Patent attributes
A method is provided for shifting a powershift transmission in a vehicle having an electronic engine control unit and an electronic transmission control unit. The method rapidly reduces off-going clutch pressure to a pressure which is slightly higher than a Predicted Off Slip Pressure, and rapidly increases on-coming clutch pressure P-on to a pressure that is slightly lower than a Predicted On Slip Pressure. Then, the method includes gradually decreasing P-off and gradually increasing P-on until slipping of the off-going clutch is detected, and gradually and more slowly decreasing P-off and gradually more slowly increasing P-on until the oncoming clutch begins to carry torque previously carried by the off-going clutch. Finally, the method includes more rapidly decreasing P-off to reservoir pressure, and more rapidly increasing P-on to a full on pressure.
