• When the spark plugs ignite the fuel-air mixture in the combustion chamber, the resulting explosion forces the pistons downward with tremendous force. The function of the crankshaft is to change the up-and-down motion of the pistons to a rotating motion. This is accomplished by having the connecting rods (which are attached to the pistons) connect to the crankshaft in an offset manner, so that as they go up and down their angle changes. This can be easily seen in the video link supplied
