Wheels don’t eat. But some wheels use teeth to help them do work, work that other wheels can’t do.
A wheel with teeth is called a gear. It is a wheel that makes other wheels move. If you look at an eggbeater, you can see three gears. The big one with the handle is the gear you turn. The teeth on this gear fit into the spaces between the teeth on the two smaller gears. When you turn the handle, the teeth on the big gear push against the teeth on the small gears and make these gears turn. One turn of the big gear makes the small gears turn many times. So the beater blades move very quickly.
First, second, third, fourth – these are the different-sized gears that fit together in a car. The engine turns a set of gears connected to a rod called a crankshaft. The crankshaft turns the axle and the wheels. The lowest gear is first gear. It allows the crankshaft to turn much more quickly than the wheels. This makes more power for starting and for climbing steep hills. Fourth gear allows the wheels to travel around more quickly while using less power. Fourth gear is used for cruising along at the same speed without stopping and starting. It’s the gear that is used on a motorway.
Picture Credit : Google