What is journal in bearings

Update: 30-06-2020

All rotating shafts have to be supported. For this purp […]

All rotating shafts have to be supported. For this purpose we go in the for the use of bearings. In the process of supporting the shaft loss of power in the form of frictional heat due to rubbing of the bearing and shaft is to be avoided. This is ensured by going in for rolling contact bearings or journal bearings.

We see a shaft supported in ball bearings. The inner race is press fitted to the shaft and the outer race to the housing.

Another type of bearing in common use is the sliding contact bearing. Here, the shaft rotates within a sleeve and use is made of lubricants between the two contact surfaces. There is a film of oil that separates the shaft and the supporting bearing as shown below

There are two types of sliding contact bearings namely; Hydro static bearings and hydrodynamic bearings. Whatever be the case, the length of shaft supported within the bearing is referred to as the journal.