UCP vs UCF vs UCFL: pillow block or flange bearing, which housing do I need?

A UCP205 and UCF205 take the same 25 mm UC205 insert; only the housing differs. A UCP is a pillow block, a two-bolt foot on a surface parallel to the shaft. A UCF is a four-bolt square flange and a UCFL a two-bolt diamond flange, bolted to a face the shaft passes through. Ours are the UCP205, UCF205 and UCFL205.

If you only needed the difference, you can stop here. The table below gives the bolt pattern for the 204, 205 and 206 sizes.

UCP vs UCF vs UCFL at a glance

Source: bearing makers' published unit tables (see Sources), read 30 September 2026. Where both makers list a figure, they agree. Pillow block figures match our UCP204, UCP205 and UCP206 dimensions chart.

The letters name the housing, not the bearing

The unit numbers follow the Japanese Industrial Standard (JIS), read left to right: UC is the bearing type, the next letters are the housing, 2 is the series and the last two digits are the bore code. So a UCP205, UCF205, UCFL205 and UCT205 (take-up) all carry the same UC205 insert, with a 25 mm bore and a 34.1 mm wide inner ring.

What changes is the bolt pattern, and sometimes the bolt size at the same shaft size. A UCF205 bolts up with four M10s on a 70 mm square. A UCFL205 takes two M14s in 16 mm holes, 99 mm apart. That 99 mm is also the diagonal of the UCF205's 70 mm square, so a square flange measured corner to corner reads like a UCFL205. The same near-match holds at 204 (90.5 mm diagonal, UCFL204 90 mm) and 206 (117.4 mm, UCFL206 117 mm). Measure a square flange along one side.

So you can't swap a pillow block for a flange without new holes. Swapping a four-bolt flange for a two-bolt one depends on the size: the two-bolt's hole spacing is close to the square's diagonal at 204, 205 and 206, but at 205 and 206 it takes M14 bolts where the square flange uses M10. You can still replace just the insert. The housing is reusable: the old insert tilts through 90 degrees and comes out at the notch. A UC205 insert fits a standard 205 pillow block or flange.

Our units arrive with the insert already fitted, but you may need to align it for your job. It aligns in the housing, not inside the bearing: the insert's outer surface and the housing's bore are both spherical, which is what makes the unit self-aligning.

Pillow block or flange bearing: which one do I need?

1. Look at what it bolts to. A flat base or rail running alongside the shaft takes a pillow block (UCP). A plate, wall or frame side that the shaft passes through takes a flange (UCF or UCFL).
2. Pick the flange on space. The UCF needs room for four bolts on a square. The two-bolt UCFL is designed mainly for places where the mounting area is restricted. A standard UCFL205 is 68 mm across and a UCF205 95 mm.
3. Does the shaft need to move? If it slides to tension a belt or a conveyor, you need a take-up unit (UCT). Take-up units are made for shaft adjustment and belt tightening, such as on conveyors.
4. Measure the shaft with vernier callipers and find the size number in the next table.
5. Measure the old bolt spacing: slot middle to slot middle on a pillow block, along one side on a square flange, hole centre to hole centre on a two-bolt flange. Check the bolt size against the table above as well.

What number is a 20 mm, 25 mm, 40 mm or 1 inch pillow block?

Put UCP, UCF or UCFL in front of the number: a 40 mm pillow block is a UCP208, and a 1" two-bolt flange is a UCFL205/16. We list every size below in all three housings, except 2-3/8" (212/38), which we list as the insert only.

Source: shaft diameters from bearing makers' published pillow block tables (see Sources; some makers write the imperial bores differently, e.g. UCP205-100 for 1"), our supplier's size chart for 206 to 212, and our product listings, 8 October 2026. The number after the slash is the bore in sixteenths of an inch. 1-1/4" and 2" each come in two housing sizes, so measure the old bolt spacing and compare it with the maker figures, or ask us before you order.

