Patent Abstract:
An automatic transmission includes four planetary gear sets, a plurality of friction and synchronizing clutches and two chain drive assemblies. Input torque is provided to four clutches which selectively provide torque to one element of a compound assembly comprising first and second planetary assemblies. The second planetary assembly includes only a sun gear and a planet carrier including elongate, stepped pinion gears which extend into the planet carrier of the adjacent first planetary assembly. The sun and ring gears of the first planetary assembly drive respective chain drive sprockets. A pair of chains transfer torque to respective driven chain sprockets. The chain driven by the first planetary assembly sun gear drives a third planetary assembly sun gear. The chain driven by the first planetary assembly ring gear drives a fourth planetary assembly sun gear. The transmission output is connected to the planet carriers of the third and fourth planetary assemblies.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/047,431 filed on Mar. 13, 2008 now U.S. Pat. No. 8,113,977, which claims priority to U.S. Provisional Patent Application No. 60/979,687, filed on Oct. 12, 2007, and as such, claims priority thereto under 35 U.S.C. §120. 
    
    
     FIELD 
     The present disclosure relates to automatic transmissions for a motor vehicle and more particularly to eight and nine speed automatic transmissions for motor vehicles having four planetary gear sets and a plurality of friction and synchronizer clutches. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     Many current passenger car multiple speed automatic transmissions include a combination of planetary gear sets and selectively engaged clutches and brakes which provide a plurality of forward torque or gear ratios. 
     Whereas three and four speed automatic transmissions were once commonplace and considered suitable to provide the requisite flexibility and performance, increasingly demanding economic and performance goals as well as consumer preference continue to encourage automatic transmission research and development. One result of this effort has been an increase in the number of available forward gears or speed ratios provided by the transmission. Six, seven and eight speed automatic transmissions are increasingly available. 
     Because they so closely match the power and torque curves of an engine to the vehicle speed and load, such six, seven and eight speed transmissions provide significant performance enhancements and fuel economies. 
     Study of these transmissions configurations, however, reveals that improvements are possible. For example, each of the selectively engaged frictional couplings, i.e., the clutches and the brakes, contribute to frictional losses, referred to as spin losses, when they are not engaged. Such spin losses are the result of relative rotation between the multiple, interleaved plates or discs of such devices. Two primary factors influence spin losses: the size or torque capacity of the clutch or brake and the speed difference across the clutch or brake. Reducing such spin losses therefore provides improved transmission efficiency which is highly desirable. 
     SUMMARY 
     The present invention provides an eight and a nine forward speed automatic transmission for a motor vehicle which includes four planetary gear sets, a plurality of friction and synchronizing clutches and two chain drive assemblies. The transmission is arranged along two parallel axes of rotation: a first axis defined by the input shaft and a second axis defined by the output shaft. The chain drive assemblies transfer power between sprockets disposed on the two axes. Alternatively, pairs of helical or spur gears may be utilized in place of the chain drive assemblies. 
     Input torque is provided commonly to four input clutches and, by engagement of one of four input clutches, to one element of a compound input gear assembly comprising a first planetary gear assembly and a second planetary gear assembly. The second planetary gear assembly includes only a sun gear and a planet gear carrier having a plurality of elongate, stepped pinion gears which extend into the planet gear carrier of the adjacent first planetary gear assembly. The sun gear and the ring gear of the first planetary gear assembly are coupled to a respective pair of chain drive sprockets disposed about the input axis. A pair of chains transfer torque to a respective pair of driven chain sprockets disposed on the output axis. The chain driven by the sun gear of the first planetary gear assembly directly drives a sun gear of a third planetary gear set that acts as a first sub-transmission. The chain driven by the ring gear of the first planetary gear assembly directly drives a sun gear of a fourth planetary gear assembly that acts as a second sub-transmission. The transmission output is commonly connected to and driven by a planet gear carrier of the third planetary gear assembly and a planet gear carrier of the fourth planetary gear assembly. Engagement of various combinations of the input clutches and a plurality of synchronizer clutches provides eight or nine forward speeds or gear ratios and a plurality of reverse speeds or gear ratios. 
