UCFL309 bearing: complete specifications & equivalents
The UCFL309 is a JIS B 1559 radial bearing sized 45 x 100 x 57 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 | 45 mm |
| Outer diameter D | 100 mm |
| Width B | 57 mm |
| Seal / shield | 2RS |
| Basic dynamic load rating C | 58.5 kN |
| Basic static load rating C0 | 32 kN |
| Fatigue load limit Pu | 2.5 kN |
| Mass | 3000 g |
| Housing height H | 230 mm |
| Housing overall length L | 125 mm |
| Mounting bolt center distance J | 177 mm |
| Mounting hole diameter N | 25 mm |
| Manufacturer designation | UCFL309 |
| 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 | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 2.244 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 27.5 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) | 9 of 25 |
| Bore above smallest UCFL-series size | 33 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| UCFL309 | 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 UCFL309 model number is decoded
NTN delivers UCFL309 as a matched unit — the UC309D1 insert is locked into the FL309 rhombus cast-iron flange at the factory and arrives greased and sealed. On the nameplate, UCFL309 decodes as a UC wide-inner-ring insert in a FL diamond flange, 3-series duty, 45 mm bore; the UC309D1 designation shows the D1 greasable execution. Boundary data for the 45 mm bore: 230 mm high flange, 125 mm long over the rhombus, 177 mm hole centres for M22 fasteners through 25 mm holes; insert OD is 100 mm. The 3-series section is the heavy-duty end of the range: a UC3 high-capacity insert in the longest, strongest housing, specified for shock loads and long conveyor centres. 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. The 25–50 mm bore band is the workhorse of industry — belt conveyors, fans, agricultural drives and small process machines — which is why this range has the fullest choice of series and cover options. 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 UC309D1 insert are 58.5 kN dynamic and 32 kN static; the assembled UCFL309 weighs about 3.0 kg.
Typical equipment & failure modes
Common applications
- small crushers and screening feeds
- textile line-shafting
- machine-tool chip conveyors
- washdown-duty food and pharmaceutical areas using purge relubrication
Known failure patterns
- water-emulsified grease after washdown with the fitting facing upward
- 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
Selection pitfalls — read before you substitute
- At replacement time, measure the 45 mm shaft journal — a worn or deeply indented journal under the setscrews will let a brand-new UCFL309 creep identically to the old one.
- UCFL309 is located on the shaft by setscrews only; for shock reversing drives consider an adapter-lock insert family instead, since setscrew points indent the 45 mm journal over time.
- In this bore band the temptation is to choose UCFL309 on shaft size alone; belt pull often dominates the radial load, so rate the unit against the overhung pulley force, not just transmitted power.
- The 3-series insert makes UCFL309 the highest-rated unit at 45 mm; its advantage disappears on a soft foundation, so spend the saved margin on base stiffness rather than skipping shims.
- As a rhombus flange, UCFL309 pulls against the frame through only two M22 bolts on 177 mm centres; the mounting plate must be stiff enough not to bend between them under belt load.
Frequently asked questions
How is UCFL309 locked to the shaft, and how tight should the setscrews be?
The UC309D1 insert uses two collar setscrews on the 45 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 UCFL309 instead of a pillow block?
Choose the UCFL309 two-bolt flange when the 45 mm shaft meets a vertical frame or side plate: the diamond housing bolts flush with two M22 bolts on 177 mm centres. A UCP pillow block is used when the shaft runs above a horizontal mounting surface.
Can I replace just the insert inside an UCFL309 unit?
Yes — UCFL309 is an assembly of the FL309 housing and UC309D1 insert, and the insert can be ordered separately if the spherical seat and feet are undamaged. Clean the seat, coat it with anti-seize, and confirm the setscrew indentations on the 45 mm shaft are not the reason the old insert failed.
What are the dimensions of an UCFL309 mounted bearing?
UCFL309 takes a 45 mm shaft (insert UC309D1, 100 mm OD) and has a unit mass of about 3.0 kg. Flange figures: height H 230 mm, length L 125 mm, bolt centres J 177 mm, holes 25 mm for M22 bolts.
What does the UCFL309 designation mean?
UC identifies the wide-inner-ring, setscrew-locking ball bearing insert; FL the two-bolt rhombus flange housing; 3 is the duty series; the last digits encode the 45 mm bore. UCFL309 is built from housing FL309 plus insert UC309D1 (D1 = greasable).
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.