Fashionable cars and trucks use helical gears and synchromesh devices inside the gearboxes, that synchronize the rotation of gears which have been going to mesh. This eliminates clashing from the gears and tends to make gear shifting easier. It had been to start with released in 1939 for cars. https://gearbox93604.mdkblog.com/39628490/gearbox-things-to-know-before-you-buy