61805-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 61805-RSR-NTN model number is decoded

61805-RSR uses two non-contact elastomer lips with very low drag; coarse debris stays out, but the bearing is not liquid-tight. Within the extra-thin 618xx section (diameter series 8 of ISO 15), multiplying bore code 05 by five gives the 25 mm bore; the 37 mm outside diameter and 7 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 25 mm shaft under normal load, catalogue practice seats it on a k5 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 6805JRLLB), 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

• A 25 mm shaft for 61805 should be finished to Ra ≤ 1.6 µm with square seating faces; at this bore a scored or oval journal shows up directly as running noise and early raceway damage.
• Only 6.0 mm of radial section separates bore and OD on the 618xx series at 25 mm: ring flex from clamping or an oval housing bore transfers straight into raceway stress, so seat roundness matters more here than on a 6205.
• RSR low-friction seals on 61805-RSR-NTN run faster than contact-seal 61805-2RS but let fine dust and moisture past the non-contact lip; in dirty or wet duty specify 61805-2RS instead.
• The low-drag lip of 61805-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.
• Do not quieten a noisy bearing by preloading it: the 61800-series is a deep-groove design, not angular-contact; axial preload raises temperature and shortens grease life.
• Shaft and housing fillets must clear the bearing chamfer so the 7 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 6805JRLLB (suffix RLLB), 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).
• The 25 mm bore puts 61805 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 61805 at 18000 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.
• At 4.75 kN dynamic load rating (C) and 2.95 kN static (C0), 0.21 kN fatigue load limit Cu, 61805 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 22 g, 61805 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 25×37×7 mm envelope of 61805 gives a D/d ratio of 1.48 and 6.0 mm radial section height — this thin section saves space but is sensitive to misalignment and shock; confirm the housing stays round within IT7 and the shaft does not deflect past the raceway contact angle under load.
• The 4.75/2.95 kN load ratings, 0.21 kN fatigue load limit Cu NTN lists the grease limiting speed at 18000 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 22 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6805JRLLB on the 25×37×7 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61805 in a rated drive.
• Order the C3 internal-clearance version (61805 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 61805 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.