Automatic transmission for vehicle

An automatic transmission for a vehicle having an input shaft, an output shaft and a speed changer for achieving five forward gear stages comprising first and second speed stages which decrease speed of rotation received from the input shaft and transmit it to the output shaft, a third speed stage which transmits rotation from the input shaft, unchanged in speed, to the output shaft, and fourth and fifth speed stages which increase speed of rotation received from the input shaft and transmit it to the output shaft, said speed changer comprising:

• interconnected first, second and third planetary gear sets;
• said first planetary gear set including, as speed change elements, a first ring gear drivably connected to the output shaft, a first carrier rotatably supporting a first pinion gear meshing with the first ring gear, and a first sun gear meshing with the first pinion gear;
• said second planetary gear set including, as speed change elements, a second carrier drivably connected to the first carrier and rotatably supporting a second pinion gear having a smaller diameter than the first pinion gear and connected to the first pinion gear in a manner preventing rotation relative thereto, and a second sun gear meshing with the second pinion gear;
• a plurality of clutches, for connecting the input shaft to predetermined speed change elements of the first, second and third planetary gear sets, including a first clutch for selectively drivably connecting the first carrier to the input shaft;
• and
• a plurality of brakes, for stopping predetermined speed change elements of the first, second and third planetary gear sets, including a first brake for selectively stopping the first sun gear and a second brake for selectively stopping the second sun gear.