Automatic vehicle transmission with lock-up clutch

摘要

A detector senses the inspect revolution speed of the transmission and an output revolution speed. A discriminator judges the start of gear change by comparing the ratio between the input and output revolution speeds with the gear ratio before the gear change. A second discriminator judges the completion of gear change by comparing the ratio between an input and an output revolution speed with the gear ratio after the gear change. A lock-up solenoid (10) releases a lock-up clutch (6) during gear change on receiving output signals of the discriminators.