     More particularly, the outputs of the four input clutches are connected to the sun gear and the ring gear of the first planetary gear assembly, the common planet gear carrier of the first and second planetary gear assemblies and the sun gear of the second planetary gear assembly and form an ordered set of speeds due to the gearset constraints. The ring gear of the first planetary gear assembly is connected to a first drive sprocket on the input axis which drives a chain which, in turn, drives a first driven chain sprocket on the output axis. The first driven sprocket is connected to the sun gear of the third planetary gear assembly the planet gear carrier of which is connected to the output shaft. A synchronizer clutch selectively connects the ring gear of the third planetary gear assembly to ground, providing a large mechanical advantage (underdrive), and another synchronizer clutch selectively connects the ring gear of the third planetary gear assembly to the sun gear of the third planetary gear assembly, providing direct drive. Together, the third planetary gear assembly and the two synchronizer clutches form a first two speed sub-transmission. Similarly, the sun gear of the first planetary gear assembly is connected to a second chain sprocket, second chain and second driven sprocket which drives a sun gear of a fourth planetary gear assembly. A pair of synchronizer clutches selectively connect the ring gear of the fourth planetary gear assembly either to ground or to the sun gear of the fourth planetary gear assembly. The fourth planetary gear assembly and the pair of synchronizer clutches form a second two speed sub-transmission. Thus, there are two torque paths between the input shaft and the output shaft through the two independent two speed sub-transmissions. 
     The gear ratios of the planetary gear assemblies and the ratios of the chain sprockets are chosen to provide the following “coarse” four speed ratio progression, in order of increasing speed ratio (decreasing mechanical advantage) through the first sub-transmission: input clutch to the sun gear of the first planetary gear assembly and the ring gear of the third planetary gear assembly grounded—underdrive; input clutch to the ring gear of the first planetary gear assembly and the ring gear of the third planetary gear assembly grounded—underdrive; input clutch to the sun gear of the first planetary gear assembly and the ring gear and the sun gear of the third planetary gear assembly connected together—overdrive; and input clutch to the ring gear of the first planetary gear assembly and the ring gear and the sun gear of the third planetary gear assembly connected together—overdrive. 
     There are two additional blended or virtual ratios available between each consecutive pair of “coarse” ratios by utilizing the two other input clutches which drive the common planet gear carrier of the first and second planetary gear assemblies and the sun gear of the second planetary gear assembly. This action is such that the torque ratios are interpolated according to the particular ratios of the planetary gear assemblies on the input shaft and the choice of the input clutch. 
     Thus, in addition to eight and nine speed operation, there is defined a ten speed progression that can be achieved with single transition, clutch-to-clutch shifts between the input clutches, with the synchronizer clutches changing ratios on the respective sub-transmissions only when all of the power and torque are being transmitted through the other sub-transmission. 
     Reverse ratios are achieved using a synchronizer clutch which grounds the planet gear carrier of the first planetary gear assembly. This causes the sun gears of the first and the second planetary gear assemblies to rotate backward if the input clutch associated with the ring gear of the first planetary gear assembly is applied, and the ring gear of the first planetary gear assembly to rotate backward if either of the input clutches associated with the sun gear of the first or the second planetary gear assembly is engaged. Thus, there are potentially six different reverse ratios that can be achieved: each of the input clutches associated with the sun and ring gear of the first planetary gear assembly and with the sun gear of the second planetary gear assembly can drive a two speed sub-transmission in a reverse direction. 
     In a first implementation of the present invention, the fifth forward ratio (the first interpolated ratio between underdrive through the ring gear of the first planetary gear assembly and direct drive through the sun gear of the first planetary gear assembly) is skipped in order to smooth out the ratio progression, providing a nine speed transmission having excellent ratio progression spanning an overall range of approximately 7:1 to 9:1. 
     In a second implementation of the present invention with slightly different planetary gear assembly and chain sprocket ratios, both fifth and sixth gear are skipped, providing a wider ratio eight speed transmission with a similarly smooth progression spanning an overall range of approximately 10:1 to 13:1. 
     In each implementation, there is a good two speed clutch-to-clutch reverse progression, with the lowest reverse gear offering at least as much mechanical advantage as first gear. Additionally, the lowest forward and lowest reverse gears are achieved by applying the same clutch. Thus, these transmissions form an ideal platform for so-called “friction launch” applications which eliminate the torque converter associated with traditional automatic transmissions. 
