6309-RSR-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 6309-RSR-NTN model number is decoded

In the 6300-series (diameter series 3 of ISO 15) the last two digits encode the bore: 6309 carries bore code 09 = 45 mm. Outside diameter 100 mm and width 25 mm come from the ISO 15 boundary-dimensions general plan. Suffix -RSR denotes two low-friction non-contact elastomer seals; they keep coarse debris out with minimal drag but are not liquid-tight. For normal-load mounting with a rotating inner ring on a 45 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. NTN's non-contact seal suffix is LLB/LLF (catalogue number 6309LLB), mapped here from the industry-neutral -RSR spelling; speed capability matches the open bearing but it is not liquid-tight.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At a 45 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 6309-RSR-NTN; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
• The 63xx medium series gains rating at 45 mm bore through a 100 mm OD and 25 mm width; the heavier rolling elements also trade away some speed versus a 6209.
• RSR low-friction seals on 6309-RSR-NTN run faster than contact-seal 6309-2RS but let fine dust and moisture past the non-contact lip; in dirty or wet duty specify 6309-2RS instead.
• The low-drag lip of 6309-RSR-NTN barely touches the inner ring; after long shelf storage the grease can separate, so rotate the rings by hand and confirm smooth, silent running before fitting.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 100 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 6309-RSR-NTN.
• Measure the shaft, do not trust the drawing: a 45 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 6309-RSR-NTN.
• NTN catalogues this low-friction non-contact seal as 6309LLB (suffix LLB), mapped here from the industry-neutral -RSR spelling. NTN rates its speed capability the same as the open bearing, but it is not liquid-tight — for wet or fine-dust duty step up to the LLU contact seal (industry-neutral -2RS).
• The 45 mm bore puts 6309 in NTN's general-purpose industrial range; the standard pressed-steel cage and CN clearance cover most electric-motor and 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.
• At 5600 r/min the grease limiting speed for 6309 covers medium-duty industrial drives; the open or shielded execution can run continuously at this speed with standard lithium-soap grease.
• NTN rates 6309 at 58.5 kN dynamic (C) and 32 kN static (C0), 2.5 kN fatigue load limit Cu; this upper-medium rating covers conveyor and gearbox drives, but at these loads the pressed-steel cage can be the limiting factor under shock — consider the machined brass cage (suffix M) for impact duty.
• At 814 g, 6309 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 45×100×25 mm envelope of 6309 gives a D/d ratio of 2.22 and 27.5 mm radial section height — a heavy 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 58.5/32 kN load ratings, 2.5 kN fatigue load limit Cu NTN lists the grease limiting speed at 5600 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 814 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6309LLB on the 45×100×25 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6309 in a rated drive.
• NTN's pressed-steel cage (no cage suffix) is the quiet standard for this size; for sustained running close to the limiting speed or for heavy shock duty, ask the NTN channel whether a machined-cage execution of 6309 is listed.
• Order the C3 internal-clearance version (6309 with C3 after the seal code) when the shaft fit is tight or the shaft-to-housing temperature gradient exceeds roughly 10 °C — the residual clearance after mounting, not the catalogue CN figure, decides service life.