Automatic Transmission For A Vehicle

• US 20080125280A1
• Filed: 03/08/2006
• Published: 05/29/2008
• Est. Priority Date: 03/09/2005
• Status: Active Grant

• Current Assignee: Aisin AW Company Limited (Aisin Corp.)
• Original Assignee: Aisin AW Company Limited (Aisin Corp.)
• Inventors: Ishii, Takuya, Aoki, Toshihiko, Fukuyama, Satoshi, Andoh, Yousuke, Todo, Minoru, Ozaki, Kazuhisa, Inagaki, Tomochika
• Granted Patent: US 7,819,773 B2
• Time in Patent Office: Days
• US Class Current: 475/330
• CPC Class Codes: F16H 2200/006 the gear ratios comprising eight forward speeds
• CPC Class Codes: F16H 2200/0086 the gear ratios comprising two reverse speeds
• CPC Class Codes: F16H 2200/2007 with two sets of orbital gears
• CPC Class Codes: F16H 2200/2023 using a Ravigneaux set with 4 connections
• CPC Class Codes: F16H 2200/2046 with six engaging means
• CPC Class Codes: F16H 2200/2048 with seven engaging means
• CPC Class Codes: F16H 2200/2097 comprising an orbital gear set member permanently connected to the housing, e.g. a sun wheel permanently connected to the housing
• CPC Class Codes: F16H 3/663 with conveying rotary motion between axially spaced orbital gears, e.g. RAVIGNEAUX
• CPC Class Codes: F16H 3/666 with compound planetary gear units, e.g. two intermeshing orbital gears F16H3/663 takes precedence

Abstract

An output side transfer member 103 of a second clutch C-2 extends around the outer circumferences of the output side transfer members 101, 102 of the third and first clutches C-3, C-1, the output side transfer member 104 (or 13, 101) of a fourth clutch C-4 and the output side transfer member 101 of a third clutch C-3 are linked to a sun gear S2, the output side transfer member 104 (or 13, 101) of a fourth clutch C-4, an output side transfer member 101 of a third clutch C-3, and a sun gear S2, which rotate integrally, are disposed radially inward with respect to the output side transfer member 102 of the first clutch C-1. Thereby, it becomes possible to reduce the diameter of the output side transfer member 104 (or 13, 101) of the fourth clutch C-4, to reduce the weight and inertia, and to improve the controllability of the automatic transmission 1.

Claims

1. An automatic transmission for a vehicle, comprising:

a case including a sidewall;

an input shaft;

a speed reduction planetary gear set that comprises a stationary element which is held against rotation, an input rotary element that receives input rotation from the input shaft;

a reduced speed rotary element that outputs a reduced speed rotation at a speed less than that of the input rotation;

a planetary gear unit that includes first, second, third, and fourth rotary elements that are arranged in a rotational speed relationship according to their gear relationships;

a first input transfer clutch, having output side and input side transfer members, for selective transfer of the input rotation to the first rotary element;

a second input transfer clutch, having output side and input side transfer members, for selective transfer of the input rotation to the third rotary element;

a first speed reduction transfer clutch, having output side and input side transfer members, for selective transfer of reduced speed rotation through the speed reduction planetary gear set to the first rotary element;

a second speed reduction transfer clutch, having output side and input side transfer members, for selective transfer of reduced speed rotation through the speed reduction planetary gear set to the second rotary element;

a first brake for selectively locking the first rotary element against rotation; and

a second brake for selectively locking the third rotary element against rotation; and

wherein the automatic transmission outputs rotation from the fourth rotary element;

wherein the output side transfer member of the second input transfer clutch extends coaxially with and radially outward of the output side transfer members of the first and second speed reduction transfer clutches to link with the third rotary element; and

wherein the output side transfer member of the first input transfer clutch and the output side transfer member of the first speed reduction transfer clutch are linked to the first rotary element, thereby rotate integrally, and are coaxial with and radially inward of the output side transfer member of the second speed reduction transfer clutch.

