What engine part converts linear motion to rotational motion inside a reciprocating internal combustion engine?

In a reciprocating internal combustion engine, the component that converts linear motion to rotational motion is the crankshaft. As the pistons move linearly within the cylinders due to the combustion process, the connecting rods attached to the pistons are connected to the crankshaft. This design allows the up-and-down motion of the pistons to turn the crankshaft, which then translates that motion into rotational energy to drive the vehicle.