21310 bearing: complete specifications & equivalents
The 21310 is a ISO 15 radial bearing sized 50 x 110 x 27 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 50 mm |
| Outer diameter D | 110 mm |
| Width B | 27 mm |
| Seal / shield | open |
| Internal clearance | CN / C3 / C4 available |
| Tolerance class | P0 |
| Cage | steel |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 1039 g |
| Standard | ISO 15 |
| Catalog version | iso15-srb-geometry |
| Last verified | 2026-09-24 |
Source: ISO 15 boundary-dimensions standard · extracted 2026-09-24
Standard-interchange bearing: dimensions per ISO 15; CN clearance, P0 tolerance and a stamped-steel cage are catalogue defaults unless the supplier states otherwise, and mass is a geometry-derived estimate. Brand catalogue load ratings and limiting speeds for 21310 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 21300-series range
| Bore d | 1.969 in |
|---|---|
| Outer diameter D | 4.331 in |
| Width B | 1.063 in |
| ISO bore code | 10 |
| Radial section height (D−d)/2 | 30 mm |
| Smallest bore in 21300-series | 50 mm |
| Largest outer diameter in 21300-series | 240 mm |
| Width range across 21300-series | 27–50 mm |
| Bore position in 21300-series (smallest first) | 1 of 12 |
| Bore above smallest 21300-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21310 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 21310 model number is decoded
In the 21300-series (ISO 15 dimension series) the leading 2 marks a double-row spherical roller and the last two digits of 21310 encode the bore: code 10 = 50 mm (code × 5 from 04 upward). The ISO 15 envelope is 110 mm outside diameter and 27 mm width — 1.969 × 4.331 × 1.063 in, with a 30.0 mm radial section height. Two rows of symmetrical barrel rollers on a common sphered outer raceway self-align to shaft deflection while carrying heavy radial load and bidirectional axial load. Typical catalogue practice for a rotating inner ring is a k5 shaft seat, H7 housing and C3 internal clearance; K variants use a 1:12 tapered bore on an adapter sleeve — verify against the mounting arrangement.
Typical equipment & failure modes
Common applications
- paper machine felt and press rolls
- industrial gearbox and drive shafts
- elevator winches and hoist drums
- process crane travel wheels
- conveyor head and tail pulleys
Known failure patterns
- raceway and roller spalling after the L10 life or from sustained overload and shock in crusher duty
- roller smearing and skid marks when the radial load falls below the minimum load needed to drive the roller set
- cage fatigue and fracture on vibratory screens supplied with normal CN clearance instead of a vibratory C4 fit
- fretting corrosion on a tapered-bore sleeve seat when drive-up is insufficient and the inner ring works on the adapter
- lubricant starvation and cage wear where the relubrication interval ignores the slow-speed, dirty operating regime
Selection pitfalls — read before you substitute
- On this 50 mm-bore 21310, specify C3 clearance as the default for an interference inner-ring fit and verify residual play after mounting; a medium-section row that ran free on the bench can be fully clamped at operating temperature on the 50 mm shaft.
- The 213 series at 50 mm bore keeps the 27 mm width comparatively narrow for its 110 mm OD; it fits restricted axial space but carries less load than a 22310, so substitution into heavy 223 duty — even at identical bore and OD — will shorten life.
- Before fitting 21310, machine the 50 mm shaft seat and 110 mm housing bore with a relief or small fillet so nothing bridges the bearing chamfer; the 27 mm-wide rings only load correctly when the full faces abut, and a large radius pinches the 30.0 mm radial section.
- On a K tapered bore with adapter sleeve, tighten the KM locknut to drive the 21310 up the sleeve, rotating the inner ring, and stop on residual clearance — measured with feelers at the unloaded rollers — not on torque alone; then lock the tab washer so the 50 mm seat cannot creep.
- Relubricate 21310 through the W33 groove while the shaft turns slowly so fresh grease flushes the full 27 mm-wide roller set; pumping grease into a stationary bearing channels it past one row and leaves the other side of the 50 mm bore starved.
- Specify W33 when the 27 mm-wide bearing must be relubricated in place: it is the outer-ring annular groove with lubrication holes; without W33 grease only reaches the contacts through the shaft or housing arrangement.
- Press 21310 using the right ring: force on the inner ring for an interference shaft fit and on the outer ring for a housing fit — transmitting mounting force through the barrel rollers brinells the sphered raceways of the 110 mm assembly.
Frequently asked questions
What are the dimensions of a 21310 spherical roller bearing?
A 21310 double-row spherical roller bearing per ISO 15 has a 50 mm bore, 110 mm outer diameter and 27 mm width (1.969 × 4.331 × 1.063 in), a 30.0 mm radial section and roughly 1039 g geometry-based estimated mass; catalogue masses vary with cage and design.
How does the 21310 bore code work?
The leading 2 in 21310 denotes a double-row spherical roller, the middle digits give the ISO 15 dimension series, and the last two digits are bore code 10: 10 × 5 = 50 mm. The 110 mm OD and 27 mm width come from the dimension series (21300), not from the bore code alone.
How much misalignment can a 21310 accommodate?
Thanks to the sphered outer ring raceway, 21310 normally accommodates angular misalignment of around 1° under load (up to about 2° in favourable, lightly loaded conditions); the permissible value is smaller under full load and depends on clearance and cage design, so check the catalogue figure for the actual duty.
What is the difference between 21310 and 21310K?
The plain 21310 has a cylindrical bore for a straight shaft seat. The K suffix denotes a 1:12 tapered bore, normally mounted on an H3xx adapter sleeve over a commercial shaft (or directly on a tapered journal); the bearing is driven up the sleeve to a specified residual clearance and locked with a KM nut and tab washer.
Should the 21310 be ordered with CN, C3 or C4 clearance?
Use C3 as the usual default when the rotating inner ring has an interference fit, because the fit plus thermal expansion reduces residual play; choose C4 (often with a vibratory cage design) for screens and feeders; order CN mainly for loose fits on stationary shafts or split housings. A W33 outer-ring lubrication groove is a separate, commonly combined option.
Reviewed & verified by the MPN Base engineering desk against source catalog iso15-srb-geometry on 2026-09-24. Read our editorial & correction policy.