Abstract:
A transmission includes an input member, an output member, three planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. A first interconnecting member continuously interconnects the third member of the first planetary pear set with the second member of the second planetary gear set. A second interconnecting member continuously interconnects the third member of the second planetary sear set with the third member of the third planetary gear set. The torque transmitting devices include three clutches and two brakes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 61/231,545, filed on Aug. 5, 2009, which is hereby incorporated in its entirety herein by reference. 
    
    
     FIELD 
     The invention relates generally to a multiple speed transmission having a plurality of planetary gear sets and a plurality of torque transmitting devices and more particularly to a transmission having six or more speeds, three planetary gear sets and a plurality of torque transmitting devices. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     A typical multiple speed transmission uses a combination of friction clutches, planetary gear arrangements and fixed interconnections to achieve a plurality of gear ratios. The number and physical arrangement of the planetary gear sets, generally, are dictated by packaging, cost and desired speed ratios. 
     While current transmissions achieve their intended purpose, the need for new and improved transmission configurations which exhibit improved performance, especially from the standpoints of efficiency, responsiveness and smoothness and improved packaging, primarily reduced size and weight, is essentially constant. Accordingly, there is a need for an improved, cost-effective, compact multiple speed transmission. 
     SUMMARY 
     A transmission is provided having an input member, an output member, three planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices are for example clutches and brakes. 
     In one embodiment, a transmission includes an input member, an output member, first, second and third planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the second member of the first planetary gear set with the third member of the second planetary gear set, and a second interconnecting member continuously interconnecting the first member of the second planetary gear set with the first member of the third planetary gear set. A first torque transmitting mechanism is selectively engageable to interconnect the third member of the first planetary gear set with the second member of the third planetary gear set, a second torque transmitting mechanism is selectively engageable to interconnect the first member of the first planetary gear set and the input member with the second member of the second planetary gear set, a third torque transmitting mechanism is selectively engageable to interconnect the second member of the second planetary gear set with the second member of the third planetary gear set, a fourth torque transmitting mechanism is selectively engageable to interconnect the third member of the first planetary gear set with a stationary member, and a fifth torque transmitting mechanism is selectively engageable to interconnect the first member of the second planetary gear set and the first member of the third planetary gear set with the stationary member. The torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least six forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
     In another embodiment, a transmission includes an input member, an output member, first, second and third planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the second member of the first planetary gear set with the third member of the second planetary gear set and a second interconnecting member continuously interconnecting the second member of the second planetary gear set with the second member of the third planetary gear set. A first torque transmitting mechanism is selectively engageable to interconnect the third member of the first planetary gear set with the third member of the third planetary gear set, a second torque transmitting mechanism is selectively engageable to interconnect the first member of the first planetary gear set with the third member of the third planetary gear set, a third torque transmitting mechanism is selectively engageable to interconnect the first member of the second planetary gear set and the input member with the first member of the first planetary gear set, a fourth torque transmitting mechanism is selectively engageable to interconnect the third member of the first planetary gear set with a stationary member, and a fifth torque transmitting mechanism is selectively engageable to interconnect the second member of the second planetary gear set and the second member of the third planetary gear set with the stationary member. The torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least six forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
     Further features, aspects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature. 
    
    
     
       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. 
         FIG. 1  is a lever diagram of an embodiment of a six speed transmission according to the present invention; 
         FIG. 2  is a diagrammatic illustration of an embodiment of a six speed transmission according to the present invention; 
         FIG. 3  is a truth table presenting the state of engagement of the various torque transmitting elements in each of the available forward and reverse speeds or gear ratios of the transmission illustrated in  FIGS. 1 and 2 ; 
         FIG. 4  is a lever diagram of an embodiment of a six speed transmission according to the present invention; 
         FIG. 5  is a diagrammatic illustration of an embodiment of a six speed transmission according to the present invention; 
         FIG. 6  is a truth table presenting the state of engagement of the various torque transmitting elements in each of the available forward and reverse speeds or gear ratios of the transmission illustrated in  FIGS. 4 and 5 ; 
         FIG. 7  is a lever diagram of an embodiment of a six speed transmission according to the present invention; 
         FIG. 8  is a diagrammatic illustration of an embodiment of a six speed transmission according to the present invention; and 
         FIG. 9  is a truth table presenting the state of engagement of the various torque transmitting elements in each of the available forward and reverse speeds or gear ratios of the transmission illustrated in  FIGS. 7 and 8 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     At the outset, it should be appreciated that the embodiments of the six speed automatic transmission of the present invention have an arrangement of permanent mechanical connections between the elements of the three planetary gear sets. A first component or element of a first planetary gear set is permanently coupled to a second component or element of a second planetary gear set. A second component or element of the second planetary gear set is permanently coupled to a first component or element of a third planetary gear set. 
