Patent Publication Number: US-6991577-B2

Title: Wide ratio transmissions with three planetary gear sets and a stationary interconnecting member

Description:
TECHNICAL FIELD 
     The present invention relates to a family of power transmissions having three planetary gear sets that are controlled by seven torque-transmitting devices to provide at least eight forward speed ratios and at least one reverse speed ratio. 
     BACKGROUND OF THE INVENTION 
     Passenger vehicles include a powertrain that is comprised of an engine, multi-speed transmission, and a differential or final drive. The multi-speed transmission increases the overall operating range of the vehicle by permitting the engine to operate through its torque range a number of times. The number of forward speed ratios that are available in the transmission determines the number of times the engine torque range is repeated. Early automatic transmissions had two speed ranges. This severely limited the overall speed range of the vehicle and therefore required a relatively large engine that could produce a wide speed and torque range. This resulted in the engine operating at a specific fuel consumption point during cruising, other than the most efficient point. Therefore, manually-shifted (countershaft transmissions) were the most popular. 
     With the advent of three- and four-speed automatic transmissions, the automatic shifting (planetary gear) transmission increased in popularity with the motoring public. These transmissions improved the operating performance and fuel economy of the vehicle. The increased number of speed ratios reduces the step size between ratios and therefore improves the shift quality of the transmission by making the ratio interchanges substantially imperceptible to the operator under normal vehicle acceleration. 
     It has been suggested that the number of forward speed ratios be increased to six or more. Six-speed transmissions are disclosed in U.S. Pat. No. 4,070,927 issued to Polak on Jan. 31, 1978; and U.S. Pat. No. 6,422,969 issued to Raghavan and Usoro on Jul. 23, 2002. 
     Six-speed transmissions offer several advantages over four- and five-speed transmissions, including improved vehicle acceleration and improved fuel economy. While many trucks employ power transmissions having six or more forward speed ratios, passenger cars are still manufactured with three- and four-speed automatic transmissions and relatively few five or six-speed devices due to the size and complexity of these transmissions. 
     Seven-speed transmissions are disclosed in U.S. Pat. No. 6,623,397 issued to Raghavan, Bucknor and Usoro. Eight speed transmissions are disclosed in U.S. Pat. No. 6,425,841 issued to Haka. The Haka transmission utilizes three planetary gear sets and six torque transmitting devices, including two brakes and two clutches, to provide eight forward speed ratios and a reverse speed ratio. One of the planetary gear sets is positioned and operated to establish two fixed speed input members for the remaining two planetary gear sets. The Haka transmission requires two double-transition shifts. Seven-, eight- and nine-speed transmissions provide further improvements in acceleration and fuel economy over six-speed transmissions. However, like the six-speed transmissions discussed above, the development of seven-, eight- and nine-speed transmissions has been precluded because of complexity, size and cost. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved family of transmissions having three planetary gear sets controlled to provide at least eight forward speed ratios and at least one reverse speed ratio. 
     In one aspect of the present invention, the family of transmissions has three planetary gear sets, each of which includes a first, second and third member, which members may comprise a sun gear, a ring gear, or a planet carrier assembly member. 
     In referring to the first, second and third gear sets in this description and in the claims, these sets may be counted “first” to “third” in any order in the drawings (i.e., left to right, right to left, etc.). Additionally, the first, second or third members of each gear set may be counted “first” to “third” in any order in the drawings (i.e., top to bottom, bottom to top, etc.) for each gear set. 
     In another aspect of the present invention, planet carrier assembly members of each of the planetary gear sets may be single pinion-carriers or double pinion-carriers. 
     In yet another aspect of the present invention, a first member of the first planetary gear set is continuously interconnected to a first member of the second planetary gear set and with a stationary member (transmission housing) through a first interconnecting member. 
     In yet another aspect of the present invention, a second member of the first planetary gear set is continuously interconnected to a second member of the second planetary gear set through a second interconnecting member. 
     In yet a further aspect of the invention, each family member incorporates an input shaft which is continuously connected with a member of the third planetary gear set and an output shaft which is continuously connected with another member of the third planetary gear set. 
     In still a further aspect of the invention, a first torque-transmitting mechanism, such as a clutch, selectively interconnects a member of the first planetary gear set with a member of the third planetary gear set. 
     In another aspect of the invention, a second torque-transmitting mechanism, such as a clutch, selectively interconnects a member of the second planetary gear set with a member of the third planetary gear set. 
     In a still further aspect of the invention, a third torque-transmitting mechanism, such as a clutch, selectively interconnects a member of the third planetary gear set with a member of the first planetary gear set. The pair of members interconnected by the third torque-transmitting mechanism are different from the pair of members interconnected by the first torque-transmitting mechanism. 
     In a still further aspect of the invention, a fourth torque-transmitting mechanism, such as a clutch, selectively interconnects a member of the third planetary gear set with a member of the second planetary gear set. The pair of members interconnected by the fourth torque-transmitting mechanism is different from the pair of members interconnected by the second torque-transmitting mechanism. 
     In a still further aspect of the invention, a fifth torque-transmitting mechanism, such as a clutch, selectively interconnects a member of the third planetary gear set with a member of the first or second planetary gear set. The pair of members interconnected by the firth torque-transmitting mechanism is different from the pairs of members interconnected by the first, second, third and fourth torque-transmitting mechanisms, respectively. 
     In still another aspect of the invention, a sixth torque-transmitting mechanism, such as a clutch, selectively interconnects a member of the third planetary gear set with another member of the first, second or third planetary gear set. The pair of members interconnected by the sixth torque-transmitting mechanism is different from the pairs of members interconnected by the first, second, third, fourth and fifth torque-transmitting mechanisms, respectively. 
     In still another aspect of the invention, a seventh torque-transmitting mechanism, such as a clutch, selectively interconnects a member of the first or second planetary gear set with a member of the third planetary gear set. Alternatively, the seventh torque-transmitting mechanism, such as a brake, selectively interconnects a member of the first or second planetary gear set with the stationary member (transmission housing). 
     In still another aspect of the invention, the seven torque-transmitting mechanisms are selectively engageable in combinations of two to yield at least eight forward speed ratios and at least one reverse speed ratio. 
     The resulting transmission provides a significantly wider ratio spread in comparison to transmissions with fewer speed ratios. 
     The above features and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a schematic representation of a powertrain including a planetary transmission incorporating a family member of the present invention; 
         FIG. 1   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 1   a;    
         FIG. 2   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 2   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 2   a;    
         FIG. 3   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 3   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 3   a;    
         FIG. 4   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 4   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 4   a;    
         FIG. 5   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 5   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 5   a;    
         FIG. 6   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 6   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 6   a;    
         FIG. 7   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 7   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 7   a;    
         FIG. 8   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 8   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 8   a;    
         FIG. 9   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 9   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 9   a;    
         FIG. 10   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 10   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 10   a;    
         FIG. 11   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; 
         FIG. 11   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 11   a;    
         FIG. 12   a  is a schematic representation of a powertrain having a planetary transmission incorporating another family member of the present invention; and 
         FIG. 12   b  is a truth table and chart depicting some of the operating characteristics of the powertrain shown in  FIG. 12   a.    
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like characters represent the same or corresponding parts throughout the several views, there is shown in  FIG. 1   a  a powertrain  10  having a conventional engine and torque converter  12 , a planetary transmission  14 , and a conventional final drive mechanism  16 . 
     The planetary transmission  14  includes an input shaft  17  continuously connected with the engine and torque converter  12 , a planetary gear arrangement  18 , and an output shaft  19  continuously connected with the final drive mechanism  16 . The planetary gear arrangement  18  includes three planetary gear sets  20 ,  30  and  40 . 
