What is the function of the crankshaft in an internal combustion engine?

The crankshaft plays a crucial role in an internal combustion engine by converting the linear motion of the pistons into rotational motion, which is essential for the engine to function. As the fuel mixture is ignited within the cylinders, it creates pressure that pushes the pistons down. The crankshaft is connected to these pistons via connecting rods. When the pistons move down and up, the crankshaft rotates in response, enabling the engine to convert the stored energy from the combustion process into mechanical energy. This rotational motion is what ultimately drives the vehicle's wheels.

Understanding this function is key because it underpins the operation of various components in the powertrain system. The other functions mentioned in the options are not related to the crankshaft's primary role in converting motion. Igniting the fuel mixture is the job of the spark plug, measuring engine speed is typically the role of a tachometer, and cooling the engine is managed through the coolant system and the radiator.