shifting element S 61  is provided. 
         [0141]    The wheel planes I to IV and V to VII in  FIG. 7  are identical in  FIG. 9 . The wheel plane VIII in  FIG. 7  corresponds to the wheel plane IX in  FIG. 9 . 
         [0142]    The tenth shifting element S 61  is arranged on the input shaft axis  4  and is connected, on the one hand, to a ninth hollow shaft H 9  and, on the other hand, to a tenth hollow shaft H 10 , such that the tenth hollow shaft H 10  is in the form of a planetary carrier shaft PTW and is thus connected to the planetary carrier  42 ′ of the planetary gear assembly GP 2 . The ninth hollow shaft H 9  and the tenth hollow shaft H 10  are arranged coaxially with and parallel to the second sun shaft SW 2 . Thus, when actuated the tenth shifting element S 61  forms a force- and torque-transmitting connection between the ninth H 9  and tenth H 10  hollow shafts. On the ninth hollow shaft H 9  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 1   a , VW 1   b  of the countershaft axes  5   a ,  5   b  to form the eighth wheel plane VIII. 
         [0143]    Furthermore,  FIG. 9  shows the transmission ratios of the individual wheel planes and of the planetary gear assembly. The first wheel plane I has a transmission ratio i 1  of 1.70. The second wheel plane II has a transmission ratio i 2  of 1.40. 
         [0144]    The third wheel plane III has a transmission ratio i 3  of 1.08. The fourth wheel plane IV has a transmission ratio i 4  of 0.72. The ninth wheel plane IX has a transmission ratio i 5  of −0.89. 
         [0145]    The fifth wheel plane V has a transmission ratio i 7  of 1.51. The sixth wheel plane VI has a transmission ratio i 8  of 1.52. The seventh wheel plane VII has a transmission ratio i 6  of 1.09. 
         [0146]    The eight wheel plane VIII has a transmission ratio i 9  of 2.51. The planetary gear assembly GP 2  has a transmission ratio i 08  of −4.24. 
         [0147]      FIG. 10  shows a shifting matrix for a transmission according to the sixth embodiment of the present invention. 
         [0148]    Unless otherwise stated below, all the clutches K 1 , K 2  and all the shifting elements S 11  S 12 , S 21 , S 22 , S 31 , S 41 , S 42 , S 51 , S 52  and S 61  are in each case open. 
         [0149]      FIG. 10  shows a shifting matrix for a transmission  1  according to  FIG. 9 . To obtain the first forward gear V 1  by means of the transmission  1  according to  FIG. 9 , the clutch K 1  and the shifting elements S 12 , S 41  and S 51  are closed. To obtain the second forward gear V 2  the clutch K 2  and the shifting elements S 21 , S 41  and S 51  are closed. 
         [0150]    To obtain the third forward gear V 3  the clutch K 1  and the shifting elements S 11 , S 41  and S 51  are closed. To obtain the fourth forward gear V 4  the clutch K 2  and the shifting elements S 31  and S 51  are closed. 
         [0151]    To obtain the fifth forward gear V 5  the clutch K 1  and the shifting elements S 12 , S 42  and S 51  are closed. To obtain the sixth forward gear V 6  the clutch K 2  and the shifting elements S 21 , S 42  and S 51  are closed. 
         [0152]    To obtain the seventh forward gear V 7  the clutch K 1  and the shifting elements S 11 , S 42  and S 51  are closed. To obtain the eighth forward gear V 8  the clutch K 2  and the shifting element S 61  are closed. 
         [0153]    To obtain the ninth forward gear V 9  the clutch K 1  and the shifting elements S 12 , S 41  and S 52  are closed. To obtain the tenth forward gear V 10  the clutch K 2  and the shifting elements S 21 , S 41  and S 52  are closed. 
         [0154]    To obtain the eleventh forward gear V 11  the clutch K 1  and the shifting elements  811 , S 41  and S 52  are closed. To obtain the twelfth forward gear V 12  the clutch K 2  and the shifting elements S 31  and S 52  are closed. 
         [0155]    To obtain the thirteenth forward gear V 13  the clutch K 1  and the shifting elements S 12 , S 42  and S 52  are closed. To obtain the fourteenth forward gear V 14  the clutch K 2  and the shifting elements S 21 , S 42  and S 52  are closed. 
         [0156]    To obtain the fifteenth forward gear V 15  the clutch K 1  and the shifting elements S 11 , S 42  and S 52  are closed. 
         [0157]    To obtain the first reverse gear R 1  the clutch K 2  and the shifting elements S 22 , S 41  and S 51 . are closed. To obtain the second reverse gear R 2  the clutch K 2  and the shifting elements S 22 , S 42  and S 51  are closed. 
