UCP204 bearing: complete specifications & equivalents
The UCP204 is a JIS B 1559 radial bearing sized 20 x 47 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 | 20 mm |
| Outer diameter D | 47 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 | 700 g |
| Housing height H | 33.3 mm |
| Housing overall length L | 127 mm |
| Mounting bolt center distance J | 95 mm |
| Mounting hole diameter N | 13 mm |
| Manufacturer designation | UCP204 |
| 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 | 0.787 in |
|---|---|
| Outer diameter D | 1.85 in |
| Width B | 1.22 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 13.5 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) | 4 of 25 |
| Bore above smallest UCP-series size | 8 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| UCP204 | 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 UCP204 model number is decoded
UCP204 belongs to NTN's UCP line of cast-iron pillow blocks built to JIS B 1559 housing boundary dimensions around a JIS B 1558 UC204D1 insert. The code breaks down as insert family UC, housing form P (pillow block), duty series 2, bore code ending in the 20 mm shaft size; the unit is built from insert UC204D1 and housing P204. For layout work on UCP204: the 20 mm shaft centre sits 33.3 mm above the sole (H), the footprint is 127 mm long (L), bolt centres are 95 mm (J), and the foot holes suit M10 (13 mm) bolts. 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 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. At 12–20 mm bore these are the light-drive units: small conveyors, packaging machines and appliance-grade equipment, where the cast housing is over-engineered relative to the load but forgiving of imperfect mounts. Belt-conveyor builders fit this unit at the drive and tail pulleys: the spherical seat absorbs the small angular errors of a welded truss, and the setscrew lock keeps the inner ring stationary on a shaft that reverses every time the belt is run back. Torque the two setscrews in sequence: run the first to half value, the second to full value, then come back to the first; NTN’s recommended setscrew torque rises sharply with shaft size, so use the table for this bore rather than a wrench feel inherited from smaller units. Basic ratings of the UC204D1 insert are 14.2 kN dynamic and 6.65 kN static; the assembled UCP204 weighs about 0.7 kg.
Typical equipment & failure modes
Common applications
- small fans and blowers
- light agricultural augers
- light belt and roller conveyors
- continuous one-direction running where creep risk concentrates on the setscrew points
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
- Never weld a bracket to the P204 housing of UCP204: local heat cracks cast iron and distorts the spherical bore that the insert depends on.
- At 20 mm bore the unit is cheap but the shaft is slender: a bent or undersized shaft, not the bearing, is the usual failure cause for UCP204, so check journal straightness before fitting.
- The standard 2-series insert in UCP204 is the lightest section at 20 mm — do not substitute it into a position that previously ran an X or 3 unit: the 95 mm mounting may match while the load rating does not.
- As a pillow block, UCP204 needs a prepared horizontal surface at the 33.3 mm centre height: shim both feet with full-width packs so the 127 mm base seats over its full area.
Frequently asked questions
How is UCP204 locked to the shaft, and how tight should the setscrews be?
The UC204D1 insert uses two collar setscrews on the 20 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 UCP204 instead of a flanged unit?
Choose the UCP204 pillow block when the shaft runs parallel to a horizontal base plate, rail or plinth — the upright housing holds the shaft centre 33.3 mm above the 127 mm bolt-down base. Choose a UCFL flange when the shaft meets a vertical frame face and the housing bolts flat against it.
What are the dimensions of an UCP204 mounted bearing?
UCP204 takes a 20 mm shaft (insert UC204D1, 47 mm OD) and has a unit mass of about 0.7 kg. Housing figures: centre height H 33.3 mm, length L 127 mm, bolt centres J 95 mm, foot holes 13 mm for M10 bolts.
What does the UCP204 designation mean?
UC identifies the wide-inner-ring, setscrew-locking ball bearing insert; P the upright pillow block housing; 2 is the duty series; the last digits encode the 20 mm bore. UCP204 is built from housing P204 plus insert UC204D1 (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.