There is a certain gap between the inner ring, outer ring and rolling element of rolling bearing, so there can be relative displacement between the inner ring and outer ring. When there is no load, one ring is fixed, and the movement of the other ring from one limit part to another along the radial and axial direction of the bearing is called radial clearance and axial clearance respectively. According to the mode of the bearing, the clearance is divided into three types.
(1) Initial clearance. It refers to the clearance in free mode before the installation of rolling bearings, which is determined by the manufacturer's processing and assembly.
(2) Installation clearance, also known as fit clearance. It refers to the clearance between the bearing and the shaft and the bearing seat when they are installed but not yet in operation.
Because of interference installation, or the inner ring is expanded, or the outer ring is reduced, or both, the installation clearance is smaller than the initial clearance.
(3) Running clearance. The clearance of the rolling bearing in the working state, when running, the inner ring temperature rise is larger, and the thermal expansion is larger, which reduces the bearing clearance.
And because of the load, the elastic deformation occurs at the contact between the rolling element and the raceway, which expands the bearing clearance. Whether the running clearance of the bearing is larger or smaller than the installation clearance depends on the combined action of these two factors.
