61806-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 61806-NTN model number is decoded

In the 61800-series (diameter series 8 of ISO 15) the last two digits encode the bore: 61806 carries bore code 06 = 30 mm. Outside diameter 42 mm and width 7 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 30 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 30 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 61806-NTN; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
• The 618xx thin section at 30 mm bore has only a 6.0 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 6206.
• The open 61806-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 30×42×7 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 61806-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.
• 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.
• Vibration during standstill brinells the raceways of a 30 mm bearing at ball spacing; if the machine sits idle next to running equipment, turn the shaft over periodically or isolate the arrangement.
• The open 61806 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 30 mm bore puts 61806 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 61806 at 15000 r/min grease limiting speed — this is an electric-motor range; keep the grease fill at 25–35% of the free bearing volume and avoid mixing grease thickener types if regreasing through the housing.
• NTN rates 61806 at 5.2 kN dynamic (C) and 3.65 kN static (C0), 0.24 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 26 g, 61806 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 30×42×7 mm envelope of 61806 gives a D/d ratio of 1.40 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 5.2/3.65 kN load ratings, 0.24 kN fatigue load limit Cu NTN lists the grease limiting speed at 15000 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 26 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6806JR on the 30×42×7 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61806 in a rated drive.
• Standard catalogue stock of 61806 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 date-codes its packaging; rotate stock first-in-first-out, because the grease inside sealed units ages on the shelf — after three to five years of storage, check the grease condition before putting the bearing into service.