     The planetary gear set  20  includes a sun gear member  22 , a ring gear member  24 , and a planet carrier assembly  26 . The planet carrier assembly  26  includes a plurality of pinion gears  27  rotatably mounted on a carrier member  29  and disposed in meshing relationship with both the sun gear member  22  and the ring gear member  24 . 
     The planetary gear set  30  includes a sun gear member  32 , a ring gear member  34 , and a planet carrier assembly member  36 . The planet carrier assembly member  36  includes a plurality of pinion gears  37  rotatably mounted on a carrier member  39  and disposed in meshing relationship with both the sun gear member  32  and the ring gear member  34 . 
     The planetary gear set  40  includes a sun gear member  42 , a ring gear member  44 , and a planet carrier assembly member  46 . The planet carrier assembly member  46  includes a plurality of pinion gears  47  rotatably mounted on a carrier member  49  and disposed in meshing relationship with both the sun gear member  42  and the ring gear member  44 . 
     The planetary gear arrangement also includes seven torque-transmitting mechanisms  50 ,  52 ,  54 ,  56 ,  57 ,  58  and  59 . The torque-transmitting mechanisms  50 ,  52 ,  54 ,  56   57 ,  58  and  59  are rotating-type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the sun gear member  42 , and the output shaft  19  is continuously connected with the planet carrier assembly member  46 . The sun gear member  22  is continuously connected with the sun gear member  32  and with the stationary member  60  through the interconnecting member  70 . The interconnecting member  70  may be one component or two separate components. The ring gear member  24  is continuously connected with the planet carrier assembly member  36  through the interconnecting member  72 . 
     The planet carrier assembly member  36  is selectively connectable with the planet carrier assembly member  46  through the clutch  50 . The planet carrier assembly member  36  is selectively connectable with the ring gear member  44  through the clutch  52 . The planet carrier assembly member  26  is selectively connectable with the sun gear member  42  through the clutch  54 . The planet carrier assembly member  26  is selectively connectable with the planet carrier assembly member  46  through the clutch  56 . The planet carrier assembly member  26  is selectively connectable with the ring gear member  44  through the clutch  57 . The ring gear member  34  is selectively connectable with the planet carrier assembly member  46  through the clutch  58 . The ring gear member  34  is selectively connectable with the ring gear member  44  through the clutch  59 . 
     As shown in  FIG. 1   b , and in particular the truth table disclosed therein, the torque-transmitting mechanisms are selectively engaged in combinations of two to provide eight forward speed ratios (as well as an extra third forward speed ratio (3′)) and two reverse speed ratios. 
     The second reverse speed ratio (Reverse #2) is established with the engagement of the clutch  56  and the clutch  59 . The clutch  56  connects the planet carrier assembly member  26  with the planet carrier assembly member  46 , and the clutch  59  connects the ring gear member  34  with the ring gear member  44 . The ring gear member  24  rotates at the same speed as the planet carrier assembly member  36 . The planet carrier assembly member  26  rotates at the same speed as the planet carrier assembly member  46  and the output shaft  19 . The sun gear member  22  and the sun gear member  32  do not rotate. The speed of the planet carrier assembly member  26  is determined from the speed of the ring gear member  24  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The ring gear member  34  rotates at the same speed as the ring gear member  44 . The ring gear member  34  rotates at a speed determined from the speed of the planet carrier assembly member  36  and the ring gear/sun gear tooth ratio of the planetary gear set  30 . The sun gear member  42  rotates at the same speed as the input shaft  17 . The speed of the planet carrier assembly member  46 , and therefore the speed of the output shaft  19 , is determined from the speed of the ring gear member  44 , the speed of the sun gear member  42  and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the Reverse #2 speed ratio is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  20 ,  30  and  40 . 
     The first reverse speed ratio (Reverse #1) is established with the engagement of the clutch  52  and the clutch  56 . The clutch  52  connects the planet carrier assembly member  36  with the ring gear member  44 , and the clutch  56  connects the planet carrier assembly member  26  with the planet carrier assembly member  46 . The ring gear member  22  and the planet carrier assembly member  36  rotate at the same speed as the ring gear member  44 . The planet carrier assembly member  26  and the planet carrier assembly member  46  rotate at the same speed as the output shaft  19 . The sun gear member  22  and the sun gear member  32  do not rotate. The speed of the planet carrier assembly member  26  is determined from the speed of the ring gear member  24  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The sun gear member  42  rotates at the same speed as the input shaft  17 . The planet carrier assembly member  46 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the ring gear member  44 , the speed of the sun gear member  42  and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the Reverse #1 speed ratio is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  20  and  40 . 
     The first forward speed ratio is established with the engagement of the clutch  57  and the clutch  59 . The clutch  57  connects the planet carrier assembly member  26  with the ring gear member  44 , and the clutch  59  connects the ring gear member  34  with the ring gear member  44 . The sun gear member  42  rotates at the same speed as the input shaft  17 . The ring gear member  44 , and the planetary gear sets  20  and  30  do not rotate. The planet carrier assembly member  46  rotates at the same speed as the output shaft  19 . The planet carrier assembly member  46 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the sun gear member  42 , and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the first forward speed ratio is determined utilizing the ring gear/sun gear tooth ratio of the planetary gear set  40 . 
     The second forward speed ratio is established with the engagement of the clutch  57  and the clutch  58 . The clutch  57  connects the planet carrier assembly member  26  with the ring gear member  44 , and the clutch  58  connects the ring gear member  34  with the planet carrier assembly member  46 . The ring gear member  24  rotates at the same speed as the planet carrier assembly member  36 . The sun gear member  22  and the sun gear member  32  do not rotate. The planet carrier assembly member  26  rotates at the same speed as the ring gear member  44 . The planet carrier assembly member  26  rotates at a speed determined from the speed of the ring gear member  24  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The ring gear member  34  and the planet carrier assembly member  46  rotate at the same speed as the output shaft  19 . The ring gear member  34  rotates at a speed determined from the speed of the planet carrier assembly member  36  and the ring gear/sun gear tooth ratio of the planetary gear set  30 . The sun gear member  42  rotates at the same speed as the input shaft  17 . The planet carrier assembly member  46 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the ring gear member  44 , the speed of the sun gear member  42  and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the second forward speed ratio is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  20 ,  30  and  40 . 
     The extra third forward speed ratio (3′) is established with the engagement of the clutch  50  and the clutch  57 . The clutch  50  connects the planet carrier assembly member  36  with the planet carrier assembly member  46 , and the clutch  57  connects the planet carrier assembly member  26  with the ring gear member  44 . The ring gear member  24 , the planet carrier assembly member  36  and the planet carrier assembly member  46  rotate at the same speed as the output shaft  19 . The sun gear member  22  and the sun gear member  32  do not rotate. The planet carrier assembly member  26  rotates at the same speed as the ring gear member  44 . The planet carrier assembly member  26  rotates at a speed determined from the speed of the ring gear member  24  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The sun gear member  42  rotates at the same speed as the input shaft  17 . The planet carrier assembly member  46 , and therefore the output shaft  19 , rotates a speed determined from the speed of the ring gear member  44 , the speed of the sun gear member  42  and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the extra third forward speed ratio (3′) is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  20  and  40 . 