     It is thus an object of the present invention to provide an automatic transmission for motor vehicles which provides nine forward speeds. 
     It is a further object of the present invention to provide an automatic transmission for motor vehicles which provides eight forward speeds. 
     It is a still further object of the present invention to provide an automatic transmission for motor vehicles having an input shaft on a first axis and an output shaft on a second, offset, parallel axis. 
     It is a still further object of the present invention to provide an automatic transmission for motor vehicles having four planetary gear sets and a plurality of friction and synchronizer clutches. 
     It is a still further object of the present invention to provide an automatic transmission for motor vehicles having a pair of chain drives connecting components disposed about a pair of parallel, spaced apart axes. 
     Further objects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. Like reference numbers in the various Figures consistently refer to the same element, component or feature. 
         FIG. 1  is a lever diagram of a multiple speed automatic transmission according to the present invention; 
         FIG. 2  is a diagrammatic view of a first embodiment of a nine speed automatic transmission according to the present invention; 
         FIG. 3  is a diagrammatic view of a second embodiment of a nine speed automatic transmission according to the present invention; 
         FIG. 4  is a truth table presenting the various combinations of engaged clutches and brakes which achieve a given forward or reverse gear or speed ratio in the first and second embodiments of a nine speed automatic transmission according to the present invention; and 
         FIG. 5  is a truth table presenting the various combinations of engaged clutches and brakes which achieve a given forward or reverse gear or speed ratio in the first and second embodiments of a eight speed automatic transmission according to the present invention; 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application or uses. 
     Referring now to  FIG. 1 , a multiple, e.g., eight or nine, speed automatic transmission  10  according to the present invention is illustrated in a lever diagram. A lever diagram is a schematic representation of the components of an automatic transmission wherein certain components such as planetary gear and chain drive assemblies are represented by nodes. The relative lengths of the vertical bars between nodes of a given component represent the ratios between the components. Mechanical couplings or interconnections between the nodes of various components are illustrated by horizontal lines and torque transmitting devices such as friction clutches are represented by interleaved or nested fingers and synchronizer clutches by pairs of parallel, oblique lines. Further explanation of the format, purpose and use of lever diagrams can be found in SAE Paper No. 810102 entitled, “The Lever Analogy: A New Tool in Transmission Analysis” by Benford and Leising which is fully incorporated herein by reference. 
     The multiple speed automatic transmission  10  includes an input shaft  12  which is coupled to and directly and commonly drives a first friction clutch  14 , a second friction clutch  16 , a third friction clutch  18  and a fourth friction clutch  20 . Drive torque from the transmission  10  is provided to an output shaft  22 . The outputs of the clutches  14 ,  16   18  and  20  are coupled to a compound input gear assembly  30 . The output of the first friction clutch  14  is coupled to a first node  30 A of the compound input gear assembly  30 , the output of the second friction clutch  16  is coupled to a second node  30 B of the compound input gear assembly  30 , the output of the third friction clutch  18  is coupled to a third node  30 C of the compound input gear assembly  30  and the output of the fourth friction clutch  20  is coupled to a fourth node  30 D of the compound input gear assembly  30 . 
     The first node  30 A of the compound input gear assembly  30  is coupled to a first node  50 A of a first chain drive assembly  50  A second node  50 B of the first chain drive assembly  50  is coupled the a first node  60 A of a third planetary gear assembly  60 . The third node  50 C of the first chain drive assembly  50  is grounded. The fourth node  30 D of the compound input gear assembly  30  is coupled to a second node  70 B of a second chain drive assembly  70 . A first node  70 A of the second chain drive assembly  70  is coupled the a first node  80 A of a fourth planetary gear assembly  80 . The third node  70 C of the second chain drive assembly  70  is grounded. A second node  60 B of the third planetary gear assembly  60  and a second node  80 B of the fourth planetary gear assembly  80  are coupled to the output shaft  22 . 
