61856-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 61856-NTN model number is decoded

In the 61800-series (diameter series 8 of ISO 15) the last two digits encode the bore: 61856 carries bore code 56 = 280 mm. Outside diameter 350 mm and width 33 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 280 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

• Mount this 280 mm bore bearing by heating the inner ring (induction heater, max 120 °C) — never drive it home through the outer ring or balls, that brinells the raceways.
• The 618xx thin section at 280 mm bore has only a 35.0 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 6256.
• The open 61856-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 280×350×33 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 61856-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.
• Measure the shaft, do not trust the drawing: a 280 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 61856-NTN.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 350 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 61856-NTN.
• The open 61856 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 280 mm bore places 61856 in NTN's extra-large range; the pressed-steel cage is not recommended at this diameter and NTN supplies a machined brass cage (suffix M) as the standard offering. Speed ratings are low, housing alignment is critical, and oil lubrication with a defined relubrication interval is mandatory — consult NTN engineering before sizing.
• NTN lists the grease limiting speed at 1600 r/min for 61856; 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.
• At 151 kN dynamic load rating (C) and 177 kN static (C0), 6.65 kN fatigue load limit Cu, 61856 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 7400 g (7.4 kg), 61856 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 280×350×33 mm envelope of 61856 gives a D/d ratio of 1.25 and only 35.0 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 151/177 kN load ratings, 6.65 kN fatigue load limit Cu NTN lists the grease limiting speed at 1600 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 7400 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6856 on the 280×350×33 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61856 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 61856 is listed.
• NTN date-codes its packaging; rotate stock first-in-first-out, because the grease inside sealed units ages on the shelf — after three to five years of storage, check the grease condition before putting the bearing into service.