     The third forward speed ratio is established with the engagement of the clutch  52  and the clutch  58 . The clutch  52  connects the planet carrier assembly member  36  with the ring gear member  44 , and the clutch  58  connects the ring gear member  34  with the planet carrier assembly member  46 . The ring gear member  24  and the planet carrier assembly member  36  rotate at the same speed as the ring gear member  44 . The sun gear member  22  and the sun gear member  32  do not rotate. The ring gear member  34  and the planet carrier assembly member  46  rotate at the same speed as the output shaft  19 . The ring gear member  34  rotates at a speed determined from the speed of the planet carrier assembly member  36  and the ring gear/sun gear tooth ratio of the planetary gear set  30 . The sun gear member  42  rotates at the same speed as the input shaft  17 . The planet carrier assembly member  46 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the ring gear member  44 , the speed of the sun gear member  42  and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the third forward speed ratio is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  30  and  40 . 
     The fourth forward speed ratio is established with the engagement of the clutch  50  and the clutch  52 . In this configuration, the input shaft  17  is directly connected with the output shaft  19 . The numerical value of the fourth forward speed ratio is one. 
     The fifth forward speed ratio is established with the engagement of the clutch  52  and the clutch  54 . The clutch  52  connects the planet carrier assembly member  36  with the ring gear member  44 , and the clutch  54  connects the planet carrier assembly member  26  with the sun gear member  42 . The ring gear member  24  and the planet carrier assembly member  36  rotate at the same speed as the ring gear member  44 . The sun gear member  22  and the sun gear member  32  do not rotate. The planet carrier assembly member  26  and the sun gear member  42  rotate at the same speed as the input shaft  17 . The planet carrier assembly member  26  rotates at a speed determined from the speed of the ring gear member  24  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The planet carrier assembly member  46  rotates at the same speed as the output shaft  19 . The planet carrier assembly member  46 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the ring gear member  44 , the speed of the sun gear member  42  and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the fifth forward speed ratio is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  20  and  40 . 
     The sixth forward speed ratio is established with the engagement of the clutch  50  and the clutch  54 . The clutch  50  connects the planet carrier assembly member  36  with the planet carrier assembly member  46 , and the clutch  54  connects the planet carrier assembly member  26  with the sun gear member  42 . The planet carrier assembly member  26  and the sun gear member  42  rotate as the same speed as the input shaft  17 . The sun gear member  22  and the sun gear member  32  do not rotate. The ring gear member  24 , the planet carrier assembly member  36  and the planet carrier assembly member  46  rotate at the same speed as the output shaft  19 . The ring gear member  24 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the planet carrier assembly member  26  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The numerical value of the sixth forward speed ratio is determined utilizing the ring gear/sun gear tooth ratio of the planetary gear set  20 . 
     The seventh forward speed ratio is established with the engagement of the clutch  54  and the clutch  59 . The clutch  54  connects the planet carrier assembly member  26  with the sun gear member  42 , and the clutch  59  connects the ring gear member  34  with the ring gear member  44 . The ring gear member  24  rotates at the same speed as the planet carrier assembly member  36 . The sun gear member  22  and the sun gear member  32  do not rotate. The planet carrier assembly member  26  and the sun gear member  42  rotate at the same speed as the input shaft  17 . The planet carrier assembly member  26  rotates at a speed determined from the speed of the ring gear member  24  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The ring gear member  34  rotates at the same speed as the ring gear member  44 . The ring gear member  34  rotates at a speed determined from the speed of the planet carrier assembly member  36  and the ring gear/sun gear tooth ratio of the planetary gear set  30 . The planet carrier assembly member  46  rotates at the same speed as the output shaft  19 . The planet carrier assembly member  46 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the ring gear member  44 , the speed of the sun gear member  42  and the ring gear/sun gear tooth ratio of the planetary gear set  40 . The numerical value of the seventh forward speed ratio is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  20 ,  30  and  40 . 
     The eight forward speed ratio is established with the engagement of the clutch  54  and the clutch  58 . The clutch  54  connects the planet carrier assembly member  26  with the sun gear member  42 , and the clutch  58  connects the ring gear member  34  with the planet carrier assembly member  46 . The ring gear member  24  rotates at the same speed as the planet carrier assembly member  36 . The sun gear member  22  and the sun gear member  32  do not rotate. The planet carrier assembly member  26  and the sun gear member  42  rotate at the same speed as the input shaft  17 . The planet carrier assembly member  26  rotates at a speed determined from the speed of the ring gear member  24  and the ring gear/sun gear tooth ratio of the planetary gear set  20 . The ring gear member  34  and the planet carrier assembly member  46  rotate at the same speed as the output shaft  19 . The ring gear member  34 , and therefore the output shaft  19 , rotates at a speed determined from the speed of the planet carrier assembly member  36  and the ring gear/sun gear tooth ratio of the planetary gear set  30 . The numerical value of the eight forward speed ratio is determined utilizing the ring gear/sun gear tooth ratios of the planetary gear sets  20  and  30 . 
     As set forth above, the engagement schedule for the torque-transmitting mechanisms is shown in the truth table of  FIG. 1   b . This truth table also provides an example of speed ratios that are available utilizing the ring gear/sun gear tooth ratios given by way of example in  FIG. 1   b . The N R1 /S R1  value is the tooth ratio of the planetary gear set  20 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  30 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  40 . Also, the chart of  FIG. 1   b  describes the ratio steps that are attained utilizing the sample of tooth ratios given. For example, the step ratio between the first and second forward speed ratios is 1.45, while the step ratio between the second reverse speed ratio (R2) and first forward ratio is −0.54. It should be noted that the single step forward ratio interchanges are of the single transition variety. 
       FIG. 2   a  shows a powertrain  110  having a conventional engine and torque converter  12 , a planetary transmission  114 , and a conventional final drive mechanism  16 . 
     The planetary transmission  114  includes an input shaft  17  continuously connected with the engine and torque converter  12 , a planetary gear arrangement  118 , and an output shaft  19  continuously connected with the final drive mechanism  16 . The planetary gear arrangement  118  includes three planetary gear sets  120 ,  130  and  140 . 
     The planetary gear set  120  includes a sun gear member  122 , a ring gear member  124 , and a planet carrier assembly  126 . The planet carrier assembly  126  includes a plurality of pinion gears  127  rotatably mounted on a carrier member  129  and disposed in meshing relationship with both the sun gear member  122  and the ring gear member  124 . 
     The planetary gear set  130  includes a sun gear member  132 , a ring gear member  134 , and a planet carrier assembly member  136 . The planet carrier assembly member  136  includes a plurality of pinion gears  137  rotatably mounted on a carrier member  139  and disposed in meshing relationship with both the sun gear member  132  and the ring gear member  134 . 
     The planetary gear set  140  includes a sun gear member  142 , a ring gear member  144 , and a planet carrier assembly member  146 . The planet carrier assembly member  146  includes a plurality of pinion gears  147  rotatably mounted on a carrier member  149  and disposed in meshing relationship with both the sun gear member  142  and the ring gear member  144 . 
     The planetary gear arrangement  118  also includes seven torque-transmitting mechanisms  150 ,  152 ,  154 ,  156 ,  157 ,  158  and  159 . The torque-transmitting mechanisms  150 ,  152 ,  154 ,  156 ,  157  and  158  are rotating-type torque-transmitting mechanisms, commonly termed clutches. The torque-transmitting mechanism  159  is a stationary-type torque-transmitting mechanism, commonly termed a brake or reaction clutch. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  146 , and the output shaft  19  is continuously connected with the ring gear member  144 . The ring gear member  124  is continuously connected with the sun gear member  132  and the stationary member  160  through the interconnecting member  170 . The interconnecting member  170  may be one component or separate components. The planet carrier assembly member  126  is continuously connected with the ring gear member  134  through the interconnecting member  172 . 
