21317 bearing: complete specifications & equivalents
The 21317 is a ISO 15 radial bearing sized 85 x 180 x 41 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 85 mm |
| Outer diameter D | 180 mm |
| Width B | 41 mm |
| Seal / shield | open |
| Internal clearance | CN / C3 / C4 available |
| Tolerance class | P0 |
| Cage | steel |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 4136 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 21317 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 21300-series range
| Bore d | 3.346 in |
|---|---|
| Outer diameter D | 7.087 in |
| Width B | 1.614 in |
| ISO bore code | 17 |
| Radial section height (D−d)/2 | 47.5 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) | 8 of 12 |
| Bore above smallest 21300-series size | 35 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21317 | 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 21317 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 21317 encode the bore: code 17 = 85 mm (code × 5 from 04 upward). The ISO 15 envelope is 180 mm outside diameter and 41 mm width — 3.346 × 7.087 × 1.614 in, with a 47.5 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
- large gear drives and mill pinions
- heavy conveyor drum pulleys
- cement and aggregate processing machinery
- mining and aggregate vibrating screens
- jaw and cone crusher eccentric shafts
Known failure patterns
- thermal seizure when an interference shaft fit plus hot running removes all residual radial clearance from a CN bearing
- 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
Selection pitfalls — read before you substitute
- The large 85 mm-bore 21317 mounts with real force: use induction heating or hydraulic drive-up on the tapered seat, measure residual clearance in micrometres, and plan lifting fixtures — the 41 mm double-row assembly cannot be drifted into position without brinelling.
- The 213 series at 85 mm bore keeps the 41 mm width comparatively narrow for its 180 mm OD; it fits restricted axial space but carries less load than a 22317, so substitution into heavy 223 duty — even at identical bore and OD — will shorten life.
- Check the shoulder geometry for 21317: a generous fillet on the 85 mm shaft looks strong but stops the 41 mm inner ring seating home; use the catalogue corner-relief radius and provide a withdrawal groove so the 47.5 mm-section outer ring presses flush in the 180 mm housing.
- Large 21317 tapers should be mounted with a hydraulic nut or oil injection: controlled drive-up sets the residual radial clearance on the 41 mm-wide double row, whereas bar-and-spanner force either under-drives (fretting) or over-drives (thermal seizure on first hot run).
- Read the damage pattern on a removed 21317: spalling concentrated on one side of the 180 mm outer race points to misalignment or thrust overload, while uniform roller-end smearing means minimum-load skidding — the two failures demand opposite corrections.
- Order clearance for the mounting method: an interference fit on a rotating inner ring plus thermal growth eats into CN play, so most industrial 85 mm-bore mounts use C3, vibrating screens use C4, and CN is mainly for loose/split-housing fits — the designation suffix states the class.
- Specify W33 when the 41 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.
Frequently asked questions
What are the dimensions of a 21317 spherical roller bearing?
A 21317 double-row spherical roller bearing per ISO 15 has a 85 mm bore, 180 mm outer diameter and 41 mm width (3.346 × 7.087 × 1.614 in), a 47.5 mm radial section and roughly 4136 g geometry-based estimated mass; catalogue masses vary with cage and design.
How does the 21317 bore code work?
The leading 2 in 21317 denotes a double-row spherical roller, the middle digits give the ISO 15 dimension series, and the last two digits are bore code 17: 17 × 5 = 85 mm. The 180 mm OD and 41 mm width come from the dimension series (21300), not from the bore code alone.
How much misalignment can a 21317 accommodate?
Thanks to the sphered outer ring raceway, 21317 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 21317 and 21317K?
The plain 21317 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 21317 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.