UC204 Bearing — Cross-Reference & Equivalents
The UC204 is an insert (mounted) ball bearing with ISO 9628 boundary dimensions 20×47×31 mm. The table below lists how 8 major brands designate it, with catalog links and interchange notes.
Replacing a UC204? The cross-reference table below gives the equivalent part number for every major brand — but read the interchange rules first: an identical size is not always a safe swap.
Specifications
| Bore (d) | 20 mm |
|---|---|
| Outer Diameter (D) | 47 mm |
| Total Width (B) | 31 mm |
| Type | Insert (Mounted) Ball Bearing |
| Standard | ISO 9628 |
Cross-Reference by Brand
| Brand | Part No. | Boundary dims | Catalog |
|---|---|---|---|
| SKF | UC204 | match | SKF catalog ↗ |
| NSK | UC204 | match | NSK catalog ↗ |
| FAG | UC204 | match | FAG catalog ↗ |
| NTN | UC204 | match | NTN catalog ↗ |
| KOYO | UC204 | match | KOYO catalog ↗ |
| NACHI | UC204 | match | NACHI catalog ↗ |
| Timken | UC204 | match | Timken catalog ↗ |
| INA | UC204 | match | INA catalog ↗ |
Interchange notes
All brands build this designation to the same boundary dimensions (bore d, spherical outer diameter D, total width B), so the bearing itself is interchangeable. But an insert (mounted) ball bearing is used differently: (1) It has a convex SPHERICAL outer surface that self-aligns inside a housing (pillow block P, flange F, take-up T) — it is NOT a drop-in for a standard deep groove bearing of the same bore, and the value is usually the complete unit (e.g. UCP204 = UC204 insert + P204 housing). (2) Shaft locking differs and is NOT interchangeable: UC = set screws, UEL = eccentric collar, UK = adapter sleeve on a tapered bore. (3) Bore may be metric (UC204 = 20 mm) OR inch (UC204-12 = 3/4") — do not confuse them. (4) Designation differs by brand for the same size: most makers use UC, SKF uses YAR, Schaeffler (FAG/INA) uses GYE/RALE. Match seal and set-screw/collar type. Load ratings (dynamic Cr, static C0r) are intentionally NOT listed here: they vary by brand and internal design and are a safety-critical selection parameter — read them directly from the manufacturer catalog linked in the table above.
Where to buy a UC204
Compare current listings and prices for the UC204 across brands and sellers:
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FAQ
What bearings are equivalent to a UC204?
The UC204 is built to ISO 9628 boundary dimensions 20×47×31 mm by SKF, NSK, FAG, NTN, KOYO, NACHI, Timken, INA. All share the same mounting envelope; match clearance, precision class and (where applicable) seal suffix before substituting.
What are the dimensions of a UC204 bearing?
Bore 20 mm, outer diameter 47 mm, B 31 mm (ISO 9628).
Is the UC204 the same as a UCP204 pillow block?
The UC204 is the insert bearing itself (20×47×31 mm, spherical OD). A UCP204 is that same insert already fitted into a P-type pillow-block housing; UCF204 is in a flange housing. The insert is common across brands (SKF calls it YAR, Schaeffler GYE), but check the shaft locking (set screw vs eccentric collar vs adapter sleeve) and whether the bore is metric or inch.
Related sizes
Boundary-dimension cross-reference only. Per the applicable ISO standard (ISO 15 for ball, ISO 355 for tapered), the boundary dimensions are common across brands, so the mounting envelope is interchangeable. This is NOT a drop-in part equivalence. Internal clearance, precision class, seal/shield type (where applicable), cage material and factory lubrication are encoded in brand-specific suffixes and must be matched separately. Always verify against the manufacturer's catalog before substituting.