What is a Pillow Block Bearing?

A Pillow Block Bearing is a mounted anti-friction bearing that is contained within a solid cast iron, ductile iron or cast steel housing unit. Also referred to as a housed bearing unit, meaning they are self-contained, greased, sealed and ready for installation on the equipment.  Pillow Block bearings are typically bolted to a surface, so that the attached shaft runs parallel with the surface. There are two types of housings used for pillow block bearings, solid and split housings. Solid housed bearings are single-piece housings, while split housed bearings are two-piece housings.  Pillow block bearings can contain several types of bearings, including ball, roller and tapered. Shaft attachment devices can be set screw, eccentric lock, single or double set collar, concentric lock or tapered adapter. Each device has their own positive and negatives. Seals vary as well, including clearance seals, light contact, heavy contact and auxiliary type seals.  Pillow Block Bearings, in most cases, also come in a fixed or expansion version.  The expansion bearings allow for shaft growth and can reduce the risk of loading one bearing against the other. Choosing the best shaft mount device and seal will prolong bearing life.  When installed properly, pillow block bearings can last years without needing to be replaced. Follow these steps to ensure minimal downtime and a longer service life.

*This procedure is for the most common shaft locking device set screw or set collar, utilizing a fixed and expansion unit, but the general guidelines apply to all bearing installs.

1) Check and Clean the Shaft

First, check your shafting to ensure it is clean, round, straight, free of burrs and nicks and is not undersized or oversized, per the manufacturers specification. Use fine sandpaper or scotch bright to clean the shaft of any rust. Then use a light coat of oil to remove any debris. 
Blog Content Image

2) Position the Bearings on the Shaft

When placing the bearing on the shaft, if it is necessary to tap the bearing into place, use a mallet and a hardwood block or soft steel tube against the inner ring. DO NOT strike or exert pressure on the housing or seals.
Blog Content Image

3) Lightly Bolt the Housing to the Mounting Structure

Locate the shaft in position by lightly bolting the housing to the mounting structure. Bridge over the housing mounting bolt slots with heavy washers, or heavy spring lock washers. This may help prevent loosening.
Blog Content Image

4) Establish the Final Mounting Position

Prior to securing the bolts, establish your final mounting position by aligning the bearing units by hand or a rubber mallet. 
Blog Content Image

5) Securely Bolt the Housing to the Mounting Structure

Once the bearing is properly aligned, securely bolt both units to the mounting structure.
Blog Content Image

6) Ensure the Shaft can Move Axially

Ensure that the shaft can move axially through the bearing bores to confirm proper alignment. If this cannot be done, loosen the housings and realign the shaft. 
Blog Content Image

7) Tighten Both Collar Set Screws

Tighten both collar set screws, and then rotate the shaft and alternately tighten to the manufacturer recommended torque values. If a torque wrench is not available, tighten the set screws until a permanent twist is established with an allen wrench. 
Blog Content Image

8) Expansion Unit*

If you are using an expansion unit, always lock the fixed bearing first. Move the expansion bearing axially to center in the housing. Once centered, alternately tighten the set screws on the expansion unit as you did on the fixed unit. 
Blog Content Image

For full installation manuals and documentation, visit Rexnord.com/documentation. Or Call 1-866-REXNORD for technical and sales support.

How to Install a Pillow Block Bearing

For a video on how to properly install a Pillow Block Bearing, Visit the Rexnord YouTube account to watch the “How to Install Rexnord IIoT Smart PT Select Bearings” video.

Watch Video

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.”