21313 bearing: complete specifications & equivalents
The 21313 is a ISO 15 radial bearing sized 65 x 140 x 33 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 65 mm |
| Outer diameter D | 140 mm |
| Width B | 33 mm |
| Seal / shield | open |
| Internal clearance | CN / C3 / C4 available |
| Tolerance class | P0 |
| Cage | steel |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 2033 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 21313 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 21300-series range
| Bore d | 2.559 in |
|---|---|
| Outer diameter D | 5.512 in |
| Width B | 1.299 in |
| ISO bore code | 13 |
| Radial section height (D−d)/2 | 37.5 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) | 4 of 12 |
| Bore above smallest 21300-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21313 | 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 21313 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 21313 encode the bore: code 13 = 65 mm (code × 5 from 04 upward). The ISO 15 envelope is 140 mm outside diameter and 33 mm width — 2.559 × 5.512 × 1.299 in, with a 37.5 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
- process crane travel wheels
- conveyor head and tail pulleys
- vibrating screens, feeders and shakeout machines
- paper machine felt and press rolls
- industrial gearbox and drive shafts
Known failure patterns
- 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
- water and grit pitting of open bearings in mining and pulping duty after the housing seals degrade
- unloaded-row scuffing when pure thrust exceeds the catalogue axial capacity and one roller row unloads completely
- thermal seizure when an interference shaft fit plus hot running removes all residual radial clearance from a CN bearing
Selection pitfalls — read before you substitute
- On this 65 mm-bore 21313, 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 65 mm shaft.
- The 213 series at 65 mm bore keeps the 33 mm width comparatively narrow for its 140 mm OD; it fits restricted axial space but carries less load than a 22313, so substitution into heavy 223 duty — even at identical bore and OD — will shorten life.
- Before fitting 21313, machine the 65 mm shaft seat and 140 mm housing bore with a relief or small fillet so nothing bridges the bearing chamfer; the 33 mm-wide rings only load correctly when the full faces abut, and a large radius pinches the 37.5 mm radial section.
- On a K tapered bore with adapter sleeve, tighten the KM locknut to drive the 21313 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 65 mm seat cannot creep.
- Relubricate 21313 through the W33 groove while the shaft turns slowly so fresh grease flushes the full 33 mm-wide roller set; pumping grease into a stationary bearing channels it past one row and leaves the other side of the 65 mm bore starved.
- In a classic two-bearing arrangement the 21313 often serves as the non-locating (floating) bearing, taking radial load while the housing bore lets it drift; it can locate axially in both directions, but sustained pure thrust beyond the catalogue limit unloads one roller row.
- Self-aligning is not a licence to ignore alignment: 21313 accommodates typically around 1° of angular misalignment under normal load (roughly 2° only in favourable, light-load conditions) — the exact figure falls with load, so check the catalogue value rather than designing to the maximum.
Frequently asked questions
What are the dimensions of a 21313 spherical roller bearing?
A 21313 double-row spherical roller bearing per ISO 15 has a 65 mm bore, 140 mm outer diameter and 33 mm width (2.559 × 5.512 × 1.299 in), a 37.5 mm radial section and roughly 2033 g geometry-based estimated mass; catalogue masses vary with cage and design.
How does the 21313 bore code work?
The leading 2 in 21313 denotes a double-row spherical roller, the middle digits give the ISO 15 dimension series, and the last two digits are bore code 13: 13 × 5 = 65 mm. The 140 mm OD and 33 mm width come from the dimension series (21300), not from the bore code alone.
How much misalignment can a 21313 accommodate?
Thanks to the sphered outer ring raceway, 21313 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 21313 and 21313K?
The plain 21313 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 21313 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.