6238-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 6238-ZZ model number is decoded

6238-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 light 62xx section (diameter series 2 of ISO 15), multiplying bore code 38 by five gives the 190 mm bore; the 340 mm outside diameter and 55 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 190 mm shaft under normal load, catalogue practice seats it on a m6 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. NSK catalogue order number: 6238ZZ (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

• Large bores like the 190 mm of 6238-ZZ 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 62xx light series is the default general-purpose section at 190 mm bore; before upgrading to a 6338 for extra capacity, confirm the housing accepts a 340 mm OD and 55 mm width — it is not a drop-in swap.
• ZZ shields are non-contact: 6238-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 6238-2RS for that.
• Do not wash 6238-ZZ in solvent before mounting: the grease inside the shielded cavity is the service fill, and solvent creeping past the shield gap strips it out.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 340 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 6238-ZZ.
• Measure the shaft, do not trust the drawing: a 190 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 6238-ZZ.
• NSK catalogues the shielded version as 6238ZZ — 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.
• The 190 mm bore places 6238 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 6238 at 280 kN dynamic (C) and 282 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 22300 g (22.3 kg), 6238 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 190×340×55 mm envelope of 6238 gives a D/d ratio of 1.79 and 75.0 mm radial section height — a standard NSK medium section that balances load capacity and speed; for this geometry the pressed-steel cage is adequate up to NSK's listed speed ratings, and C3 clearance is the common choice for hot shafts.
• The 280/282 kN load ratings, mass 22300 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6238ZZ on the 190×340×55 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6238 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 6238; 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.