61868-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 61868-NTN model number is decoded

In the 61800-series (diameter series 8 of ISO 15) the last two digits encode the bore: 61868 carries bore code 68 = 340 mm. Outside diameter 420 mm and width 38 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 340 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 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

• Large bores like the 340 mm of 61868-NTN 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 618xx thin section at 340 mm bore has only a 40.0 mm radial section height: it saves space but is highly sensitive to misalignment, shaft deflection and shock loads — verify shaft stiffness before choosing it over a 6268.
• The open 61868-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 340×420×38 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Open bearings tolerate the highest speeds in the 61800-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 61868 units.
• Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 61800-series position can soften the mixture and leak — clean out the old fill before switching grease types.
• Measure the shaft, do not trust the drawing: a 340 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 61868-NTN.
• The open 61868 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 340 mm bore places 61868 in NTN's maximum-size range at the lower end; this is a heavy-engineering bearing where centrifugal force and cage inertia dominate the design envelope. NTN supplies a machined brass cage (suffix M) and expects oil lubrication; do not use catalogue grease speed figures for this size without an NTN engineering review.
• NTN lists the grease limiting speed at 1300 r/min for 61868; this is a large-section size where the pressed-steel cage is speed-limited — NTN recommends the machined brass cage (suffix M) and oil lubrication for any continuous operation above this figure.
• At 189 kN dynamic load rating (C) and 236 kN static (C0), 8.05 kN fatigue load limit Cu, 61868 is a heavy-load bearing for industrial gearboxes and large conveyors; NTN expects a machined brass cage (suffix M) at this rating for shock duty, and the static C0 must be checked against any mounting or lifting loads.
• At 11500 g (11.5 kg), 61868 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 340×420×38 mm envelope of 61868 gives a D/d ratio of 1.24 and only 40.0 mm radial section height — this is an ultra-thin section where shaft deflection and housing ovality directly load the ball-raceway contact; verify shaft stiffness (target deflection under 0.05 mm) before specifying it over a 62-series.
• The 189/236 kN load ratings, 8.05 kN fatigue load limit Cu NTN lists the grease limiting speed at 1300 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 11500 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6868 on the 340×420×38 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61868 in a rated drive.
• Standard catalogue stock of 61868 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.
• Order the C3 internal-clearance version (61868 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.