61903-RSR-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 61903-RSR-NTN model number is decoded

61903-RSR uses two non-contact elastomer lips with very low drag; coarse debris stays out, but the bearing is not liquid-tight. Within the thin 619xx section (diameter series 9 of ISO 15), multiplying bore code 17 by five gives the 17 mm bore; the 30 mm outside diameter and 7 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 17 mm shaft under normal load, catalogue practice seats it on a j5 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. NTN's non-contact seal suffix is LLB/LLF (catalogue number 6903JRXLLB), mapped here from the industry-neutral -RSR spelling; speed capability matches the open bearing but it is not liquid-tight.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At 17 mm bore the ring mass is significant: heat 61903 on an induction heater (max 120 °C), never over an open flame, and plan puller access or a withdrawal sleeve now for the day it has to come off again.
• The 619xx thin section at 17 mm bore (6.5 mm section height) cannot shrug off the misalignment a standard section tolerates; keep the housing bores round and aligned, or edge contact will spall the raceways early.
• RSR low-friction seals on 61903-RSR-NTN run faster than contact-seal 61903-2RS but let fine dust and moisture past the non-contact lip; in dirty or wet duty specify 61903-2RS instead.
• The low-drag lip of 61903-RSR-NTN barely touches the inner ring; after long shelf storage the grease can separate, so rotate the rings by hand and confirm smooth, silent running before fitting.
• Axial location must clamp the ring face, not the seal area: a shoulder or circlip bearing on the seal side of the 7 mm-wide ring of 61903-RSR-NTN drags the lip and overheats it.
• A 17 mm bore listing showing the right d/D/B but no standard or precision-class reference may be a loose-tolerance import; measure bore/OD spread before fitting it to a machined shaft.
• NTN catalogues this low-friction non-contact seal as 6903JRXLLB (suffix RXLLB), mapped here from the industry-neutral -RSR spelling. NTN rates its speed capability the same as the open bearing, but it is not liquid-tight — for wet or fine-dust duty step up to the LLU contact seal (industry-neutral -2RS).
• At 17 mm bore the 61903 sits in NTN's small-bore range; ABEC-1/P0 runout is standard, and the pressed-steel cage is adequate up to the grease limiting speed — for higher accuracy (spindles, instruments) ask NTN for a P6 or P5 tolerance-class listing before relying on catalogue P0 figures.
• NTN rates 61903 at 22000 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 seal lip.
• NTN rates 61903 at 5.15 kN dynamic (C) and 2.58 kN static (C0), 0.2 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 18 g, 61903 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 17×30×7 mm envelope of 61903 gives a D/d ratio of 1.76 and 6.5 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 5.15/2.58 kN load ratings, 0.2 kN fatigue load limit Cu NTN lists the grease limiting speed at 22000 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 18 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6903JRXLLB on the 17×30×7 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61903 in a rated drive.
• Order the C3 internal-clearance version (61903 with C3 after the seal code) when the shaft fit is tight or the shaft-to-housing temperature gradient exceeds roughly 10 °C — the residual clearance after mounting, not the catalogue CN figure, decides service life.
• Standard catalogue stock of 61903 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.