         [0158]    The absolute transmission ratio i_ of the first forward gear V 1  is 18.1. The absolute transmission ratio i_ of the second forward gear V 2  is 14.8, The absolute transmission ratio i_ of the third forward gear V 3  is 12.0. The absolute transmission ratio i_ of the fourth forward gear V 4  is 9.75. The absolute transmission ratio i_ of the fifth forward gear V 5  is 7.93. The absolute transmission ratio i_ of the sixth forward gear V 6  is 6.44. The absolute transmission ratio i_ of the seventh forward gear V 7  is 5.24. The absolute transmission ratio i_ of the eighth forward gear V 8  is 4.27. The absolute transmission ratio i_ of the ninth forward gear V 9  is 3.46. The absolute transmission ratio i_ of the tenth forward gear V 10  is 2.82. The absolute transmission ratio i_ of the eleventh forward gear V 11  is 2.29. The absolute transmission ratio i_ of the twelfth forward gear V 12  is 1.86. The absolute transmission ratio i_ of the thirteenth forward gear V 13  is 1.51. The absolute transmission ratio i_ of the fourteenth forward gear V 14  is 1.23. The absolute transmission ratio i_ of the fifteenth forward gear V 15  is 1.0, The absolute transmission ratio i_ of the first reverse gear R 1  is −18.2. The absolute transmission ratio i_ of the second reverse gear R 2  is −7.93. 
         [0159]      FIG. 11  shows a transmission according to a seventh embodiment of the present invention. 
         [0160]      FIG. 11  shows a transmission substantially according to  FIG. 9 . In the transmission  1  according to  FIG. 11  the difference from the transmission  1  according to  FIG. 9  is that the reverse gear stage IX is arranged between the third wheel plane III and the fourth wheel plane IV. For this, on the fourth hollow shaft H 4  there is arranged the corresponding transmission element, which cooperates with respective intermediate wheels ZR 1 , ZR 2  between the input shaft axis  4  and in each case one of the two countershaft axes  5   a ,  5   b  and the corresponding transmission elements on the two countershafts VW 2   a , VW 2   b  to form the ninth wheel plane IX in the form of the reverse gear stage. Furthermore, the countershafts VW 2   a , VW 2   b  extend in the axial direction from the second wheel plane II, through the third wheel plane III and as far as the ninth wheel plane IX. The reverse gear stage can be engaged by means of the shifting element S 21 . 
         [0161]    In addition,  FIG. 11  shows the transmission ratios of the individual wheel planes and the planetary gear assembly. The first wheel plane I has a transmission ratio i 1  of 1.70. The second wheel plane II has a transmission ratio i 2  of 1.40. The third wheel plane III has a transmission ratio i 3  of 1.08. The ninth wheel plane IX has a transmission ratio i 5  of −1.08. The fourth wheel plane IV has a transmission ratio i 4  of 0.72. The fifth wheel plane V has a transmission ratio i 7  of 1.51. The sixth wheel plane VI has a transmission ratio i 8  of 1.52. The seventh wheel plane VII has a transmission ratio i 6  of 1.09, The eighth wheel plane VIII has a transmission ratio i 9  of 2.51. The planetary gear assembly GP 2  has a transmission ratio i 08  of −4.24. 
         [0162]      FIG. 12  shows a shifting matrix for a transmission according to the seventh embodiment of the present invention. 
         [0163]    Unless otherwise stated below, all the clutches K 1 , K 2  and all the shifting elements S 11 , S 12 , S 21 , S 22 , S 31 , S 41 , S 42 , S 51 , S 52  and S 61  are in each case open. 
         [0164]      FIG. 12  shows a shifting matrix for a transmission  1  according to  FIG. 11 . To obtain the first forward gear V 1  with the transmission  1  according to  FIG. 11 , the clutch K 1  and the shifting elements S 12 , S 41  and S 51  are closed. To obtain the second forward gear V 2 , the clutch K 2  and the shifting elements S 22 , S 41  and S 51  are closed. 
         [0165]    To obtain the third forward gear V 3 , the clutch K 1  and the shifting elements S 11 , S 41  and S 51  are closed. To obtain the fourth forward gear V 4 , the clutch K 2  and the shifting elements S 31  and S 51  are closed. 
         [0166]    To obtain the fifth forward gear V 5 , the clutch K 1  and the shifting elements S 12 , S 42  and S 51  are closed. To obtain the sixth forward gear V 6 , the clutch K 2  and the shifting elements S 22 , S 42  and S 51  are closed. 
         [0167]    To obtain the seventh forward gear V 7 , the clutch K 1  and the shifting elements S 11 , S 42  and S 51  are closed. To obtain the eighth forward gear V 8 , the clutch K 2  and the shifting element S 61  are closed. 
         [0168]    To obtain the ninth forward gear V 9 , the clutch K 1  and the shifting elements S 12 , S 41  and S 52  are closed. To obtain the tenth forward gear V 10 , the clutch K 2  and the shifting elements S 22 , S 41  and S 52  are closed. 
         [0169]    To obtain the eleventh forward gear V 11 , the clutch K 1  and the shifting elements S 11 , S 41  and S 52  are closed. To obtain the twelfth forward gear V 12 , the clutch K 2  and the shifting elements S 31  and S 52  are closed. 
         [0170]    To obtain the thirteenth forward gear V 13 , the clutch K 1  and the shifting elements S 12 , S 42  and S 52  are closed. To obtain the fourteenth forward gear V 14 , the clutch K 2  and the shifting elements S 22 , S 42  and S 52  are closed. 
         [0171]    To obtain the fifteenth forward gear V 15 , the clutch K 1  and the shifting elements S 11 , S 42  and S 52  are closed. 
         [0172]    To obtain the first reverse gear R 1 , the clutch K 1  and the shifting elements S 21 , S 41  and S 51  are closed. To obtain the second reverse gear R 2 , the clutch K 1  and the shifting elements S 21 , S 42  and S 51  are dosed. 
