61918-2RS-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 61918-2RS-NTN model number is decoded

In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61918 carries bore code 18 = 90 mm. Outside diameter 125 mm and width 18 mm come from the ISO 15 boundary-dimensions general plan. Suffix -2RS denotes two contact-type elastomer seals over a lifetime grease fill; the sealing lips add drag compared with open or shielded versions. For normal-load mounting with a rotating inner ring on a 90 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. NTN's contact-seal catalogue number is 6918LLU (suffix LLU, or LLH low-torque variant), mapped here from the industry-neutral -2RS spelling; the contacting lip lowers the speed ceiling versus the open bearing.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Large bores like the 90 mm of 61918-2RS-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 619xx thin section at 90 mm bore (17.5 mm section height) cannot shrug off the misalignment a standard section tolerates; keep the housing bores round and aligned, or edge contact will spall the raceways early.
• Heat is the enemy of the sealed 61918-2RS: sustained running near the lip temperature limit hardens the rubber, after which grease escapes and dirt tracks in — watch the housing temperature in hot drives.
• Never wash a sealed 61918-2RS-NTN in solvent or press it home via the outer ring; solvent destroys the grease thickener and mounting force through the seal deforms the lip.
• Do not quieten a noisy bearing by preloading it: the 61900-series is a deep-groove design, not angular-contact; axial preload raises temperature and shortens grease life.
• Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 61900-series position can soften the mixture and leak — clean out the old fill before switching grease types.
• NTN catalogues the contact-sealed version as 6918LLU (suffix LU), mapped here from the industry-neutral -2RS spelling; it is greased for life and the contacting lip lowers the speed ceiling versus the open bearing.
• At 90 mm bore 61918 is in NTN's medium industrial range; the pressed-steel cage is standard but large-section 63xx/64xx 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.
• NTN lists the grease limiting speed at 2900 r/min for 61918; 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 61918 at 36.5 kN dynamic (C) and 31.5 kN static (C0), 2.05 kN fatigue load limit Cu; this upper-medium rating covers conveyor and gearbox drives, but at these loads the pressed-steel cage can be the limiting factor under shock — consider the machined brass cage (suffix M) for impact duty.
• At 554 g, 61918 requires a soft-jaw vise or arbor press for mounting — never hammer it onto the shaft, and support the opposite ring to avoid brinelling the raceways.
• The 90×125×18 mm envelope of 61918 gives a D/d ratio of 1.39 and only 17.5 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 36.5/31.5 kN load ratings, 2.05 kN fatigue load limit Cu NTN lists the grease limiting speed at 2900 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 554 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6918LLU on the 90×125×18 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61918 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 61918 is listed.
• Order the C3 internal-clearance version (61918 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.