6338 bearing: complete specifications & equivalents
The 6338 is a ISO 15 radial bearing sized 190 x 400 x 78 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 190 mm |
| Outer diameter D | 400 mm |
| Width B | 78 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 371 kN |
| Basic static load rating C0 | 430 kN |
| Fatigue load limit Pu | 10.8 kN |
| Reference speed (thermal) | 3400 rpm |
| Limiting speed (mechanical) | 2200 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 42000 g |
| Manufacturer designation | SKF 6338 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-25 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-24
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); 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 & 6300-series range
| Bore d | 7.48 in |
|---|---|
| Outer diameter D | 15.748 in |
| Width B | 3.071 in |
| ISO bore code | 38 |
| Radial section height (D−d)/2 | 105 mm |
| Smallest bore in 6300-series | 2 mm |
| Largest outer diameter in 6300-series | 500 mm |
| Width range across 6300-series | 3–95 mm |
| Bore position in 6300-series (smallest first) | 37 of 40 |
| Bore above smallest 6300-series size | 188 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6338 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
| 6338-NSK | NSK | 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. |
| 6338-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. |
| 6338-M | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF 6338 M (machined brass cage, open arrangement) is the same-size execution on the 190×400×78 mm envelope with ratings within 10 % — boundary dimensions interchangeable. |
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 6338 model number is decoded
In the 6300-series (diameter series 3 of ISO 15) the last two digits encode the bore: 6338 carries bore code 38 = 190 mm. Outside diameter 400 mm and width 78 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 190 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the SKF catalogue this open execution carries the bare designation; protected variants are ordered separately as -2Z and -2RSH.
Typical equipment & failure modes
Common applications
- medium and heavy industrial drives
- large gearboxes
- industrial fans and blowers
- hoists and winches
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- false brinelling from vibration while the shaft is stationary
- fretting corrosion on a loose shaft seat
Selection pitfalls — read before you substitute
- Large bores like the 190 mm of 6338 demand clean, burr-free seats; one raised burr under a ring this size cocks the bearing and concentrates load at the raceway edge, cutting life drastically.
- The 63xx medium section at 190 mm bore gains dynamic rating through larger rolling elements on a 400 mm OD; the penalty is mass and a lower limiting speed than the 6238 — do not specify it for speed-critical shafts.
- The open 6338 has no lubricant retention: grease escapes and contaminants migrate straight into the 190×400×78 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- Open bearings tolerate the highest speeds in the 6300-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 6338 units.
- Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 6300-series position can soften the mixture and leak — clean out the old fill before switching grease types.
- Vibration during standstill brinells the raceways of a 190 mm bearing at ball spacing; if the machine sits idle next to running equipment, turn the shaft over periodically or isolate the arrangement.
- The open 6338 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 6338-2Z (shields) and 6338-2RSH (contact seals), not suffix-free 6338.
- The 371/430 kN ratings here are SKF Explorer-class figures from catalogue PUB BU/P1 17000/1 EN (Oct 2018); SKF can revise internal geometry and ratings without changing the designation, so treat the catalogue version and date as part of the specification and re-verify for critical drives.
Frequently asked questions
What are the dimensions of a 6338 bearing?
A 6338 deep-groove ball bearing has a 190 mm bore, 400 mm outer diameter and 78 mm width (7.48 × 15.748 × 3.071 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
What lubrication does 6338 need?
The open 6338 is lubricated by the application; a NLGI 2 lithium-soap grease filled to roughly 25–35% of the free volume is the common choice, with a defined relubrication interval.
How does the 6338 bore code work?
The last two digits of 6338 are bore code 38, giving 38 × 5 = 190 mm bore. The 400 mm outside diameter and 78 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 6338 mean?
A bare 6338 designation means open: no shields or seals, normal CN radial clearance and P0 normal tolerance unless further suffixes are ordered. The application must supply and retain the lubrication.
What is the SKF designation and catalogue data for 6338?
In the SKF Rolling Bearings catalogue this size is listed as 6338 — the open (unsealed) execution, 190×400×78 mm per ISO 15. Quoted values: C 371 kN, C0 430 kN, Pu 10.8 kN, limiting speed 2200 r/min, mass 42000 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 6338.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-25. Read our editorial & correction policy.