How To Determine Pillow Block Bearing Size
Measure shaft, bolt hole spacing and base-to-centre height, then read the insert marking to identify UCP, UCF or UCFL replacements. Printable.
If the old unit’s marking is unreadable, these six measurements identify the housing style and size without it.
Six-step measuring checklist
- Measure the shaft bore. This is the bore of the insert bearing, not the outside of the housing. Use the shaft the unit is currently fitted to, or the inside of the insert if it is off the shaft.
- Measure bolt-hole centre spacing. On a pillow block this is the two-bolt spacing along the base; on a four-bolt flange it is both the horizontal and vertical spacing.
- Measure base-to-shaft-centre height. On a pillow block, measure from the bottom of the base to the centre of the shaft bore; this is the H dimension on the size tables.
- Note the housing shape. A pillow block base is rectangular and bolts flat to a frame. A flange housing is round or square with a bolt circle and bolts to a wall or plate the shaft passes through — four-bolt (UCF) or two-bolt oval (UCFL).
- Check for a part marking. If any marking survives on the insert or housing, it is the fastest check — read bearing number decoder for what each part of the number means.
- Compare against the size table. Match the bore and housing shape from steps 1 and 4 against the size table on the relevant page: pillow block bearing, flange bearing or mounted bearing for an overview of all housing styles.
What the measurements rule in or out
| Measurement | Narrows down |
|---|---|
| Shaft bore | The size number (for example 205, 206) |
| Bolt hole spacing | Housing style and confirms the size number |
| Base-to-centre height | Pillow block vs a taller or shorter housing of the same bore |
| Housing shape | Pillow block vs flange vs take-up |
Once you have the bore and housing style, send them with the quantity needed to sales@fuli-bearings.com or use the request a quote form for a confirmed match and price.
FAQ
The old unit's marking is worn off. Can I still identify it?
Yes. The shaft bore, bolt hole spacing and base-to-centre height together narrow the match to one or two sizes even without a readable marking; compare your measurements against the size table on the housing's page.
Does bolt hole spacing alone identify the size?
Usually, within one housing style, but pillow block and flange housings of the same bore can share similar footprints. Measure the shaft bore as well and check both figures against the size table.
What if my measurements fall between two listed sizes?
Re-measure the shaft bore first, since it is the figure the insert size is built around; a bore that reads between two standard sizes usually means wear on the old bearing rather than a non-standard size.