The crankshaft turns because of the forces transmitted through the connecting rods. At the same time, it must be held in place. That's done by bearings. They reduce friction, and allow free movement.
The Crankshaft is held in place in the engine block by main bearings at points called journals. Different bearings do different jobs These bearings support the crankshaft in place but let it turn freely.
The crankshaft also needs to be located to stop lateral movement. This is done by using flanges between the connecting rod and the crankshaft are connecting rod bearings. They protect the spinning crankshaft at points also called journals.
On the rear of the crankshaft is a heavy flywheel. It stores up energy from the power stroke and helps keep the crankshaft turning.
Source: CDX Global
