6340 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 6340 model number is decoded

In the 6300-series (diameter series 3 of ISO 15) the last two digits encode the bore: 6340 carries bore code 40 = 200 mm. Outside diameter 420 mm and width 80 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 200 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the NSK catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes ZZ (steel shields), VV (non-contact rubber seals) and DDU (contact rubber seals).

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Large bores like the 200 mm of 6340 demand clean, burr-free seats; one raised burr under a ring this size cocks the bearing and concentrates load at the raceway edge, cutting life drastically.
• The 63xx medium section at 200 mm bore gains dynamic rating through larger rolling elements on a 420 mm OD; the penalty is mass and a lower limiting speed than the 6240 — do not specify it for speed-critical shafts.
• The open 6340 has no lubricant retention: grease escapes and contaminants migrate straight into the 200×420×80 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Open bearings tolerate the highest speeds in the 6300-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 6340 units.
• Suffixes stack in a defined order — clearance follows the seal code, e.g. 6340-C3. No clearance suffix means normal CN clearance.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 420 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 6340.
• The open 6340 has no integral sealing; in the NSK E1103 catalogue the protected variants carry suffixes ZZ (non-contact steel shields), VV (non-contact rubber seals) and DDU (contact rubber seals). NSK does not offer a low-torque contact seal equivalent to NTN's LLH in this catalogue — for high-speed sealed duty specify the VV non-contact seal and an external housing labyrinth.
• The 200 mm bore places 6340 in NSK's large-size range; at these diameters the pressed-steel cage is speed-limited and NSK commonly supplies a machined brass cage (suffix M) as an option. Verify cage material and relubrication interval with the NSK distributor, and do not extrapolate small-bore speed ratings to this size.
• NSK rates 6340 at 415 kN dynamic (C) and 445 kN static (C0); this is an extreme-load bearing at the top of the E1103 Part C single-row deep-groove range, where mounting, shaft stiffness and housing alignment dominate the achievable life. Consult NSK engineering for a full application review rather than relying on catalogue L10 alone.
• At 55300 g (55.3 kg), 6340 is a very heavy NSK bearing where handling and mounting method directly affect service life; NSK requires induction heating of the inner ring (max 120 °C), a mechanical puller for removal, and a defined lifting procedure to avoid damaging the cage.
• The 200×420×80 mm envelope of 6340 gives a D/d ratio of 2.10 and 110.0 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 415/445 kN load ratings, mass 55300 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6340 on the 200×420×80 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6340 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.
• 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.