In essence, gears are only circles with teeth connecting them. A equipment transmits a round movement between two different shafts by rotating and meshing with A further gear on the opposite shaft. Gears come in many different sizes and shapes, including spur gear, helical gear, bevel equipment, and worm equipment. https://charlieopmic.pointblog.net/not-known-details-about-automobile-gearbox-78014634