21317K bearing: complete specifications & equivalents
The 21317K 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 |
|---|---|
| Brand | NTN |
| Bore diameter d | 85 mm |
| Outer diameter D | 180 mm |
| Width B | 41 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 320 kN |
| Basic static load rating C0 | 355 kN |
| Fatigue load limit Pu | 45 kN |
| Limiting speed (mechanical) | 2400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5280 g |
| Manufacturer designation | NTN 21317K |
| Standard | ISO 15 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
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 | — |
| Radial section height (D−d)/2 | 47.5 mm |
| Smallest bore in 21300-series | 40 mm |
| Largest outer diameter in 21300-series | 240 mm |
| Width range across 21300-series | 23–50 mm |
| Bore position in 21300-series (smallest first) | 10 of 14 |
| Bore above smallest 21300-series size | 45 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21317-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 21300-series envelope, cage and ratings; this is the tapered-bore execution (K, 1:12) of the cylindrical-bore 21317-NTN — mounting (adapter/withdrawal sleeve or tapered seat, drive-up) differs. Verify shaft arrangement. |
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 21317K model number is decoded
21317K is an NTN double-row spherical roller bearing: two rows of symmetric rollers on a sphered outer raceway, 85×180×41 mm to ISO 15, with pressed-steel cage of the 213-series C design. On the NTN nameplate the suffix cluster after the size reads in order: cage design (C/CK), bore (K), lubrication feature (none); 21317K is assembled exactly in that order. The sphered outer raceway lets the inner-ring assembly pivot, accommodating shaft deflection and housing misalignment (around 1–2° for this class; use the 2203E value for the exact series) without edge loading the rollers. Grease/oil ratio: the 2,400 r/min limiting value is .77 of the 3,100 r/min oil value; heavy 41 mm-wide cages run hot in churning grease, so quantity and groove supply both matter. Fillet radii on shaft and housing must clear the ring chamfers of the 41 mm-wide set; use the NTN shoulder/withdrawal-groove table rather than copying a ball-bearing layout.
Typical equipment & failure modes
Common applications
- large gearbox and marine gear shafts
- wind-turbine gearbox and rotor bearings
- large vibrating screens and mining feeders
- heavy conveyor and bucket-excavator pulleys
Known failure patterns
- lubricant starvation at the centre rib area when the D1/W33 groove is not connected to a relubrication supply
- pressed EA cage fatigue under sustained vibration when minimum load is not maintained
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- rolling-contact fatigue after the catalogue L10 life at the actual load
- false brinelling on stopped machines exposed to screen or crusher vibration
Selection pitfalls — read before you substitute
- Mount the 85 mm ring with induction heat or the sleeve drive-up procedure; at 5280 g cocking damages the spherical raceways, and repositioning after seating is impractical.
- The two roller rows must share load equally — a tilted spacer or unequal abutment on the 41 mm-wide ring loads one row only and shows as asymmetric race polish during inspection.
- Never substitute 21317K by envelope alone: the 355 kN C0 and 45 kN Pu are specific to the NTN C design-code execution, and vibrating duty depends heavily on cage identity.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 320 kN rating no longer applies.
- Minimum load must be maintained even at rest under vibration: an unloaded 21317K on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- The 320/355 kN ratings, 45 kN Pu and 5280 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 21317K (C design-code); another maker's same-envelope part revises internal geometry, so re-verify ratings and cage before substitution on vibrating or rated drives.
Frequently asked questions
What are the dimensions and catalogue data of 21317K?
21317K is an NTN double-row spherical roller bearing to ISO 15: 85 mm bore, 180 mm OD and 41 mm width (3.346 × 7.087 × 1.614 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 320 kN, C0 355 kN, Pu 45 kN, grease limiting speed 2,400 r/min, oil 3,100 r/min, mass about 5280 g. It is open, with pressed-steel cage of the 213-series C design and a 1:12 tapered bore.
What is the difference between the K/K30 tapered bore and the cylindrical bore versions?
K denotes a 1:12 tapered bore. 21317K mounts on an adapter sleeve (or tapered shaft seat) and is driven up to the specified residual clearance; its cylindrical-bore counterpart in the same envelope and ratings is 21317.
What do EA and EM mean on NTN spherical roller bearings?
EA is the NTN standard-capacity/high-capacity execution with a pressed sheet-steel window cage; EM is the high-capacity execution with a one-piece machined brass cage. Both use the optimised symmetric-roller design, but cage identity changes mass, speed behaviour and suitability for duties like vibrating screens, so they are separate order numbers. 21317K is the C design-code execution.
What do D1 and W33 mean on 21317K?
21317K is listed without a D1/W33 outer-ring groove in 2203E; lubrication is supplied from the ring sides. D1 (NTN spelling) and W33 add the annular groove plus holes and are ordered as distinct suffixed executions of the same envelope.
How much misalignment and axial load can 21317K take?
The sphered outer raceway compensates static and dynamic misalignment in the order of 1–2° (verify the exact 2203E figure for the 21300 series); beyond that, load concentrates on one roller row. Load is predominantly radial with a moderate axial share in either direction — 320 kN C / 355 kN C0 — but sustained pure axial load is not recommended because it unloads one row.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.