     The third node  30 C of the compound input gear assembly  30  is selectively connected to ground through a first synchronizer clutch  92 . The third node  60 C of the third planetary gear assembly  60  is selectively connected to ground through a second synchronizer clutch  94 . The third node  80 C of the fourth planetary gear assembly  80  is selectively connected to ground through a third synchronizer clutch  96 . The second node  50 B of the first chain drive assembly  50  and the first node  60 A of the third planetary gear assembly  60  are selectively connected to the third node  60 C of the third planetary gear assembly  60  through a fourth synchronizer clutch  98 . Finally, the first node  70 A of the second chain drive assembly  70  and the first node  80 A of the fourth planetary gear assembly  80  are selectively connected to the third node  80 C of the fourth planetary gear assembly  80  through a fifth synchronizer clutch  100 . 
     With reference to  FIG. 2 , a first embodiment of a nine speed automatic transmission according to the present invention is illustrated and designated by the reference number  10 . The automatic transmission  10  includes the input member or shaft  12  which is coupled to and driven by, for example, the output of an engine (not illustrated) or the turbine of a torque converter (not illustrated). The automatic transmission  10  also includes the output shaft  22  having first and second ends  22 A and  22 B. If the transmission  10  is longitudinally mounted in a vehicle, one of the ends  22 A or  22 B may be utilized to drive a final drive unit (not illustrated) in the front or rear of a vehicle or both may be utilized to drive final drive units in both the front and rear of a vehicle. Alternatively, if the transmission  10  is mounted transversely in a vehicle, either or both of the ends  22 A and  22 B may be utilized to provide drive torque to either or both sides of the vehicle. 
     The automatic transmission  10  also includes a first compound input gear set or assembly  30  disposed about the axis of the input shaft  12 , a third, simple planetary gear set or assembly  60  disposed about the axis of the output shaft  22  and a fourth, simple planetary gear set or assembly  80  also disposed about the axis of the output shaft  22 . 
     The first compound input gear assembly  30  includes a first, simple planetary gear assembly  31  having a first sun gear  32 , a first planet gear carrier  34  and a first ring gear  36 . Rotatably disposed in the first planet gear carrier  34  are a plurality of elongate, stepped first planet gears  38 , one of which is illustrated in  FIG. 2 . Each of the plurality of first planet gears  38  is in constant mesh with the first sun gear  32  and the first ring gear  36 , includes gear teeth of two different pitch diameters and extends out from the first planet gear carrier  34 . The first compound input gear assembly  30  also includes a second, partial planetary gear assembly  40  having a second sun gear  42 , a second planet gear carrier  44  and the ends of the plurality of first planet gears  38 , one of which is illustrated in  FIG. 2 . There is no ring gear in the second planetary gear assembly  40 . The first planet gear carrier  34  and the second planet gear carrier  44  are coupled and rotate together. Each of the plurality of first planet gears  38  is in constant mesh with the second sun gear  42 . It should be appreciated that other gearing configurations may be utilized to achieve the operation of the first compound input gear assembly  30  other than the arrangement illustrated. 
     The third, simple planetary gear assembly  60  includes a third sun gear  62 , a third planet gear carrier  64  and a third ring gear  66 . Rotatably disposed in the third planet gear carrier  64  are a plurality of third planet gears  68 , one of which is illustrated in  FIG. 2 . Each of the plurality of third planet gears  68  is in constant mesh with the third sun gear  62  and the third ring gear  66 . The fourth, simple planetary gear assembly  80  includes a fourth sun gear  82 , a fourth planet gear carrier  84  and a fourth ring gear  86 . Rotatably disposed in the fourth planet gear carrier  84  are a plurality of fourth planet gears  88 , one of which is illustrated in  FIG. 2 . Each of the plurality of fourth planet gears  88  is in constant mesh with the fourth sun gear  82  and the fourth ring gear  86 . 
     The automatic transmission  10  also includes a first chain drive assembly  50  having a first drive chain sprocket  52  which is coupled to and driven directly by the first ring gear  36  of the first planetary gear assembly  31 . The first chain drive sprocket  52  drives a first multiple link chain  54  and a first driven chain sprocket  56  disposed on the axis of the output shaft  22  and directly coupled to the third sun gear  62  of the third planetary gear assembly  60 . Adjacent the first chain drive assembly  50  is a second chain drive assembly  70  having a second drive chain sprocket  72  which is coupled to and driven directly by the first sun gear  32  of the first planetary gear assembly  31 . The second chain drive sprocket  72  drives a second multiple link chain  74  and a second driven chain sprocket  76  disposed on the axis of the output shaft  22  and directly coupled to the fourth sun gear  82  of the fourth planetary gear assembly  80 . 
