61820-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 61820-ZZ model number is decoded

61820-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 20 by five gives the 100 mm bore; the 125 mm outside diameter and 13 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 100 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: 6820ZZ (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

• Mount this 100 mm bore bearing by heating the inner ring (induction heater, max 120 °C) — never drive it home through the outer ring or balls, that brinells the raceways.
• Only 12.5 mm of radial section separates bore and OD on the 618xx series at 100 mm: ring flex from clamping or an oval housing bore transfers straight into raceway stress, so seat roundness matters more here than on a 6220.
• ZZ shields are non-contact: 61820-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 61820-2RS for that.
• Shielded 61820-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. 61820-C3. No clearance suffix means normal CN clearance.
• The housing bore for the 125 mm OD should be round within IT7; an oval bore pinches the outer ring of 61820-ZZ and shows up later as two-point loaded raceway wear.
• NSK catalogues the shielded version as 6820ZZ — 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.
• At 100 mm bore 61820 is in NSK's medium industrial range; the pressed-steel cage is standard, but large-section 63xx sizes at this bore can be ordered with a machined brass cage (suffix M) for heavy-shock or very-low-speed duty — confirm cage material with the NSK channel if the application sees impact loads.
• At 21.5 kN dynamic load rating (C) and 23 kN static (C0), 61820 is a medium-load NSK bearing suitable for most electric-motor and pump duty; the C0/C0r ratio matters for preloaded or thrust-loaded arrangements, so confirm the static safety factor with the NSK catalogue.
• At 310 g, 61820 requires a soft-jaw vise or arbor press for mounting — never hammer it onto the shaft, and support the opposite ring to avoid brinelling the raceways.
• The 100×125×13 mm envelope of 61820 gives a D/d ratio of 1.25 and only 12.5 mm radial section height — this is an ultra-thin section in NSK's E1103 catalogue where shaft deflection and housing ovality directly load the ball-raceway contact; verify shaft stiffness (target deflection under 0.05 mm) before specifying it over a 62-series.
• The 21.5/23 kN load ratings, mass 310 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6820ZZ on the 100×125×13 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61820 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.
• NSK supplies its sealed units pre-greased for general duty between roughly -10 and +110 °C; low-temperature, food-grade and high-temperature fills are special executions — ask at order time, because DDU/VV units are not designed to be opened and repacked.
• Keep NSK bearings in the original packaging until fitting: the wrapper carries the production lot, and the unopened shelf life of greased sealed units is typically quoted at three to five years in dry, vibration-free storage.