Multi-speed transmission

1. A transmission comprising:

an input member;

an output member;

first, second, third and fourth planetary gear sets each having first, second and third members;

a first torque transmitting device selectively engageable to interconnect the first member of the first planetary gear set with the first member of the second planetary gear set, the first member of the third planetary gear set, and the first member of the fourth planetary gear set;

a second torque transmitting device selectively engageable to interconnect the first member of the first planetary gear set with the third member of the fourth planetary gear set;

a third torque transmitting device selectively engageable to interconnect the third member of the third planetary gear set with the first member of the second planetary gear set, the first member of the third planetary gear set, and the first member of the fourth planetary gear set;

a fourth torque transmitting device selectively engageable to interconnect the third member of the third planetary gear set with the second member of the fourth planetary gear set and the output member; and

a fifth torque transmitting device selectively engageable to interconnect the third member of the fourth planetary gear set with a stationary member, and

wherein at least two of the torque transmitting devices are disengaged to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

2. The transmission of claim 1 wherein one of the at least one reverse speed ratios is achieved by engagement of the second and fifth torque transmitting devices.

3. The transmission of claim 2 wherein a first of the at least eight forward speed ratios is achieved by engagement of the first, third, and fifth torque transmitting devices.

4. The transmission of claim 3 wherein a second of the at least eight forward speed ratios is achieved by engagement of the first and fifth torque transmitting devices.

5. The transmission of claim 4 wherein a third of the at least eight forward speed ratios is achieved by engagement of the fourth and fifth torque transmitting devices.

6. The transmission of claim 5 wherein a fourth of the at least eight forward speed ratios is achieved by engagement of the first and fourth torque transmitting devices.

7. The transmission of claim 6 wherein a fifth of the at least eight forward speed ratios is achieved by engagement of the third and fourth torque transmitting devices.

8. The transmission of claim 7 wherein a sixth of the at least eight forward speed ratios is achieved by engagement of the second and fourth torque transmitting devices.

9. The transmission of claim 8 wherein a seventh of the at least eight forward speed ratios is achieved by engagement of the second and third torque transmitting devices.

10. The transmission of claim 9 wherein an eighth of the at least eight forward speed ratios is achieved by engagement of the first and second torque transmitting devices.

11. The transmission of claim 1 wherein the third member of the first planetary gear set is continuously interconnected with the stationary member, the second member of the first planetary gear set is continuously interconnected with the second member of the second planetary gear set, the first member of the second planetary gear set is continuously interconnected with at least one of the first member of the third planetary gear set and the first member of the fourth planetary gear set, and the third member of the second planetary gear set is continuously interconnected with at least one of the second member of the third planetary gear set and the input member.

12. The transmission of claim 1 wherein the third member of the first planetary gear set and the first members of the second, third, and fourth planetary gear sets are sun gears, wherein the second member of the first, second, third and fourth planetary gear sets are carrier members, and wherein the first member of the first planetary gear set and the third members of the second, third, and fourth planetary gear sets are ring gears.

13. The transmission of claim 1 wherein the input member is continuously interconnected with at least one of the third member of the second planetary gear set and the second member of the third planetary gear set and wherein the output member is continuously interconnected with the second member of the fourth planetary gear set.

14. The transmission of claim 1 wherein each of the torque transmitting devices is engaged in at least three of the at least eight forward speed ratios.

15. A transmission comprising:

an input member;

an output member;

first, second, third and fourth planetary gear sets each having sun, carrier, and ring members;

a first torque transmitting device selectively engageable to interconnect the ring member of the first planetary gear set with the sun member of the second planetary gear set, the sun member of the third planetary gear set, and the sun member of the fourth planetary gear set;

a second torque transmitting device selectively engageable to interconnect the ring member of the first planetary gear set with the ring member of the fourth planetary gear set;

a third torque transmitting device selectively engageable to interconnect the ring member of the third planetary gear set with at least one of the sun member of the second planetary gear set, the sun member of the third planetary gear set, and the sun member of the fourth planetary gear set;

a fourth torque transmitting device selectively engageable to interconnect the ring member of the third planetary gear set with the carrier member of the fourth planetary gear set and the output member; and

a fifth torque transmitting device selectively engageable to interconnect the ring member of the fourth planetary gear set with the stationary member, and

wherein at least two of the torque transmitting devices are disengaged to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

16. The transmission of claim 15 wherein the first torque transmitting mechanism is engaged in at least a first, second, and fourth speed ratio of the at least eight forward speed ratios.

17. The transmission of claim 15 wherein the second torque transmitting mechanism in engaged in at least a sixth, seventh, and eighth speed ratio of the at least eight forward speed ratios and at least one of the at least one reverse speed ratios.

18. The transmission of claim 15 wherein the third torque transmitting mechanism is engaged in at least a first, fifth, and seventh speed ratio of the at least eight forward speed ratios.

19. The transmission of claim 15 wherein the fourth torque transmitting mechanism is engaged in at least a third, fourth, fifth, and sixth speed ratio of the at least eight forward speed ratios.

20. The transmission of claim 15 wherein the fifth torque transmitting mechanism in engaged in at least a first, second, and third speed ratio of the at least eight forward speed ratios and at least one of the at least one reverse speed ratios.

21. A transmission comprising:

an input member;

an output member;

first, second, third and fourth planetary gear sets each having first, second and third members;

a selectively engaged reverse torque transfer path including the first member of the first planetary gear set interconnected with the third member of the fourth planetary gear set and a stationary member;

a selectively engaged first torque transfer path including the first member of the first planetary gear set interconnected with the third member of the third planetary gear set and the first members of the second, third, and fourth planetary gear sets, and the third member of the fourth planetary gear set interconnected with the stationary member;

a selectively engaged second torque transfer path including the first member of the first planetary gear set interconnected with the first members of the second, third, and fourth planetary gear sets, and the third member of the fourth planetary gear set interconnected with the stationary member;

a selectively engaged third torque transfer path including the third member of the third planetary gear set interconnected with the second member of the fourth planetary gear set and the output member, and the third member of the fourth planetary gear set interconnected with the stationary member;

a selectively engaged fourth torque transfer path including the first member of the first planetary gear set interconnected with the first members of the second, third, and fourth planetary gear sets, and the third member of the third planetary gear set interconnected with the second member of the fourth planetary gear set and the output member;

a selectively engaged fifth torque transfer path including the third member of the third planetary gear set interconnected with the first members of the second, third, and fourth planetary gear sets and the second member of the fourth planetary gear set and the output member;

a selectively engaged sixth torque transfer path including the first member of the first planetary gear set interconnected with the third member of the fourth planetary gear set, and the third member of the third planetary gear set interconnected with the second member of the fourth planetary gear set and the output member;

a selectively engaged seventh torque transfer path including the first member of the first planetary gear set interconnected with the third member of the fourth planetary gear set, and the third member of the third planetary gear set interconnected with the first members of the second, third, and fourth planetary gear sets; and

a selectively engaged eighth torque transfer path including the first member of the first planetary gear set interconnected with the third member of the fourth planetary gear set and the first members of the second, third, and fourth planetary gear sets.