Double-row series at a 25 mm bore
The same 25 mm bore is available in six double-row series. The cross-section height is (D − d) / 2. A larger section and width carry more load and need more space.
| Model | Series | d | D | B | Section height |
|---|
| 3805 | 3800 | 25 | 37 | 10 | 6 |
| 3905 | 3900 | 25 | 42 | 13 | 8.5 |
| 3005 | 3000 | 25 | 47 | 16 | 11 |
| 3205 | 3200 / 5200 | 25 | 52 | 20.6 | 13.5 |
| 4205 | 4200 | 25 | 52 | 18 | 13.5 |
| 3305 | 3300 / 5300 | 25 | 62 | 25.4 | 18.5 |
How 3800 and 3900 numbers are built
| Number or suffix | Meaning | Example |
|---|
| 30/x | Miniature double-row sizes. The number after the slash is the bore in mm. | 30/7 = 7 × 19 × 10 |
| 3000–3008 | Light double-row series. Smaller OD and narrower than 3200 at the same bore. | 3005 = 25 × 47 × 16 |
| 38xx | Thinner double-row series. | 3805 = 25 × 37 × 10 |
| 39xx | A separate series, thicker than 38xx at the same bore. It is not another name for 3800. | 3905 = 25 × 42 × 13 |
| Bore code | 00 = 10 mm, 01 = 12 mm, 02 = 15 mm, 03 = 17 mm, 04 and up = code × 5 mm | 3810 = 50 × 65 × 12 |
| ZZ or 2Z / 2RS | Metal shields / rubber seals on both sides | 3805ZZ, 3005-2Z, 3805-2RS |
| C3 | Internal clearance larger than normal | 3006-2RS-C3 |
30/x, 3000, 3800 and 3900 size charts
Each row is one size and links to its model page, where load ratings and drawings are given. Dimensions are in millimetres.
30/x miniature series
3000 series
3800 series
3900 series
Dimensions are the same as on each model page. ZZ and 2RS versions are available for these sizes; see each model page.
Selection checks for double-row bearings
- A thin ring takes the shape of its seat. Check shaft and housing roundness, not only diameter.
- The axial clearance or preload is set when the bearing is made. State it as a measured value with the test load.
- A tight fit reduces the clearance more on thin rings. Choose the fits and the clearance together.
- A 3805 has the same bore and OD as a 6805 but is 10 mm wide instead of 7 mm. Check the axial space before you swap them.
Custom miniature double-row bearings
Some designs mount two miniature bearings side by side on one shaft. At higher speed this pair can be replaced by one double-row angular contact bearing: a 30/x size from the table, or a size made to your drawing. Both rows are ground in one pair of rings and the clearance is set at the factory.
Send the two bearings you use now, the shaft and housing size, speed, loads and quantity. We check the space and propose a size before quoting.
Frequently asked questions
What is the difference between 3800 and 3900 bearings?
They are two separate series. At the same bore a 3900 bearing has a larger OD and width, so it carries more load. A 3805 is 25 × 37 × 10 mm; a 3905 is 25 × 42 × 13 mm.
Can a 3805 replace a 6805?
It has the same bore and OD, but it is 10 mm wide instead of 7 mm, and it carries axial load in both directions. It fits only if the housing has the axial space.
What is the smallest double-row bearing you make?
The 30/5 has a 5 mm bore: 5 × 14 × 7 mm. Other miniature double-row sizes can be made to drawing. Send the current bearings and the space available.
Should I choose 2RS or ZZ?
2RS rubber seals keep out more dirt and water. ZZ metal shields run with lower friction. Choose by contamination and speed.
Related pages
