Internals of the manual transmission incorporate quite a few gears that you can pick out according to your velocity and driving conditions. Most transmissions in modern vehicles use synchromesh to synchronise the speeds from the enter and output shafts. Even so, previous to the 1950s, most automobiles used non-synchronous transmissions. https://lorenzohhebw.madmouseblog.com/14634643/automobile-gearbox-fundamentals-explained