         [0173]    The absolute transmission ratio i_ of the first forward gear V 1  is 18.1. The absolute transmission ratio i_ of the second forward gear V 2  is 14.8. The absolute transmission ratio i_ of the third forward gear V 3  is 12.0. The absolute transmission ratio i_ of the fourth forward gear V 4  is 9.75. The absolute transmission ratio i_ of the fifth forward gear V 5  is 7.93. The absolute transmission ratio i_ of the sixth forward gear V 6  is 6.44. The absolute transmission ratio i_ of the seventh forward gear V 7  is 5.24. The absolute transmission ratio i_ of the eighth forward gear V 8  is 4.27. The absolute transmission ratio i_ of the ninth forward gear V 9  is 3.46. The absolute transmission ratio i_ of the tenth forward gear V 10  is 2.82. The absolute transmission ratio i_ of the eleventh forward gear V 11  is 2.29. The absolute transmission ratio i_ of the twelfth forward gear V 12  is 1.86. The absolute transmission ratio i_ of the thirteenth forward gear V 13  is 1.51. The absolute transmission ratio i_ of the fourteenth forward gear V 14  is 1.23. The absolute transmission ratio i_ of the fifteenth forward gear V 15  is 1.0. The absolute transmission ratio i_ of the first reverse gear R 1  is −18.2. The absolute transmission ratio i_ of the second reverse gear R 2  is −7.93. 
         [0174]      FIG. 13  shows a transmission according to an eighth embodiment of the present invention. 
         [0175]      FIG. 13  shows a transmission substantially the same as that of  FIG. 9 . The difference from the transmission  1  according to  FIG. 9  is that the third shifting device SE 3  and the tenth shifting device SE 6  are arranged in the form of a dual shifting element SD 1 . The wheel planes I to VII and the ninth wheel plane IX in  FIGS. 9 and 13  are identical. 
         [0176]    The fifth shifting element S 31  is arranged on the input shaft axis  4  and is connected, on the one hand, to a sixth hollow shaft H 6  and, on the other hand, to the second sun shaft SW 2 . The sixth hollow shaft H 6  is arranged coaxially with and parallel to the second sun shaft SW 2 . Thus, when actuated the fifth shifting element S 31  forms a force- and torque-transmitting connection between the sixth hollow shaft H 6  and the second sun shaft SW 2 . On the sixth hollow shaft H 6  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 1   a , VW 1   b  of the countershaft axes  5   a ,  5   b  to form the seventh wheel plane VII. 
         [0177]    The tenth shifting element S 61  is arranged on the input shaft axis  4  and is connected, on the one hand, to a ninth hollow shaft H 9  and, on the other hand, to a tenth hollow shaft H 10 . The ninth hollow shaft H 9  is arranged coaxially with and parallel to the tenth hollow shaft H 10 , radially on the outside thereof, and thus also coaxially with the second sun shaft SW 2 , Thus, when actuated the tenth shifting element S 61  forms a force- and torque-transmitting connection between the ninth hollow shaft H 9  and the tenth hollow shaft H 10 . On the ninth hollow shaft H 9  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 1   a , VW 1   b  of the countershaft axes  5   a ,  5   b  to form the eighth wheel plane VIII. 
         [0178]    The fifth shifting element S 31  is accommodated in a third shifting device SE 3  and can be actuated by means of a third shifting element actuating device SB 3 . The tenth shifting element S 61  is accommodated in a sixth shifting device SE 6  and can be actuated by means of a sixth shifting element actuating device SB 6 . The fifth shifting element S 31  and the tenth shifting element S 61  as well as the third shifting element actuating device SB 3  and the sixth shifting element actuating device SB 6  are combined in the first dual shifting element SD 1 . 
         [0179]    A shifting matrix for a transmission according to  FIG. 13  corresponds to the shifting matrix shown in  FIG. 10 . 
         [0180]      FIG. 14  shows a transmission according to a ninth embodiment of the present invention. 
         [0181]      FIG. 14  shows a transmission  1  substantially the same as the transmission in  FIG. 13 . In contrast to  FIG. 13 , in  FIG. 14  a countershaft assembly  6  with only one countershaft axis  5   a  is provided. Otherwise, the wheel planes I to VI and wheel plane IX are identical in  FIGS. 13 and 14 . 
         [0182]    The fifth shifting element S 31  is arranged on the countershaft axis  5   a  and is connected, on the one hand, to the countershaft VW 4   a  and on the other hand to the countershaft VW 1   a , and when actuated, forms a force- and torque-transmitting connection between the countershafts VW 4   a  and VW 1   a . The countershaft VW 4   a  is arranged coaxially with and parallel to the countershaft VW 1   a . On the countershaft VW 4   a  there is arranged a transmission element, which cooperates with a transmission element on the second sun shaft SW 2  on the input shaft axis  4  to form the seventh wheel plane VII. 