2. The automatic transmission for a vehicle according to claim 1, further comprising:

a first hydraulic servo, including a clutch drum, for operating the second input transfer clutch;

a boss extending form the side wall of the case and supporting the stationary element; and

wherein the input side transfer member of the second input transfer clutch is linked to the input rotary element, a portion of the input side transfer member of the second input transfer clutch forming the clutch drum of the first hydraulic servo; and

wherein the first hydraulic servo is disposed around the boss axially intermediate the speed reduction planetary gear set and the side wall.

3. The automatic transmission for a vehicle according to claim 2, further comprising:

a second hydraulic servo, including a clutch drum, for operating the second speed reduction transfer clutch; and

wherein the second speed reduction transfer clutch has its input side transfer member linked to the reduced speed rotary element and its output side transfer member linked to the second rotary element;

wherein a portion of the output side transfer member of the second speed reduction transfer clutch forms the clutch drum of the second hydraulic servo; and

wherein the second hydraulic servo is disposed around the boss axially intermediate the speed reduction planetary gear set and the first hydraulic servo.

4. The automatic transmission for a vehicle according to claim 3, further comprising:

a counter gear linked to the fourth rotary element of the planetary gear unit and located on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set; and

wherein the second brake is a multi-plate brake comprising a plurality of friction plates is located radially outward of the planetary gear unit.

5. The automatic transmission for a vehicle according to claim 2, further comprising:

a counter gear linked to the fourth rotary element of the planetary gear unit and located on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set; and

wherein the second brake is a multi-plate brake comprising a plurality of friction plates and is located radially outward of the planetary gear unit.

6. The automatic transmission for a vehicle according to claim 1, further comprising:

a first hydraulic servo, including a clutch drum, for operating the second input transfer clutch;

a counter gear linked to the fourth rotary element and located between the planetary gear unit and the speed reduction planetary gear set; and

a support member joined to a wall extending from the case and supporting the counter gear; and

wherein the input side transfer member of the second input transfer clutch extends around the outer circumferences of the first and second speed reduction transfer clutches to link to the input rotary element, and has an output side transfer member which forms the clutch drum of the first hydraulic servo; and

wherein the first hydraulic servo is disposed around the support member and is located axially intermediate the speed reduction planetary gear set and the counter gear.

7. The automatic transmission for a vehicle according to claim 6, further comprising:

a second hydraulic servo, including a drum, for operating the second speed reduction transfer clutch;

a third hydraulic servo, including a drum, for operating the first speed reduction transfer clutch;

a boss extending from the side wall of the case and supporting the stationary element; and

wherein the input side transfer member of the first speed reduction transfer clutch is linked to the reduced speed rotary element of the of the first speed reduction transfer clutch and forms the clutch drum of the third hydraulic servo;

wherein the third hydraulic servo is located around the boss axially intermediate the speed reduction planetary gear set and the side wall;

wherein the input side transfer member of the second speed reduction transfer clutch is linked to the input side transfer member of the first speed reduction transfer clutch;

wherein a portion of the input side transfer member of the second speed reduction transfer clutch forms the clutch drum of the second hydraulic servo; and

wherein the second hydraulic servo is disposed around the support member axially intermediate the speed reduction planetary gear set and the first hydraulic servo.

8. The automatic transmission for a vehicle according to claim 6, further comprising:

a second hydraulic servo, including a drum, for operating the second speed reduction transfer clutch, the second hydraulic servo being disposed on the support member axially intermediate the speed reduction planetary gear set and the first hydraulic servo;

a third hydraulic servo, including a drum, for operating the first speed reduction transfer clutch; and

wherein the output side transfer member of the second speed reduction transfer clutch is linked to the second rotary element and forms the clutch drum of the second hydraulic servo;

wherein the output side transfer member of the first speed reduction transfer clutch is linked to the first rotary element;

wherein the output side transfer member of the first speed reduction transfer clutch forms the clutch drum of the third hydraulic servo; and

wherein the third hydraulic servo is disposed axially intermediate the speed reduction planetary gear set and the second hydraulic servo.

