UCP309 bearing: complete specifications & equivalents
The UCP309 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 | 4100 g |
| Housing height H | 67 mm |
| Housing overall length L | 245 mm |
| Mounting bolt center distance J | 190 mm |
| Mounting hole diameter N | 20 mm |
| Manufacturer designation | UCP309 |
| 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 & UCP-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 UCP-series | 12 mm |
| Largest outer diameter in UCP-series | 300 mm |
| Width range across UCP-series | 31–145 mm |
| Bore position in UCP-series (smallest first) | 9 of 25 |
| Bore above smallest UCP-series size | 33 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| UCP309 | 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 UCP309 model number is decoded
UCP309 belongs to NTN's UCP line of cast-iron pillow blocks built to JIS B 1559 housing boundary dimensions around a JIS B 1558 UC309D1 insert. NTN's numbering ties the unit to its components: UCP309 means the P309 housing carrying the UC309D1 insert, with the last two digits denoting the 45 mm bore in the 3-series duty class. The foundation drawing needs four numbers: H 67 mm centre height, L 245 mm total length, J 190 mm between the 20 mm bolt holes, and a 45 mm shaft passing through the 100 mm OD 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 upright base carries the shaft parallel to and above the mounting surface, which is the arrangement fan, conveyor and transmission drives use whenever a plinth or rail is available. This mid bore range dominates agricultural and bulk-handling builds, where standard shafts, cast feet and greasable inserts keep replacement a stock-room, not a workshop, exercise. Food and packaging lines choose this unit when the layout allows an external mount: it lives outside the washdown zone, sealed and greased for life intervals that outlast a production campaign. Use grade 8.8 foundation bolts with flat washers under both head and nut, and pull them in stages in a cross pattern; the cast feet are strong in compression but a single over-torqued bolt can crack an ear. Basic ratings of the UC309D1 insert are 58.5 kN dynamic and 32 kN static; the assembled UCP309 weighs about 4.1 kg.
Typical equipment & failure modes
Common applications
- textile line-shafting
- machine-tool chip conveyors
- belt conveyor head, tail and bend pulleys
- frequent stop-start and reversing duty such as shuttle and tripper conveyors
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
- The 3-series insert makes UCP309 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 pillow block, UCP309 needs a prepared horizontal surface at the 67 mm centre height: shim both feet with full-width packs so the 245 mm base seats over its full area.
- When ordering covers for UCP309, note the steel and cast-iron cover executions change the unit mass and envelope but not the 190 mm mounting centres.
- The standard section of UCP309 can look adequate at 45 mm while the X or 3 section is the real choice for long conveyor centres; compare ratings rather than fitting the same unit line-wide.
Frequently asked questions
What are the dimensions of an UCP309 mounted bearing?
UCP309 takes a 45 mm shaft (insert UC309D1, 100 mm OD) and has a unit mass of about 4.1 kg. Housing figures: centre height H 67 mm, length L 245 mm, bolt centres J 190 mm, foot holes 20 mm for M16 bolts.
What does the UCP309 designation mean?
UC identifies the wide-inner-ring, setscrew-locking ball bearing insert; P the upright pillow block housing; 3 is the duty series; the last digits encode the 45 mm bore. UCP309 is built from housing P309 plus insert UC309D1 (D1 = greasable).
How is UCP309 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 pillow block like UCP309 instead of a flanged unit?
Choose the UCP309 pillow block when the shaft runs parallel to a horizontal base plate, rail or plinth — the upright housing holds the shaft centre 67 mm above the 245 mm bolt-down base. Choose a UCFL flange when the shaft meets a vertical frame face and the housing bolts flat against it.
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.