How to properly secure or mount bearings

Bearings can be affected by unbalanced loads. This can change the performance of the bearing significantly. The most important thing to be aware of is how to securely mount the bearing. There are several methods, each with different tools and complexity. This article will explain the methods and points you need to know when mounting bearings.

Bearing mounting

To secure a rolling bearing to a shaft or housing, an ’interference ring’ is used. However, there are cases in which fastening by means of an interference ring alone is not sufficient. Bearings that are subjected to axial loads or loads applied in the axial direction, must be firmly secured to prevent the raceways from moving in the axial direction. Cylindrical roller bearings, for example, are not subject to axial loads, but shaft deflection caused by moment loads generated when the shaft rotates may cause the raceway rings to move. In such cases, the bearings may be damaged, so they must be properly secured in the axial direction.

In addition to firmly securing the bearing, it is essential to pay attention to the following points and properly design the shaft and housing,  to maximize the performance of the bearing.

  • Shaft: Make it thick and short.
  • Shaft shoulder end-face: Finish at a right angle to the shaft center.
  • Housing: Make the structure solid and rigid.
  • Housing shoulder end-face: Finish at right angles to the inner diameter surface of the housing.
  • Shaft-to-housing fitting surfaces: Finish with sufficient accuracy and surface roughness.
  • Shaft and housing shoulder height: Should be greater than the maximum chamfer dimension of the bearing.
  • Rounded corners of shaft and housing: Make it smaller than the minimum chamfer dimensions of the bearing.
  • Mating surfaces of split housings: Carefully finished, with clearance on the inner diameter side.

Main methods of mounting bearings

 For general bearings

The method commonly used to secure the inner and outer rings is to use tightening nuts and bolts. Tighten the raceway ring end-face to the shaft shoulder or housing shoulder. When tightening with nuts, use washers to prevent them from loosening. When mounting angular contact ball bearings or tapered roller bearings with a loose fit, it is important to insert a thin washer (a few mm in thickness) and tighten it. In addition, the use of the type of retaining rings specified by JIS can simplify the structure and is also suitable for cases where space in the equipment is limited. In such cases, be careful and ensure that the dimensions of the bearing mounting are met. This mounting method is not suitable for cases where large axial loads are applied to the retaining ring or where high precision is required.

When mounting with end plates, it is important to drill bolt holes at the end of the shaft.

When mounting to a plate, provide a stepped hole in the plate or use a bearing with a ’collar’ such as a retaining ring or flange.

Fortapered bore bearings

In the case of mounting on a cylindrical shaft, mount using an adapter sleeve or removal sleeve.By doing so, it is possible to mount the shaft in the axial direction. At that time, the adapter sleeve is secured by the frictional force between the inner diameter of the sleeve and the shaft.

Since the adapter sleeve simply attaches to the shaft and tightens the nut, this makes axial positioning the easiest mounting method. To prevent the nut from loosening, a washer with a shaft diameter of 180mm or less or a stopper with a shaft diameter of 200mm or more should be used.

When using a removal sleeve, a nut or end-plate is used to secure the bearing after the removal sleeve is pushed in. This method has the advantage that the bearing can be easily removed.

There are also cases where shaft nuts are used. Like cylindrical bore bearings, shaft nuts are threaded on the shaft and are fastened with a nut.

There is also a mounting method where a split ring is used. When mounting on a tapered shaft, a nut or split ring with a threaded outer diameter is inserted into the groove of the shaft and then secured with a nut.


Bearings will not perform as they should if they are not properly mounted. When installing, be careful not to allow the bearing to move or come off.