9. The automatic transmission for a vehicle according to claim 1, further comprising:

a counter gear linked to the fourth rotary element;

a second shaft arranged in parallel with the input shaft and linked to the counter gear for receipt of output rotation from the fourth rotary element.

10. The automatic transmission for a vehicle according to claim 9, further comprising:

a wall extending radially inward from the case and having, at its distal end, a support member extending in parallel with the input shaft; and

wherein the counter gear is axially intermediate the planetary gear unit and the speed reduction planetary gear set and is supported by the support member.

11. The automatic transmission for a vehicle according to claim 9, further comprising:

a wall extending radially inward from the case and having, at its distal end, a support member extending in parallel with the input shaft; and

wherein the counter gear is located on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set and is supported by the support member.

12. The automatic transmission for a vehicle according to claim 1, wherein the input rotary element is linked to the input shaft on the side of the speed reduction planetary gear set facing the planetary gear unit, and is linked to the input side transfer member of the second input transfer clutch at the side of the speed reduction planetary gear set that is axially opposite the planetary gear unit.

13. The automatic transmission for a vehicle according to claim 1, wherein the first brake has a locking force transfer member linked to the first rotary element at a side of the planetary gear unit that is axially opposite the speed reduction planetary gear set.

14. The automatic transmission for a vehicle according to claim 1:

wherein the stationary element of the speed reduction planetary gear set comprises a first sun gear;

wherein the input rotary element of the speed reduction planetary gear set is linked to the input shaft and comprises a first carrier that rotatably supports a first pinion gear that meshes with the first sun gear and a second pinion gear that meshes with the first pinion gear; and

wherein the reduced speed rotary element of the speed reduction planetary gear set comprises a first ring gear that meshes with the second pinion gear and outputs the reduced speed rotation.

15. The automatic transmission for a vehicle according to claim 1, wherein:

the planetary gear unit is a Ravigneaux planetary gear set that comprises a second sun gear, a third sun gear, a third pinion gear that meshes with the third sun gear, a fourth pinion gear that meshes with the second sun gear and with the third pinion gear;

a second carrier that rotatably supports the third pinion gear and the fourth pinion gear; and

a second ring gear that meshes with the fourth pinion gear;

the first rotary element comprises the second sun gear;

the second rotary element comprises the third sun gear;

the third rotary element comprises the second carrier; and

the fourth rotary element comprises the second ring gear.

16. The automatic transmission for a vehicle according to claim 1, wherein:

a first forward speed is established by engaging the second speed reduction transfer clutch and locking the second brake;

a second forward speed is established by engaging the second speed reduction transfer clutch and locking the first brake;

a third forward speed is established by engaging the second speed reduction transfer clutch and the first speed reduction transfer clutch;

a fourth forward speed is established by engaging the second speed reduction transfer clutch and the first input transfer clutch;

a fifth forward speed is established by engaging the second speed reduction transfer clutch and the second input transfer clutch;

a sixth forward speed is established by engaging the second input transfer clutch and the first input transfer clutch;

a seventh forward speed is established by engaging the second input transfer clutch and the first speed reduction transfer clutch;

an eighth forward speed is established by engaging the second input transfer clutch and locking the first brake; and

a reverse speed is established by engaging the first speed reduction transfer clutch or the first input transfer clutch, and locking the second brake.

17. The automatic transmission for a vehicle according to claim 1, wherein, in a velocity diagram in which the rotational speed relationships correspond to the gear ratios based on the gear relationships of the first, second, third and fourth rotary elements, the respective speeds of the first, second, third, and fourth rotary elements of the planetary gear unit are shown on the ordinate, and the corresponding gear ratios of the first, second, third, and fourth rotary elements are shown on the abscissa, the first rotary element is positioned at the farthest left end of the ordinate and, arranged in sequence to the right thereof, are the third rotary element, the fourth rotary element that is linked to the counter gear, and the second rotary element.