         [0183]    The tenth shifting element S 61  is arranged on the countershaft axis  5   a  and is connected, on the one hand, to the countershaft VW 5   a  and, on the other hand, to the countershaft VW 1   a , and when actuated, forms a force- and torque-transmitting connection between the countershafts VW 5   a  and VW 1   a . The countershaft VW 5   a  is arranged coaxially with and parallel to the countershaft VW 1   a , On the countershaft VW 5   a  there is arranged a transmission element, which cooperates with a transmission element on the tenth hollow shaft H 10  on the input shaft axis  4  to form the eighth wheel plane VIII. The tenth hollow shaft H 10  is arranged coaxially with and parallel to the second sun shaft SW 2  on the input shaft axis  4 . The fifth shifting element S 31  and the tenth shifting element S 61  are combined in a seventh shifting device SE 7  and can be actuated by means of a seventh shifting element actuating device SB 7 . 
         [0184]    A shifting matrix for a transmission  1  according to  FIG. 14  is shown in  FIG. 10 . 
         [0185]      FIG. 15  shows a transmission according to a tenth embodiment of the present invention. 
         [0186]      FIG. 15  shows a transmission  1  substantially the same as that of  FIG. 9 . The difference from the transmission  1  of  FIG. 9  is that the second range group RG 2  is in the form not of a planetary gear assembly, but of a countershaft assembly. Thereby, two further wheel planes VIII and IX are provided. The wheel planes I to IV and V to VII and the first main shaft HW 1  in  FIG. 9  are identical in  FIG. 15 . The wheel plane IX in  FIG. 9  corresponds to the wheel plane XI in  FIG. 15 . The first range group RG 1  in  FIG. 9  corresponds to the first range group RG 1  in  FIG. 15 . The second sun shaft SW 2  in  FIG. 9  is replaced by the second main shaft HW 2 . The second main shaft HW 2  is connected to the drive output shaft AW by means of the ninth shifting element S 52 . 
         [0187]    The ninth shifting element S 52  is arranged on the input shaft axis  4  and is connected, on the one hand, to a tenth hollow shaft H 10  and, on the other hand, to the drive output shaft AW. The tenth hollow shaft H 10  is arranged coaxially with and parallel to the second main shaft HW 2 , and is functionally connected thereto. The ninth shifting element S 52 , when actuated, forms a force- and torque-transmitting connection between the tenth hollow shaft H 10  and the drive output shaft AW. A transmission element on the input shaft axis  4  is connected both to the tenth hollow shaft H 10  and to the second main shaft HW 2 , which element cooperates with respective transmission elements on the two countershafts VW 4   a , VW 4   b  of the countershaft axes  5   a ,  5   b  to form the eighth wheel plane VIII. The countershafts VW 4   a , VW 4   b , which are in the form of hollow shafts, extend in the axial direction from the eighth wheel plane VIII as far as the ninth wheel plane IX. 
         [0188]    The eighth shifting element S 51  is arranged on the input shaft axis  4  and is connected, on the one hand, to an eleventh hollow shaft H 11  and, on the other hand, to the drive output shaft AW, and when actuated, forms a force- and torque-transmitting connection between the eleventh hollow shaft H 11  and the drive output shaft AW. The eleventh hollow shaft H 11  is arranged coaxially with and parallel to the drive output shaft AW, radially on the outside thereof. On the eleventh hollow shaft H 11  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 4   a , VW 4   b  of the countershaft axes  5   a ,  5   b  to form the ninth wheel plane IX. 
         [0189]    The tenth shifting element S 61  is arranged on the input shaft axis  4  and is connected, on the one hand, to a ninth hollow shaft H 9  and, on the other hand, to the drive output shaft AW, and when actuated, forms a force- and torque-transmitting connection between the ninth hollow shaft H 9  and the drive output shaft AW. The ninth hollow shaft H 9  is arranged coaxially with and parallel to the drive output shaft AW, radially on the outside thereof. On the ninth hollow shaft H 9  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 1   a , VW 1   b  of the countershaft axes  5   a ,  5   b  to form the tenth wheel plane X. 
         [0190]    In addition,  FIG. 15  shows the transmission ratios of the individual wheel planes. The first wheel plane I has a transmission ratio i 1  of 1.70. The second wheel plane II has a transmission ratio i 2  of 1.40. The third wheel plane III has a transmission ratio i 3  of 1.08. The fourth wheel plane IV has a transmission ratio i 4  of 0.72. The eleventh wheel plane XI has a transmission ratio i 5  of −0.89. The fifth wheel plane V has a transmission ratio i 7  of 1.51. The sixth wheel plane VI has a transmission ratio i 8  of 1.52. The seventh wheel plane VII has a transmission ratio i 6  of 1.09. The eighth wheel plane VIII has a transmission ratio i 10  of 2.29. The ninth wheel plane IX has a transmission ratio i 11  of 2.29. The tenth wheel plane X has a transmission ratio i 9  of 2.51. 
         [0191]    A shifting matrix for a transmission  1  according to  FIG. 15  corresponds to the shifting matrix according to  FIG. 10 . 
         [0192]      FIG. 16  shows a transmission according to an eleventh embodiment of the present invention. 
         [0193]      FIG. 16  shows a transmission  1  substantially the same as that of  FIG. 1 . The difference from the transmission  1  according to  FIG. 1  is that two further wheel planes IV and VIII as well as a fifth shifting device SE 5  are additionally provided. The wheel planes I to III in  FIG. 1  are identical in  FIG. 16 . The wheel planes IV and V in  FIG. 1  correspond to the wheel planes V and VII in  FIG. 16 . The first range group RG 1  in  FIG. 1  corresponds to the first range group RG 1  in  FIG. 16 . 