     The planet carrier assembly member  126  is selectively connectable with the planet carrier assembly member  146  through the clutch  150 . The ring gear member  134  is selectively connectable with the sun gear member  142  through the clutch  152 . The sun gear member  122  is selectively connectable with the planet carrier assembly member  146  through the clutch  154 . The sun gear member  122  is selectively connectable with the sun gear member  142  through the clutch  156 . The planet carrier assembly member  136  is selectively connectable with the sun gear member  142  through the clutch  158 . The planet carrier assembly member  126  is selectively connectable with the transmission housing  160  through the brake  159 . 
     The truth tables given in  FIGS. 2   b ,  3   b ,  4   b ,  5   b ,  6   b ,  7   b ,  8   b ,  9   b ,  10   b ,  11   b  and  12   b  show the engagement sequences for the torque-transmitting mechanisms to provide at least eight forward speed ratios and at least one reverse ratio. As shown and described above for the configuration in  FIG. 1   a , those skilled in the art will understand from the respective truth tables how the speed ratios are established through the planetary gear sets identified in the written description. 
     As set forth above, the truth table of  FIG. 2   b  describes the engagement sequence of the torque-transmitting mechanisms utilized to provide a reverse speed ratio and nine forward speed ratios. The truth table also provides an example of the ratios that can be attained with the family members shown in  FIG. 2   a  utilizing the sample tooth ratios given in  FIG. 2   b . The N R1 /S R1  value is the tooth ratio of the planetary gear set  120 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  130 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  140 . Also shown in  FIG. 2   b  are the ratio steps between single step ratios in the forward direction as well as the reverse to first ratio step. For example, the first to second step ratio is 1.91. 
     Turning to  FIG. 3   a , a powertrain  210  includes the engine and torque converter  12 , a planetary transmission  214 , and a final drive mechanism  16 . The planetary transmission  214  includes an input shaft  17  continuously connected with the engine and torque converter  12 , a planetary gear arrangement  218 , and an output shaft  19  continuously connected with the final drive mechanism  16 . The planetary gear arrangement  218  includes three planetary gear sets  220 ,  230  and  240 . 
     The planetary gear set  220  includes a sun gear member  222 , a ring gear member  224 , and a planet carrier assembly  226 . The planet carrier assembly  226  includes a plurality of pinion gears  227  rotatably mounted on a carrier member  229  and disposed in meshing relationship with both the sun gear member  222  and the ring gear member  224 . 
     The planetary gear set  230  includes a sun gear member  232 , a ring gear member  234 , and a planet carrier assembly member  236 . The planet carrier assembly member  236  includes a plurality of pinion gears  237  rotatably mounted on a carrier member  239  and disposed in meshing relationship with both the sun gear member  232  and the ring gear member  234 . 
     The planetary gear set  240  includes a sun gear member  242 , a ring gear member  244 , and a planet carrier assembly member  246 . The planet carrier assembly member  246  includes a plurality of pinion gears  247  rotatably mounted on a carrier member  249  and disposed in meshing relationship with both the sun gear member  242  and the ring gear member  244 . 
     The planetary gear arrangement  218  also includes seven torque-transmitting mechanisms  250 ,  252 ,  254 ,  256 ,  257 ,  258  and  259 . The torque-transmitting mechanisms  250 ,  252 ,  254 ,  256 ,  257  and  258  are rotating type torque-transmitting mechanisms, commonly termed clutches. The torque-transmitting mechanism  259  is stationary-type torque-transmitting mechanism, commonly termed a brake or reaction clutch. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  246 , and the output shaft  19  is continuously connected with the ring gear member  244 . The ring gear member  224  is continuously connected with the sun gear member  232  and the transmission housing  260  through the interconnecting member  270 . The interconnecting member  270  may be one component or separate components. The planet carrier assembly member  226  is continuously connected with the ring gear member  234  through the interconnecting member  272 . 
     The planet carrier assembly member  226  is selectively connectable with the planet carrier assembly member  246  through the clutch  250 . The planet carrier assembly member  226  is selectively connectable with the sun gear member  242  through the clutch  252 . The sun gear member  222  is selectively connectable with the planet carrier assembly member  246  through the clutch  254 . The sun gear member  222  is selectively connectable with the sun gear member  242  through the clutch  256 . The sun gear member  222  is selectively connectable with the ring gear member  244  through the clutch  257 . The planet carrier assembly member  236  is selectively connectable with the ring gear member  244  through the clutch  258 . The planet carrier assembly member  236  is selectively connectable with the transmission housing  260  through the clutch  259 . 
     As shown in the truth table of  FIG. 3   b , the torque-transmitting mechanisms are engaged in combinations of two to establish eight forward speed ratios (as well as an extra eighth forward speed ratio (8′)) and one reverse ratio. As previously set forth, the truth table of  FIG. 3   b  describes the combinations of engagements utilized for the eight forward speed ratios, the extra eighth speed ration (8′) and one reverse ratio. 
     The truth table also provides an example of speed ratios that are available with the family member described above. These examples of speed ratios are determined utilizing the tooth ratios given in  FIG. 3   b . The N R1 /S R1  value is the tooth ratio of the planetary gear set  220 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  230 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  240 . Also depicted in  FIG. 3   b  is a chart representing the ratio steps between adjacent forward speed ratios and the reverse speed ratio. For example, the first to second ratio interchange has a step of 2.04. It can also be readily determined from the truth table of  FIG. 3   b  that all of the single step and double step forward ratio interchanges are of the single transition variety. 
     A powertrain  310 , shown in  FIG. 4   a , includes the engine and torque converter  12 , a planetary transmission  314 , and the final drive mechanism  16 . The planetary transmission  314  includes an input shaft  17  continuously connected with the engine and torque converter  12 , a planetary gear arrangement  318 , and output shaft  19  continuously connected with the final drive mechanism  16 . The planetary gear arrangement  318  includes three planetary gear sets  320 ,  330  and  340 . 
     The planetary gear set  320  includes a sun gear member  322 , a ring gear member  324 , and a planet carrier assembly member  326 . The planet carrier assembly member  326  includes a plurality of pinion gears  327  rotatably mounted on a carrier member  329  and disposed in meshing relationship with both the sun gear member  322  and the ring gear member  324 . 
     The planetary gear set  330  includes a sun gear member  332 , a ring gear member  334 , and a planet carrier assembly member  336 . The planet carrier assembly member  336  includes a plurality of pinion gears  337  rotatably mounted on a carrier member  339  and disposed in meshing relationship with both the sun gear member  332  and the ring gear member  334 . 
     The planetary gear set  340  includes a sun gear member  342 , a ring gear member  344 , and a planet carrier assembly member  346 . The planet carrier assembly member  346  includes a plurality of pinion gears  347  rotatably mounted on a carrier member  349  and disposed in meshing relationship with both the sun gear member  342  and the ring gear member  344 . 
     The planetary gear arrangement  318  also includes seven torque-transmitting mechanisms  350 ,  352 ,  354 ,  356 ,  357 ,  358  and  359 . The torque-transmitting mechanisms  350 ,  352 ,  354 ,  356 ,  357 ,  358  and  359  are rotating type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  346 , and the output shaft  19  is continuously connected with the ring gear member  344 . The ring gear member  324  is continuously connected with the sun gear member  332  and the stationary member  360  through the interconnecting member  370 . The interconnecting member  370  may be one component or separate components. The planet carrier assembly member  326  is continuously connected with the ring gear member  334  through the interconnecting member  372 . 
