61801-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 61801-NTN model number is decoded

In the 61800-series (diameter series 8 of ISO 15) the last two digits encode the bore: 61801 carries bore code 12 = 12 mm. Outside diameter 21 mm and width 5 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 12 mm shaft, typical catalogue practice is a j5 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

• Interference on a 12 mm shaft plus running heat consumes radial clearance: where the shaft runs hot or the fit is tight, order 61801 with C3 clearance and re-check the residual value after mounting.
• The 618xx thin section at 12 mm bore has only a 4.5 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 6212.
• The open 61801-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 12×21×5 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 61801-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 12 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 61801-NTN.
• Never mix components between two 61801-NTN units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
• The open 61801 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.
• At 12 mm bore the 61801 sits in NTN's small-bore range; ABEC-1/P0 runout is standard, and the pressed-steel cage is adequate up to the grease limiting speed — for higher accuracy (spindles, instruments) ask NTN for a P6 or P5 tolerance-class listing before relying on catalogue P0 figures.
• The 29000 r/min grease limiting speed puts 61801 in NTN's high-speed range; at these speeds relubrication interval shortens sharply and the pressed-steel cage must be checked for cage-bar critical speed.
• At 2.12 kN dynamic load rating (C) and 1.04 kN static (C0), 0.08 kN fatigue load limit Cu, 61801 is a light-load bearing: the L10 life at catalogue C is short above a few kN of equivalent load, so size up to a 62-series on the same bore if the application sees shock or frequent starts.
• At only 6 g, 61801 is a lightweight bearing that can be handled by hand; still, press it onto the shaft with a sleeve against the inner ring — never through the balls or outer ring.
• The 12×21×5 mm envelope of 61801 gives a D/d ratio of 1.75 and 4.5 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 2.12/1.04 kN load ratings, 0.08 kN fatigue load limit Cu NTN lists the grease limiting speed at 29000 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 6 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6801 on the 12×21×5 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61801 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 61801 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.