UCFL308 bearing: complete specifications & equivalents
The UCFL308 is a JIS B 1559 radial bearing sized 40 x 90 x 52 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 | 40 mm |
| Outer diameter D | 90 mm |
| Width B | 52 mm |
| Seal / shield | 2RS |
| Basic dynamic load rating C | 45 kN |
| Basic static load rating C0 | 24 kN |
| Fatigue load limit Pu | 1.83 kN |
| Mass | 2200 g |
| Housing height H | 200 mm |
| Housing overall length L | 112 mm |
| Mounting bolt center distance J | 158 mm |
| Mounting hole diameter N | 23 mm |
| Manufacturer designation | UCFL308 |
| 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 | 1.575 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 2.047 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 25 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) | 8 of 25 |
| Bore above smallest UCFL-series size | 28 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| UCFL308 | 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 UCFL308 model number is decoded
In NTN's mounted-bearing range, UCFL308 is the two-bolt rhombus flange option for a 40 mm shaft: insert UC308D1, housing FL308, through-bolt mounting. NTN's numbering ties the unit to its components: UCFL308 means the FL308 housing carrying the UC308D1 insert, with the last two digits denoting the 40 mm bore in the 3-series duty class. The mounting detail needs four numbers: H 200 mm flange height, L 112 mm across the ears, J 158 mm between the 23 mm holes, and a 40 mm shaft through the 90 mm OD UC308D1 insert. 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. Most general industrial shafting in the 25–50 mm range ends up on exactly this class of unit: designers trade the 2, X and 3 sections against conveyor centres and belt tension rather than against absolute capacity. Small marine and dockside conveyors use this unit with stainless fasteners through the feet; the cast iron tolerates salt atmosphere far better than pressed-steel housings once paint is chipped. In wet or washdown positions, orient the grease fitting at 45° and purge after every wash; water trapped between the slinger and lip seal emulsifies the grease even when the unit is sealed. Basic ratings of the UC308D1 insert are 45 kN dynamic and 24 kN static; the assembled UCFL308 weighs about 2.2 kg.
Typical equipment & failure modes
Common applications
- agricultural augers and bucket elevators
- small crushers and screening feeds
- textile line-shafting
- elevated-temperature positions where grease life, not bearing rating, sets the interval
Known failure patterns
- over-greasing that churns the charge, overheats the bearing and blows the seal lip
- cracked cast ear from mounting on an uneven face and pulling one bolt fully first
- housing-foot cracking beside an over-torqued or under-supported foundation bolt
Selection pitfalls — read before you substitute
- Never weld a bracket to the FL308 housing of UCFL308: local heat cracks cast iron and distorts the spherical bore that the insert depends on.
- With a 40 mm shaft the M20 foundation bolts of UCFL308 must be re-checked after run-in — paint crush under the feet is enough to loosen both the feet and the setscrews.
- The 3-series insert makes UCFL308 the highest-rated unit at 40 mm; its advantage disappears on a soft foundation, so spend the saved margin on base stiffness rather than skipping shims.
- As a rhombus flange, UCFL308 pulls against the frame through only two M20 bolts on 158 mm centres; the mounting plate must be stiff enough not to bend between them under belt load.
Frequently asked questions
How is UCFL308 locked to the shaft, and how tight should the setscrews be?
The UC308D1 insert uses two collar setscrews on the 40 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 UCFL308 instead of a pillow block?
Choose the UCFL308 two-bolt flange when the 40 mm shaft meets a vertical frame or side plate: the diamond housing bolts flush with two M20 bolts on 158 mm centres. A UCP pillow block is used when the shaft runs above a horizontal mounting surface.
What are the dimensions of an UCFL308 mounted bearing?
UCFL308 takes a 40 mm shaft (insert UC308D1, 90 mm OD) and has a unit mass of about 2.2 kg. Flange figures: height H 200 mm, length L 112 mm, bolt centres J 158 mm, holes 23 mm for M20 bolts.
What does the UCFL308 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 40 mm bore. UCFL308 is built from housing FL308 plus insert UC308D1 (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.