         [0194]    The eighth shifting element S 51  is arranged on the input shaft axis  4  and is connected, on the one hand, to an eighth hollow shaft H 8  and, on the other hand, to the first main shaft HW 1 . The eighth hollow shaft H 8  is arranged coaxially with the first main shaft HW 1 . When actuated, the eighth shifting element S 51  forms a force- and torque-transmitting connection between the eighth hollow shaft H 8  and the first main shaft HW 1 . Connected to the eighth hollow shaft H 8  there is a transmission element on the input shaft axis  4 , which cooperates with respective transmission elements on the two countershafts VW 2   a , VW 2   b  of the countershaft axes  5   a ,  5   b  to form the fourth wheel plane IV. 
         [0195]    The ninth shifting element S 52  is arranged on the input shaft axis  4  and is connected, on the one hand, to a ninth hollow shaft H 9  and, on the other hand, to the first main shaft HW 1 . The ninth hollow shaft H 9  is arranged coaxially with the first main shaft HW 1 . When actuated, the ninth shifting element S 52  forms a force- and torque-transmitting connection between the ninth hollow shaft H 9  and the first main shaft HW 1 . On the ninth hollow shaft H 9  there is arranged a transmission element, which cooperates with respective intermediate wheels ZR 1 , ZR 2  between the input shaft axis  4  and respectively one of the two countershaft axes  5   a ,  5   b , and with the corresponding transmission elements on the two countershafts VW 1   a , VW 1   b , to form the eighth wheel plane VIII in the form of the reverse gear stage. 
         [0196]    The eighth and ninth shifting elements S 51 , S 52  are arranged combined in a fifth shifting device SE 5  and can be actuated by means of a common, fifth shifting element actuating device SB 5 . 
         [0197]    The fourth shifting element S 22  is arranged on the input shaft axis  4  and is connected, on the one hand, to the fifth hollow shaft H 5  and, on the other hand, to the first main shaft HW 1 . The fifth hollow shaft H 5  is arranged coaxially with the first main shaft HW 1 . When actuated, the fourth shifting element S 22  forms a force- and torque-transmitting connection between the fifth hollow shaft H 5  and the first main shaft HW 1 . To the fifth hollow shaft H 5  there is connected a transmission element on the input shaft axis  4 , which cooperates with respective transmission elements on the two countershafts VW 1   a , VW 1   b  of the countershaft axes  5   a ,  5   b  to form the sixth wheel plane VI. 
         [0198]    Furthermore,  FIG. 16  shows the transmission ratios of the individual wheel planes I, II, III, IV, V, VI, VII and VIII, as well as that of the planetary gear assembly GP 1 . The first wheel plane I has a transmission ratio i 1  of 2.91, The second wheel plane II has a transmission ratio i 2  of 3.38. The third wheel plane III has a transmission ratio i 3  of 1.02, The fourth wheel plane IV has a transmission ratio i 4  of 1.86. The eighth wheel plane VIII has a transmission ratio iR of −0.87. The fifth wheel plane V has a transmission ratio i 6  of 1.18, The sixth wheel plane VI has a transmission ratio i 5  of 2.16. The seventh wheel plane VII has a transmission ratio i 7  of 0.65, The planetary gear assembly GP 1  has a transmission ratio i 08  of −5.05. 
         [0199]      FIG. 17  shows a shifting matrix for a transmission according to the eleventh embodiment of the present invention. 
         [0200]    Unless otherwise stated below, all the clutches K 1 , K 2  and all the shifting elements S 11 , S 12 , S 21 , S 22 , S 31 , S 41 , S 42 , S 51  and S 52  are in each case open. 
         [0201]      FIG. 17  shows a shifting matrix for a transmission  1  according to  FIG. 16 . To obtain the first forward gear V 1  with the transmission  1  of  FIG. 16 , the clutch K 1  and the shifting elements S 12  and S 41  are closed. To obtain the second forward gear V 2 , the clutch K 2  and the shifting elements S 21  and S 41  are closed. 
         [0202]    To obtain the third forward gear V 3 , the clutch K 1  and the shifting elements S 41  and S 51  are closed. To obtain the fourth forward gear V 4 , the clutch K 2  and the shifting elements S 22  and S 41  are closed. 
         [0203]    To obtain the fifth forward gear V 5 , the clutch K 1  and the shifting elements S 11  and S 41  are closed. To obtain the sixth forward gear V 6 , the clutch K 2  and the shifting element S 31  are closed. 
         [0204]    To obtain the seventh forward gear V 7 , the clutch K 1  and the shifting elements S 12  and S 42  are closed. To obtain the eighth forward gear V 8 , the clutch K 2  and the shifting elements S 21  and S 42  are closed. 
         [0205]    To obtain the ninth forward gear V 9 , the clutch K 1  and the shifting elements S 42  and S 51  are closed. To obtain the tenth forward gear V 10 , the clutch K 2  and the shifting elements S 22  and S 42  are closed. 
         [0206]    To obtain the eleventh forward gear V 11 , the clutch K 1  and the shifting elements S 11  and S 42  are closed. 
         [0207]    To obtain the first reverse gear R 1 , the clutch K 2  and the shifting element S 52  are closed. To obtain the second reverse gear R 2 , the clutch K 2  and the shifting element S 52  are closed. 
