Contents
- What is a pillow block (UCP)
- What is a flange bearing (UCF/UCFL)
- Mounting differences
- Space and load considerations
- How to choose
- Common models
What is a pillow block (UCP)
A pillow block bearing (UCP) has a cast P-housing that bolts flat to a machine base. The shaft runs horizontally and the unit supports radial load from below.
It is the most common mounted bearing for conveyors and general machinery because the base mount is simple and stable.
What is a flange bearing (UCF/UCFL)
A flange bearing mounts to a vertical face or side surface. UCF uses a four-bolt square flange; UCFL uses a two-bolt oval flange for narrower profiles.
Flange units are used where there is no suitable base, such as on a wall, frame side or machine panel.
Mounting differences
UCP needs a flat horizontal base and bolt holes in line with the shaft. UCF/UCFL need a vertical or side face with bolt holes arranged around the shaft axis.
Because the mounting surfaces differ, the two types are not directly interchangeable even with the same bore.
Space and load considerations
Pillow blocks generally offer good stability for horizontal shafts and are easy to align. Flange units save base space and suit compact frames, but the mounting face must be rigid.
For the same bore, choose the unit whose housing shape fits the available structure. Load rating depends more on the UC insert and series (UCP200 vs UCP300) than on pillow vs flange.
How to choose
If you have a flat base along the shaft, choose UCP. If you must mount on a wall or side panel, choose UCF (square) or UCFL (oval, narrow).
Confirm bolt hole pattern and available space, then match the bore and series to the load. Send the application and a photo to the manufacturer for confirmation.
Common models
Typical pillow block: UCP205, UCP210, UCP305. Typical square flange: UCF205, UCF210. Typical 2-bolt flange: UCFL205, UCFL210.
All use the same UC insert bore groups, so the bore stays consistent across mounting types.
Pillow block vs flange
| Factor | UCP pillow block | UCF / UCFL flange |
|---|---|---|
| Mounting | Flat horizontal base | Vertical or side face |
| Bolt pattern | In line with shaft | Around shaft axis |
| Best for | Conveyors, base mounts | Walls, panels, narrow frames |
| Space | Needs base width | Saves base space |
Selection checklist
- Mounting surface type.
- Available bolt hole space.
- Shaft diameter.
- Expected load and series.
- Rigidity of the mounting face.
Key Takeaways
- UCP mounts to a flat base; UCF/UCFL mount to a vertical or side face.
- They are not directly interchangeable even with the same bore.
- Choose by mounting surface, then match bore and series to the load.
Frequently Asked Questions
Can I replace a UCP with a UCF?
Not directly. They mount to different surfaces and use different bolt patterns, even if the bore is the same.
Which flange: UCF or UCFL?
Use UCF (square, 4-bolt) for rigid flat faces; use UCFL (oval, 2-bolt) where the profile is narrow and a square flange will not fit.
Does pillow vs flange change load rating?
Load rating depends mainly on the UC insert and the series (UCP200 vs UCP300), not on pillow versus flange shape.
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