6301-2RS-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 6301-2RS-NSK model number is decoded

In the 6300-series (diameter series 3 of ISO 15) the last two digits encode the bore: 6301 carries bore code 12 = 12 mm. Outside diameter 37 mm and width 12 mm come from the ISO 15 boundary-dimensions general plan. Suffix -2RS denotes two contact-type elastomer seals over a lifetime grease fill; the sealing lips add drag compared with open or shielded versions. For normal-load mounting with a rotating inner ring on a 12 mm shaft, typical catalogue practice is a j5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. NSK's contact-seal catalogue number is 6301DDU (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 6301 against the shaft shoulder while it cools so the ring cannot creep back.
• The 63xx medium section at 12 mm bore gains dynamic rating through larger rolling elements on a 37 mm OD; the penalty is mass and a lower limiting speed than the 6212 — do not specify it for speed-critical shafts.
• Contact seals add drag and heat: 6301-2RS-NSK runs slower and cooler-limited than the open 6301; 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 6301-2RS: 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. 6301-2RS-NSK-C3. No clearance suffix means normal CN clearance.
• Shaft and housing fillets must clear the bearing chamfer so the 12 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
• NSK catalogues the contact-sealed version as 6301DDU (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 6301 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.
• NSK rates 6301 at 10.7 kN dynamic (C) and 4.2 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 60 g, 6301 is light enough for hand assembly but should be pressed on with a fitting sleeve against the inner ring; do not strike the outer ring or cage with a hammer.
• The 12×37×12 mm envelope of 6301 gives a D/d ratio of 3.08 and 12.5 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 10.7/4.2 kN load ratings, mass 60 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6301DDU on the 12×37×12 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6301 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.
• 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.
• When replacing a failed unit, inspect the shaft and housing seats before fitting the new 6301 — a new bearing pressed onto a worn or oval seat reproduces the original failure mode in a fraction of its expected life.