61901-2RS-NSK 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 61901-2RS-NSK model number is decoded

61901-2RS is closed by two contacting elastomer lips over a lifetime grease fill; the lips add friction, so the speed ceiling sits below the open execution. Within the thin 619xx section (diameter series 9 of ISO 15), multiplying bore code 12 by five gives the 12 mm bore; the 24 mm outside diameter and 6 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 12 mm shaft under normal load, catalogue practice seats it on a j5 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. NSK's contact-seal catalogue number is 6901DD (suffix DDU), mapped here from the industry-neutral -2RS spelling; it is greased for life and the contacting lip lowers the speed ceiling versus the open bearing.

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 61901 against the shaft shoulder while it cools so the ring cannot creep back.
• The 619xx thin section (6.0 mm section height at 12 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
• Contact seals add drag and heat: 61901-2RS-NSK runs slower and cooler-limited than the open 61901; rubber lips are generally limited to roughly 80–110 °C continuous depending on grease, and C3 clearance is the common hot-duty choice.
• Heat is the enemy of the sealed 61901-2RS: sustained running near the lip temperature limit hardens the rubber, after which grease escapes and dirt tracks in — watch the housing temperature in hot drives.
• Suffixes stack in a defined order — clearance follows the seal code, e.g. 61901-2RS-NSK-C3. No clearance suffix means normal CN clearance.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 24 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 61901-2RS-NSK.
• NSK catalogues the contact-sealed version as 6901DD (suffix DDU), mapped here from the industry-neutral -2RS spelling; it is greased for life and the contacting lip lowers the speed ceiling versus the open bearing. NSK's DDU lip design is single-lip contact, so grease life is longer than VV but drag torque is higher.
• At 12 mm bore the 61901 sits in NSK's small-bore range; NSK ships these sizes with a pressed-steel cage and P0 tolerance as standard, and NSK's EA (extra-precision) or P5 class is a special-order upgrade for spindle duty — do not assume catalogue P0 figures hold for instrument use without an NSK engineering check.
• At 3.2 kN dynamic load rating (C) and 1.46 kN static (C0), 61901 is a light-load NSK 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 10 g, 61901 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 12×24×6 mm envelope of 61901 gives a D/d ratio of 2.00 and 6.0 mm radial section height — a heavy NSK section built for high-load, lower-speed duty; specifying it in a high-rpm motor generates excess heat and shortens grease life, so prefer a 62/63-series there.
• The 3.2/1.46 kN load ratings, mass 10 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6901DD on the 12×24×6 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61901 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's VV non-contact seal keeps frictional torque close to the open 61901; in motor duty where heat build-up matters, VV is the usual compromise between debris protection and speed capability.
• NSK does not recommend washing new shielded or sealed bearings; the rust-preventive film on open units is compatible with standard lithium greases and needs no removal unless the application demands a special fill.