Pillow Block Bearing Shaft Mounting Using Adapter Sleeve

The unit shown above is the pillow block and can be used to house a spherical roller bearing. The bearing in this case has a tapered bore which has to connect to a parallel circular shaft. An adapter sleeve will enable a connection from tapered bore to parallel shaft.
The pillow block can be quickly mounted onto a machined flat face on a machine or piece of equipment. The split housing aids easy assembly after the shaft, bearings and adapter sleeve are located.
Spherical roller bearings have exceptional radial load carrying capabilities, fair axial load carrying capabilities as well as good accommodation of shaft misalignment.

This image shows a section through the assembly with a 1:12 taper.
The pillow block housing is coloured blue, the tapered adapter sleeve is red and the bearing lies between these two components.
Adapter sleeves are selected to suit both the bearing and the shaft and can only accommodate a very small variation in shaft size.
In this arrangement, the shaft diameter and the bearing bore must form an interference fit with the adapter sleeve.
Properly mounting the bearing onto the shaft can be done by any of three methods. The most suitable method for an application will depend on the bearing size and the specific design arrangement.
1.      Locknut angular tightening.
This method is based upon setting the axial engagement of the bearing inner ring as it is pushed up and onto the tapered adapter sleeve. The locknut of known thread pitch is rotated using a locknut spanner through a specific angle from the start of the assembly process. The increasing angular adjustment and resulting axial engagement is proportional to the interference fit between the bearing inner ring bore, adapter sleeve and the shaft.

2.         Radial clearance reduction.
This method measures the reduction in bearing internal clearance due to the expanding inner ring as the bearing is pushed up and along the adapter sleeve’s tapered body. Using a locknut spanner to tighten the locknut, the bearing internal clearance is repeatedly measured using feeler blades until the correct value is reached. The reduction in bearing internal clearance is proportional to the interference fit between the bearing inner ring bore, adapter sleeve and the shaft.

3.         Hydraulic take up.
Relies on measuring the engagement of the adapter sleeve into the bearing inner ring bore as it is forced into position using a hydraulic nut. This is a device which screws onto the shaft and through the action of pressurising an internal fluid, the nut extends (on the same principle as a hydraulic jack) and pushes the adapter sleeve or the bearing into the required position.

A tapered adapter sleeve assembly showing the locknut and lock washer located onto the split sleeve.

The original mechanical designer of the machine and it’s bearing arrangements will be able to provide mounting instructions for the task. Alternatively, the bearing manufacturer’s technical representative may also provide recommendations. There are also some comprehensive installation guide catalogues available online which highlight each method and the data required to perform them correctly.