A gear shift control apparatus has a higher degree of freedom for selecting a
gear
ratio than that of a Ravigneaux type composite planetary gear train, while achieving
a strength advantage of the gear train, an improvement in the fuel economy, a coaxial
positioning of an input portion and an output position, and a size reduction of
an automatic transmission. The apparatus achieves six forward speeds and one reverse
speed by properly engaging/releasing three clutches and two brakes. One of three
planetary gearsets is a speed-reducing or speed-increasing device for reducing/increasing
the speed of an input rotation. One of the remaining two planetary gearsets is
a double sun gear type planetary gearset, a carrier of which has a center member
for inputting or outputting a rotation from between two sun gears.
