Basically, the overdrive gear rotates a lot quicker in comparison to the motor speed. Hence, it provides larger velocity and far better efficiency since the motor runs in a reduce rpm in relation to the vehicle velocity. For most vehicles, There's two key different types of gearboxes: handbook and automated. https://automobilegearbox63838.bligblogging.com/34770678/5-simple-statements-about-automobile-gearbox-explained