         [0208]    The absolute transmission ratio i_ of the first forward gear V 1  is 20.1. The absolute transmission ratio i_ of the second forward gear V 2  is 14.9 and the relative transmission ratio phi between the first and the second forward gears V 1 , V 2  is 1.35. 
         [0209]    The absolute transmission ratio i_ of the third forward gear V 3  is 11.0 and the relative transmission ratio phi between the second and the third forward gears V 2 , V 3  is 1.35. The absolute transmission ratio i_ of the fourth forward gear V 4  is 8.17 and the relative transmission ratio phi between the third and the fourth forward gears V 3 , V 4  is 1.35. 
         [0210]    The absolute transmission ratio i_ of the fifth forward gear V 5  is 6.05 and the relative transmission ratio phi between the fourth and the fifth forward gears V 4 , V 5  is 1.35. The absolute transmission ratio i_ of the sixth forward gear V 6  is 4.48 and the relative transmission ratio phi between the fifth and the sixth forward gears V 5 , V 6  is 1.35. 
         [0211]    The absolute transmission ratio i_ of the seventh forward gear V 7  is 3.32 and the relative transmission ratio phi between the sixth and the seventh forward gears V 6 , V 7  is 1.35. The absolute transmission ratio i_ of the eighth forward gear V 8  is 2.46 and the relative transmission ratio phi between the seventh and the eighth forward gears V 7 , V 8  is 1.35. 
         [0212]    The absolute transmission ratio i_ of the ninth forward gear V 9  is 1.82 and the relative transmission ratio phi between the eighth and the ninth forward gears V 8 , V 9  is 1.35. The absolute transmission ratio i_ of the tenth forward gear V 10  is 1.35 and the relative transmission ratio phi between the ninth and the tenth forward gears V 9 , V 10  is 1.35. 
         [0213]    The absolute transmission ratio i_ of the eleventh forward gear V 11  is 1.00 and the relative transmission ratio phi between the tenth and the eleventh forward gears V 10 , V 11  is 1.35. 
         [0214]    The absolute transmission ratio i_ of the first reverse gear R 1  is −20.2. The absolute transmission ratio i_ of the second reverse gear R 2  is −3.34. 
         [0215]      FIG. 18  shows a transmission according to a twelfth embodiment of the present invention. 
         [0216]      FIG. 18  shows a transmission substantially like that of  FIG. 16 . The difference from the transmission  1  according to  FIG. 16  is that in the transmission  1  according to  FIG. 18  the reverse gear stage VIII is associated with the first partial transmission  2 . For this, the countershaft axes  5   a ,  5   b  extend from the second wheel plane II, through the third wheel plane III and the fourth wheel plane IV, as far as the eighth wheel plane VIII. Furthermore, on the ninth hollow shaft H 9  there is arranged a transmission element which cooperates with respective intermediate wheels ZR 1 . ZR 2  between the input shaft axis  4  and, respectively, one of the two countershaft axes  5   a ,  5   b  and with the corresponding transmission elements on the countershafts VW 2   a , VW 2   b , to form the eighth wheel plane VIII in the form of the reverse gear stage. The reverse gear stage VIII can be engaged or actuated by means of the ninth shifting element S 52 . 
         [0217]    Furthermore,  FIG. 18  shows the transmission ratios of the individual wheel planes I, H, III, IV, V, VI, VII and VIII, as well as that of the planetary gear assembly GP 1 . The first wheel plane I has a transmission ratio i 1  of 2.91. The second wheel plane II has a transmission ratio i 2  of 3.38. The third wheel plane III has a transmission ratio i 3  of 1.02. The fourth wheel plane IV has a transmission ratio i 4  of 1.86. The eighth wheel plane VIII has a transmission ratio iR of −0.87. The fifth wheel plane V has a transmission ratio i 6  of 1.18. The sixth wheel plane VI has a transmission ratio i 5  of 2.16. The seventh wheel plane VII has a transmission ratio i 7  of 0.65. The planetary gear assembly GP 1  has a transmission ratio i 08  of −5.05. 
         [0218]      FIG. 19  shows a shifting matrix for a transmission according to the twelfth embodiment of the present invention. 
         [0219]    Unless otherwise stated below, all the clutches K 1 , K 2  and all the shifting elements S 11 , S 12 , S 21 , S 22 , S 31 , S 41 , S 42 , S 51  and S 52  are in each case open. 
         [0220]      FIG. 19  shows a shifting matrix for a transmission  1  according to  FIG. 18 . The forward gears V 1  to V 11  are obtained in the same way as in  FIG. 17 , so that to avoid repetition reference should be made to the description relating to  FIG. 17 . 
         [0221]    To obtain the first reverse gear R 1 , the clutch K 1  and the shifting element S 52  are closed. To obtain the second reverse gear R 2 , the clutch K 1  and the shifting element S 52  are closed. 
         [0222]    The absolute transmission ratio i_ of the first forward gear V 1  is 20.1, The absolute transmission ratio i_ of the second forward gear V 2  is 14.9 and the relative transmission ratio phi between the first and the second forward gears V 1 , V 2  is 1.35. 
         [0223]    The absolute transmission ratio i_ of the third forward gear V 3  is 11.0 and the relative transmission ratio phi between the second and the third forward gears V 2 , V 3  is 1.35. The absolute transmission ratio i_ of the fourth forward gear V 4  is 8.17 and the relative transmission ratio phi between the third and the fourth forward gears V 3 , V 4  is 1.35. 
