Most transmissions in modern vehicles use synchromesh to synchronise the speeds in the input and output shafts. On the other hand, ahead of the fifties, most cars and trucks made use of non-synchronous transmissions. Torque converter does precisely the same perform which the clutch does inside the handbook gearbox https://gearbox85318.onesmablog.com/considerations-to-know-about-gearbox-74398463