18. An automatic transmission for a vehicle, comprising:

a case including a sidewall;

an input shaft;

a speed reduction planetary gear set that comprises a stationary element which is held against rotation by the case, an input rotary element that receives the input rotation of the input shaft, and a reduced speed rotary element that outputs a reduced speed rotation at a speed less than that of the input rotation;

a planetary gear unit that includes first, second, third, and fourth rotary elements that are arranged in a rotational speed relationship according to their gear relationships;

a first input transfer clutch for selective transfer of the input rotation to the first rotary element;

a second input transfer clutch for selective transfer of the input rotation to the third rotary element;

a first speed reduction transfer clutch for transfer of a reduced speed rotation through the speed reduction planetary gear set to the first rotary element;

a second speed reduction transfer clutch for transfer of a reduced speed rotation through the speed reduction planetary gear set to the second rotary element;

a first brake for selectively stopping the rotation of the first rotary element by locking it to the case; and

a second brake for selectively stopping the rotation of the third rotary element by locking it to the case; and

wherein the automatic transmission outputs rotation from the fourth rotary element;

wherein the first and second speed reduction transfer clutches are disposed on the speed reduction planetary gear set side relative to the planetary gear unit and have output side transfer members which are respectively linked to the first rotary element and the second rotary element;

wherein the first input transfer clutch is disposed on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set and has an output side transfer member which is linked to the first rotary element; and

wherein the second input transfer clutch is disposed on the side of the speed reduction planetary gear set axially opposite planetary gear unit and has an output side transfer member which extends coaxially with and radially outward of the output side transfer members of the first and second speed reduction transfer clutches to link with the third rotary element.

19. The automatic transmission for a vehicle according to claim 18, further comprising:

a first hydraulic servo, including a drum, for operating the first input transfer clutch; and

wherein the first input transfer clutch has an input side transfer member linked to the input shaft at a radially inner side of the planetary gear unit; and

wherein a portion of the input side transfer member of the first input transfer clutch forms the clutch drum of the hydraulic servo of the first input transfer clutch.

20. The automatic transmission for a vehicle according to claim 18, further comprising:

a second hydraulic servo, including a drum, for operating the second input transfer clutch; and

a boss extending from the side wall of the case and on which the stationary element is mounted; and

wherein the second input transfer clutch has an input side transfer member linked to the input rotary element;

wherein a portion of the input side transfer member of the second input transfer clutch forms the clutch drum of the second hydraulic servo; and

wherein the second hydraulic servo is disposed around the boss axially intermediate the speed reduction planetary gear set and the side wall.

21. The automatic transmission for a vehicle according to claim 20, further comprising:

a third hydraulic servo, including a drum, for operating the second input transfer clutch; and

wherein the input side transfer member of the second speed reduction transfer clutch is linked to the reduced speed rotary element;

wherein the output side transfer member of the second speed reduction clutch is linked to the second rotary element;

wherein a portion of the output side transfer member of the second speed reduction transfer clutch forms the clutch drum of the third hydraulic servo; and

wherein the third hydraulic servo is disposed around the boss axially intermediate the speed reduction planetary gear set and the second hydraulic servo.

22. The automatic transmission for a vehicle according to claim 21, further comprising:

a counter gear linked to the fourth rotary element of the planetary gear set; and

wherein the counter gear is disposed on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set; and

wherein the second brake is a multi-plate brake comprising a plurality of friction plates and is disposed radially outward of the planetary gear unit.

23. The automatic transmission for a vehicle according to claim 20, further comprising:

a counter gear linked to the fourth rotary element of the planetary gear set; and

wherein the counter gear is on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set; and

wherein the second brake is a multi-plate brake comprising a plurality of friction plates and is disposed radially outward of the planetary gear set.