     It should be understood that the chain drive assemblies  50  and  70  of both the first embodiment of  FIG. 2  and the second embodiment of  FIG. 3  may be replaced with pairs of helical or spur gears. With such a change, of course, the rotation of the output shaft  22  would be “backward” or non-standard from conventional practice. 
     The automatic transmission  10  further includes a plurality of torque transmitting devices such as friction clutches and synchronizer clutches. As utilized herein, the term “friction clutch” refers to a torque transmitting device having first and second pluralities of interleaved friction plates or discs which are compressed by an associated operator or actuator and which is capable of carrying high levels of torque, i.e., the actual torque carried by the automatic transmission  10 . On the other hand, a “synchronizer clutch,” as utilized herein, refers to a torque transmitting device having a limited torque capacity synchronizer which is capable of carrying sufficient torque to overcome the inertia of an associated gear in order to synchronize it with a shaft and a positive clutch such as a dog clutch which engages to positively couple the gear and shaft and which is capable of carrying high levels of torque. Furthermore, it should be understood that while these devices are referred to as synchronizer clutches which suggests that they synchronize and connect two rotating members, three of the synchronizer clutches are, in fact, utilized as brakes, i.e., they slow and connect a rotatable member to a fixed or stationary member, thereby inhibiting rotation of the rotatable member. In the following description, those synchronizer clutches functioning as brakes will be noted by the parenthetical addition of the word “brake.” 
     It should also be appreciated that the use of the friction clutches and synchronizer clutches as herein described contributes to the low spin losses exhibited by the transmissions of the present invention. The friction clutches are of relatively low torque capacity and generally low slip speeds. Similarly, synchronizer clutches inherently have relatively low spin losses and their use in many locations in the transmissions of the present invention further reduces spin losses relative to other automatic transmission configurations. 
     The first high torque capacity friction clutch  14  having, as noted, interleaved pluralities of friction clutch plates or discs is operably disposed between and selectively connects the input shaft  12  to a first shaft, quill or concentric member  104  which is coupled to and drives the first sun gear  32  of the first planetary gear assembly  31  and the second drive chain sprocket  72  of the second chain drive assembly  70 . The second high torque capacity friction clutch  16  is operably disposed between and selectively connects the input shaft  12  to a second shaft, quill or concentric member  106  which is coupled to and drives the second sun gear  42  of the second partial planetary gear assembly  40 . The third high torque capacity friction clutch  18  is operably disposed between and selectively connects the input shaft  12  to a third shaft, quill or concentric member  108  which is coupled to and drives the first planet gear carrier  34  of the first planetary gear assembly  31  and the second planet gear carrier  44  of the second partial planetary gear assembly  40 . The fourth high torque capacity friction clutch  20  is operably disposed between and selectively connects the input shaft  12  to a fourth shaft, quill or concentric member  110  which is coupled to and drives the first ring gear  36  of the first planetary gear assembly  31 . 
     A first synchronizer clutch (brake)  92  having, as noted above, a synchronizer and positive clutch is operably disposed between and selectively connects or grounds the first planet gear carrier  34  of the first planetary gear assembly  31  to a stationary housing  120  of the automatic transmission  10 . A second synchronizer clutch (brake)  94  is operably disposed between and selectively connects or grounds the third ring gear  66  of the third planetary gear assembly  60  to the stationary housing  120 . A third synchronizer clutch (brake)  96  is operably disposed between and selectively connects or grounds the fourth ring gear  86  of the fourth planetary gear assembly  80  to the stationary housing  120 . 
     A fourth synchronizer clutch  98  is operably disposed between and selectively connects the third ring gear  66  of the third planetary gear assembly  60  to a fifth shaft, quill or concentric member  112  which is coupled to the third sun gear  62  of the third planetary gear assembly  60  and the first driven chain sprocket  56  of the first chain drive assembly  50 . A fifth synchronizer clutch  100  is operably disposed between and selectively connects the fourth ring gear  86  of the fourth planetary gear assembly  80  to a sixth shaft, quill or concentric member  114 . The sixth shaft, quill or concentric member  114  is coupled to the fourth sun gear  82  of the fourth planetary gear assembly  80  and the second driven chain sprocket  76  of the second chain drive assembly  70 . 
