What is the function of the crankshaft in a reciprocating engine?

The crankshaft plays a crucial role in the operation of reciprocating engines by converting the linear motion of the pistons, which are driven by the combustion process, into rotational motion. This conversion is essential because the engine's output needs to be in the form of rotational energy to drive the propeller or the vehicle’s drive train.

As the pistons move up and down within the cylinders due to the force generated from the fuel-air mixture igniting, this motion is transferred through the connecting rods to the crankshaft. The design of the crankshaft, with its offset journal locations, allows it to turn as these pistons move, translating this linear movement into the rotational movement required to power the aircraft or vehicle.

This function is fundamental to the operation of the engine, as it is directly linked to how power is generated and delivered. Other choices pertain to different components or functions within the engine system, such as fuel-air mixture regulation or engine temperature control, which do not relate to the crankshaft's primary function of motion conversion. The support and mounting of pistons are also not functions attributed to the crankshaft but rather to the engine design as a whole.