     Referring now to  FIG. 1 , an embodiment of a six speed transmission  10  is illustrated in a lever diagram format. A lever diagram is a schematic representation of the components of a mechanical device such as an automatic transmission. Each individual lever represents a planetary gear set wherein the three basic mechanical components of the planetary gear are each represented by a node. Therefore, a single lever contains three nodes: one for the sun gear, one for the planet gear carrier, and one for the ring gear. The relative length between the nodes of each lever can be used to represent the ring-to-sun ratio of each respective gear set. These lever ratios, in turn, are used to vary the gear ratios of the transmission in order to achieve an appropriate ratios and ratio progression. Mechanical couplings or interconnections between the nodes of the various planetary gear sets are illustrated by thin, horizontal lines and torque transmitting devices such as clutches and brakes are presented as interleaved fingers. Further explanation of the format, purpose and use of lever diagrams can be found in SAE Paper 810102, “The Lever Analogy: A New Tool in Transmission Analysis” by Benford and Leising which is hereby fully incorporated by reference. 
     The transmission  10  includes an input shaft or member  12 , a first planetary gear set  14 , a second planetary gear set  16 , a third planetary gear set  18  and an output shaft or member  22 . The first planetary gear set  14  has three nodes: a first node  14 A, a second node  14 B, and a third node  14 C. The second planetary gear set  16  has three nodes: a first node  16 A, a second node  16 B, and a third node  16 C. The third planetary gear set  18  has three nodes: a first node  18 A, a second node  18 B and a third node  18 C. 
     The input member  12  is continuously coupled to the first node  14 A of the first planetary gear set  14 . The output member  22  is coupled to the second node  18 B of the third planetary gear set  18 . The third node  14 C of the first planetary gear set  14  is coupled to the second node  16 B of the second planetary gear set  16 . The third node  16 C of the second planetary gear set  16  is coupled to the third node  18 C of the third planetary gear set  18 . 
     A first clutch  26  selectively connects the third node  14 C of the first planetary gear set  14  and the second node  16 B of the second planetary gear set  16  with the first node  18 A of the third planetary gear set  18 . A second clutch  28  selectively connects the first node  14 A of the first planetary gear set  14  and input member  12  with the first node  18 A of the third planetary gear set  18 . A third clutch  30  selectively connects the second node  14 B of the first planetary gear set  14  with the second node  18 B of the third planetary gear set  18  and the output member or shaft  22 . A first brake  32  selectively connects the third node  16 C of the second planetary gear set  16  and the third node  18 C of the third planetary gear set  18  with a stationary member or transmission housing  36 . A second brake  34  selectively connects the first node  16 A of the second planetary gear set  16  with a stationary member or transmission housing  36 . 
     Referring now to  FIG. 2 , a stick diagram presents a schematic layout of the embodiment of the six speed transmission  10  according to the present invention. In  FIG. 2 , the numbering from the lever diagram of  FIG. 1  is carried over. The clutches and couplings are correspondingly presented whereas the nodes of the planetary gear sets now appear as components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers. 
     For example, the planetary gear set  14  includes a sun gear member  14 A, a ring gear member  14 B and a planet gear carrier member  14 C that rotatably supports a set of planet gears  14 D (only one of which is shown) and a set of planet gears  14 E (only one of which is shown). The sun gear member  14 A is connected for common rotation with the input member  12  and with a first shaft or interconnecting member  42 . The ring gear member  14 B is connected for common rotation with a second shaft or interconnecting member  44 . The planet carrier member  14 C is connected for common rotation with a third shaft or interconnecting member  46  and with a fourth shaft or interconnecting member  48 . The planet gears  14 D are each configured to intermesh with both the ring gear member  14 B and the planet gears  14 E. The planet gears  14 E are each configured to intermesh with both the planet gears  14 D and the sun gear member  14 A. 