24. The automatic transmission for a vehicle according to claim 18, further comprising:

a second hydraulic servo, including a drum, for operating the second input transfer clutch;

a counter gear linked to the fourth rotary element and disposed axially intermediate the planetary gear unit and the speed reduction planetary gear set;

a support wall extending radially inward from the case and a support member appended to the inner circumference of the support wall, with the counter gear mounted on the support member; and

wherein the second input transfer clutch has an input side transfer member which extends around the outer circumferences of the first and second speed reduction transfer clutches to link to the input rotary element;

wherein a portion of the output side transfer member of the second input transfer clutch forms the clutch drum of the second hydraulic servo; and

wherein the second hydraulic servo is disposed around the support member axially intermediate the speed reduction planetary gear set and the counter gear.

25. The automatic transmission for a vehicle according to claim 24, further comprising:

a third hydraulic servo, including a drum, for operating the second speed reduction transfer clutch;

a fourth hydraulic servo, including a drum, for operating the first input transfer clutch;

a boss extending from the side wall of the case and supporting the stationary element thereon; and

wherein the first speed reduction transfer clutch has an input side transfer member linked to the reduced speed rotary element;

wherein a portion of the input side transfer member of the first speed reduction transfer clutch forms the clutch drum of the fourth hydraulic servo;

wherein the fourth hydraulic servo is disposed around the boss axially intermediate the speed reduction planetary gear set and the side wall; and

wherein the input side transfer member of the second speed reduction transfer clutch is linked to the input side transfer member of the first speed reduction transfer clutch;

wherein a portion of the input side transfer member of the second speed reduction transfer clutch forms the clutch drum of the third hydraulic servo; and

wherein the third hydraulic servo is disposed around the support member axially intermediate the speed reduction planetary gear set and the second hydraulic servo.

26. The automatic transmission for a vehicle according to claim 24, further comprising:

a third hydraulic servo, including a drum, for operating the second speed reduction transfer clutch;

a fourth hydraulic servo, including a drum, for operating the first speed reduction transfer clutch; and

wherein the output side transfer member of the second speed reduction transfer clutch is linked to the second rotary element;

wherein a portion of the output side transfer member of the second speed reduction transfer clutch forms the clutch drum of the third hydraulic servo;

wherein the third hydraulic servo is disposed around the support member axially intermediate the speed reduction planetary gear set and the second hydraulic servo;

wherein the output side transfer member of the first speed reduction transfer clutch is linked to the first rotary element;

wherein a portion of the output side transfer member of the first speed reduction transfer clutch forms the clutch drum of the fourth hydraulic servo; and

wherein the fourth hydraulic servo is disposed axially intermediate the speed reduction planetary gear set and the third hydraulic servo.

27. The automatic transmission for a vehicle according to claim 18, further comprising:

a counter gear linked to the fourth rotary element;

a second shaft arranged in parallel with the input shaft and linked to the counter gear for receipt of output rotation from the fourth rotary element.

28. The automatic transmission for a vehicle according to claim 27, further comprising:

a support wall extending radially inward from the case and a support member extending in parallel to the input shaft and appended to the inner circumference of the support wall; and

wherein the counter gear is disposed axially intermediate the planetary gear unit and the speed reduction planetary gear set and is supported by the support member.

29. The automatic transmission for a vehicle according to claim 27, further comprising:

a support wall extending radially inward from the case and a support member extending in parallel to the input shaft and appended to the inner circumference of the support wall; and

wherein the counter gear is disposed on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set and is supported by the support member.

30. The automatic transmission for a vehicle according to claim 18, wherein the input rotary element is linked to the input shaft at the side of the speed reduction planetary gear set axially facing the planetary gear unit, and is linked to the input side transfer member of the second input transfer clutch at the side of the speed reduction planetary gear set that is axially opposite the planetary gear unit.

31. The automatic transmission for a vehicle according to claim 18, wherein the first brake has a locking force transfer member linked to the first rotary element on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set.