     The planet carrier assembly member  326  is selectively connectable with the planet carrier assembly member  346  through the clutch  350 . The planet carrier assembly member  326  is selectively connectable with the ring gear member  344  through the clutch  352 . The planet carrier assembly member  326  is selectively connectable with the sun gear member  342  through the clutch  354 . The sun gear member  322  is selectively connectable with the planet carrier assembly member  346  through the clutch  356 . The sun gear member  322  is selectively connectable with the ring gear member  344  through the clutch  357 . The sun gear member  322  is selectively connectable with the sun gear member  342  through the clutch  358 . The planet carrier assembly member  336  is selectively connectable with the ring gear member  344  through the clutch  359 . 
     The truth table shown in  FIG. 4   b  describes the engagement combination and the engagement sequence necessary to provide a reverse drive ratio, eight forward speed ratios (as well as an extra second forward speed ratio (2′) and an extra third forward speed ratio (3′)). A sample of the numerical values for the ratios is also provided in the truth table of  FIG. 4   b . These values are determined utilizing the ring gear/sun gear tooth ratios also given in  FIG. 4   b . The N R1 /S R1  value is the tooth ratio for the planetary gear set  320 ; the N R2 /S R2  value is the tooth ratio for the planetary gear set  330 ; and the N R3 /S R3  value is the tooth ratio for the planetary gear set  340 . Also given in  FIG. 4   b  is a chart describing the step ratios between the adjacent forward speed ratios and the reverse to first forward speed ratio. For example, the first to second forward speed ratio step is 1.91. It can be readily determined from the truth table of  FIG. 4   b  that each of the forward single step ratio interchanges is of the single transition variety. 
     A powertrain  410 , shown in  FIG. 5   a , includes the engine and torque converter  12 , a planetary transmission  414  and the final drive mechanism  16 . The planetary transmission  414  includes a planetary gear arrangement  418 , input shaft  17  and output shaft  19 . The planetary gear arrangement  418  includes three simple planetary gear sets  420 ,  430  and  440 . 
     The planetary gear set  420  includes a sun gear member  422 , a ring gear member  424 , and a planet carrier assembly  426 . The planet carrier assembly  426  includes a plurality of pinion gears  427  rotatably mounted on a carrier member  429  and disposed in meshing relationship with both the sun gear member  422  and the ring gear member  424 . 
     The planetary gear set  430  includes a sun gear member  432 , a ring gear member  434 , and a planet carrier assembly member  436 . The planet carrier assembly member  436  includes a plurality of pinion gears  437  rotatably mounted on a carrier member  439  and disposed in meshing relationship with both the sun gear member  432  and the ring gear member  434 . 
     The planetary gear set  440  includes a sun gear member  442 , a ring gear member  444 , and a planet carrier assembly member  446 . The planet carrier assembly member  446  includes a plurality of pinion gears  447  rotatably mounted on a carrier member  449  and disposed in meshing relationship with both the sun gear member  442  and the ring gear member  444 . 
     The planetary gear arrangement  418  also includes seven torque-transmitting mechanisms  450 ,  452 ,  454 ,  456 ,  457 ,  458  and  459 . The torque-transmitting mechanisms  450 ,  452 ,  454 ,  456 ,  457 ,  458  and  459  are rotating type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  446 , and the output shaft  19  is continuously connected with the ring gear member  444 . The sun gear member  422  is continuously connected with the ring gear member  434  and the transmission housing  460  through the interconnecting member  470 . The interconnecting member  470  may be one component or separate components. The ring gear member  424  is continuously connected with the planet carrier assembly member  436  through the interconnecting member  472 . 
     The planet carrier assembly member  436  is selectively connectable with the planet carrier assembly member  446  through the clutch  450 . The ring gear member  424  is selectively connectable with the sun gear member  442  through the clutch  452 . The planet carrier assembly member  426  is selectively connectable with the planet carrier assembly member  446  through the clutch  454 . The planet carrier assembly member  426  is selectively connectable with the sun gear member  442  through the clutch  456 . The planet carrier assembly member  426  is selectively connectable with the ring gear member  444  through the cutch  457 . The sun gear member  432  is selectively connectable with the planet carrier assembly member  446  through the clutch  458 . The sun gear member  432  is selectively connectable with the sun gear member  442  through the clutch  459 . 
     The truth table shown in  FIG. 5   b  describes the engagement combination and sequence of the torque-transmitting mechanisms  450 ,  452 ,  454 ,  456 ,  457 ,  458  and  459  that are employed to provide two reverse drive ratios and eight forward speed ratios (as well as an extra third forward speed ratio (3′) and an extra sixth forward speed ratio (6′)). 
     Also given in the truth table of  FIG. 5   b  is a set of numerical values that are attainable with the present invention utilizing the ring gear/sun gear tooth ratios shown. The N R1 /S R1  value is the tooth ratio of the planetary gear set  420 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  430 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  440 . As can also be determined from the truth table of  FIG. 5   b , all of the single step forward interchanges are of the single transition variety. 
       FIG. 5   b  also provides a chart of the ratio steps between adjacent forward ratios and between the reverse two ratio and first forward ratio. For example, the ratio step between the first and second forward ratios is 2.04. 
     A powertrain  510 , shown in  FIG. 6   a , includes an engine and torque converter  12 , a planetary gear transmission  514  and the final drive mechanism  16 . The planetary transmission  514  includes the input shaft  17 , a planetary gear arrangement  518  and the output shaft  19 . The planetary gear arrangement  518  includes three planetary gear sets  520 ,  530  and  540 . 
     The planetary gear set  520  includes a sun gear member  522 , a ring gear member  524 , and a planet carrier assembly  526 . The planet carrier assembly  526  includes a plurality of pinion gears  527  rotatably mounted on a carrier member  529  and disposed in meshing relationship with both the sun gear member  522  and the ring gear member  524 . 
     The planetary gear set  530  includes a sun gear member  532 , a ring gear member  534 , and a planet carrier assembly member  536 . The planet carrier assembly member  536  includes a plurality of pinion gears  537  rotatably mounted on a carrier member  539  and disposed in meshing relationship with both the sun gear member  532  and the ring gear member  534 . 
     The planetary gear set  540  includes a sun gear member  542 , a ring gear member  544 , and a planet carrier assembly member  546 . The planet carrier assembly member  546  includes a plurality of pinion gears  547  rotatably mounted on a carrier member  549  and disposed in meshing relationship with both the sun gear member  542  and the ring gear member  544 . 
     The planetary gear arrangement  518  also includes seven torque-transmitting mechanisms  550 ,  552 ,  554 ,  556 ,  557 ,  558  and  559 . The torque-transmitting mechanisms  550 ,  552 ,  554 ,  556 ,  557 ,  558  and  559  are rotating type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  546 , and the output shaft  19  is continuously connected with the ring gear member  544 . The ring gear member  524  is continuously connected with the sun gear member  532  and the transmission housing  560  through the interconnecting member  570 . The interconnecting member  570  may be one component or separate components. The sun gear member  522  is continuously connected with the planet carrier assembly member  536  through the interconnecting member  572 . 
     The planet carrier assembly member  536  is selectively connectable with the planet carrier assembly member  546  through the clutch  550 . The sun gear member  522  is selectively connectable with the sun gear member  542  through the clutch  552 . The planet carrier assembly member  526  is selectively connectable with the planet carrier assembly member  546  through the clutch  554 . The planet carrier assembly member  526  is selectively connectable with the sun gear member  542  through the clutch  556 . The planet carrier assembly member  526  is selectively connectable with the ring gear member  544  through the clutch  557 . The ring gear member  534  is selectively connectable with the planet carrier assembly member  546  through the clutch  558 . The ring gear member  534  is selectively connectable with the sun gear member  542  through the clutch  559 . 