     The planetary gear set  16  includes a sun gear member  16 A, a ring gear member  16 C and a planet gear carrier member  16 B that rotatably supports a set of planet gears  16 D (only one of which is shown). The sun gear member  16 A is connected for common rotation with a fifth shaft or interconnecting member  50 . The ring gear member  16 C is connected for common rotation with a sixth shaft or interconnecting member  52  and with a seventh shaft or interconnecting member  54 . The planet carrier member  16 B is connected for common rotation with the third shaft or interconnecting member  46 . The planet gears  16 D are each configured to intermesh with both the sun gear member  16 A and the ring gear member  16 C. 
     The planetary gear set  18  includes a sun gear member  18 A, a ring gear member  18 C and a planet gear carrier member  18 B that rotatably supports a set of planet gears  18 D (only one of which is shown). The sun gear member  18 A is connected for common rotation with an eighth shaft or interconnecting member  56 . The ring gear member  18 C is connected for common rotation with the seventh shaft or interconnecting member  54 . The planet carrier member  18 B is connected for common rotation with a ninth shaft or interconnecting member  58  and with the output member or shaft  22 . The planet gears  18 D are each configured to intermesh with both the sun gear member  18 A and the ring gear member  18 C. 
     The input shaft or member  12  is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member  22  is continuously connected with the final drive unit or transfer case (not shown). 
     The torque-transmitting mechanisms or clutches  26 ,  28 ,  30  and brakes  32  and  34  allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch  26  is selectively engageable to connect the fourth shaft or interconnecting member  48  and the third shaft or interconnecting member  46  with the eighth shaft or interconnecting member  56 . The second clutch  28  is selectively engageable to connect the eighth shaft or interconnecting member  56  with the first shaft or interconnecting member  42 . The third clutch  30  is selectively engageable to connect the second shaft or interconnecting member  44  with the ninth shaft or interconnecting member  58 . The first brake  32  is selectively engageable to connect the sixth shaft or interconnecting member  52  with the stationary element or the transmission housing  36  in order to restrict the member  52  from rotating relative to the transmission housing  36 . The second brake  34  is selectively engageable to connect the fifth shaft or interconnecting member  50  with the stationary element or the transmission housing  36  in order to restrict the member  50  from rotating relative to the transmission housing  36 . 
     Referring now to  FIG. 2  and  FIG. 3 , the operation of the embodiment of the six speed transmission  10  will be described. It will be appreciated that transmission  10  is capable of transmitting torque from the input shaft or member  12  to the output shaft or member  22  in at least six forward speed or torque ratios and at least one reverse speed or torque ratio. Each forward and reverse speed or torque ratio is attained by engagement of one or more of the torque-transmitting mechanisms (i.e. first clutch  26 , second clutch  28 , third clutch  30 , first brake  32  and second brake  34 ), as will be explained below.  FIG. 3  is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake is engaged to achieve the desired gear state. An “O” represents that the particular torque transmitting device (i.e. a brake or clutch) is on or active, but not carrying torque. Actual numerical gear ratios of the various gear states are also presented although it should be appreciated that these numerical values are exemplary only and that they may be adjusted over significant ranges to accommodate various applications and operational criteria of the transmission  10 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 3 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
     To establish a reverse gear, the first clutch  26 , the third clutch  30 , and the first brake  32  are engaged or activated. The first clutch  26  connects the fourth shaft or interconnecting member  48  and the third shaft or interconnecting member  46  with the eighth shaft or interconnecting member  56 . The third clutch  30  connects the second shaft or interconnecting member  44  with the ninth shaft or interconnecting member  58 . The first brake  32  connects the sixth shaft or interconnecting member  52  with the stationary element or the transmission housing  36  in order to restrict the member  52  from rotating relative to the transmission housing  36 . Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 3 . 
     It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission  10  assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated. 
     Referring now to  FIG. 4 , another embodiment of a six speed transmission  100  is illustrated in a lever diagram format. The transmission  100  includes an input shaft or member  112 , a first planetary gear set  114 , a second planetary gear set  116 , a third planetary gear set  118  and an output shaft or member  122 . The first planetary gear set  114  has three nodes: a first node  114 A, a second node  114 B, and a third node  114 C. The second planetary gear set  116  has three nodes: a first node  116 A, a second node  116 B, and a third node  116 C. The third planetary gear set  118  has three nodes: a first node  118 A, a second node  118 B and a third node  118 C. 