32. The automatic transmission for a vehicle according to claim 18, wherein:

the stationary element of the speed reduction planetary gear set comprises a first sun gear;

the input rotary element of the speed reduction planetary gear set comprises a first carrier that rotatably supports a first pinion gear that meshes with the first sun gear and a second pinion gear that meshes with the first pinion gear, and that is linked to the input shaft; and

the reduced speed rotary element of the speed reduction planetary gear set comprises a first ring gear that meshes with the second pinion gear and outputs the reduced speed rotation.

33. The automatic transmission for a vehicle according to claim 18, wherein:

the planetary gear unit is a Ravigneaux planetary gear set that comprises a second sun gear, a third sun gear, a third pinion gear that meshes with the third sun gear, a fourth pinion gear that meshes with the second sun gear and with the third pinion gear;

a second carrier that rotatably supports the third pinion gear and the fourth pinion gear; and

a second ring gear that meshes with the fourth pinion gear;

the first rotary element comprises the second sun gear;

the second rotary element comprises the third sun gear;

the third rotary element comprises the second carrier; and

the fourth rotary element comprises the second ring gear.

34. The automatic transmission for a vehicle according to claim 18, wherein:

a first forward speed is established by engaging the second speed reduction transfer clutch and locking the second brake;

a second forward speed is established by engaging the second speed reduction transfer clutch and locking the first brake;

a third forward speed is established by engaging the second speed reduction transfer clutch and the first speed reduction transfer clutch;

a fourth forward speed is established by engaging the second speed reduction transfer clutch and the first input transfer clutch;

a fifth forward speed is established by engaging the second speed reduction transfer clutch and the second input transfer clutch;

a sixth forward speed is established by engaging the second input transfer clutch and the first input transfer clutch;

a seventh forward speed is established by engaging the second input transfer clutch and the first speed reduction transfer clutch;

an eighth forward speed is established by engaging the second input transfer clutch and locking the first brake; and

a reverse speed is established by engaging the first speed reduction transfer clutch or the first input transfer clutch, and locking the second brake.

35. The automatic transmission for a vehicle according to claim 18, wherein, in a velocity diagram in which the rotational speed relationships correspond to the gear ratios based on the gear relationships of the first, second, third and fourth rotary elements, the respective speeds of the first, second, third, and fourth rotary elements of the planetary gear unit are shown on the ordinate and the corresponding gear ratios of the first, second, third, and fourth rotary elements are shown on the abscissa, the first rotary element is positioned at the farthest left end of the ordinate and, arranged in sequence to the right thereof, are the third rotary element, the fourth rotary element that is linked to a counter gear, and the second rotary element.

36. An automatic transmission for a vehicle, comprising:

a case having a side wall;

an input shaft;

a speed reduction planetary gear set that comprises a stationary element that is held stationary by the case, an input rotary element that receives the input rotation of the input shaft, and a speed reduction rotary element that outputs a reduced speed rotation at a speed less than that of the input rotation;

a planetary gear unit that includes first, second, third, and fourth rotary elements that are arranged in rotational speed relationships according to their gear relationships;

a first input transfer clutch, having input side and output side transfer members, for selective transfer of the input rotation to the first rotary element;

a second input transfer clutch, having input side and output side-transfer members, for selective transfer of the input rotation to the third rotary element;

a first speed reduction transfer clutch, having input side and output side transfer members, for selective transfer of a reduced speed rotation through the speed reduction planetary gear set to the first rotary element;

a second speed reduction transfer clutch, having input side and output side transfer members, for selective transfer of a reduced speed rotation through the speed reduction planetary gear set to the second rotary element;

a first brake for selectively stopping rotation of the first rotary element by locking the first rotary element to the case; and

a second brake for selectively stopping rotation of the third rotary element by locking the third rotary element to the case; and

wherein the automatic transmission outputs output rotation at the fourth rotary element;

wherein the first and second speed reduction transfer clutches are disposed on the speed reduction planetary gear set side relative to the planetary gear set;

wherein the output side transfer members of the first and second speed reduction transfer clutches are respectively linked to the first rotary element and the second rotary element;

wherein the first input transfer clutch is disposed on the speed reduction planetary gear set side relative to the planetary gear unit and its output side transfer member is linked to the first rotary element; and

wherein the second input transfer clutch is disposed on the speed reduction planetary gear set side relative to the planetary gear unit and its output side transfer member extends around the outer circumferences of the output side transfer members of the first and second speed reduction transfer clutches to link with the third rotary element.

