51215-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 51215-SKF model number is decoded

Listed in SKF 17000 chapter 5, 51215 is an ISO 104 single-direction thrust ball bearing, 75 mm bore and 110 mm OD on a flat housing seat, standing 27 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 15: bore 75 mm (code 15 × 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 75×110×27 mm (2.953×4.331×1.063 in), 17.5 mm radial section, C 63.7 kN, C0 170 kN, Pu 6.2 kN. reference speed 2,400 r/min (thermal) and limiting speed 3,400 r/min (mechanical), catalogue mass 830 g. Envelope economics: the 27 mm axial height over a 17.5 mm radial section yields 2.4 kN of dynamic capacity per height millimetre, and the bearing weighs 830 g for 63.7 kN C — about 13 g per rated kN. Mass and section check: 830 g inside the 75×110×27 mm outline leaves a 17.5 mm radial section, and the 170 kN static rating is 2.67× the dynamic rating — plan static safety and minimum preload against those figures. Pitch-diameter arithmetic: dm = (75+110)/2 = 92.5 mm; at the 3,400 r/min limiting speed that corresponds to roughly 315k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. Load balance: C0 170 kN against C 63.7 kN gives a 2.67 ratio — thrust ball bearings are chosen on static rating and F_a/C0 far more often than on L10 life, while Pu 6.2 kN enters the adjusted-life check. Bore-to-OD planning: OD 110 over bore 75 is a 1.47× step for this size, and the 27 mm height gives a bore/height ratio of 2.78; use these ratios when the housing recess around the 75 mm shaft is the first constraint. 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 27 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 63.7 kN C.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• When the housing seat cannot be machined square to the 75 mm shaft, the sphered 53-series execution of this size with its U seat washer is the self-aligning counterpart of this flat 51200 bearing.
• Heat the shaft washer to at most 120 °C for mounting, or press it via a sleeve on its ground bore — force applied through the housing washer or the ball set brinells the 63.7 kN track before first rotation.
• 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 27 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 63.7/170 kN and the available 110 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• Ordering discipline for 51215: the catalogue page quotes 51215 and its 63.7/170 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.