         [0224]    The absolute transmission ratio i_ of the fifth forward gear V 5  is 6.05 and the relative transmission ratio phi between the fourth and the fifth forward gears V 4 , V 5  is 1.35. The absolute transmission ratio i_ of the sixth forward gear V 6  is 4.48 and the relative transmission ratio phi between the fifth and the sixth forward gears V 5 , V 6  is 1.35. 
         [0225]    The absolute transmission ratio i_ of the seventh forward gear V 7  is 3.32 and the relative transmission ratio phi between the sixth and the seventh forward gears V 6 , V 7  is 1.35. The absolute transmission ratio i_ of the eighth forward gear V 8  is 2.46 and the relative transmission ratio phi between the seventh and the eighth forward gears V 7 , V 8  is 1.35. 
         [0226]    The absolute transmission ratio i_ of the ninth forward gear V 9  is 1.82 and the relative transmission ratio phi between the eighth and the ninth forward gears V 8 , V 9  is 1.35. The absolute transmission ratio i_ of the tenth forward gear V 10  is 1.35 and the relative transmission ratio phi between the ninth and the tenth forward gears V 9 , V 10  is 1.35. 
         [0227]    The absolute transmission ratio i_ of the eleventh forward gear V 11  is 1.00 and the relative transmission ratio phi between the tenth and the eleventh forward gears V 10 , V 11  is 1.35. 
         [0228]    The absolute transmission ratio i_ of the first reverse gear R 1  is −20.2. The absolute transmission ratio i_ of the second reverse gear R 2  is −3.34. 
         [0229]      FIG. 20  shows a transmission according to a thirteenth embodiment of the present invention. 
         [0230]      FIG. 20  shows a transmission  1  substantially the same as that of  FIG. 16 . The difference from the transmission  1  of  FIG. 16  is that the first range group RG 1  is made not as a planetary gear assembly, but as a countershaft assembly. In this way two further wheel planes VII and VIII are additionally provided. The wheel planes I to IV and VIII in  FIG. 16  correspond to the wheel planes I to IV and X in  FIG. 20 . The first main shaft HW 1  is connected to the drive output shaft AW by means of the seventh shifting element S 42 . The ninth wheel plane IX in  FIG. 20  corresponds to the seventh wheel plane VII in  FIG. 16 . 
         [0231]    The fifth shifting element S 31  is arranged on the input shaft axis  4  and is connected, on the one hand, to a sixth hollow shaft H 6  and, on the other hand, to the drive output shaft AW, and when actuated, forms a force- and torque-transmitting connection between the sixth hollow shaft H 6  and the drive output shaft AW. The sixth hollow shaft H 6  is arranged coaxially with and parallel to the drive output shaft, radially on the outside thereof. With the sixth hollow shaft H 6  is connected a transmission element on the input shaft axis  4 , which cooperates with respective transmission elements on the two countershafts VW 1   a , VW 1   b  of the countershaft axes  5   a ,  5   b  to form the ninth wheel plane IX. The fifth shifting element S 31  is arranged in a third shifting device SE 3  and can be actuated by means of a third shifting element actuating device SB 3 . 
         [0232]    The seventh shifting element S 42  is arranged on the input shaft axis  4  and is connected, on the one hand, to a seventh hollow shaft H 7  and, on the other hand, to the drive output shaft AW. The seventh hollow shaft H 7  is arranged coaxially with the first main shaft HW 1  and is functionally connected thereto. When actuated, the seventh shifting element S 42  forms a force- and torque-transmitting connection between the seventh hollow shaft H 7  and the drive output shaft AW. Both with the seventh hollow shaft H 7  and also with the drive output shaft AW, there is connected a transmission element on the input shaft axis  4 , which cooperates with respective transmission elements on the two countershafts VW 3   a , VW 3   b  of the countershaft axes  5   a ,  5   b  to form the seventh wheel plane VII. The countershafts VW 3   a , VW 3   b , which are in the form of hollow shafts, extend in the axial direction from the seventh wheel plane VII as far as the eighth wheel plane VIII. 
         [0233]    The sixth shifting element S 41  is arranged on the input shaft axis  4  and is connected, on the one hand, to an eighth hollow shaft H 8  and, on the other hand, to the drive output shaft AW, and when actuated, forms a force- and torque-transmitting connection between the eighth hollow shaft H 8  and the drive output shaft AW. The eighth hollow shaft H 8  is arranged coaxially with and parallel to the drive output shaft AW, radially on the outside thereof. On the eighth hollow shaft H 8  there is arranged a transmission element, which cooperates with respective transmission elements on the two countershafts VW 3   a , VW 3   b  of the countershaft axes  5   a ,  5   b  to form the eighth wheel plane VIII. 
         [0234]    The sixth shifting element S 41  and the seventh shifting element S 42  are combined in a fourth shifting device SE 4  and can be actuated by means of a common, fourth shifting element actuating device SB 4 . 
