NN4938 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 NN4938 model number is decoded

NN4938 is an NTN NN cylindrical roller bearing: two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially, inside the 190×260×69 mm ISO 15 envelope. Reading the code: NN for the double-row precision type, then the ISO 15 diameter/width series and the bore code — ×5 = 190 mm (00–03 use the 10/12/15/17 exception table). NTN prints two speed ceilings: 2,200 r/min grease and 2,600 r/min oil — the pressed-steel cage and lubricant film set the real limit at the 190 mm bore. Rating life at 525 kN C assumes clean oil and adequate film; the 98 kN Pu floor means contamination derating — not the C rating alone — governs adjusted life in dusty gearboxes. Heat the inner ring to max 120 °C for the 190 mm interference fit and support the ring face square during fitting; cocking over a keyway brinells the raceway before first rotation.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At 190 mm bore, oil-lubricated arrangements toward 2,600 r/min need positive flow and drain design; the 9930 g NN4938 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
• Do not replace NN4938 with a deep-groove ball bearing on rating alone: line contact gives 525 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
• Double-row NN precision bearings are typically ordered P5/P4 with specific radial clearance for spindle preloading; a P0/CN NN4938 does not substitute a precision-class execution.
• Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NN4938 skids at 2,200 r/min and fails by smearing long before L10 fatigue.
• Double-row NN precision bearings are typically ordered P5/P4 with specific radial clearance for spindle preloading; a P0/CN NN4938 does not substitute a precision-class execution.
• The 525/1030 kN ratings, 98 kN Pu and 9930 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN4938 (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.