6238-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 6238-NTN model number is decoded

6238 is supplied open, without shields or seals, so the arrangement around it must supply and retain the lubricant. 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. In the NTN catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes ZZ (shields), LLB/LLF (non-contact seals), LLH (low-torque contact seal) and LLU (contact seal).

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At 190 mm bore the ring mass is significant: heat 6238 on an induction heater (max 120 °C), never over an open flame, and plan puller access or a withdrawal sleeve now for the day it has to come off again.
• 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.
• The open 6238-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 190×340×55 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 6238-NTN leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
• The housing bore for the 340 mm OD should be round within IT7; an oval bore pinches the outer ring of 6238-NTN and shows up later as two-point loaded raceway wear.
• 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-NTN.
• The open 6238 has no integral sealing; in the NTN 2203 catalogue the protected variants carry suffixes ZZ (non-contact steel shields), LLB/LLF (non-contact rubber seals), LLU (contact rubber seals) and LLH (a low-torque contact seal with higher speed capability than LLU). A JR or JRX suffix (printed for some thin-section sizes) denotes a pressed-steel cage, not a seal.
• The 190 mm bore places 6238 in NTN's large-size range; at these diameters the pressed-steel cage is speed-limited and NTN commonly supplies a machined brass cage (suffix M) as an option. Verify cage material and relubrication interval with the NTN distributor, and do not extrapolate small-bore speed ratings to this size.
• NTN lists the grease limiting speed at 1800 r/min for 6238; this is a large or heavy-section size where centrifugal force and cage inertia cap the speed — for higher shaft speeds either step to a smaller bearing on the same bore or consult NTN for an oil-lubricated, machined-cage variant.
• NTN rates 6238 at 282 kN dynamic (C) and 281 kN static (C0), 13.5 kN fatigue load limit Cu; this is an upper heavy-load rating where the pressed-steel cage is not recommended — NTN supplies a machined brass cage (suffix M) and the static C0 must be verified against any shock or lifting loads the bearing sees during mounting.
• At 18200 g (18.2 kg), 6238 is a heavy bearing that requires a crane or hoist for handling; induction-heat the inner ring (max 120 °C) and use a mechanical puller for removal — never apply heat directly to the balls or 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 medium section that balances load capacity and speed; for this geometry the pressed-steel cage is adequate up to the listed limiting speed, and C3 clearance is the common choice for hot shafts.
• The 282/281 kN load ratings, 13.5 kN fatigue load limit Cu NTN lists the grease limiting speed at 1800 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 18200 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6238 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.
• 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 6238 is listed.
• Standard catalogue stock of 6238 is the general-purpose execution; for low-noise motor duty NTN offers low-torque seal and special-grease variants in this size class, which are separate order numbers.