NNU4948K 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 NNU4948K model number is decoded

NTN lists NNU4948K on the 240×320 mm envelope, 80 mm wide: a line-contact radial bearing with a machined or stamped steel cage per the precision execution and a grease limiting speed of 1,700 r/min. The leading NNU defines the rib arrangement (double row, ribbed outer ring, separable inner); the dimension-series digits and the two-digit bore code resolve to 240 mm, with 320 mm OD and 80 mm width from the ISO 15 general plan. Double-row NNU precision cylindrical roller bearing: ribbed outer ring with a separable inner ring, two roller rows for high radial stiffness on machine-tool spindles; the K suffix is a 1:12 tapered bore — mounted on a tapered seat or adapter sleeve and driven up to a precise radial clearance/preload; precision classes P5/P4/P2 and clearance are ordered separately. Equivalent-load planning treats NNU4948K as a pure radial bearing: keep P below 680 kN at the required L10, and let a paired angular-contact or thrust part carry any sustained axial component. Provide axial location with an adjacent locating bearing rather than expecting the float cylindrical set to hold thrust on the 240 mm shaft.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At 240 mm bore, oil-lubricated arrangements toward 2,000 r/min need positive flow and drain design; the 16400 g NNU4948K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
• Open NNU4948K units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 240 mm contact.
• The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 680/1410 kN pair here belongs to NNU4948K as printed, not to the bare size.
• Grease limiting speed 1,700 r/min and oil 2,000 r/min are different limits for NNU4948K: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
• The 80 mm width and abutment faces must be square to the axis; a tilted spacer concentrates load across the roller set and shows as uneven raceway polish on the 240 mm inner ring.
• The 680/1410 kN ratings, 126 kN Pu and 16400 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU4948K (standard execution); other makes sharing the ISO 15 envelope revise internal geometry without changing the order number, so keep the 2203E reference with the specification for critical drives.