How are the journal, shaft head and shaft body defined? What is the difference between them?

Definition of journal, shaft head and shaft body:
1. The journal is where the bearing is installed on the shaft. Refers to a section of shaft with the same diameter or different diameters on the shaft but the outer circular surface formed is a uniform continuous cylindrical surface. The outer circular surface must be uniform and continuous, with no shoulder or groove broken.
2. The shaft head refers to the two ends of the shaft. The shaft is a mechanical part that supports rotating parts and rotates with it to transmit motion, torque or bending moments. It is generally a metal round rod. Each section can have a different diameter. The rotating parts are mounted on the shaft.
3. The shaft body is the part connecting the shaft head and the journal.
The difference between the three:
1. Different structure
The ends of the journal and the shaft head are chamfered.
The surface of the journal must be uniform and continuous, and there should be no broken shoulder or groove.
2. Different functions
The journal is used to install the bearing;
The shaft head is used to install the wheel hub and plays the role of carrying the equipment on the shaft;
The shaft body is used to connect the journal and the shaft head.
3. Different degrees of easy wear
The shaft head is most likely to be worn and deformed, followed by the journal, and the shaft body is relatively difficult to wear.