61904-NTN bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203-3/E (2024)) · extracted 2026-09-25

Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203-3/E (2024)); 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 61904-NTN model number is decoded

In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61904 carries bore code 04 = 20 mm. Outside diameter 37 mm and width 9 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 20 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the NTN catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes ZZ (shields), LLB/LLF (non-contact seals), LLH (low-torque contact seal) and LLU (contact seal).

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At a 20 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 61904-NTN; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
• The 619xx thin section (8.5 mm section height at 20 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
• The open 61904-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 20×37×9 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 61904-NTN leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
• Suffixes stack in a defined order — clearance follows the seal code, e.g. 61904-NTN-C3. No clearance suffix means normal CN clearance.
• The housing bore for the 37 mm OD should be round within IT7; an oval bore pinches the outer ring of 61904-NTN and shows up later as two-point loaded raceway wear.
• The open 61904 has no integral sealing; in the NTN 2203 catalogue the protected variants carry suffixes ZZ (non-contact steel shields), LLB/LLF (non-contact rubber seals), LLU (contact rubber seals) and LLH (a low-torque contact seal with higher speed capability than LLU). A JR or JRX suffix (printed for some thin-section sizes) denotes a pressed-steel cage, not a seal.
• The 20 mm bore puts 61904 in NTN's light industrial range; the standard pressed-steel cage and CN clearance cover most fractional-horsepower motor and small-pump duty, but for continuous high-speed use specify the LLH low-torque seal (not LLU) and confirm the housing allows the listed limiting speed.
• NTN rates 61904 at 19000 r/min grease limiting speed — this is a high-speed electric-motor range; keep the grease fill at 20–30% of the free bearing volume and avoid mixing grease thickener types if regreasing through the housing.
• NTN rates 61904 at 7.05 kN dynamic (C) and 3.7 kN static (C0), 0.29 kN fatigue load limit Cu; this light-to-medium rating suits fractional-horsepower drives and instruments — for conveying or gearbox duty with shock loads, verify the equivalent dynamic load stays well below C.
• At only 36 g, 61904 is a lightweight bearing that can be handled by hand; still, press it onto the shaft with a sleeve against the inner ring — never through the balls or outer ring.
• The 20×37×9 mm envelope of 61904 gives a D/d ratio of 1.85 and 8.5 mm radial section height — a standard medium section that balances load capacity and speed; for this geometry the pressed-steel cage is adequate up to the listed limiting speed, and C3 clearance is the common choice for hot shafts.
• The 7.05/3.7 kN load ratings, 0.29 kN fatigue load limit Cu NTN lists the grease limiting speed at 19000 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 36 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6904 on the 20×37×9 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61904 in a rated drive.
• Standard catalogue stock of 61904 is the general-purpose execution; for low-noise motor duty NTN offers low-torque seal and special-grease variants in this size class, which are separate order numbers.
• NTN's pressed-steel cage (no cage suffix) is the quiet standard for this size; for sustained running close to the limiting speed or for heavy shock duty, ask the NTN channel whether a machined-cage execution of 61904 is listed.