51406-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 51406-SKF model number is decoded

Listed in SKF 17000 chapter 5, 51406 is an ISO 104 single-direction thrust ball bearing, 30 mm bore and 70 mm OD on a flat housing seat, standing 28 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 06: bore 30 mm (code 06 × 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 30×70×28 mm (1.181×2.756×1.102 in), 20.0 mm radial section, C 70.2 kN, C0 122 kN, Pu 4.5 kN. reference speed 3,000 r/min (thermal) and limiting speed 4,300 r/min (mechanical), catalogue mass 520 g. At the printed limiting speed of 4,300 r/min the mean pitch diameter dm ≈ 50.0 mm implies a dn value around 215k mm·r/min; the 3,000 r/min reference speed is the thermal-planning value under catalogue load. Mass and section check: 520 g inside the 30×70×28 mm outline leaves a 20.0 mm radial section, and the 122 kN static rating is 1.74× the dynamic rating — plan static safety and minimum preload against those figures. Pitch-diameter arithmetic: dm = (30+70)/2 = 50.0 mm; at the 4,300 r/min limiting speed that corresponds to roughly 215k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. Rating split for documentation: dynamic 70.2 kN (L10 life), static 122 kN (safety factor s0), fatigue limit 4.5 kN (adjusted life) — three different uses of three different numbers for 51406, none interchangeable with another. Minimum-load arithmetic: with dm ≈ 50.0 mm and factor A 0.097, Fam ≈ A·(n·dm/1000)² at the 3,000 r/min reference speed is about 2.2 kN for 51406; below that preload the balls skid and smear the tracks. 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. Inspection after removal of a 28 mm-high stack means checking both washer faces: the loose housing washer often shows the first false-brinell marks under machine vibration even though the tight shaft washer carries the rotating load of 70.2 kN C.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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 51406 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.
• 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 28 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• Identify the washers before fitting: the shaft washer has the ground, smaller bore and takes an interference fit on the 30 mm shaft, while the housing washer bore is larger and runs loose; swapping them locks the ball set and burns the tracks.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for 51406 as the single flat pressed steel execution; other order numbers of the 51406 size are different products and may carry different ratings or seating geometry — always quote the full designation when purchasing.