37. The automatic transmission for a vehicle according to claim 36, further comprising:

a first hydraulic servo for operating the first input transfer clutch; and

wherein the first input transfer clutch has an input side transfer member directly linked to the input rotary element and a portion of the input rotary element forms a portion of the hydraulic servo of the first input transfer clutch.

38. The automatic transmission for a vehicle according to claim 36, further comprising:

a first hydraulic servo, including a drum, for operating the second input transfer clutch;

a boss extending from the side wall of the case and supporting the stationary element and fixing the stationary element against rotation; and

wherein the input side transfer member of the second input transfer clutch is linked to the input rotary element;

wherein a portion of the input side transfer member of the second input transfer clutch forms the clutch drum of the first hydraulic servo; and

wherein the hydraulic servo is disposed around the boss axially intermediate the first speed reduction planetary gear set and the side wall.

39. The automatic transmission for a vehicle according to claim 38, further comprising:

a second hydraulic servo, including a drum, for operating the second speed reduction transfer clutch;

wherein the input side transfer member of the second speed reduction transfer clutch is linked to the reduced speed rotary element;

wherein the output side transfer member of the second speed reduction transfer clutch is linked to the second rotary element;

wherein a portion of the output side transfer member of the second speed reduction transfer clutch forms the clutch drum of the second hydraulic servo; and

wherein the second hydraulic servo is disposed around the boss axially intermediate the speed reduction planetary gear set and the first hydraulic servo.

40. The automatic transmission for a vehicle according to claim 39, further comprising:

a counter gear linked to the fourth rotary element of the planetary gear unit, the counter gear being disposed on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set; and

wherein the second brake is a multi-plate brake comprising a plurality of friction plates and is located radially outward of the planetary gear unit.

41. The automatic transmission for a vehicle according to claim 38, further comprising:

a counter gear linked to the fourth rotary element of the planetary gear unit, the counter gear being disposed on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set; and

wherein the second brake is a multi-plate brake comprising a plurality of friction plates and is located radially outward of the planetary gear set.

42. The automatic transmission for a vehicle according to claim 36, further comprising:

a first hydraulic servo, including a drum, for operating the second input transfer clutch;

a counter gear linked to the fourth rotary element and located axially intermediate the planetary gear unit and the speed reduction planetary gear set; and

a support wall extending radially inward from the case and having a distal end with a support member appended thereto and supporting the counter gear; and

wherein the input side transfer member of the second input transfer clutch extends around the outer circumferences of the first and second speed reduction transfer clutches to link with the input rotary member;

wherein a portion of the output side transfer member of the second input transfer clutch forms the clutch drum of the first hydraulic servo; and

wherein the first hydraulic servo is disposed around the support member axially intermediate the speed reduction planetary gear set and the counter gear.

43. The automatic transmission for a vehicle according to claim 42, further comprising:

a second hydraulic servo, including a drum, for operating the first speed reduction transfer clutch;

a boss extending from the side wall of the case and supporting the stationary element while holding the stationary element stationary; and

wherein the input side transfer member of the first speed reduction transfer clutch is linked to the reduced speed rotary element;

wherein a portion of the input side transfer member of the first speed reduction transfer clutch forms the clutch drum of the second hydraulic servo;

wherein the second hydraulic servo is disposed around the boss axially intermediate the speed reduction planetary gear set and the side wall;

wherein the input side transfer member of the second speed reduction transfer clutch is linked to the input side transfer member of the first speed reduction transfer clutch;

wherein a portion of the input side transfer member of the second speed reduction transfer clutch forms the clutch drum of the second hydraulic servo; and

wherein the second hydraulic servo is disposed around the support member axially intermediate the speed reduction planetary gear and the first hydraulic servo.

