61900 Series Bearings
The thin series: thinner than a 6000 at the same bore, but with enough ring section to take a real radial load. It is the middle answer between an ultra-thin 61800 that may be too weak and a 6000 that may not fit.
Thin serieswhere it sits and what it trades away
The 61900 series sits one step in from the ultra-thin 61800 series, and that step is worth understanding because it is the one people actually weigh. At a 25 mm bore a 61905 is 42 mm across and 9 mm wide; the 61805 is 37 × 7 and the 6005 is 47 × 12. So the 61900 gives up 5 mm of outside diameter to the 61800 and takes 5 mm off the 6000 — and the ring section it gains over the 61800 is what turns a bearing that merely locates a shaft back into one that can carry a load.
That is the whole argument for the series. Where a 61800 is chosen by space and accepts a low rating, and a 6000 is chosen as the default with capacity to spare, the 61900 is chosen when the housing is tight but the bearing still has to do work: small gearmotors, pumps, fans — the everyday case of a shaft that is thin because the machine is small, turning in a housing that is tight because the machine is small too.
The series runs from 61900 (10 mm bore, 22 mm outside diameter, 6 mm wide) to 61920 (100 mm bore, 140 mm outside diameter, 20 mm wide) in the 21 designations tabulated here. The progression is regular: the radial section grows from 6 mm at the 10 mm bore to 20 mm at the 100 mm bore, staying narrower than the equivalent 6000 at every bore in between.
Every designation in the table below links to its own page with the ISO 15 dimensions, the bore-code arithmetic, the ISO 5753-1 clearance ranges for its bore, and the same-bore comparison against the other four series.
All 21 designationsISO 15 boundary dimensions, mm
| Designation | Bore code | d | D | B | r s min | Section (D − d)/2 |
|---|---|---|---|---|---|---|
| 61900 | 00 | 10 | 22 | 6 | 0.3 | 6 |
| 61901 | 01 | 12 | 24 | 6 | 0.3 | 6 |
| 61902 | 02 | 15 | 28 | 7 | 0.3 | 6.5 |
| 61903 | 03 | 17 | 30 | 7 | 0.3 | 6.5 |
| 61904 | 04 | 20 | 37 | 9 | 0.3 | 8.5 |
| 61905 | 05 | 25 | 42 | 9 | 0.3 | 8.5 |
| 61906 | 06 | 30 | 47 | 9 | 0.3 | 8.5 |
| 61907 | 07 | 35 | 55 | 10 | 0.6 | 10 |
| 61908 | 08 | 40 | 62 | 12 | 0.6 | 11 |
| 61909 | 09 | 45 | 68 | 12 | 0.6 | 11.5 |
| 61910 | 10 | 50 | 72 | 12 | 0.6 | 11 |
| 61911 | 11 | 55 | 80 | 13 | 1 | 12.5 |
| 61912 | 12 | 60 | 85 | 13 | 1 | 12.5 |
| 61913 | 13 | 65 | 90 | 13 | 1 | 12.5 |
| 61914 | 14 | 70 | 100 | 16 | 1 | 15 |
| 61915 | 15 | 75 | 105 | 16 | 1 | 15 |
| 61916 | 16 | 80 | 110 | 16 | 1 | 15 |
| 61917 | 17 | 85 | 120 | 18 | 1.1 | 17.5 |
| 61918 | 18 | 90 | 125 | 18 | 1.1 | 17.5 |
| 61919 | 19 | 95 | 130 | 18 | 1.1 | 17.5 |
| 61920 | 20 | 100 | 140 | 20 | 1.1 | 20 |
d = bore, D = outside diameter, B = width, r s min = minimum single chamfer dimension. All four are ISO 15 standard values and are the same for every manufacturer. The last column is derived: radial section = (D − d) / 2, the wall thickness you are working with when you size the housing. No load rating and no limiting speed appears here — see the bearings index for why.
Every series at one boresame shaft, different housing
| Series | Type | 10 mm bore | 12 mm bore | 15 mm bore | 17 mm bore | 20 mm bore |
|---|---|---|---|---|---|---|
| 61800 Series | Ultra-thin | 19 × 5 | 21 × 5 | 24 × 5 | 26 × 5 | 32 × 7 |
| 61900 Series | Thin | 22 × 6 | 24 × 6 | 28 × 7 | 30 × 7 | 37 × 9 |
| 6000 Series | Extra-light | 26 × 8 | 28 × 8 | 32 × 9 | 35 × 10 | 42 × 12 |
| 6200 Series | Light | 30 × 9 | 32 × 10 | 35 × 11 | 40 × 12 | 47 × 14 |
| 6300 Series | Medium | 35 × 11 | 37 × 12 | 42 × 13 | 47 × 14 | 52 × 15 |
Outside diameter × width in millimetres, for the five smallest bores in this batch. The full chart across all 21 bores and all 5 series is on the bearings index. Reading a row is what a machine designer does when the shaft is already fixed: the bore does not change, the housing bore does.
Frequently asked questionsreading a bearing designation
What is the difference between the 61900 and 6000 series?
Both are thin, and the 61900 is the thinner of the two. On a 25 mm bore a 61905 is 42 mm across and 9 mm wide, against 47 × 12 for a 6005. The 61900 saves 5 mm of housing bore; the 6000 carries more load.
Is the 61900 series the same as the 6900 series?
Yes — the same series under two naming conventions. 61900 is the SKF / FAG form and 6900 the NSK form, and a 6914 and a 61914 are the same bearing: 70 mm bore, 100 mm outside diameter, 16 mm wide.
When should I use a thin section bearing?
When the envelope is fixed and nothing else will fit. A thin-section bearing trades load capacity for outside diameter, so it is the right answer when the housing cannot grow — and the wrong answer when it can, because a larger series then costs nothing but the housing bore and carries more load.