61918-RSR bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NSK Rolling Bearings E1103 Part C) · extracted 2026-09-24

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-RSR 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 -RSR denotes two low-friction non-contact elastomer seals; they keep coarse debris out with minimal drag but are not liquid-tight. 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. NSK's non-contact seal suffix is VV (catalogue number 6918VV), mapped here from the industry-neutral -RSR spelling; speed capability is close to the open bearing but VV is not liquid-tight.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At 90 mm bore the ring mass is significant: heat 61918 on an induction heater (max 120 °C), never over an open flame, and plan puller access or a withdrawal sleeve now for the day it has to come off again.
• 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.
• RSR low-friction seals on 61918-RSR run faster than contact-seal 61918-2RS but let fine dust and moisture past the non-contact lip; in dirty or wet duty specify 61918-2RS instead.
• The non-contact lip of 61918-RSR does not retain a lifetime grease fill the way a contact seal does; confirm the regreasing interval for the 90 mm bore position before relying on it as sealed-for-life.
• Measure the shaft, do not trust the drawing: a 90 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 61918-RSR.
• 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.
• NSK catalogues this low-friction non-contact seal as 6918VV (suffix VV), mapped here from the industry-neutral -RSR spelling. NSK rates its speed capability close to the open bearing, but VV is not liquid-tight — for wet or fine-dust duty step up to the DDU contact seal (industry-neutral -2RS).
• At 90 mm bore 61918 is in NSK's medium industrial range; the pressed-steel cage is standard, but large-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 NSK channel if the application sees impact loads.
• NSK rates 61918 at 36 kN dynamic (C) and 31.5 kN static (C0); 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 585 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 in NSK's E1103 catalogue 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 36/31.5 kN load ratings, mass 585 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6918VV 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. NSK does not tabulate reference or limiting speeds in the E1103 Part C dimension tables used for this page — consult NSK's separate speed-rating tables before high-speed service.
• NSK does not recommend washing new shielded or sealed bearings; the rust-preventive film on open units is compatible with standard lithium greases and needs no removal unless the application demands a special fill.
• NSK's VV non-contact seal keeps frictional torque close to the open 61918; in motor duty where heat build-up matters, VV is the usual compromise between debris protection and speed capability.