7305B bearing: complete specifications & equivalents
The 7305B is a ISO 15 radial bearing sized 25 x 62 x 17 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 25 mm |
| Outer diameter D | 62 mm |
| Width B | 17 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 27 kN |
| Basic static load rating C0 | 14.6 kN |
| Fatigue load limit Pu | 1.14 kN |
| Limiting speed (mechanical) | 11000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 234 g |
| Manufacturer designation | NTN 7305B |
| 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 | 0.984 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 0.669 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 18.5 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) | 6 of 32 |
| Bore above smallest 7300-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7305B | 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 7305B model number is decoded
NTN 7305B belongs to the heavy-duty 7300 single-row family: the catalogue boundary dimensions read 25 / 62 / 17 mm (bore / OD / width). Reading the code: 73 is the single-row dimension series (heavy-duty 7300 single-row family), 05 encodes the 25 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). NTN prints 27 kN dynamic and 14.6 kN static for this size and a 1.14 kN fatigue load limit Pu. 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. Grease quantity matters as much as grade at 11,000 r/min: fill about a third of the free space and let the bearing purge on first run.
Typical equipment & failure modes
Common applications
- high-speed router, grinder and woodworking spindles
- small pump and compressor shafts with combined load
- servo and stepper motor shafts with axial preload
- bicycle and motorcycle wheel and steering positions
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
- machined-cage land scoring when a high-speed spindle runs past its grease rating and the cage runs dry on its guidance surface
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
- edge loading and early spalling from housing bores that are out of round or shoulders that are too small for the ring face
Selection pitfalls — read before you substitute
- At 25 mm bore the rings are thin-sectioned: press force must go through the ring being fitted, never through the balls, or the first damage is already in the raceway before the machine runs.
- 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 11,000 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.
- 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.
- Never use a four-point or double-row bearing as a like-for-like swap for a single 7305B without re-checking axial float, heat and housing width — the kinematics differ.
- The 27/14.6 kN ratings and 1.14 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7305B; 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 7305B?
7305B is a single-row angular contact ball bearing to ISO 15: 25 mm bore, 62 mm outside diameter, 17 mm width (0.984 x 2.441 x 0.669 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 27 kN, C0 14.6 kN and a 1.14 kN fatigue load limit Pu; the grease limiting speed is 11,000 r/min and the oil rating 15,000 r/min; mass about 234 g.
How is the 7305B designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 05 encodes the 25 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 62 mm OD and 17 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7305B support?
One 7305B 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 7305B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 11,000 r/min and the oil rating 15,000 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 7305B?
The 25/62/17 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 27 kN / C0 14.6 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.