61806-ZZ bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NSK Rolling Bearings E1103 Part C) · extracted 2026-09-24

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-ZZ model number is decoded

61806-ZZ carries two non-contact sheet-steel shields that hold the factory grease in and keep coarse debris out; they do not seal against liquids. Within the extra-thin 618xx section (diameter series 8 of ISO 15), multiplying bore code 06 by five gives the 30 mm bore; the 42 mm outside diameter and 7 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 30 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. NSK catalogue order number: 6806ZZ (suffix ZZ), two non-contact steel shields, mapped here from the industry-neutral -ZZ spelling.

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-ZZ; 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.
• Do not wash 61806-ZZ in solvent before mounting: the grease inside the shielded cavity is the service fill, and solvent creeping past the shield gap strips it out.
• Shielded 61806-ZZ units are typically greased for life; prying the shields out for regreasing usually bends them and leaves a gap that throws grease in service.
• Suffixes stack in a defined order — clearance follows the seal code, e.g. 61806-C3. No clearance suffix means normal CN clearance.
• The housing bore for the 42 mm OD should be round within IT7; an oval bore pinches the outer ring of 61806-ZZ and shows up later as two-point loaded raceway wear.
• NSK catalogues the shielded version as 6806ZZ — suffix ZZ, two non-contact steel shields. The industry-neutral page spelling is -ZZ; quote the NSK order number when buying through an NSK channel.
• The 30 mm bore puts 61806 in NSK's light industrial range; the standard pressed-steel cage and CN clearance cover most fractional-horsepower motor and small-pump duty. NSK's VV non-contact seal is the high-speed choice here — DDU contact seal costs roughly 30–40% of the open-bearing speed ceiling.
• NSK rates 61806 at 5.2 kN dynamic (C) and 3.65 kN static (C0); 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 24 g, 61806 is a lightweight NSK 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 NSK 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, mass 24 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6806ZZ 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. NSK does not tabulate reference or limiting speeds in the E1103 Part C dimension tables used for this page — consult NSK's separate speed-rating tables before high-speed service.
• When replacing a failed unit, inspect the shaft and housing seats before fitting the new 61806 — a new bearing pressed onto a worn or oval seat reproduces the original failure mode in a fraction of its expected life.
• Standard P0 runout from NSK is adequate up to the catalogue limiting speed on ground shaft seats; spindle or instrument positions should specify P6/P5 accuracy explicitly — it is a different order code, not a sorting of standard stock.