Patent ID: 6752738
Filing Date: 2004-06-22
Classification: F16H

Abstract:
An eight-speed automatic transmission comprising:a compound planetary gear set having a pair of sun gears, a first carrier, and a first ring gear; a second planetary gear set having a second sun gear, a second carrier, and a second ring gear, said second sun gear drivingly engaged with said first carrier, said second carrier drivingly engaged with one of said pair of sun gears; a third planetary gear set having a third sun gear, a third carrier, and a third ring gear, said third carrier drivingly engaged with said second ring gear and drivingly engaged with an output shaft, said third ring gear drivingly engaged with said second carrier; a first clutch selectively receiving a torque input from an engine, said first clutch drivingly engagable with said third sun gear; a second clutch selectively receiving a torque input from said engine, said second clutch drivingly engagable with said one of said pair of sun gears and said second carrier; a third clutch selectively receiving a torque input from said engine, said third clutch drivingly engagable with the other of said pair of sun gears; a first brake engagable with said third ring gear and said second carrier for selectively fixing said third ring gear and said second carrier from rotation; a second brake engagable with said first ring gear for selectively fixing said first ring gear from rotation; a third brake engagable with said first carrier for selectively fixing said first carrier from rotation; and a fourth brake engagable with said other of said pair of sun gears for selectively fixing said other of said pair of sun gears from rotation; wherein selectively engaging one or more of said first clutch, said second clutch, said third clutch, said first brake, said second brake, said third brake, and said fourth brake provides a torque input-to-output ratio corresponding to one of eight forward gear ratios and at least one reverse ratio, and said first, second, and third clutches and said first, second, third, and fourth brakes are selectively engaged by flow regulating valves.