21311 Bearing Dimensions
21311 spherical roller bearing: bore 55 mm, dimensions 55x120x29 mm (FULI catalog). Designation breakdown, bore options and size-equivalent codes.
21311 specifications
| Bore d | 55 mm |
|---|---|
| Outside diameter D | 120 mm |
| Width B | 29 mm |
| Seal / shield options | Open |
| Material | GCr15 chrome bearing steel (rings and rolling elements) |
| Precision | P0 (standard); P6 on request |
| Radial clearance | C0 (standard); C3 on request |
Load ratings & speed
| Dynamic load rating Cr | 158 kN |
|---|---|
| Static load rating C0r | 166 kN |
| Speed ratings | 5,600 / 7,500 rpm — two catalogue speed columns; lubrication basis not stated |
| Weight | 1.70 kg — approx. |
Values from FULI's catalog; confirm for your application.
Nearby 21300 series sizes: 21308 bearing · 21312 bearing
Grease quantity for 21311: bearing grease fill calculator.
Buying 21311 in quantity? See bearing wholesale supplier for pricing by quantity and shipping, and bearing manufacturer in China for how to check the factory.
How to read the 21311 designation
| Segment | Meaning |
|---|---|
| 2 | Spherical roller bearing (double row, self-aligning) |
| 13 | Dimension series 13 |
| 11 | Bore code 11 → 55 mm bore. ISO bore code (00–03 = 10/12/15/17 mm; 04 and above = code × 5 mm). |
21311 interchange
21311 is an ISO designation: bore d, outside diameter D and width B are the same at each maker. The letters each maker adds are design and cage codes, not seal codes; K marks a tapered bore, and each maker marks the oil groove and holes in its own way. Send us the full number on your old bearing and we confirm the match.
Brand names are trademarks of their respective owners. FULI is not affiliated with, authorized by or endorsed by these companies. Part numbers are shown for interchange reference only. FULI dimensions, load ratings and speeds come from the FULI catalog.
Tolerances and fits for 21311
FULI makes 21311 to P0 as standard, with P6 on request. P0 is the Normal tolerance class of ISO 492; P6 limits are tighter. These are the P0 limits for the 55 × 120 × 29 mm size.
| Dimension | Nominal, mm | Deviation, µm | Limits, mm |
|---|---|---|---|
| Bore d (Δdmp) | 55 | 0 / −15 | 55.000 / 54.985 |
| Outside diameter D (ΔDmp) | 120 | 0 / −15 | 120.000 / 119.985 |
| Width B (ΔBs) | 29 | 0 / −150 | 29.000 / 28.850 |
Δdmp and ΔDmp: deviation of the mean bore and mean outside diameter in one radial plane. ΔBs: inner ring width; the outer ring width has the same limits.
Shaft and housing fits (general guidance)
For an inner ring that turns with a solid steel shaft under normal load, bearing makers’ fit tables give 55 m5 for the shaft of 21311. The housing bore is usually H7, or J7 where the outer ring must not creep.
| Seat | Deviation, µm | Limits, mm | Fit with 21311 |
|---|---|---|---|
| Shaft 55 m5 | +24 / +11 | 55.024 / 55.011 | 11 to 39 µm interference |
| Housing 120 H7 | +35 / 0 | 120.035 / 120.000 | 0 to 50 µm clearance |
| Housing 120 J7 | +22 / −13 | 120.022 / 119.987 | 13 µm interference to 37 µm clearance |
Taking the loosest and the tightest combination of limits, a P0 21311 on a 55 mm m5 shaft has 11 to 39 µm interference. Its outer ring has 0 to 50 µm clearance in an H7 bore and 13 µm interference to 37 µm clearance in a J7 bore.
This is general guidance, not a FULI specification. Heavy or shock loads, a hollow shaft, a thin-walled, split or light-alloy housing, or a large temperature difference between shaft and housing call for other classes, and the drawing of your machine takes priority. A tight shaft fit or a hot housing uses up internal clearance, and that is when C3 is chosen instead of C0.
If the outer ring turns and the shaft stands still, as in an idler pulley or a wheel hub, the fits are reversed: the housing gets the interference fit (for example N7 or P7) and the shaft a sliding one (g6 or h6).
Sources: ISO 492 tables as printed in the NTN catalogue CAT. No. 2203/E (Tables 6.4 and 6.5) and the RKB tolerance catalogue; ISO 286-2 for the seats; SKF and NTN fit tables for the shaft and housing classes.
21311 compared with nearby sizes
21311 measures 55 × 120 × 29 mm: bore d, outside diameter D and width B. Other spherical roller bearings on this site for the same 55 mm shaft are 22211 (55 × 100 × 25 mm) and 22311 (55 × 120 × 43 mm).
22311 is the next heavier choice for a 55 mm shaft, with the same 120 mm outside diameter and 14 mm more width (43 mm). In FULI's catalog 22311 has a dynamic load rating of 270 kN against 158 kN and a weight of about 2.45 kg against 1.70 kg for 21311.
22211 is the lighter option on the same shaft, with an outside diameter 20 mm smaller (100 mm) and 4 mm less width (25 mm), for housings with less room. In FULI's catalog 22211 has a dynamic load rating of 125 kN against 158 kN and a weight of about 0.84 kg against 1.70 kg for 21311.
22213 has the same 120 mm outside diameter with a 65 mm bore, so it fits the same housing bore on a larger shaft.