Fitting a flange or pillow block bearing

• Mount it on something solid. The mounting surface must be rigid and as flat as possible, and the mounting face should ideally be within 2 degrees of true to the shaft.
• Tighten the mounting bolts evenly and don't overdo it. That's our team's advice: over-tightening can crack a housing. Bearing makers also recommend a washer under each bolt.
• Then lock the insert to the shaft. On a set screw insert, tighten the two set screws uniformly. The full steps are in how to get an insert bearing into a housing.

Which BES product fits

Our ACCOR UCP housings are made to the standard P204, P205 and P206 dimensions. The flange figures in this article come from bearing makers' catalogues. All the UCP, UCF and UCFL listings below are pairs (2x in the title).

• Pick the UCP205 25 mm pillow block if it bolts to a flat base alongside the shaft. UCP201 to UCP212 are in the collection.
• Pick the UCF205 25 mm four-bolt flange if it bolts to a plate the shaft passes through and there's room for four bolts on a square.
• Pick the UCFL205 25 mm two-bolt flange where the mounting area is narrow.
• Pick the UCFL204 20 mm or UCFL206 30 mm two-bolt flange for the sizes either side. A standard UCFL206 takes M14 bolts 117 mm apart.
• Pick a take-up unit (UCT201 to UCT215, 12 to 75 mm) if the shaft slides to tension a belt or conveyor.
• Pick a UC205 insert on its own (25 x 52 mm) if the housing is sound and only the bearing is worn.

All these sizes and housings are in insert and transmission bearings.

Questions people also ask

What is a pillow block bearing?

An insert bearing in a housing with a foot, bolted to a flat surface so it carries a shaft running parallel to that surface. It's the P in UCP. Our listings name uses from farm machinery and lawn mowers to go-karts, pumps and fans.

What is the difference between a pillow block and a flange bearing?

Which way the housing faces the shaft. A pillow block sits on a surface alongside the shaft; a flange bearing bolts to a face the shaft goes through. The insert inside can be identical.

What is a two bolt or 4 bolt flange bearing?

A two-bolt flange is a UCFL, diamond-shaped with a hole at each end; a four-bolt flange is a UCF, square with a hole in each corner. At 25 mm, a standard UCFL205 has 99 mm bolt centres and M14 bolts, and a UCF205 a 70 mm square and M10 bolts.

What size is a 2 inch flange bearing?

A 2" bore is a 210/32 or a 211/32, so a UCF210/32 or UCFL210/32, or the same in the bigger 211 housing. The bore doesn't tell you which: measure the old bolt spacing.

Is a four-bolt flange stronger than a two-bolt flange?

Not in the bearing: both carry the same UC205 insert. Choose on the mounting space and bolt pattern.

Related reading

• UCP204, UCP205 and UCP206 pillow block dimensions
• How to get an insert bearing into a housing

Sources

• NTN, Bearing Units, Cat. No. 2400/E, dimension tables UCP2 (pp. 62 to 64), UCF2 (p. 120), UCFL2 (p. 164), UCT2 (p. 212), ntnglobal.com/en/products/catalog/pdf/2400E_04.pdf, read 30 September 2026.
• NTN, Bearing Units, Cat. No. 2400/E, technical data: construction (p. 11), self-aligning (p. 13), part numbering (p. 16), take-up mounting (p. 50), mounting the housing (p. 51), set screw mounting (p. 54), replacing the bearing (p. 60), ntnglobal.com/en/products/catalog/pdf/2400E_03.pdf, read 30 September 2026.
• Timken CAD, UCP 200 Pillow Block, UCF 200 Four-Bolt Flanged, UCFL 200 Two-Bolt Flanged and UCT 200 Take-Up Mounted Bearings, set screw locking (cad.timken.com), read 30 September 2026.

Checked against the NTN Bearing Units catalogue, the Timken CAD pages, the Bearings Express team and our product listings on 30 September 2026.