What is the crankshaft journal?

In the context of an engine, the crankshaft journal refers to the cylindrical part where the crankpin or bearing sits. The crankshaft is the rotating part that converts reciprocating motion from the pistons into rotational motion. The crankshaft journal is where the crankpins are attached to the crankshaft. These crankpins are then connected to the connecting rod bearings by the big-end bearings. As the pistons move up and down in the engine cylinders, they turn the crankshaft by applying force on the crankpins, which in turn rotates the crankshaft. The crankshaft journal provides the bearing surface for the crankpin and experiences high loads and forces during engine operation.