In the 213 series the sizes either side of 21311 are 21308 for a 40 mm shaft and 21312 for a 60 mm shaft.
| Model | Compared with this page | d × D × B (mm) | Cr (kN) | Weight (kg) |
|---|---|---|---|---|
| 21311 | This page | 55 × 120 × 29 | 158 | 1.70 |
| 21308 | Next size down | 40 × 90 × 23 | 104 | 0.75 |
| 21312 | Next size up | 60 × 130 × 31 | 212 | 2.10 |
| 22211 | Same bore | 55 × 100 × 25 | 125 | 0.84 |
| 22311 | Same bore | 55 × 120 × 43 | 270 | 2.45 |
| 22213 | Same outside diameter | 65 × 120 × 31 | — | 1.55 |
Cr and weight from FULI's catalog; — = not listed on this site.
21311 weight, load ratings and speed
FULI's catalog gives the weight of 21311 as about 1.70 kg, so 100 bearings weigh about 170 kg and 1,000 about 1700 kg before packing. The cylindrical bore (W33) and tapered bore (K/W33) versions share this catalog line.
21311 has a dynamic load rating Cr of 158 kN and a static load rating C0r of 166 kN. Cr is the load used to work out rating life; C0r is the reference for loads carried while the bearing is stationary or turning slowly. The catalog lists two speed values, 5,600 and 7,500 rpm, without stating the lubrication for each column.
Values from FULI's catalog; confirm for your application.
21311 bore and clearance versions
FULI's catalog lists 21311 in two bore versions on one line, both 55 × 120 × 29 mm: 21311W33 with a cylindrical bore and 21311K/W33 with a 1:12 tapered bore. W33 marks the lubrication groove and holes in the outer ring. The K version is mounted on an adapter sleeve, a withdrawal sleeve or a tapered shaft seat. Radial clearance is C0 as standard and C3 on request.
| Designation | What it is |
|---|---|
| 21311W33 | Cylindrical 55 mm bore, lubrication groove and holes, C0 clearance |
| 21311K/W33 | Tapered bore 1:12 for sleeve mounting, lubrication groove and holes |
| 21311W33 C3 | Cylindrical bore with C3 radial clearance |
| 21311K/W33 C3 | Tapered bore with C3 radial clearance |
21311 dimensions in inches
The nearest common inch shaft size to the 55 mm bore of 21311 is 2-3/16 in (55.56 mm), 0.56 mm larger than the bore, so 21311 will not go on it. Inch shafts need an inch bearing, not a metric one with a sleeve or shim.
| Dimension | Millimetres | Inches |
|---|---|---|
| Bore d | 55 mm | 2.1654 in |
| Outside diameter D | 120 mm | 4.7244 in |
| Width B | 29 mm | 1.1417 in |
Converted at 1 in = 25.4 mm and rounded to four decimals. The bearing itself is made to the millimetre sizes.
Grease for 21311
Relubricating 21311 from the side takes about 17.4 g each time by the formula in our grease calculator: 0.005 × D × B = 0.005 × 120 × 29. 21311W33 has a lubrication groove and holes in the outer ring; when grease goes in through them the formula is 0.002 × D × B, about 6.96 g for 21311.
How FULI supplies 21311
The standard 21311 from FULI has GCr15 chrome steel rings and rollers, P0 precision and C0 radial clearance, with P6 and C3 on request.
Rings are marked with a brand you are authorised to use, with the FULI brand, or left neutral, as your order states. The box is printed with the model, precision class and brand.
Inquiries that leave out the prefix or suffix letters are the usual cause of a wrong quote, so write the full designation, for example 21311K/W33 C3.
Tools and guides for 21311
Typical applications
- Crushers and vibrating screens
- Conveyor drums
- Fans and blowers
- Gearboxes
- Paper and textile machinery
FAQ
What is the difference between 21311 and 22311?
Both fit a 55 mm shaft. 21311 is 55 × 120 × 29 mm and 22311 is 55 × 120 × 43 mm, so 22311 has the same 120 mm outside diameter and 14 mm more width (43 mm). In FULI's catalog 22311 has a dynamic load rating of 270 kN against 158 kN and a weight of about 2.45 kg against 1.70 kg for 21311. Choose 22311 for a higher load where the housing has room for it; 21311 keeps the housing smaller.
What is the difference between 21311 and 22211?
Both fit a 55 mm shaft. 21311 is 55 × 120 × 29 mm and 22211 is 55 × 100 × 25 mm, so 22211 has an outside diameter 20 mm smaller (100 mm) and 4 mm less width (25 mm). In FULI's catalog 22211 has a dynamic load rating of 125 kN against 158 kN and a weight of about 0.84 kg against 1.70 kg for 21311. 22211 suits a housing with less room; 21311 carries more load.
What size is 21311 in inches?
21311 is 2.1654 × 4.7244 × 1.1417 in (55 × 120 × 29 mm, d × D × B). The nearest common inch shaft size to the 55 mm bore of 21311 is 2-3/16 in (55.56 mm), 0.56 mm larger than the bore, so 21311 will not go on it. Use an inch bearing on an inch shaft.
How much does 21311 weigh?
About 1.70 kg in FULI's catalog, so 100 pieces weigh about 170 kg before packing. The cylindrical bore (W33) and tapered bore (K/W33) versions share this catalog line.
How much grease does 21311 need?
About 17.4 g each time it is relubricated from the side (0.005 × 120 × 29).
Is 21311 the same size across brands?
Bore d, outside diameter D and width B are the same: 21311 is an ISO designation. The letters each maker adds (SKF E or CC, NSK CE4, EAE4 or CDE4, NTN EAD1, Koyo RZ, NACHI EX or E, FAG E1-XL) are design and cage codes, not seal codes. K marks a tapered bore, and the oil groove and holes are marked differently by each maker (SKF W33, NSK E4, NTN D1).