     The truth table shown in  FIG. 6   b  describes the engagement sequence and combination of the torque-transmitting mechanisms to provide two reverse speed ratios and eight forward speed ratios (as well as an extra fourth speed ratio (4′)). The chart of  FIG. 6   b  describes the ratio steps between adjacent forward speed ratios and the ratio step between the second reverse (Reverse #2) and first forward speed ratio. 
     The sample speed ratios given in the truth table are determined utilizing the tooth ratio values also given in  FIG. 6   b . The N R1 /S R1  wvalue is the tooth ratio of the planetary gear set  520 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  530 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  540 . As can also be determined from the truth table of  FIG. 6   b , each of the single step forward interchanges is of the single transition variety. 
     A powertrain  610 , shown in  FIG. 7   a , has the engine and torque converter  12 , a planetary transmission  614  and the final drive mechanism  16 . The planetary transmission  614  includes the input shaft  17 , a planetary gear arrangement  618  and the output shaft  19 . The planetary gear arrangement  618  includes three planetary gear sets  620 ,  630  and  640 . 
     The planetary gear set  620  includes a sun gear member  622 , a ring gear member  624 , and a planet carrier assembly  626 . The planet carrier assembly  626  includes a plurality of pinion gears  627  rotatably mounted on a carrier member  629  and disposed in meshing relationship with both the sun gear member  622  and the ring gear member  624 . 
     The planetary gear set  630  includes a sun gear member  632 , a ring gear member  634 , and a planet carrier assembly member  636 . The planet carrier assembly member  636  includes a plurality of pinion gears  637  rotatably mounted on a carrier member  639  and disposed in meshing relationship with both the sun gear member  632  and the ring gear member  634 . 
     The planetary gear set  640  includes a sun gear member  642 , a ring gear member  644 , and a planet carrier assembly member  646 . The planet carrier assembly member  646  includes a plurality of pinion gears  647  rotatably mounted on a carrier member  649  and disposed in meshing relationship with both the sun gear member  642  and the ring gear member  644 . 
     The planetary gear arrangement  618  also includes seven torque-transmitting mechanisms  650 ,  652 ,  654 ,  656 ,  657 ,  658  and  659 . The torque-transmitting mechanisms  650 ,  652 ,  654 ,  656 ,  657 ,  658  and  659  are rotating type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  646 , and the output shaft  19  is continuously connected with the ring gear member  644 . The ring gear member  624  is continuously connected with the sun gear member  632  and the transmission housing  660  through the interconnecting member  670 . The interconnecting member  670  may be a single component or separate components. The sun gear member  622  is continuously connected with the ring gear member  634  through the interconnecting member  672 . 
     The ring gear member  634  is selectively connectable with the planet carrier assembly member  646  through the clutch  650 . The ring gear member  634  is selectively connectable with the sun gear member  642  through the clutch  652 . The planet carrier assembly member  626  is selectively connectable with the planet carrier assembly member  646  through the clutch  654 . The planet carrier assembly member  626  is selectively connectable with the sun gear member  642  through the clutch  656 . The planet carrier assembly member  626  is selectively connectable with the ring gear member  644  through the clutch  657 . The planet carrier assembly member  636  is selectively connectable with the planet carrier assembly member  646  through the clutch  658 . The ring gear member  644  is selectively connectable with the planet carrier assembly member  646  through the clutch  659 . 
     The truth table shown in  FIG. 7   b  describes the combination of torque-transmitting mechanism engagements that will provide a reverse drive ratio and eight forward speed ratios, as well as the sequence of these engagements and interchanges. 
     The ratio values given are by way of example and are established utilizing the ring gear/sun gear tooth ratios given in  FIG. 7   b . For example, the N R1 /S R1  value is the tooth ratio of the planetary gear set  620 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  630 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  640 . The ratio steps between adjacent forward ratios and the third reverse to first ratio are also given in  FIG. 7   b . For example, the ratio step between the first and second forward ratio is 1.50. As can also be determined from the truth table of  FIG. 7   b , each of the single step forward interchanges are of the single transition variety. 
     A powertrain  710 , shown in  FIG. 8   a , has the conventional engine and torque converter  12 , a planetary transmission  714 , and the conventional final drive mechanism  16 . The engine and torque converter  12  are drivingly connected with the planetary transmission  714  through the input shaft  17 . The planetary transmission  714  is drivingly connected with the final drive mechanism  16  through the output shaft  19 . The planetary transmission  714  includes a planetary gear arrangement  718  that has a first planetary gear set  720 , a second planetary gear set  730 , and a third planetary gear set  740 . 
     The planetary gear set  720  includes a sun gear member  722 , a ring gear member  724 , and a planet carrier assembly  726 . The planet carrier assembly  726  includes a plurality of pinion gears  727  rotatably mounted on a carrier member  729  and disposed in meshing relationship with the sun gear member  722 . Pinion gears  728  are disposed in meshing relationship with both the ring gear member  724  and the pinion gears  727 . 
     The planetary gear set  730  includes a sun gear member  732 , a ring gear member  734 , and a planet carrier assembly member  736 . The planet carrier assembly member  736  includes a plurality of pinion gears  737  rotatably mounted on a carrier member  739  and disposed in meshing relationship with both the sun gear member  732  and the ring gear member  734 . 
     The planetary gear set  740  includes a sun gear member  742 , a ring gear member  744 , and a planet carrier assembly member  746 . The planet carrier assembly member  746  includes a plurality of pinion gears  747  rotatably mounted on a carrier member  749  and disposed in meshing relationship with both the sun gear member  742  and the ring gear member  744 . 
     The planetary gear arrangement  718  also includes seven torque-transmitting mechanisms  750 ,  752 ,  754 ,  756 ,  757 ,  758  and  759 . The torque-transmitting mechanisms  750 ,  752 ,  754 ,  756 ,  757 ,  758  and  759  are rotating type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  746 , and the output shaft  19  is continuously connected with the ring gear member  744 . The planet carrier assembly member  726  is continuously connected with the sun gear member  732  and the transmission housing  760  through the interconnecting member  770 . The interconnecting member  770  may be one component or separate components. The sun gear member  722  is continuously connected with the planet carrier assembly member  736  through the interconnecting member  772 . 
     The planet carrier assembly member  736  is selectively connectable with the planet carrier assembly member  746  through the clutch  750 . The ring gear member  724  is selectively connectable with the planet carrier assembly member  746  through the clutch  752 . The ring gear member  724  is selectively connectable with the sun gear member  742  through the clutch  754 . The ring gear member  724  is selectively connectable with the ring gear member  744  through the clutch  756 . The ring gear member  734  is selectively connectable with the planet carrier assembly member  746  through the clutch  757 . The ring gear member  734  is selectively connectable with the sun gear member  742  through the clutch  758 . The ring gear member  744  is selectively connectable with the planet carrier assembly member  746  through the clutch  759 . 
     The truth table of  FIG. 8   b  defines the torque-transmitting mechanism engagement sequence utilized for each of the eight forward speed ratios and the reverse speed ratio. Also given in the truth table is a set of numerical values that are attainable with the present invention utilizing the ring gear/sun gear tooth ratios given in  FIG. 8   b . The N R1 /S R1  wvalue is the tooth ratio of the planetary gear set  720 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  730 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  740 . As may be determined from the truth table of  FIG. 8   b , each of the single step forward interchanges is of the single transition variety. 
       FIG. 8   b  also provides a chart of the ratio steps between adjacent forward ratios and between the reverse and first forward ratio. For example, the ratio step between the first and second forward ratios is 1.41. 
