Patent attributes
An automatic transmission for a vehicle includes a main box controlled using a series of clutches, and an underdrive assembly controlled using a series of clutches and at least one overrunning clutch. In achieving a double-swap downshift from a first transmission “gear” employing a first main box clutch and a first underdrive assembly clutch, to a second transmission “gear” employing a second main box clutch and a second underdrive assembly clutch, a controller delays release of the first main box clutch until after the second underdrive assembly clutch has been prefilled, and fully applies the second underdrive assembly clutch only after slip has been detected in both the main box and the underdrive assembly. Additionally, the controller fully applies the second main box clutch only after the second underdrive assembly clutch has itself been fully applied.
