The transmission has a 'drive' setting in which the automatic control sets the gear ratio in line with a programme. The driver is able to select a manual control by switching the gear ratio up or down by one setting. The improved control predicts the engine speed which will be reached after changing down a gear and delays the gear change for a set period to allow the engine speed to fall to a safe level. The control determines the predicted engine speed in relation to the rate of change of throttle setting, the rate of change of vehicle speed and the level of braking. Also calculated is the time delay required to lower the engine speed to a safe level. If this time delay is less than a preset value the delayed change down proceeds.
