An Engine in an automobile relies on internal moving parts. One of these moving parts is the crankshaft and is the main moving part in the engine. The crankshaft rotates constantly when the engine is running. There are connecting rods and pistons attached to the crankshaft that rotate along with it.
The crankshaft keeps all the moving parts in motion and at the same time transferring the energy created by the engine to the transmission that is connected to it.