A crankshaft pulley, also called a harmonic balance wheel or crankshaft sheave, is a grooved, wheel-shaped device that connects directly to the vehicle's crankshaft. The crankshaft essentially converts the linear, or straight, movement of pistons into a rotational motion. The crankshaft gear drives two different intermediate gears: one intermediate gear transmits power to the camshaft gear, which in turn drives the valve mechanism via the camshaft. This ensures opening and closing of the valves.