UCFL203 bearing: complete specifications & equivalents
The UCFL203 is a JIS B 1559 radial bearing sized 17 x 40 x 31 mm (bore x OD x width) with 2RS sealing. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 17 mm |
| Outer diameter D | 40 mm |
| Width B | 31 mm |
| Seal / shield | 2RS |
| Basic dynamic load rating C | 14.2 kN |
| Basic static load rating C0 | 6.65 kN |
| Fatigue load limit Pu | 0.505 kN |
| Mass | 500 g |
| Housing height H | 113 mm |
| Housing overall length L | 60 mm |
| Mounting bolt center distance J | 90 mm |
| Mounting hole diameter N | 12 mm |
| Manufacturer designation | UCFL203 |
| Standard | JIS B 1559 |
| Catalog version | CAT. No. 2203-3/E 2024 |
| Last verified | 2026-09-25 |
Source: catalog reference (CAT. No. 2203-3/E 2024) · extracted 2026-09-25
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (CAT. No. 2203-3/E 2024); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & UCFL-series range
| Bore d | 0.669 in |
|---|---|
| Outer diameter D | 1.575 in |
| Width B | 1.22 in |
| ISO bore code | 03 |
| Radial section height (D−d)/2 | 11.5 mm |
| Smallest bore in UCFL-series | 12 mm |
| Largest outer diameter in UCFL-series | 300 mm |
| Width range across UCFL-series | 31–145 mm |
| Bore position in UCFL-series (smallest first) | 3 of 25 |
| Bore above smallest UCFL-series size | 5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| UCFL203 | ISO 15 | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | ISO 15 boundary-dimension envelope; seal suffix convention varies by brand (2RS / DDU / LLU / 2RSR) — verify seal design and temperature range. Brand-specific OEM equivalents pending multi-source data. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the UCFL203 model number is decoded
In NTN's mounted-bearing range, UCFL203 is the two-bolt rhombus flange option for a 17 mm shaft: insert UC203D1, housing FL204, through-bolt mounting. The code breaks down as insert family UC, housing form FL (flange), duty series 2, bore code ending in the 17 mm shaft size; the unit is built from insert UC203D1 and housing FL204. For the frame-face drawing of UCFL203: the two holes are 90 mm apart (J), the rhombus spans 60 mm (L) and 113 mm (H), and M10 (12 mm) bolts clamp it around the 17 mm shaft. The 2-series section is the standard-duty choice — the slimmest, lightest housing at this bore, selected when shaft speed and load are moderate and space is normal. The diamond flange carries the shaft square to a vertical face — a welded frame, side plate or gearbox wall — so no base plinth and no shim pack under the bearing are required. Small-bore mounted units like this are chosen mostly to eliminate bearing-housing design work on OEM machines built in the tens of units rather than for duty-cycle reasons. Sawmill and woodworking machinery mounts this unit on saw arbors and feed rolls, where vibration is continuous and the setscrews must be re-checked after the first hours of running. After the first 24–48 running hours, re-torque both setscrews and the foundation bolts — seating of the inner ring on the shaft and crush of any paint under the feet otherwise leaves the bearing loose at the worst possible time. Basic ratings of the UC203D1 insert are 14.2 kN dynamic and 6.65 kN static; the assembled UCFL203 weighs about 0.5 kg.
Typical equipment & failure modes
Common applications
- appliance and HVAC OEM drives
- food-table and bottle-line rollers
- small fans and blowers
- wet, abrasive or chemically aggressive environments relying on the lip seals and slingers
Known failure patterns
- setscrew loosening and inner-ring fretting on a shaft that was never re-torqued after run-in
- insert brinelling from hammer mounting or from belt tension applied to a stationary unit
- over-greasing that churns the charge, overheats the bearing and blows the seal lip
Selection pitfalls — read before you substitute
- The standard 2-series insert in UCFL203 is the lightest section at 17 mm — do not substitute it into a position that previously ran an X or 3 unit: the 90 mm mounting may match while the load rating does not.
- As a rhombus flange, UCFL203 pulls against the frame through only two M10 bolts on 90 mm centres; the mounting plate must be stiff enough not to bend between them under belt load.
- Self-aligning is not the same as free to move: the UC203D1 insert of UCFL203 pivots to correct static misalignment, but a continuously bending shaft still frets the spherical seat.
- UCFL203 weighs little but its cast feet still crack on an uneven weldment; the 90 mm bolt centres must sit on a flat face, not bridge a weld bead.
Frequently asked questions
What are the dimensions of an UCFL203 mounted bearing?
UCFL203 takes a 17 mm shaft (insert UC203D1, 40 mm OD) and has a unit mass of about 0.5 kg. Flange figures: height H 113 mm, length L 60 mm, bolt centres J 90 mm, holes 12 mm for M10 bolts.
What does the UCFL203 designation mean?
UC identifies the wide-inner-ring, setscrew-locking ball bearing insert; FL the two-bolt rhombus flange housing; 2 is the duty series; the last digits encode the 17 mm bore. UCFL203 is built from housing FL204 plus insert UC203D1 (D1 = greasable).
How is UCFL203 locked to the shaft, and how tight should the setscrews be?
The UC203D1 insert uses two collar setscrews on the 17 mm shaft. Tighten them to NTN's torque table for this bore size in sequence — half torque on the first, full on the second, then back to the first — and re-torque after the first 24–48 running hours once the collar has seated.
When should I choose a rhombus flange unit like UCFL203 instead of a pillow block?
Choose the UCFL203 two-bolt flange when the 17 mm shaft meets a vertical frame or side plate: the diamond housing bolts flush with two M10 bolts on 90 mm centres. A UCP pillow block is used when the shaft runs above a horizontal mounting surface.
Reviewed & verified by the MPN Base engineering desk against source catalog CAT. No. 2203-3/E 2024 on 2026-09-25. Read our editorial & correction policy.