Bearing Assembly and Disassembly

Bearing Mounting

The first step in mounting is to decide on the fit that is going to be used. In most applications, inner ring and outer do not rotate at the same time. In principle, bearings are press fitted in the ring that is rotating and transtition fitted to the ring that is not rotating. However, there are other factors affecting the level of press and transition fits, such as load amount and load direction.

Ambient Load: If the load is static, ring is rotating or ring is stationary but load is rotating, then the load is ambient.
Point Load: If the ring is not rotating and load is static or if the load is rotating with the ring, then there is a point load.
Indeterminate Load: If there is ambient and point load at the same time, then there is indeterminate load.
There should always be a tight press fit between the shaft and the ring with the ambient load. The larger the load, the tighter the press fit should be. For rings with point load, transition fit should be used. A tight press fit should be used on both inner and outer ring in case of indeterminate load. Since the transition fits reduce the clearance of the bearing, the clearance of the bearing should be carefully chosen. Larger internal clearance bearings will be appropriate in this case. In order to fully utilize the capacity of the bearings, bearing type and construction as well as surrounding component structure should be carefully analyzed during mounting and dismounting operations. Proper mounting equipment and cleanliness of the surface of mounting are vital to the bearing life. Following is a list of cautions during mounting operation:

1. Hammer hits on the rings should be avoided. Instead, bushings can be used for hitting operation.
2. For the bearings that cannot be disassembled, force should be applied directly on the ring that is press fitted and this ring should be mounted first.
3. Ring of the bearings that can be disassembled can be mounted separately.
4. Bearings with smaller diameter can be mounted using cold pressing operation.
5. Heating during oil bath for mounting can be used in bearings other than the ones with tighter tolerance and seals.
6. Induction heaters can be used for mounting as well.
7. Hydraulic operations can be used for bearings with larger diameter.


Bearing Dismounting

Dismounting of bearings is as important as mounting and should be carefully handled.
Following is a list of cautions during dismounting operation:

1. If the bearing is going to be used again, pulling or mechanical press operation should be applied on the ring that is press fitted to the shaft or housing.
2. If the outer ring is press fitted into housing, housing and bearing should first be dismounted from the shaft, and then the outer ring is dismounted from the housing.
3. If the inner ring is press fitted onto shaft, shaft and bearing should first be dismounted from the shaft, and then the inner ring is dismounted from the shaft.
4. Bearings can be dismounted using induction heaters.
5. Heating rings can be used to dismount roller bearings.
6. Hydraulic operations can be used for bearings with larger diameter.