     The input member  112  is continuously coupled to the first node  114 A of the first planetary gear set  114 . The output member  122  is coupled to the third node  118 C of the third planetary gear set  118 . The second node  114 B of the first planetary gear set  114  is coupled to the third node  116 C of the second planetary gear set  116 . The first node  116 A of the second planetary gear set  116  is coupled to the first node  118 A of the third planetary gear set  118 . 
     A first clutch  126  selectively connects the third node  114 C of the first planetary gear set  114  with the second node  118 B of the third planetary gear set  118 . A second clutch  128  selectively connects the first node  114 A of the first planetary gear set  114  and input member  112  with the second node  116 B of the second planetary gear set  116 . A third clutch  130  selectively connects the second node  116 B of the second planetary gear set  116  with the second node  118 B of the third planetary gear set  118 . A first brake  132  selectively connects the third node  114 C of the first planetary gear set  114  with a stationary member or transmission housing  136 . A second brake  134  selectively connects the first node  116 A of the second planetary gear set  116  and the first node  118 A of the third planetary gear set  118  with a stationary member or transmission housing  136 . 
     Referring now to  FIG. 5 , a stick diagram presents a schematic layout of the embodiment of the six speed transmission  100  according to the present invention. In  FIG. 5 , the numbering from the lever diagram of  FIG. 4  is carried over. The clutches and couplings are correspondingly presented whereas the nodes of the planetary gear sets now appear as components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers. 
     For example, the planetary gear set  114  includes a sun gear member  114 A, a ring gear member  114 C and a planet gear carrier member  114 B that rotatably supports a set of planet gears  114 D (only one of which is shown). The sun gear member  114 A is connected for common rotation with the input member  112  and with a first shaft or interconnecting member  142 . The ring gear member  114 C is connected for common rotation with a second shaft or interconnecting member  144 . The planet carrier member  114 B is connected for common rotation with a third shaft or interconnecting member  146 . The planet gears  114 D are each configured to intermesh with both the sun gear member  114 A and the ring gear member  114 C. 
     The planetary gear set  116  includes a sun gear member  116 A, a ring gear member  116 C and a planet gear carrier member  116 B that rotatably supports a set of planet gears  116 D (only one of which is shown). The sun gear member  116 A is connected for common rotation with a fourth shaft or interconnecting member  148 . The ring gear member  116 C is connected for common rotation with the third shaft or interconnecting member  146 . The planet carrier member  116 B is connected for common rotation with a fifth shaft or interconnecting member  150  and with a sixth shaft or interconnecting member  152 . The planet gears  116 D are each configured to intermesh with both the sun gear member  116 A and the ring gear member  116 C. 
     The planetary gear set  118  includes a sun gear member  118 A, a ring gear member  118 C and a planet gear carrier member  118 B that rotatably supports a set of planet gears  118 D (only one of which is shown). The sun gear member  118 A is connected for common rotation with a seventh shaft or interconnecting member  154  and with the fourth shaft or interconnecting member  148 . The ring gear member  118 C is connected for common rotation with the output shaft or member  122 . The planet carrier member  118 B is connected for common rotation with an eighth shaft or interconnecting member  156 . The planet gears  118 D are each configured to intermesh with both the sun gear member  118 A and the ring gear member  118 C. 
     The input shaft or member  112  is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member  122  is continuously connected with the final drive unit or transfer case (not shown). 
     The torque-transmitting mechanisms or clutches  126 ,  128 ,  130  and brakes  132  and  134  allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch  126  is selectively engageable to connect the eighth shaft or interconnecting member  156  with the second shaft or interconnecting member  144 . The second clutch  128  is selectively engageable to connect the sixth shaft or interconnecting member  152  and the fifth shaft or interconnecting member  150  with the first shaft or interconnecting member  142  and the input shaft or member  112 . The third clutch  130  is selectively engageable to connect the eighth shaft or interconnecting member  156  with the fifth shaft or interconnecting member  150  and the sixth shaft or interconnecting member  152 . The first brake  132  is selectively engageable to connect the second shaft or interconnecting member  144  with the stationary element or the transmission housing  136  in order to restrict the member  144  from rotating relative to the transmission housing  136 . The second brake  134  is selectively engageable to connect the seventh shaft or interconnecting member  154  and the fourth shaft or interconnecting member  148  with the stationary element or the transmission housing  136  in order to restrict the members  154  and  148  from rotating relative to the transmission housing  136 . 
