51118-SKF bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-28

Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.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 51118-SKF model number is decoded

Listed in SKF 17000 chapter 5, 51118 is an ISO 104 single-direction thrust ball bearing, 90 mm bore and 120 mm OD on a flat housing seat, standing 22 mm high before installation. The bearing is delivered as separate, interchangeable parts: a ground-bore shaft washer, a loose-bore housing washer and the ball-cage assembly between them, designed for one axial load direction only. 51xxx breaks down as 5 for thrust ball, 1 for one load direction on a flat seat, a section digit 1–4 light-to-heavy, then the two-digit bore code. reading the ending 18: bore 90 mm (code 18 × 5) for this single-direction size, via the standard exceptions 00/01/02/03 and ×5 above them. no cage suffix means the standard stamped steel retainer — a pressed sheet-metal ball-cage assembly that covers the bulk of the thrust-ball assortment. Envelope 90×120×22 mm (3.543×4.724×0.866 in), 15.0 mm radial section, C 59.2 kN, C0 208 kN, Pu 7.5 kN. reference speed 2,600 r/min (thermal) and limiting speed 3,800 r/min (mechanical), catalogue mass 670 g. Mass and section check: 670 g inside the 90×120×22 mm outline leaves a 15.0 mm radial section, and the 208 kN static rating is 3.51× the dynamic rating — plan static safety and minimum preload against those figures. Light-load floor: Pu = 7.5 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 51118; the number is 13 % of the 59.2 kN dynamic rating. Imperial cross-check for procurement drawings: 3.543 in bore, 4.724 in OD, 0.866 in height, and the 670 g catalogue mass converts to 0.670 kg (23.6 oz). Load balance: C0 208 kN against C 59.2 kN gives a 3.51 ratio — thrust ball bearings are chosen on static rating and F_a/C0 far more often than on L10 life, while Pu 7.5 kN enters the adjusted-life check. Preload at the mechanical ceiling: repeating Fam ≈ A·(n·dm/1000)² with factor A 0.22 at the 3,800 r/min limiting speed raises the required axial preload to about 35.0 kN; the reference-speed value 16.4 kN is the thermal design point. Execution note for this order number: the flat housing seating surface must be machined square to the shaft axis and supported across the full washer face — unlike the sphered 53-series execution this pressed-cage 51-series bearing has no self-aligning capability at all, so seat squareness is checked at mounting, not compensated in service. On this 90 mm size the pressed cage and separable washers make the bearing interchangeable across brands on the ISO 104 plan, but the SKF ratings 59.2/208 kN are this catalogue's figures — confirm the replacement order's ratings rather than swapping on envelope alone.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• When the housing seat cannot be machined square to the 90 mm shaft, the sphered 53-series execution of this size with its U seat washer is the self-aligning counterpart of this flat 51100 bearing.
• On vertical shafts retain the loose housing washer positively with a cover or ring and verify the grease fill does not drain out of the 22 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• A 51-series bearing reacts thrust in one direction only — reversing positions need a mirrored single-direction pair or a 52-series double-direction unit; fitting a single 51118 against two-way load lifts the loose washer off its raceway.
• The three components are separable and interchangeable within the ISO 104 size, but keep this bearing's parts together in service and never combine washers from different manufacturers or a worn washer with a new ball set.
• Ordering discipline for 51118: the catalogue page quotes 51118 and its 59.2/208 kN ratings as one exact article; bare-number substitutions from another series or brand need a fresh dimension and rating check, not a like-for-like assumption.