     As illustrated in  FIG. 2 , with the input shaft  12  to the left in the drawing, the left side represents the input or typically the front end of the automatic transmission  10 . For various reasons, primarily related to packaging, it may be advantageous to arrange the components of the automatic transmission  10  differently than presented in  FIG. 2 . For example, locating the first and second chain drives  50  and  70  toward the rear of the transmission  10  and the third and fourth planetary gear assemblies  60  and  80  toward the front has the potential of reducing the size of the rear portion of the transmission housing  120 . Such a configuration is illustrated in  FIG. 3  as a second embodiment of the present invention. 
     Referring now to  FIG. 3 , the second embodiment of the multiple speed automatic transmission according to the present invention is illustrated and designated by the reference number  200 . The input portion (the upper half of the drawings) of the second embodiment of the multiple speed automatic transmission  200  is identical to the corresponding portion of the first embodiment of the automatic transmission  10 . As such, the second embodiment automatic transmission  200  includes the input shaft  12 , the first friction clutch  14 , the second friction clutch  16 , the third friction clutch  18 , the fourth friction clutch  20  and the output shaft  22  having the first end  22 A and the second end  22 B. 
     The automatic transmission  200  also includes the first compound input gear assembly  30  having the first, simple planetary gear assembly  31  including the first sun gear  32 , the first planet gear carrier  34 , the first ring gear  36  and the plurality of first elongate planet gears  38 . Each of the first planet gears  38  is in constant mesh with the first sun gear  32  and the first ring gear  36 , is axially elongated, includes gear teeth of two different pitch diameters and extends out from the first planet gear carrier  34 . The first compound input gear assembly  30  also includes the second, partial planetary gear assembly  40  having the second sun gear  42  and the second planet gear carrier  44  which is coupled to and rotates with the first planet gear carrier  34 . Rotatably disposed in the second planet gear carrier  44  are the ends of the plurality of first planet gears  38  of the first planet gear carrier  34 . Each of the plurality of first planet gears  36  is in constant mesh with the second sun gear  42 . 
     The second embodiment automatic transmission  200  also includes the first chain drive assembly  50  having the first drive chain sprocket  52 . The first chain drive sprocket  52  drives the first multiple link chain  54  and the first driven chain sprocket  56 . Adjacent the first chain drive assembly  50  is the second chain drive assembly  70  having the second drive chain sprocket  72 . The second chain drive sprocket  72  drives the second multiple link chain  74  and the second driven chain sprocket  76 . 
     As noted above, the output portion of the second embodiment automatic transmission  200  (the lower portion of the drawings) differs in layout, though not operation, from the first embodiment automatic transmission  10 . The third planetary gear assembly  60  and the fourth planetary gear assembly  80  are disposed adjacent one another. The third, simple planetary gear assembly  60  includes the third sun gear  62 , the third planet gear carrier  64  and the third ring gear  66 . Rotatably disposed in the third planet gear carrier  64  are the plurality of third planet gears  68 , one of which is illustrated in  FIG. 3 . The fourth, simple planetary gear assembly  80  includes the fourth sun gear  82 , the fourth planet gear carrier  84  and the fourth ring gear  86 . Rotatably disposed in the fourth planet gear carrier  84  are the plurality of fourth planet gears  88 , one of which is illustrated in  FIG. 3 . 
     Adjacent the fourth planetary gear assembly  80  is the first chain drive assembly  50  described above. Adjacent the first chain drive assembly  50  and the rear of the automatic transmission  200  (the right side in  FIG. 3 ) is the second chain drive assembly  70 . The second embodiment automatic transmission  200  also includes the first synchronizer clutch (brake)  92 , the second synchronizer clutch (brake)  94 , the third synchronizer clutch (brake)  96 , the fourth synchronizer clutch  98  and the fifth synchronizer clutch  100 . Also present are the first shaft, quill or concentric member  104 , the second shaft, quill or concentric member  106 , the third shaft, quill or concentric member  108 , the fourth shaft, quill or concentric member  110 , a fifth shaft, quill or concentric member  112 ′, a sixth shaft, quill or concentric member  114 ′ and the housing  120 . 