     Referring now to  FIG. 5  and  FIG. 6 , the operation of the embodiment of the six speed transmission  100  will be described. It will be appreciated that transmission  100  is capable of transmitting torque from the input shaft or member  112  to the output shaft or member  122  in at least six forward speed or torque ratios and at least one reverse speed or torque ratio. Each forward and reverse speed or torque ratio is attained by engagement of one or more of the torque-transmitting mechanisms (i.e. first clutch  126 , second clutch  128 , third clutch  130 , first brake  132  and second brake  134 ), as will be explained below.  FIG. 6  is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake is engaged to achieve the desired gear state. An “O” represents that the particular torque transmitting device (i.e. a brake or clutch) is on or active, but not carrying torque. Actual numerical gear ratios of the various gear states are also presented although it should be appreciated that these numerical values are exemplary only and that they may be adjusted over significant ranges to accommodate various applications and operational criteria of the transmission  100 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 6 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
     To establish a reverse gear, the second clutch  128 , the third clutch  130 , and the first brake  132  are engaged or activated. The second clutch  128  connects the sixth shaft or interconnecting member  152  with the first shaft or interconnecting member  142 . The third clutch  130  connects the eighth shaft or interconnecting member  156  with the fifth shaft or interconnecting member  150  and the sixth shaft or interconnecting member  152 . The first brake  132  connects the second shaft or interconnecting member  144  with the stationary element or the transmission housing  136  in order to restrict the member  144  from rotating relative to the transmission housing  136 . Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 6 . 
     It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission  100  assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated. 
     Referring now to  FIG. 7 , another embodiment of a six speed transmission  200  is illustrated in a lever diagram format. The transmission  200  includes an input shaft or member  212 , a first planetary gear set  214 , a second planetary gear set  216 , a third planetary gear set  218  and an output shaft or member  222 . The first planetary gear set  214  has three nodes: a first node  214 A, a second node  214 B, and a third node  214 C. The second planetary gear set  216  has three nodes: a first node  216 A, a second node  216 B, and a third node  216 C. The third planetary gear set  218  has three nodes: a first node  218 A, a second node  218 B and a third node  218 C. 
     The input member  212  is continuously coupled to the first node  216 A of the second planetary gear set  216 . The output member  222  is coupled to the first node  218 A of the third planetary gear set  218 . The third node  216 C of the second planetary gear set  216  is coupled to the second node  214 B of the first planetary gear set  214 . The second node  216 B of the second planetary gear set  216  is coupled to the second node  218 B of the third planetary gear set  218 . 
     A first clutch  226  selectively connects the third node  214 C of the first planetary gear set  214  with the third node  218 C of the third planetary gear set  218 . A second clutch  228  selectively connects the first node  214 A of the first planetary gear set  214  with the third node  218 C of the third planetary gear set  218 . A third clutch  230  selectively connects the first node  216 A of the second planetary gear set  216  and the input member  212  with the first node  214 A of the first planetary gear set  214 . A first brake  232  selectively connects the third node  214 C of the first planetary gear set  214  with a stationary member or transmission housing  236 . A second brake  234  selectively connects the second node  216 B of the second planetary gear set  216  and the second node  218 B of the third planetary gear set  218  with a stationary member or transmission housing  236 . 
     Referring now to  FIG. 8 , a stick diagram presents a schematic layout of the embodiment of the six speed transmission  200  according to the present invention. In  FIG. 8 , the numbering from the lever diagram of  FIG. 7  is carried over. The clutches and couplings are correspondingly presented whereas the nodes of the planetary gear sets now appear as components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers. 
     For example, the planetary gear set  214  includes a sun gear member  214 C, a ring gear member  214 B and a planet gear carrier member  214 A that rotatably supports a set of planet gears  214 D (only one of which is shown) and a set of planet gears  214 E (only one of which is shown). The sun gear member  214 C is connected for common rotation with a first shaft or interconnecting member  242  and a second shaft or interconnecting member  244 . The ring gear member  214 B is connected for common rotation with a third shaft or interconnecting member  246 . The planet carrier member  214 A is connected for common rotation with a fourth shaft or interconnecting member  248  and with a fifth shaft or interconnecting member  250 . The planet gears  214 D are each configured to intermesh with both the ring gear member  214 B and the planet gears  214 E. The planet gears  214 E are each configured to intermesh with both the planet gears  214 D and the sun gear member  214 C. 
