51418-M 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 51418-M model number is decoded

The 51400 series order number 51418 M is a SKF single-direction thrust ball bearing for a 90 mm seat, built to ISO 104, with a flat housing seating surface, 90×190×77 mm boundary dimensions. Three separable parts make the set: the tight-bore shaft washer that locates on the shaft, the loose-bore housing washer in its register, and the ball-cage assembly; load is purely axial and acts in one direction. reading 51xxx as a code: the 1 after 5 identifies one load direction and a flat seat, and the next digit ranks the section 1 (light) to 4 (heavy) before the two-digit bore code. bore code 18 decodes to 90 mm (code 18 × 5) under the same 00/01/02/03-exception, ×5 rule SKF uses across its coded bearing ranges. the trailing M names a solid machined brass window cage centred on the balls rather than on a washer, the catalogue choice when size, speed or interrupted lubrication rules out sheet steel. Envelope 90×190×77 mm (3.543×7.48×3.031 in), 50.0 mm radial section, C 307 kN, C0 815 kN, Pu 25.5 kN. reference speed 1,100 r/min (thermal) and limiting speed 1,500 r/min (mechanical), catalogue mass 11000 g. Bore-to-OD planning: OD 190 over bore 90 is a 2.11× step for this size, and the 77 mm height gives a bore/height ratio of 1.17; use these ratios when the housing recess around the 90 mm shaft is the first constraint. Washer-annulus check: the π/4·(D²−d²) contact annulus of 51418 M covers about 21,991 mm², distributing C0 815 kN over a mean track circle of π·dm ≈ 440 mm. Speed band width for this size is 400 r/min between reference and limiting (1.36× ratio); lubrication, preload and heat removal decide where inside that band 51418 M can actually run. Sizing arithmetic on the 90 mm bore: 307 kN C over the 50.0 mm radial section gives 6.1 kN per section millimetre, and the 77 mm stack height is 1.54× that section — proportions typical of a 51400 thrust section. Imperial cross-check for procurement drawings: 3.543 in bore, 7.48 in OD, 3.031 in height, and the 11000 g catalogue mass converts to 11.000 kg (388.0 oz). Machined-cage order-number note: the M brass cage is a one-piece ball-centred window cage, chosen at the heavy end of the section for speed and shock duty; it is heavier and stiffer than the pressed-steel execution of the smaller sizes and tolerates interrupted lubrication far better, which is why the catalogue restricts the M suffix to the large bores. The M cage of 51418 M adds a small amount of mass and cage strength without changing the 90×190×77 mm ISO 104 envelope, so the pressed-cage execution drops into the same recess but should not be assumed equal under the 1,500 r/min ceiling.

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 51400 bearing.
• 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 51418 against two-way load lifts the loose washer off its raceway.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 307/815 kN and the available 190 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• Identify the washers before fitting: the shaft washer has the ground, smaller bore and takes an interference fit on the 90 mm shaft, while the housing washer bore is larger and runs loose; swapping them locks the ball set and burns the tracks.
• Ordering discipline for 51418: the catalogue page quotes 51418 M and its 307/815 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.