         [0235]    Furthermore,  FIG. 20  shows the transmission ratios of the individual wheel planes. The first wheel plane I has a transmission ratio i 1  of 2.91. The second wheel plane II has a transmission ratio i 2  of 3.38. The third wheel plane III has a transmission ratio i 3  of 1.02. The fourth wheel plane IV has a transmission ratio i 4  of 1.86. The tenth wheel plane X has a transmission ratio iR of −0.87. The fifth wheel plane V has a transmission ratio i 6  of 1.18. The sixth wheel plane VI has a transmission ratio i 5  of 2.16. The seventh wheel plane VII has a transmission ratio i 8  of 2.46. The eighth wheel plane VIII has a transmission ratio i 9  of 0.41. The ninth wheel plane IX has a transmission ratio i 7  of 0.65. 
         [0236]    A shifting matrix for a transmission  1  according to  FIG. 20  corresponds to the shifting matrix in  FIG. 17 . 
         [0237]      FIG. 21  shows a transmission according to a fourteenth embodiment of the present invention. 
         [0238]      FIG. 21  shows a transmission  1  substantially like that of  FIG. 1 . The difference from the transmission  1  according to  FIG. 1  is that an electric machine EM is arranged on at least one transmission element of a further wheel plane, in  FIG. 21  a fifth wheel plane V, to hybridize the transmission  1 . The electric machine EM is connected by transmission elements to the first main shaft HW 1 , one of these being connected fixed to the first main shaft HW 1 . The wheel planes I to IV and V and VI in  FIG. 1  correspond to the wheel planes I to IV and VI and VII in  FIG. 21 . Thus, force and torques can be transmitted from the electric machine EM to the first main shaft HW 1 . 
         [0239]    All in all, the shifting elements S 11  to S 61  in the transmission  1  according to  FIGS. 1 to 21  can also be denoted as coupling devices and in particular can be designed as synchronizers. The shifting devices SE 1  to SE 6  or the shifting element actuating devices SB 1  to SB 6  can be designed as dual synchronizers in the case of two shifting elements, or as single synchronizers in the case of one shifting element. Particularly in the transmission  1  according to  FIGS. 1 to 21  the transmission elements can either be in the form of a fixed wheel or in the form of a loose wheel. For example, in the transmission  1  according to  FIG. 1  the transmission element on the input shaft axis  4  of the second wheel plane II can be a fixed wheel on the first input shaft EW 1 , since this is connected fixed to the first input shaft EW 1 . The transmission element of the third wheel plane III on the input shaft axis  4  is a loose wheel on the first main shaft HW 1 . This can be coupled to the first main shaft HW 1  by means of the second shifting element S 12 . 
         [0240]    The transmission elements can in particular be in the form of gearwheels, preferably spur gears, so that the wheel planes I, II, III, IV, V, VI, VII, VIII and IX and X and XI are spur gear stages. To provide various forward and reverse gears, i.e. various transmission ratios, the spur gear stages and in particular their gearwheels can correspondingly have different transmission ratios. 
         [0241]    In summary, the present invention offers among others the advantage of enabling a multiplication of the gears as well as lower loading of the transmission elements by virtue of a smaller spread, since no extreme transmission ratios are produced by individual wheel planes. Other advantages are that the transmission has good powershifting ability and good hybridization ability. 
         [0242]    Although the present invention has been described above with reference to preferred example embodiments, it is not limited thereto, but can be modified in many ways. For example, various embodiments of  FIGS. 1 to 21  can be combined, such as by an axial displacement of the reverse gear stage VI according to  FIG. 3  and the arrangement of a second range group as in  FIG. 5 . 
       INDEXES 
       [0000]    
       
           1  Transmission 
           2  First partial transmission 
           3  Second partial transmission 
           4  Input shaft axis 
           5   a ,  5   b  Countershaft axis 
           6  Countershaft assembly 
           40 ,  40 ′ Sun gear 
           41 ,  41 ′ Planetary gear 
           42 ,  42 ′ Planetary carrier/web 
           43 ,  43 ′ Ring gear 
         EW 1 , EW 2  Input shaft 
         HW 1 , HW 2  Main shaft 
         VW 1   a , VW 1   b , VW 2   a , VW 2   b , VW 3   a , VW 3   b , VW 4   a , VW 4   b , VW 5   a  Countershaft 
         SW 1 , SW 2  Sun shaft 
         PTW Planetary carrier shaft 
         AW Drive output shaft 
         GP 1 , GP 2  Planetary gear assembly 
         G Housing 
         RG 1 , RG 2  Range group 
         I, II, III, IV, V, VI, VII, VIII IX, X, XI Wheel plane 
         H 1 , H 2 , H 3 , H 4 , H 5 , H 6 , H 7 , H 8 , H 9 , H 10 , H 11  Hollow shaft 
         K 1 , K 2  First/Second powershift element 
         S 11 , S 12 , S 21 , S 22 , S 31 , S 41 , S 42 , S 51 , S 52 , S 61  Shifting element 
         SE 1 , SE 2 , SE 3 , SE 4 , SE 5 , SE 6  Shifting device 
         SB 1 , SB 2 , SB 3 , SB 4 , SB 5 , SB 6  Shifting element actuating device 
         SD 1  Dual shifting element 
         ZR 1 , ZR 2  Intermediate wheel 
         V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , V 7 , V 8 , 
         V 9 , V 10 , V 11 , V 12 , V 13 , V 14 , V 15  Forward gear 
         R 1 , R 2  Reverse gear 
         AN Drive input side 
         AB Drive output side 
         EM Electric machine