30303-NTN bearing: complete specifications & equivalents

Specification table

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.

Cross references & equivalents

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 30303-NTN model number is decoded

The NTN 2203E table prints 30303 in the large-OD 30300 family with the steeper contact angle: 17 mm bore, 47 mm cup OD, 15.25 mm T, with a grease limiting speed of 9,000 r/min and an oil-lubricated ceiling of 12,000 r/min. Reading the designation: the leading five digits follow the ISO 355 metric plan (dimension family plus two-digit bore code), and 30303 resolves to 17 mm bore; the NTN factory mark 4T is stamped on cone and cup but is a brand mark, not a size code, so the catalogue sku is printed without it. The printed contact-angle geometry gives the large-OD 30300 family with the steeper contact angle its characteristic load split — at 32/26.3 kN (C/C0) the static rating is about 0.82× C, typical of tapered bearings proportioned for heavy combined duty. The two speed columns differ by a factor of .75 (grease/limiting 9,000 vs oil 12,000 r/min); heat generation at the cone rib decides which lubrication a real 30303 arrangement can sustain. Fillet radii must clear the ring chamfers of the 47 mm cup and 17 mm cone; use undercut shoulders so the rings seat fully rather than bridging on a shaft radius.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At 17 mm bore the thin section and small rollers are adjustment-sensitive: a quarter-turn of the locknut moves end play by more than on large bearings, so set the 30303 pair with a dial indicator rather than by feel.
• The steeper contact angle of the large-OD 30300 family with the steeper contact angle raises axial capacity but lowers the speed ceiling against a 302/322 bearing at 17 mm bore; do not swap to the lighter family without re-checking the 9,000 r/min grease limit and the thrust load split.
• Open 30303 units have no seals: a wheel-hub or gearbox application needs external sealing or the 9,000 r/min grease figure is meaningless once water reaches the cone rib.
• The 15.0 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 30303 or the ring will bottom out on the radius instead of the shoulder face.
• Minimum load matters at high speed: an unloaded 30303 at a large fraction of 9,000 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
• The 32/26.3 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30303 (ISO 355 2FB); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.