51100-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 51100-SKF model number is decoded

Listed in SKF 17000 chapter 5, 51100 is an ISO 104 single-direction thrust ball bearing, 10 mm bore and 24 mm OD on a flat housing seat, standing 9 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 00: bore 10 mm 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 10×24×9 mm (0.394×0.945×0.354 in), 7.0 mm radial section, C 9.95 kN, C0 15.3 kN, Pu 0.56 kN. reference speed 9,500 r/min (thermal) and limiting speed 13,000 r/min (mechanical), catalogue mass 20 g. Minimum-load arithmetic: with dm ≈ 17.0 mm and factor A 0.0012, Fam ≈ A·(n·dm/1000)² at the 9,500 r/min reference speed is about 31 N for 51100; below that preload the balls skid and smear the tracks. Speed-ratio note for this exact unit: the reference speed is 9,500 r/min against a 13,000 r/min limiting speed, a reference-to-limit ratio of 0.73. Stack/annulus proportions: the 9 mm axial stack over the 374 mm² washer annulus gives 24.06 mm of height per annular square millimetre ×10⁻³, and at 20 g the bearing holds about 765.0 kN of C0 per kilogram. Speed band width for this size is 3,500 r/min between reference and limiting (1.37× ratio); lubrication, preload and heat removal decide where inside that band 51100 can actually run. Imperial cross-check for procurement drawings: 0.394 in bore, 0.945 in OD, 0.354 in height, and the 20 g catalogue mass converts to 0.020 kg (0.7 oz). 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 9 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 9.95 kN C.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Keep the applied thrust above Fam ≈ A·(n·dm/1000)² with the printed factor A 0.0012; for 51100 a spring preload or the rotor weight is part of the selection at light load and high speed, because unloaded balls skid rather than roll.
• 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 9.95 kN track before first rotation.
• 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 51100 against two-way load lifts the loose washer off its raceway.
• When the housing seat cannot be machined square to the 10 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.
• Ordering discipline for 51100: the catalogue page quotes 51100 and its 9.95/15.3 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.