# Cylindrical roller bearing

## Geometry

Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm. Bore d, outside diameter D, width B, chamfer r and the raceway diameters Fw (inner) and Ew (outer) are sourced and make the fit. detail = "full": a plain inner ring, an outer ring with a rib at each end, and the rollers between them, whose diameter follows from (Ew - Fw) / 2. Rib height, roller length and roller count are proportions for looks, not for design, and never change the fit dimensions; the cage is not drawn. detail = "simple": one solid ring. Axis along Z, centred on the origin.

**For the fit:** the sourced dimensions below. **For looks only, not for design:** every other proportion named above.

## Source

NTN, *Ball and Roller Bearings*, CAT. No. 2203-3/E (2024), <https://www.ntnglobal.com/en/products/catalog/pdf/2203E.pdf>, pp. B-71 to B-72 (PDF pages 147 and 148). ISO 15 sets the boundary dimensions of these series.

| Number | d | D | B |
|---|---|---|---|
| NU204 | 20 | 47 | 14 |
| NU205 | 25 | 52 | 15 |
| NU206 | 30 | 62 | 16 |
| NU207 | 35 | 72 | 17 |
| NU208 | 40 | 80 | 18 |
| NU209 | 45 | 85 | 19 |
| NU210 | 50 | 90 | 20 |
| NU304 | 20 | 52 | 15 |
| NU305 | 25 | 62 | 17 |
| NU306 | 30 | 72 | 19 |
| NU307 | 35 | 80 | 21 |
| NU308 | 40 | 90 | 23 |
| NU309 | 45 | 100 | 25 |
| NU310 | 50 | 110 | 27 |

Maker names identify the source; this part isn't made by or affiliated with any maker.

Raceway diameters Fw and Ew and chamfers r are in `part.py` (`BEARINGS`), from the same tables; the ISO 492 normal class is from Table 6.4, pp. A-58 to A-59.