Automatic transmission comprising a four planetary gear stages

摘要

An automatic transmission includes a planetary gear train of first (G1), second (G2), third (G3) and fourth (G4) planetary gears; an input rotation member (Input) connected with a ring gear (R2) of the second planetary gear; and a first connection member (M1) connecting a carrier (PC2) of the second planetary gear and a ring gear (R4) of the fourth planetary gear. A first rotation sensor (TS1) senses the rotation speed of the first connection member. A second rotation sensor (TS2) senses the rotation speed of one rotating element of the first and second planetary gears. A processing section calculates an input speed of the automatic transmission from the rotation speeds sensed by the first and second rotation sensors.