61811-ZZ-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 61811-ZZ-NTN model number is decoded

In the 61800-series (diameter series 8 of ISO 15) the last two digits encode the bore: 61811 carries bore code 11 = 55 mm. Outside diameter 72 mm and width 9 mm come from the ISO 15 boundary-dimensions general plan. Suffix -ZZ denotes two non-contact metallic shields; they retain grease and block coarse debris but are not liquid-tight. For normal-load mounting with a rotating inner ring on a 55 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. NTN catalogue order number: 6811JRZZ (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

• Interference on a 55 mm shaft plus running heat consumes radial clearance: where the shaft runs hot or the fit is tight, order 61811 with C3 clearance and re-check the residual value after mounting.
• Only 8.5 mm of radial section separates bore and OD on the 618xx series at 55 mm: ring flex from clamping or an oval housing bore transfers straight into raceway stress, so seat roundness matters more here than on a 6211.
• ZZ shields are non-contact: 61811-ZZ-NTN blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 61811-2RS for that.
• Shielded 61811-ZZ-NTN units are typically greased for life; prying the shields out for regreasing usually bends them and leaves a gap that throws grease in service.
• Shaft and housing fillets must clear the bearing chamfer so the 9 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 72 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 61811-ZZ-NTN.
• NTN catalogues the shielded version as 6811JRZZ — suffix ZZ, two non-contact steel shields. The industry-neutral page spelling is -ZZ; quote the NTN order number when buying through an NTN channel.
• At 55 mm bore 61811 is in NTN's upper general-purpose range; the pressed-steel cage is standard but mid-section 63xx sizes at this bore can be ordered with a machined brass cage (suffix M) for heavy-shock or very-low-speed duty — confirm cage material with the NTN channel if the application sees impact loads.
• At 8700 r/min the grease limiting speed for 61811 covers most general-purpose industrial drives; the open or shielded execution can run continuously at this speed with standard lithium-soap grease.
• NTN rates 61811 at 9.75 kN dynamic (C) and 8.1 kN static (C0), 0.54 kN fatigue load limit Cu; this light-to-medium rating suits fractional-horsepower drives and instruments — for conveying or gearbox duty with shock loads, verify the equivalent dynamic load stays well below C.
• At 83 g, 61811 is light enough for hand assembly but should be pressed on with a fitting sleeve against the inner ring; do not strike the outer ring or cage with a hammer.
• The 55×72×9 mm envelope of 61811 gives a D/d ratio of 1.31 and only 8.5 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 9.75/8.1 kN load ratings, 0.54 kN fatigue load limit Cu NTN lists the grease limiting speed at 8700 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 83 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6811JRZZ on the 55×72×9 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61811 in a rated drive.
• Two NTN bearings of the same designation from different production lots can carry minor internal-geometry revisions; for paired or preloaded arrangements on one shaft, order a single lot through the NTN distributor.
• Order the C3 internal-clearance version (61811 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.