Patent ID: 6120406
Filing Date: 2000-09-19
Classification: F16H

Abstract:
A hydraulic control system for an automatic transmission including a planetary gear system having at least one clutch element engagable to alter the torque ratio of the transmission, said hydraulic control system comprising:a pressurized fluid source;a manual valve selectively movable between a plurality of positions and communicating with said pressurized fluid source;a first fluid passage communicated with the at least one clutch element and said manual valve, said first fluid passage including a normally closed solenoid valve;a second fluid passage communicated with the at least one clutch element and said manual valve, said second fluid passage including a normally open solenoid valve;said hydraulic control system being capable of engaging the at least one clutch element with said manual valve in a predetermined position and said normally closed solenoid valve in an energized, open state and said normally open solenoid valve in an energized, closed state, said hydraulic control system further being capable of engaging the at least one clutch element with said manual valve in said predetermined position and said normally closed and said normally open solenoid valves de-energized.