61801-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 61801-RSR-NTN model number is decoded

In the 61800-series (diameter series 8 of ISO 15) the last two digits encode the bore: 61801 carries bore code 12 = 12 mm. Outside diameter 21 mm and width 5 mm come from the ISO 15 boundary-dimensions general plan. Suffix -RSR denotes two low-friction non-contact elastomer seals; they keep coarse debris out with minimal drag but are not liquid-tight. For normal-load mounting with a rotating inner ring on a 12 mm shaft, typical catalogue practice is a j5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. NTN's non-contact seal suffix is LLB/LLF (catalogue number 6801LLB), 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 12 mm bore, induction heating to roughly 80–100 °C is the clean mounting method; never exceed 120 °C, and hold 61801 against the shaft shoulder while it cools so the ring cannot creep back.
• The 618xx thin section at 12 mm bore has only a 4.5 mm radial section height: it saves space but is highly sensitive to misalignment, shaft deflection and shock loads — verify shaft stiffness before choosing it over a 6212.
• RSR low-friction seals on 61801-RSR-NTN run faster than contact-seal 61801-2RS but let fine dust and moisture past the non-contact lip; in dirty or wet duty specify 61801-2RS instead.
• The non-contact lip of 61801-RSR-NTN does not retain a lifetime grease fill the way a contact seal does; confirm the regreasing interval for the 12 mm bore position before relying on it as sealed-for-life.
• A 12 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.
• Shaft and housing fillets must clear the bearing chamfer so the 5 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
• NTN catalogues this low-friction non-contact seal as 6801LLB (suffix LB), 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 12 mm bore the 61801 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.
• The 29000 r/min grease limiting speed puts 61801 in NTN's high-speed range; at these speeds relubrication interval shortens sharply and the pressed-steel cage must be checked for cage-bar critical speed.
• At 2.12 kN dynamic load rating (C) and 1.04 kN static (C0), 0.08 kN fatigue load limit Cu, 61801 is a light-load bearing: the L10 life at catalogue C is short above a few kN of equivalent load, so size up to a 62-series on the same bore if the application sees shock or frequent starts.
• At only 6 g, 61801 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 12×21×5 mm envelope of 61801 gives a D/d ratio of 1.75 and 4.5 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 2.12/1.04 kN load ratings, 0.08 kN fatigue load limit Cu NTN lists the grease limiting speed at 29000 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 6 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6801LLB on the 12×21×5 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61801 in a rated drive.
• 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 61801 is listed.
• Two NTN bearings of the same designation from different production lots can carry minor internal-geometry revisions; for paired or preloaded arrangements on one shaft, order a single lot through the NTN distributor.