44. The automatic transmission for a vehicle according to claim 36, wherein a counter gear linked to the fourth rotary element and a second shaft is arranged in parallel with the input shaft and is linked via the counter gear to the fourth rotary element to receive the output rotation.

45. The automatic transmission for a vehicle according to claim 44, further comprising:

a wall member extending radially inward from the case and a support member appended to the inner circumference of the wall member; and

wherein the counter gear is located axially intermediate the planetary gear unit and the speed reduction planetary gear set and is supported on the support member.

46. The automatic transmission for a vehicle according to claim 44, further comprising:

a wall member extending radially inward from the case and a support member appended to the inner circumference of the wall member; and

wherein the counter gear is disposed on the side of the planetary gear unit that is axially opposite the speed reduction planetary gear set and is supported by the support member.

47. The automatic transmission for a vehicle according to claim 36, wherein:

the input rotary element is linked to the input shaft at the side of the speed reduction planetary gear set facing the planetary gear unit, and is linked to the input side transfer member of the second input transfer clutch at a side of the speed reduction planetary gear set that is axially opposite the planetary gear unit.

48. The automatic transmission for a vehicle according to claim 36 wherein:

the first brake has a locking force transfer member linked to the first rotary element on the side of the planetary gear set that is axially opposite the speed reduction planetary gear set.

49. The automatic transmission for a vehicle according to claim 36, wherein:

the stationary element of the speed reduction planetary gear set comprises a first sun gear;

the input rotary element of the speed reduction planetary gear set is linked to the input shaft and comprises a first carrier that rotatably supports a first pinion gear that meshes with the first sun gear and a second pinion gear that meshes with the first pinion gear; and

the reduced speed rotary element of the speed reduction planetary gear set comprises a first ring gear that meshes with the second pinion gear and outputs the reduced speed rotation.

50. The automatic transmission for a vehicle according to claim 36, wherein:

the planetary gear set is a Ravigneaux planetary gear set that comprises a second sun gear, a third sun gear, a third pinion gear that meshes with the third sun gear, a fourth pinion gear that meshes with the second sun gear and meshes with the third pinion gear;

a second carrier that rotatably supports the third pinion gear and the fourth pinion gear; and

a second ring gear that meshes with the fourth pinion gear;

the first rotary element comprises the second sun gear;

the second rotary element comprises the third sun gear;

the third rotary element comprises the second carrier; and

the fourth rotary element comprises the second ring gear.

51. The automatic transmission for a vehicle according to claim 36, wherein:

a first forward speed is established by engaging the second speed reduction transfer clutch and locking the second brake;

a second forward speed is established by engaging the second speed reduction transfer clutch and locking the first brake;

a third forward speed is established by engaging the second speed reduction transfer clutch and the first speed reduction transfer clutch;

a fourth forward speed is established by engaging the second speed reduction transfer clutch and the first input transfer clutch;

a fifth forward speed is established by engaging the second speed reduction transfer clutch and the second input transfer clutch;

a sixth forward speed is established by engaging the second input transfer clutch and the first input transfer clutch;

a seventh forward speed is established by engaging the second input transfer clutch and the first speed reduction transfer clutch;

an eighth forward speed is established by engaging the second input transfer clutch and locking the first brake; and

a reverse speed is established by engaging the first speed reduction transfer clutch or the first input transfer clutch, and locking the second brake.

52. The automatic transmission for a vehicle according to claim 36, wherein, in a velocity diagram in which the rotational speed relationships correspond to the gear ratios based on the gear relationships of the first, second, third and fourth rotary elements, the respective speeds of the first, second, third, and fourth rotary elements of the planetary gear unit are shown on the ordinate and the corresponding gear ratios of the first, second, third, and fourth rotary elements are shown on the abscissa, the first rotary element is positioned at the farthest left end of the ordinate and, arranged in sequence to the right thereof, are the third rotary element, the fourth rotary element that is linked to a counter gear, and the second rotary element.