30203 bearing: complete specifications & equivalents
The 30203 is a ISO 355 radial bearing sized 17 x 40 x 13.25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 17 mm |
| Outer diameter D | 40 mm |
| Width B | 13.25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 23.4 kN |
| Basic static load rating C0 | 18.6 kN |
| Fatigue load limit Pu | 1.83 kN |
| Reference speed (thermal) | 15000 rpm |
| Limiting speed (mechanical) | 18000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 79 g |
| Manufacturer designation | SKF 30203 |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB |
| Last verified | 2026-09-28 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB) · extracted 2026-09-28
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 30200-series range
| Bore d | 0.669 in |
|---|---|
| Outer diameter D | 1.575 in |
| Width B | 0.522 in |
| ISO bore code | 03 |
| Radial section height (D−d)/2 | 11.5 mm |
| Smallest bore in 30200-series | 15 mm |
| Largest outer diameter in 30200-series | 580 mm |
| Width range across 30200-series | 11.75–104 mm |
| Bore position in 30200-series (smallest first) | 2 of 37 |
| Bore above smallest 30200-series size | 2 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30203 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 355 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
| 30203-NTN | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 30203 model number is decoded
SKF 30203 belongs to the SKF single-row tapered roller range — the 17 mm bore entry in the 30200 series, dimensioned 40 mm OD and 13.25 mm wide to the ISO 355 boundary plan.The code breaks down as type prefix 3 (tapered roller), series 02 (the standard section), and bore code 03 = 17 mm; dimensions 17×40×13.25 mm therefore match the ISO 355 envelope. SKF lists the plain number as the basic execution; letter suffixes such as B denote a steeper contact angle and are different order numbers. The 1.83 kN Pu figure feeds the adjusted-life equation at contaminated or partial-film conditions, and the 0.79 C0/C balance shows this execution is tuned to thrust-heavy combined loads rather than pure radial running. For a 17 mm shaft the usual cone seat is j5 with an H7 housing when the inner ring rotates; arrange two 30203 bearings as a set for two-direction location and set clearance from the load diagram, never from assembly feel. Material and manufacturing detail: the 79 g catalogue mass reflects through-hardened bearing steel (density ~7.85 g/cm³) machined to the 30200 ISO envelope, with the pressed-steel cage contributing roughly 2 g of the total; the 17 mm bore is ground to IT5 roundness and the 40 mm OD to IT5 cylindricity, and the 13.25 mm width tolerance keeps the pair-setting scatter within the ISO preload class.
Typical equipment & failure modes
Common applications
- small conveyor drive pulleys
- power-tool gear heads
- small automotive wheel hubs and trailer axles
- light-duty gearbox input/output shafts
Known failure patterns
- cup or cone misalignment when the separable rings are not seated square during mounting
- loose cup rotation in the housing when the specified press fit is not achieved
- uneven load sharing in a pair when spacer faces are not parallel to the bore
- thermal preload runaway in an O-arrangement pair when inner-ring heat expands the setting
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- hard-particle indentation of the tapered raceway in unfiltered oil
Selection pitfalls — read before you substitute
- At a 17 mm bore the thin cone and cup are easily distorted by an over-tight shaft nut; check seat runout (target Ra ≤ 0.8 µm) and torque the locknut progressively — a pinched 30203 shows up as gearbox vibration long before it fails.
- The 302 series at 17 mm bore (40×13.25 mm) is the standard tapered-roller envelope; stepping to a 32203 or 32303 changes OD, width and heat generation — it is not a drop-in swap when the housing and speed are fixed.
- When the outer ring rotates, reverse the fit logic and provide cup location; the tapered contact of 30203 pushes the rings apart under load, so a non-located cup walks its seat even when the shaft is fixed.
- Setting is a design value, not an assembly feel: excessive preload in the 30203 pair raises operating temperature and can trigger thermal runaway, while too little lets the rollers skid and smear the raceway under light load.
- Open 30203 units need application-supplied sealing and a defined EP lubricant supply; the roller-rib contact is the first to fail when the additive film breaks down.
- The 23.4/18.6 kN ratings are SKF catalogue 17000 values for the basic execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
- SKF lists several executions of 30203 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 30203 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of 30203?
The SKF 30203 is a single-row tapered roller bearing with 17 mm bore, 40 mm outer diameter and 13.25 mm width (0.669 × 1.575 × 0.522 in) per ISO 355. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 23.4 kN, C0 18.6 kN, fatigue load limit Pu 1.83 kN, reference speed 15,000 r/min, limiting speed 18,000 r/min, mass about 79 g. It is an open, separable bearing with a pressed-steel cage.
How does the 30203 bore code work?
The last two digits of 30203 are bore code 03, one of the small special codes: 00 = 10 mm, 01 = 12 mm, 02 = 15 mm, 03 = 17 mm — here 03 = 17 mm bore. The 40 mm OD and 13.25 mm width come from the ISO 355 dimension-series plan, shared with other tapered bearings of the same code.
What do the 30203 series and basic execution designations mean?
The leading 3 marks a single-row tapered roller bearing; the second digit 02 is the ISO 355 series (standard section). The SKF catalogue lists the ISO 355 dimension-series code after the bare number. A steeper-contact-angle variant (B suffix) is a different order number and is not interchangeable with the basic execution.
Can a single 30203 take axial load in both directions?
No — one single-row tapered roller bearing reacts thrust in one direction only, and under radial load its contact angle induces an axial force. Use two bearings as a matched pair: O (back-to-back) for a rigid, moment-resisting arrangement, X (face-to-face) where thermal expansion must be tolerated, or tandem where one-direction thrust is shared.
How does 30203 compare with a ball bearing of the same bore?
A tapered roller bearing has line contact and a steep contact angle: much higher combined axial-plus-radial capacity and shock resistance than a ball bearing of the same bore, at the cost of speed, one-direction thrust, mandatory pairing for reversing loads and a minimum axial load requirement. A ball bearing cannot be dropped into a combined-load 30203 position and vice versa — verify load direction, Fa/Fr ratio and speed before substituting.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB on 2026-09-28. Read our editorial & correction policy.