1. When the bearing inner diameter tolerance zone and the shaft tolerance zone are matched, the tolerance code that was originally a transition fit in the general base bore system will become an overmatch, such as k5, k6, m5, m6, n6, etc., but not too big; when the bearing inner diameter tolerance is matched with h5, h6, g5, g6, etc., it is not a gap but an overwhelming fit.
2. The bearing outer diameter tolerance zone is a special tolerance one because the tolerance value is different from the general reference shaft. In most cases, the outer ring is fixed in the housing. Some bearing components require structural adjustments should not be too tight, often with H6, H7, J6, J7, JS6, JS7 and so on.