     Referring now to  FIGS. 2 ,  3  and  4 , the operation of both embodiments  10  and  200  of the nine speed automatic transmission will be described. It will be appreciated that the transmissions  10  and  200  are capable of transmitting torque from their input shafts  12  to their output shafts  22  in at least nine forward speed, torque or gear ratios and multiple reverse speed, torque or gear ratios. Each forward or reverse gear ratio is attained by activation or engagement of various combinations of three of the clutches as will be explained below.  FIG. 4  is a truth table which presents the various combinations of friction and synchronizer clutches that are activated or engaged to achieve the various forward and reverse gear ratios. Gear ratios and ratios steps are also provided although it should be understood that these numerical values are presented for purposes of example and illustration only and that such values may be adjusted over significant ranges to accommodate various applications and operational criteria of the automatic transmissions  10  and  200 . 
     In neutral, none of the clutch elements are activated or engaged. 
     In reverse gear, denominated Rev, the first friction clutch  14 , the first synchronizer clutch (brake)  92  and the third synchronizer clutch (brake)  96  are activated or engaged. 
     From neutral, first gear is achieved by activating or engaging the first friction clutch  14 , the second synchronizer clutch (brake)  94  and the third synchronizer clutch (brake)  96 . As noted by the “O” in  FIG. 4 , although the third synchronizer clutch (brake)  96  is engaged, it is not carrying torque. 
     Second gear is achieved by deactivating or disengaging the first friction clutch  14  and activating or engaging the second friction clutch  16  while maintaining engagement of the second synchronizer clutch (brake)  94  and the third synchronizer clutch (brake)  96 . In second gear, the third synchronizer clutch (brake)  96  carries torque. 
     Third gear is achieved by deactivating or disengaging the second friction clutch  16 , and activating or engaging the third friction clutch  18  while maintaining engagement of the second synchronizer clutch (brake)  94  and the third synchronizer clutch (brake)  96 . 
     Fourth gear is achieved by deactivating or disengaging the third friction clutch  18  and the second synchronizer clutch (brake)  94  and activating or engaging the fourth friction clutch  20  and the fourth synchronizer clutch  98  while maintaining engagement of the third synchronizer clutch (brake)  96 . Once again, although the fourth synchronizer clutch  98  is engaged, it is not carrying torque. 
     Fifth gear is achieved by deactivating or disengaging the fourth friction clutch  20  and activating or engaging the second friction clutch  16  while maintaining activation or engagement of the third synchronizer clutch (brake)  96  and the fourth synchronizer clutch  98 . 
     Sixth gear is achieved by deactivating or disengaging the second friction clutch  16  and the third synchronizer clutch (brake)  96  and activating or engaging the first friction clutch  14  and the fifth synchronizer clutch  100  while maintaining activation or engagement of the fourth synchronizer clutch  98 . In sixth gear, the fifth synchronizer clutch  100  is not carrying torque. 
     The engagement of clutches in the remaining forward gears, seventh, eighth and ninth, is readily determined by reference to  FIG. 4  and proceeds according to the steps described above and thus will not be further explained. 
     Referring now to  FIG. 5 , a truth table for a third embodiment of the present invention is presented. The gearing of the first and second embodiments  10  and  200  of the automatic transmission is such that it may be readily adapted to provide other shift configurations, e.g., eight or ten speed operation and operation with multiple reverse gears. The truth table of  FIG. 5  provides a clutch engagement program having eight forward gears or speeds. Essentially, fifth gear of the truth table of  FIG. 4  has been removed and the remaining higher speed gears, namely, sixth through ninth, now appear as and provide gears five through eight. 
     It will be appreciated that the foregoing explanations of the configuration, operation and gear states of the first and second embodiments  10  and  200  of the nine speed automatic transmission is wholly and accurately applicable to the configuration and operation of the third embodiment of the multiple speed transmission of the present invention. Furthermore, the explanation of operation assumes that all clutches not specifically referenced in a given gear ratio are inactive or disengaged. The explanation also assumes that during gear shifts between at least adjacent gear ratios, a clutch that is activated or engaged in both gear ratios will remain activated or engaged during the shift. Finally, the foregoing explanation assumes that downshifts follow essentially the opposite sequence of the corresponding up shifts and that several power on skip shifts, e.g., from first to third, are possible. 
     The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Technology Classification (CPC): 5