7338B bearing: complete specifications & equivalents
The 7338B 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 | NTN |
| Bore diameter d | 190 mm |
| Outer diameter D | 400 mm |
| Width B | 78 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 430 kN |
| Basic static load rating C0 | 535 kN |
| Fatigue load limit Pu | 24 kN |
| Limiting speed (mechanical) | 1500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 47000 g |
| Manufacturer designation | NTN 7338B |
| 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 & 7300-series range
| Bore d | 7.48 in |
|---|---|
| Outer diameter D | 15.748 in |
| Width B | 3.071 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 105 mm |
| Smallest bore in 7300-series | 10 mm |
| Largest outer diameter in 7300-series | 420 mm |
| Width range across 7300-series | 11–80 mm |
| Bore position in 7300-series (smallest first) | 31 of 32 |
| Bore above smallest 7300-series size | 180 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7338B | 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. |
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 7338B model number is decoded
The heavy-duty 7300 single-row family entry 7338B carries a 190 mm bore in a 400 mm outside diameter, 78 mm wide envelope. Two fields make up the code — 73 is the single-row dimension series (heavy-duty 7300 single-row family) and 38 encodes the 190 mm bore (bore code x 5), and the trailing B marks the 40 deg contact-angle execution (the no-letter standard bearing works at 30 deg). Because the contact line is angled, one bearing of this type takes radial load plus thrust from one direction only — the opposite direction needs a second bearing or a matched set. The 190/400/78 envelope is an ISO 15 boundary plan, so dimensional interchange with other makers holds — ratings and internal geometry do not automatically follow. Heat-mounting to 80-90 deg C is the clean route onto a 190 mm shaft; drive-fits through the balls transmit force through the contact ellipse and can brinell it.
Typical equipment & failure modes
Common applications
- steel-plant conveyor and table roll drives
- wind-turbine and heavy-machinery auxiliaries
- heavy industrial gearbox main shafts
- large fan, blower and turbo-compressor rotors
Known failure patterns
- false brinelling on the raceway contact ellipses when a preloaded spindle sits vibrating at standstill — visible as evenly spaced flute-like wear at ball pitch
- loss of preload after housing-fret or shaft creep, leaving the pair loose — ball skidding, cage rattle and a falling natural frequency follow
- resin-cage cracking on the 7900-series sizes after hot, dry running or solvent attack on the polymer
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
- contamination-induced denting — hard particles rolled into the contact ellipse become the initiation points for surface fatigue
Selection pitfalls — read before you substitute
- At this size the shaft fit, shoulder geometry and preload procedure dominate the outcome; a 190 mm bore bearing forgives nothing in a poorly machined housing.
- The 40 deg B-execution raises axial capacity but lowers the speed ceiling — do not copy the standard-bearing speed and preload settings onto it.
- Grease rated for deep-groove motor duty is not automatically right at 1,500 r/min with preload; check the grease speed factor against the catalogue figure.
- A single-row angular contact left loose on the shaft to "help assembly" will fret the seat: the contact angle keeps driving the ring axially under load.
- The 1,500 r/min speed figure assumes the catalogue lubrication state and a correctly set pair; real limits drop fast with excess grease fill or heavy preload.
- The 430/535 kN ratings and 24 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7338B; internal geometry legitimately differs between manufacturers, so re-verify ratings, contact angle and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 7338B?
7338B is a single-row angular contact ball bearing to ISO 15: 190 mm bore, 400 mm outside diameter, 78 mm width (7.48 x 15.748 x 3.071 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 430 kN, C0 535 kN and a 24 kN fatigue load limit Pu; the grease limiting speed is 1,500 r/min and the oil rating 2,000 r/min; mass about 47000 g.
How is the 7338B designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 38 encodes the 190 mm bore (bore code x 5), and the trailing B marks the 40 deg contact-angle execution (the no-letter standard bearing works at 30 deg). The 400 mm OD and 78 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7338B support?
One 7338B alone takes thrust in one direction only, along its 40 deg contact angle; reversing thrust calls for a second bearing or a factory-matched DB/DF/DT pair (the catalogue right-hand columns list the paired ratings). Radial load is always carried as a combined load through the angled contact.
What lubrication speeds does NTN print for 7338B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 1,500 r/min and the oil rating 2,000 r/min. These are catalogue ceilings for a correctly mounted bearing with the stated lubricant; preload, fill quantity, ambient heat and paired arrangements all move the real limit.
What should be checked before substituting another make for 7338B?
The 190/400/78 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 430 kN / C0 535 kN, the speed figures, contact angle and suffix meaning against the donor catalogue before swapping on a rated drive.
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.