7328B bearing: complete specifications & equivalents
The 7328B is a ISO 15 radial bearing sized 140 x 300 x 62 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 140 mm |
| Outer diameter D | 300 mm |
| Width B | 62 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 305 kN |
| Basic static load rating C0 | 310 kN |
| Fatigue load limit Pu | 16.3 kN |
| Limiting speed (mechanical) | 2100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 21500 g |
| Manufacturer designation | NTN 7328B |
| 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 | 5.512 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 2.441 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 80 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) | 26 of 32 |
| Bore above smallest 7300-series size | 130 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7328B | 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 7328B model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, 7328B appears as a heavy-duty 7300 single-row family bearing of 140 mm bore, 300 mm outside diameter and 62 mm width. Decoding 7328B: 73 is the single-row dimension series (heavy-duty 7300 single-row family), with 28 encodes the 140 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). On speed, the grease limiting speed is 2,100 r/min and the oil rating 2,800 r/min. For a 140 mm shaft with combined load, the practical shortlist is this series, its 7200-series lighter section, and — where thrust reverses — a back-to-back pair rather than a single row. 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
- heavy industrial gearbox main shafts
- large fan, blower and turbo-compressor rotors
- rolling-mill backup and drive spindles
- crusher and mill pinion shafts
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
- thermal runaway from excessive preload: the pair runs hot, grease darkens and the contact ellipse spreads until the raceways smear
- machined-cage land scoring when a high-speed spindle runs past its grease rating and the cage runs dry on its guidance surface
- contamination-induced denting — hard particles rolled into the contact ellipse become the initiation points for surface fatigue
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
Selection pitfalls — read before you substitute
- At this size the shaft fit, shoulder geometry and preload procedure dominate the outcome; a 140 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.
- The C0 of 310 kN is a static rating, not a permissible running thrust — sizing continuous axial load from C0 alone is a recurring drawing-office error.
- Substituting the B (40 deg) execution for the standard 30 deg bearing changes the axial/radial load split — the shaft position and the mating bearing see different forces even though the envelope is identical.
- The C0 of 310 kN is a static rating, not a permissible running thrust — sizing continuous axial load from C0 alone is a recurring drawing-office error.
- The 305/310 kN ratings and 16.3 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7328B; 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 7328B?
7328B is a single-row angular contact ball bearing to ISO 15: 140 mm bore, 300 mm outside diameter, 62 mm width (5.512 x 11.811 x 2.441 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 305 kN, C0 310 kN and a 16.3 kN fatigue load limit Pu; the grease limiting speed is 2,100 r/min and the oil rating 2,800 r/min; mass about 21500 g.
How is the 7328B designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 28 encodes the 140 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 300 mm OD and 62 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7328B support?
One 7328B 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 7328B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 2,100 r/min and the oil rating 2,800 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 7328B?
The 140/300/62 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 305 kN / C0 310 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.