     A powertrain  810 , shown in  FIG. 9   a , has the conventional engine and torque converter  12 , a planetary transmission  814 , and the final drive mechanism  16 . The engine and torque converter  12  are drivingly connected with the planetary transmission  814  through the input shaft  17 . The planetary transmission  814  is drivingly connected with the final drive mechanism  16  through the output shaft  19 . The planetary transmission  814  includes a planetary gear arrangement  818  that has a first planetary gear set  820 , a second planetary gear set  830 , and a third planetary gear set  840 . 
     The planetary gear set  820  includes a sun gear member  822 , a ring gear member  824 , and a planet carrier assembly  826 . The planet carrier assembly  826  includes a plurality of pinion gears  827  rotatably mounted on a carrier member  829  and disposed in meshing relationship with both the sun gear member  822  and the ring gear member  824 . 
     The planetary gear set  830  includes a sun gear member  832 , a ring gear member  834 , and a planet carrier assembly member  836 . The planet carrier assembly member  836  includes a plurality of pinion gears  837  rotatably mounted on a carrier member  839  and disposed in meshing relationship with both the sun gear member  832  and the ring gear member  834 . 
     The planetary gear set  840  includes a sun gear member  842 , a ring gear member  844 , and a planet carrier assembly member  846 . The planet carrier assembly member  846  includes a plurality of pinion gears  847  rotatably mounted on a carrier member  849  and disposed in meshing relationship with both the sun gear member  842  and the ring gear member  844 . 
     The planetary gear arrangement  818  also includes seven torque-transmitting mechanisms  850 ,  852 ,  854 ,  856 ,  857 ,  858  and  859 . The torque-transmitting mechanisms  850 ,  852 ,  854 ,  856 ,  857 ,  858  and  859  are rotating type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  846 , and the output shaft  19  is continuously connected with the ring gear member  844 . The ring gear member  824  is continuously connected with the sun gear member  832  and the transmission housing  860  through the interconnecting member  870 . The interconnecting member  870  may be one component or separate components. The planet carrier assembly member  826  is continuously connected with the ring gear member  834  through the interconnecting member  872 . 
     The planet carrier assembly member  826  is selectively connectable with the planet carrier assembly member  846  through the clutch  850 . The planet carrier assembly member  826  is selectively connectable with the sun gear member  842  through the clutch  852 . The sun gear member  822  is selectively connectable with the planet carrier assembly member  846  through the clutch  854 . The sun gear member  822  is selectively connectable with the sun gear member  842  through the clutch  856 . The sun gear member  822  is selectively connectable with the ring gear member  844  through the clutch  857 . The planet carrier assembly member  836  is selectively connectable with the ring gear member  844  through the clutch  858 . The ring gear member  844  is selectively connectable with the planet carrier assembly member  846  through the clutch  859 . 
     The truth table shown in  FIG. 9   b  defines the torque-transmitting mechanism engagement sequence that provides the reverse speed ratio and eight forward speed ratios shown in the truth table and available with the planetary gear arrangement  818 . A sample of numerical values for the individual ratios is also given in the truth table of  FIG. 9   b . These numerical values have been calculated using the ring gear/sun gear tooth ratios also given by way of example in  FIG. 9   b . The N R1 /S R1  value is the tooth ratio of the planetary gear set  820 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  830 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  840 . It can be readily recognized from the truth table that all of the single step forward interchanges are of the single transition variety.  FIG. 9   b  also describes the ratio steps between adjacent forward ratios and between the reverse and first forward ratio. For example, the ratio step between the first and second forward ratios is 2.04. 
     The powertrain  910 , shown in  FIG. 10   a , includes the conventional engine and torque converter  12 , a planetary transmission  914 , and the conventional final drive mechanism  16 . The engine and torque converter  12  are drivingly connected with the planetary transmission  914  through the input shaft  17 . The planetary transmission  914  is drivingly connected with the final drive mechanism  16  through the output shaft  19 . The planetary transmission  914  includes a planetary gear arrangement  918  that has a first planetary gear set  920 , a second planetary gear set  930 , and a third planetary gear set  940 . 
     The planetary gear set  920  includes a sun gear member  922 , a ring gear member  924 , and a planet carrier assembly  926 . The planet carrier assembly  926  includes a plurality of pinion gears  927  that are rotatably mounted on a carrier member  929  and disposed in meshing relationship with both the sun gear member  922  and the ring gear member  924 . 
     The planetary gear set  930  includes a sun gear member  932 , a ring gear member  934 , and a planet carrier assembly member  936 . The planet carrier assembly member  936  includes a plurality of pinion gears  937  rotatably mounted on a carrier member  939  and disposed in meshing relationship with both the sun gear member  932  and the ring gear member  934 . 
     The planetary gear set  940  includes a sun gear member  942 , a ring gear member  944 , and a planet carrier assembly member  946 . The planet carrier assembly member  946  includes a plurality of pinion gears  947  rotatably mounted on a carrier member  949  and disposed in meshing relationship with both the sun gear member  942  and the ring gear member  944 . 
     The planetary gear arrangement  918  also includes seven torque-transmitting mechanisms  950 ,  952 ,  954 ,  956 ,  957 ,  958  and  959 . The torque-transmitting mechanisms  950 ,  952 ,  954 ,  956 ,  957 ,  958  and  959  are rotating type torque-transmitting mechanisms, commonly termed clutches. 
     The input shaft  17  is continuously connected with the sun gear member  942 , and the output shaft  19  is continuously connected with the planet carrier assembly member  946 . The sun gear member  922  is continuously connected with the planet carrier assembly member  936  and the transmission housing  960  through the interconnecting member  970 . The interconnecting member  470  may be one component or separate components. The planet carrier assembly member  926  is continuously connected with the sun gear member  932  through the interconnecting member  972 . 
     The planet carrier assembly member  926  is selectively connectable with the sun gear member  942  through the clutch  950 . The sun gear member  932  is selectively connectable with the ring gear member  944  through the clutch  952 . The ring gear member  924  is selectively connectable with the sun gear member  942  through the clutch  954 . The ring gear member  924  is selectively connectable with the planet carrier assembly member  946  through the clutch  956 . The ring gear member  924  is selectively connectable with the ring gear member  944  through the clutch  957 . The ring gear member  934  is selectively connectable with the planet carrier assembly member  946  through the clutch  958 . The ring gear member  934  is selectively connectable with the ring gear member  944  through the clutch  959 . 
     The truth table of  FIG. 10   b  describes the torque-transmitting mechanism engagement sequence utilized to provide two reverse speed ratios and eight forward speed ratios (as well as an extra first forward speed ratio (1′), an extra second forward speed ratio (2′) and an extra third forward speed ratio (3′)). The truth table also provides a set of examples for the ratios for each of the reverse and forward speed ratios. These numerical values have been determined utilizing the ring gear/sun gear tooth ratios given in  FIG. 10   b . The N R1 /S R1  value is the tooth ratio of the planetary gear set  920 ; the N R2 /S R2  value is the tooth ratio of the planetary gear set  930 ; and the N R3 /S R3  value is the tooth ratio of the planetary gear set  940 . As can also be determined from the truth table of  FIG. 10   b , each of the single step forward interchanges are of the single transition variety. 
     A powertrain  1010 , shown in  FIG. 11   a , includes the conventional engine and torque converter  12 , a planetary transmission  1014 , and the conventional final drive mechanism  16 . The engine and torque converter are drivingly connected with the planetary transmission  1014  through the input shaft  17 . The planetary transmission  1014  is drivingly connected with the final drive mechanism  16  through the output shaft  19 . The planetary transmission  1014  includes a planetary gear arrangement  1018  that has a first planetary gear set  1020 , a second planetary gear set  1030 , and a third planetary gear set  1040 . 
