7238B bearing: complete specifications & equivalents
The 7238B is a ISO 15 radial bearing sized 190 x 340 x 55 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 | 340 mm |
| Width B | 55 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 300 kN |
| Basic static load rating C0 | 355 kN |
| Fatigue load limit Pu | 15.5 kN |
| Limiting speed (mechanical) | 1700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 21300 g |
| Manufacturer designation | NTN 7238B |
| 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 & 7200-series range
| Bore d | 7.48 in |
|---|---|
| Outer diameter D | 13.386 in |
| Width B | 2.165 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 75 mm |
| Smallest bore in 7200-series | 10 mm |
| Largest outer diameter in 7200-series | 540 mm |
| Width range across 7200-series | 9–85 mm |
| Bore position in 7200-series (smallest first) | 31 of 36 |
| Bore above smallest 7200-series size | 180 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 7238B model number is decoded
7238B is the 190 mm bore member of NTN's medium-duty 7200 single-row family, with a 340 mm outside diameter and 55 mm section width. NTN builds the number from 72 is the single-row dimension series (medium-duty 7200 single-row family), then 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). At roughly 75.0 mm of radial section, the catalogue still quotes 300 kN dynamic capacity for the 190 mm bore. Where the same envelope must also be sealed, or where mounting mistakes are likely, compare with the double-row 52/53 catalogue pages before fixing the bill of materials. Set preload or end-play with the pair as a unit and lock the adjustment; a single angular-contact bearing cannot run free like a deep-groove one.
Typical equipment & failure modes
Common applications
- wind-turbine and heavy-machinery auxiliaries
- heavy industrial gearbox main shafts
- large fan, blower and turbo-compressor rotors
- rolling-mill backup and drive spindles
Known failure patterns
- impact brinelling dents on the 30 deg contact path after a shaft-side hammer blow during mounting, because axial shock travels straight through the contact angle
- loss of preload after housing-fret or shaft creep, leaving the pair loose — ball skidding, cage rattle and a falling natural frequency follow
- pressed-steel cage pocket wear and rivet loosening after repeated ball skid at light load and high speed
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
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.
- Never use a four-point or double-row bearing as a like-for-like swap for a single 7238B without re-checking axial float, heat and housing width — the kinematics differ.
- Grease rated for deep-groove motor duty is not automatically right at 1,700 r/min with preload; check the grease speed factor against the catalogue figure.
- Catalogue mass and ratings belong to the open execution; shields, seals and resin cages change both the speed ceiling and the thermal behaviour of the same basic size.
- The 300/355 kN ratings and 15.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7238B; 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 7238B?
7238B is a single-row angular contact ball bearing to ISO 15: 190 mm bore, 340 mm outside diameter, 55 mm width (7.48 x 13.386 x 2.165 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 300 kN, C0 355 kN and a 15.5 kN fatigue load limit Pu; the grease limiting speed is 1,700 r/min and the oil rating 2,200 r/min; mass about 21300 g.
How is the 7238B designation structured?
72 is the single-row dimension series (medium-duty 7200 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 340 mm OD and 55 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7238B support?
One 7238B 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 7238B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 1,700 r/min and the oil rating 2,200 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 7238B?
The 190/340/55 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 300 kN / C0 355 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.