Most transmissions in present day vehicles use synchromesh to synchronise the speeds in the input and output shafts. Even so, prior to the 1950s, most vehicles used non-synchronous transmissions. Spur and helical gears are Employed in the sliding mesh gearbox to act. Spur gear’s teeth generate a parallel reference https://marcottspo.bloguetechno.com/the-2-minute-rule-for-gearbox-68911708