     The planetary gear set  1020  includes a sun gear member  1022 , a ring gear member  1024 , and a planet carrier assembly  1026 . The planet carrier assembly  1026  includes a plurality of pinion gears  1027  rotatably mounted on a carrier member  1029  and disposed in meshing relationship with both the sun gear member  1022  and the ring gear member  1024 . 
     The planetary gear set  1030  includes a sun gear member  1032 , a ring gear member  1034 , and a planet carrier assembly member  1036 . The planet carrier assembly member  1036  includes a plurality of pinion gears  1037  rotatably mounted on a carrier member  1039  and disposed in meshing relationship with both the sun gear member  1032  and the ring gear member  1034 . 
     The planetary gear set  1040  includes a sun gear member  1042 , a ring gear member  1044 , and a planet carrier assembly member  1046 . The planet carrier assembly member  1046  includes a plurality of pinion gears  1047  rotatably mounted on a carrier member  1049  and disposed in meshing relationship with the sun gear member  1042 . Pinion gears  1048  are disposed in meshing relationship with both ring gear member  1044  and the pinion gears  1047 . 
     The planetary gear arrangement  1018  also includes seven torque-transmitting mechanisms  1050 ,  1052 ,  1054 ,  1056 ,  1057 ,  1058  and  1059 . The torque-transmitting mechanisms  1050 ,  1052 ,  1054 ,  1056 ,  1057  and  1058  are rotating type torque-transmitting mechanisms, commonly termed clutches. The torque-transmitting mechanism  1059  is a stationary-type torque-transmitting mechanism, commonly termed a brake or reaction clutch. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  1046 , and the output shaft  19  is continuously connected with the ring gear member  1044 . The ring gear member  1024  is continuously connected with the sun gear member  1032  and transmission housing  1060  through the interconnecting member  1070 . The interconnecting member  1070  may be one component or separate components. The planet carrier assembly member  1026  is continuously connected with the ring gear member  1034  through the interconnecting member  1072 . 
     The planet carrier assembly member  1026  is selectively connectable with the planet carrier assembly member  1046  through the clutch  1050 . The ring gear member  1034  is selectively connectable with the sun gear member  1042  through the clutch  1052 . The ring gear member  1022  is selectively connectable with the planet carrier assembly member  1046  through the clutch  1054 . The sun gear member  1022  is selectively connectable with the sun gear member  1042  through the clutch  1056 . The planet carrier assembly member  1036  is selectively connectable with the planet carrier assembly member  1046  through the clutch  1057 . The planet carrier assembly member  1036  is selectively connectable with the ring gear member  1042  through the clutch  1058 . The planet carrier assembly member  1036  is selectively connectable with the transmission housing  1060  through the brake  1059 . 
     The truth table shown in  FIG. 11   b  describes the engagement combinations and the engagement sequence necessary to provide a reverse drive ratio and nine forward speed ratios. A sample of the numerical values for the ratios is also provided in the truth table of  FIG. 11   b . These values are determined utilizing the ring gear/sun gear tooth ratios also given in  FIG. 11   b . The N R1 /S R1  value is the tooth ratio for the planetary gear set  1020 ; the N R2 /S R2  value is the tooth ratio for the planetary gear set  1030 ; and the N R3 /S R3  value is the tooth ratio for the planetary gear set  1040 . Also given in  FIG. 11   b  is a chart describing the step ratios between the adjacent forward speed ratios and the reverse to first forward speed ratio. 
     A powertrain  1110  shown in  FIG. 12   a  includes the conventional engine and torque converter  12 , a planetary transmission  1114 , and a conventional final drive mechanism  16 . The engine and torque converter are drivingly connected with the planetary transmission  1114  through the input shaft  17 . The planetary transmission  1114  is drivingly connected with the final drive mechanism  16  through the output shaft  19 . The planetary transmission  1114  includes a planetary gear arrangement  1118  that has a first planetary gear set  1120 , second planetary gear set  1130 , and a third planetary gear set  1140 . 
     The planetary gear set  1120  includes a sun gear member  1122 , a ring gear member  1124  and a planet carrier assembly member  1126 . The planet carrier assembly member  1126  includes a plurality of pinion gears  1127  rotatably mounted on the carrier member  1129  and disposed in meshing relationship with both the sun gear member  1122  and the ring gear member  1124 . 
     The planetary gear set  1130  includes a sun gear member  1132 , a ring gear member  1134  and a planet carrier assembly member  1136 . The planet carrier assembly member  1136  includes a plurality of pinion gears  1137  rotatably mounted on the carrier member  1139  and disposed in meshing relationship with the sun gear member  1132 . Pinion gears  1138  are disposed in meshing relationship with both the ring gear member  1134  and the pinion gears  1137 . 
     The planetary gear set  1140  includes a sun gear member  1142 , a ring gear member  1144 , and a planet carrier assembly member  1146 . The planet carrier assembly member  1146  includes a plurality of pinion gears  1147  rotatably mounted on the carrier member  1149  and disposed in meshing relationship with both the sun gear member  1142  and the ring gear member  1144 . 
     The planetary gear arrangement  1118  also includes seven torque transmitting mechanisms  1150 ,  1152 ,  1154 ,  1156 ,  1157 ,  1158  and  1159 . The torque-transmitting mechanisms  1150 ,  1152 ,  1154 ,  1156 ,  1157  and  1158  are rotating type torque-transmitting mechanisms, commonly termed clutches. The torque-transmitting mechanism  1159  is a stationary type torque-transmitting mechanism, commonly termed a brake or reaction clutch. 
     The input shaft  17  is continuously connected with the planet carrier assembly member  1146 , and the output shaft  19  is continuously connected with the ring gear member  1144 . The ring gear member  1124  is continuously connected with the sun gear member  1132  and the transmission housing  1160  through the interconnecting member  1170 . The interconnecting member  1170  may be one component or separate components. The planet carrier assembly member  1126  is continuously connected with the planet carrier assembly member  1136  through the interconnecting member  1172 . 
     The planet carrier assembly member  1126  is selectively connectable with the planet carrier assembly member  1146  through the clutch  1150 . The planet carrier assembly member  1126  is selectively connectable with the sun gear member  1142  through the clutch  1152 . The sun gear member  1122  is selectively connectable with the planet carrier assembly member  1146  through the clutch  1154 . The sun gear member  1122  is selectively connectable with the sun gear member  1142  through the clutch  1156 . The sun gear member  1122  is selectively connectable with the ring gear member  1144  through the clutch  1157 . The ring gear member  1134  is selectively connectable with the ring gear member  1144  through the clutch  1158 . The planet carrier assembly member  1126  is selectively connectable with the transmission housing  1160  through the brake  1159 . 
     The truth table shown in  FIG. 12   b  describes the engagement combinations in the engagement sequence necessary to provide a reverse drive ratio and eight forward speed ratios (as well as an extra eight forward speed ratio (8′)). A sample of the numerical values for the ratios is also provided in the truth table of  FIG. 12   b . These values are determined utilizing the ring gear/sun gear tooth ratios also given in  FIG. 12   b . The N R1 /S R1  value is the tooth ratio for the planetary gear set  1120 ; the N R2 /S R2  value is the tooth ratio for the planetary gear set  1130 ; and the N R3 /S R3  value is the tooth ratio for the planetary gear set  1140 . As can be determined from  FIG. 12   b , each of the single step and double step interchanges is of the single transition variety. Also given in  FIG. 12   b  is a chart describing the step ratios between the adjacent forward speed ratios and the reverse to first forward speed ratio. 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.