     The planetary gear set  216  includes a sun gear member  216 A, a ring gear member  216 C and a planet gear carrier member  216 B that rotatably supports a set of planet gears  216 D (only one of which is shown). The sun gear member  216 A is connected for common rotation with a sixth shaft or interconnecting member  252  and the input shaft or member  212 . The ring gear member  216 C is connected for common rotation with the third shaft or interconnecting member  246 . The planet carrier member  216 B is connected for common rotation with a seventh shaft or interconnecting member  254 . The planet gears  216 D are each configured to intermesh with both the sun gear member  216 A and the ring gear member  216 C. 
     The planetary gear set  218  includes a sun gear member  218 C, a ring gear member  218 A and a planet gear carrier member  218 B that rotatably supports a set of planet gears  218 D (only one of which is shown). The sun gear member  218 C is connected for common rotation with an eighth shaft or interconnecting member  256 . The ring gear member  218 A is connected for common rotation with the output shaft or member  222 . The planet carrier member  218 B is connected for common rotation with a ninth shaft or interconnecting member  258  and with the seventh shaft or interconnecting member  254 . The planet gears  218 D are each configured to intermesh with both the sun gear member  218 C and the ring gear member  218 A. 
     The input shaft or member  212  is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member  222  is continuously connected with the final drive unit or transfer case (not shown). 
     The torque-transmitting mechanisms or clutches  226 ,  228 ,  230  and brakes  232  and  234  allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch  226  is selectively engageable to connect the eighth shaft or interconnecting member  256  with the second shaft or interconnecting member  244 . The second clutch  228  is selectively engageable to connect the eighth shaft or interconnecting member  256  with the fourth shaft or interconnecting member  248 . The third clutch  230  is selectively engageable to connect the fifth shaft or interconnecting member  250  with the sixth shaft or interconnecting member  252  and the input shaft or member  212 . The first brake  232  is selectively engageable to connect the first shaft or interconnecting member  242  with the stationary element or the transmission housing  236  in order to restrict the member  242  from rotating relative to the transmission housing  236 . The second brake  234  is selectively engageable to connect the ninth shaft or interconnecting member  258  and the seventh shaft or interconnecting member  254  with the stationary element or the transmission housing  236  in order to restrict the members  258  and  254  from rotating relative to the transmission housing  236 . 
     Referring now to  FIG. 8  and  FIG. 9 , the operation of the embodiment of the six speed transmission  200  will be described. It will be appreciated that transmission  200  is capable of transmitting torque from the input shaft or member  212  to the output shaft or member  222  in at least six forward speed or torque ratios and at least one reverse speed or torque ratio. Each forward and reverse speed or torque ratio is attained by engagement of one or more of the torque-transmitting mechanisms (i.e. first clutch  226 , second clutch  228 , third clutch  230 , first brake  232  and second brake  234 ), as will be explained below.  FIG. 9  is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake is engaged to achieve the desired gear state. An “O” represents that the particular torque transmitting device (i.e. a brake or clutch) is on or active, but not carrying torque. Actual numerical gear ratios of the various gear states are also presented although it should be appreciated that these numerical values are exemplary only and that they may be adjusted over significant ranges to accommodate various applications and operational criteria of the transmission  200 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 9 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
     To establish a reverse gear, the second clutch  228 , the third clutch  230 , and the second brake  234  are engaged or activated. The second clutch  228  connects the eighth shaft or interconnecting member  256  with the fourth shaft or interconnecting member  248 . The third clutch  230  connects the fifth shaft or interconnecting member  250  with the sixth shaft or interconnecting member  252  and the input shaft or member  212 . The second brake  234  connects the ninth shaft or interconnecting member  258  and the seventh shaft or interconnecting member  254  with the stationary element or the transmission housing  236  in order to restrict the members  258  and  254  from rotating relative to the transmission housing  236 . Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 9 . 
     It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission  200  assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated. 
     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.