Modern automobiles use helical gears and synchromesh units within the gearboxes, that synchronize the rotation of gears that happen to be about to mesh. This gets rid of clashing on the gears and would make gear shifting less complicated. Samples of this sort of transmissions are used in helicopters https://gearbox19641.yomoblog.com/40361273/gearbox-things-to-know-before-you-buy