Going 'By the Book': Installing Two Fixed Adapter Mounting Units

Article Tags:
bearing life
fixed flange blocks
fixed pillow blocks
unit handling
Installing two fixed, tapered-adapter mounted roller bearings can be challenging, and if proper mounting procedures are not followed, it can lead to bearing failure. 
The issue posed by tapered adapter mount bearings is axial movement (movement parallel to the shaft) caused by tightening of the tapered adapter nut and sleeve. If you don’t tighten according to the service instructions, the bearings:
  • can be overloaded due to axial or thrust load, or
  • could come loose on the shaft due to improper tightness.
Rexnord tapered adapter arrangements come in two types: push and pull. The Rexnord Link-Belt 600 Series pushes, while the Rex 6000 Series Shurlok pulls. Regardless of direction, care must be taken to allow for the relative axial movement created by tightening the tapered adapter to specification. 
Let’s look at two mounting scenarios:
  • two fixed pillow block units, and
  • two fixed flange block bearings.
Mounting two pillow block units is the easier of the two scenarios.  The goal during installation is to allow for sufficient axial push or pull without creating excessive load on the bearings or failing to reach proper tightness. This is accomplished by tightening the mounting bolts to the structure just enough to allow axial movement to take place between the bolt and the pillow block bolt mounting slot.
There is enough clearance in the pillow block slots, and once you have adequately tightened the bearings per service instructions, you can align the pillow block bearings and tighten the mounting bolts fully.
Mounting two fixed tapered adapter mount flange blocks creates a more complex situation.  Because a fixed distance exists between the two faces as you mount the flange blocks, there must be a procedure to adjust this fixed position to account for the push or pull distance, depending on the type of tapered adapter. (Again, the Rex 6000 Series Shurlok pulls while the Link-Belt 600 series pushes.)  Therefore, you must compensate for the axial movement distance using specified spacer thicknesses, which are listed in the service instructions. 
For the Rex 6000 Series Shurlok, tighten the mounting bolts of the first flange block and then tighten to the shaft per service instructions. Loosely bolt the second flange to the structure, and again, according to service instructions, tighten to the zero point. 
Loosen the mounting bolts to allow movement (pull) away from structure.  Bolts should be loose enough to allow for the required shim thickness listed in the service instructions. Tighten the
bearing to the shaft as specified, place the required shim stock under each bolt pad and tighten the mounting bolts.
The procedure is the same for the Link-Belt 600 Series, but remember, this bearing pushes. For the first flange bearing, tighten the mounting bolts and then tighten to the shaft per the service instructions. For the second bearing, place the proper shims under the flange and snuggly tighten the mounting bolts. Bring the bearing to the zero-fit position per service instructions. Remove the shims behind the bolts, tighten to the shaft per service instructions and then tighten mounting bolts.
By fully reading, understanding and following the service instructions, you’ll prevent loose or overloaded bearings and ensure a quality installation every time. For a demonstration of our Link-Belt 600 Series, check out this YouTube video.
For additional information or assistance, visit Rexnord.com, call us at (317) 273-5781 or email  [email protected]. For additional videos and other demos, visit our YouTube channel.

Mark Czubak

Mark Czubak is a Principal Engineer with the Rexnord Bearing business. He has spent nearly 40 years with Rexnord where he has managed all facets of engineering, including application, design and manufacturing, giving him a cradle to grave knowledge of mounted roller bearings. With this experience, Mark shares his passion and knowledge through bearing training, application assistance and installation. “Bearings are overlooked for the more expensive components of the system, but a bearing failure can cause just as much downtime as any other component so choose your bearings wisely, and save time and money.”