51268-F 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 51268-F model number is decoded

The 51200 series order number 51268 F is a SKF single-direction thrust ball bearing for a 340 mm seat, built to ISO 104, with a flat housing seating surface, 340×460×96 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 68 decodes to 340 mm (code 68 × 5) under the same 00/01/02/03-exception, ×5 rule SKF uses across its coded bearing ranges. the F suffix denotes a steel cage machined from solid and centred on the balls, reserved for the largest OD sizes whose ball mass is beyond pressed-cage guidance. Envelope 340×460×96 mm (13.386×18.11×3.78 in), 60.0 mm radial section, C 605 kN, C0 3200 kN, Pu 25.5 kN. reference speed 600 r/min (thermal) and limiting speed 800 r/min (mechanical), catalogue mass 48500 g. Selection figures for 51268 F: the C0/C ratio is 5.29, Pu 25.5 kN is about 4 % of C, and the catalogue mass works out to roughly 143 g per millimetre of bore; the printed minimum-load factor is A 53. Speed planning separates the two ceilings mechanically: the pressed steel cage and balls tolerate 800 r/min while thermal balance under catalogue load sets the 600 r/min reference; at dm ≈ 400.0 mm the corresponding dn is approximately 320k mm·r/min. Track-circle loading: per millimetre of mean track circumference the 605 kN dynamic rating corresponds to roughly 0.48 kN/mm of π·dm track, a useful comparison against the other dimension series of the 340 mm bore. Rating split for documentation: dynamic 605 kN (L10 life), static 3200 kN (safety factor s0), fatigue limit 25.5 kN (adjusted life) — three different uses of three different numbers for 51268 F, none interchangeable with another. At the printed limiting speed of 800 r/min the mean pitch diameter dm ≈ 400.0 mm implies a dn value around 320k mm·r/min; the 600 r/min reference speed is the thermal-planning value under catalogue load. Large-size execution note: the F machined steel cage exists because the ball complement and pitch diameter of the biggest 512-series sizes are beyond pressed-cage guidance; the steel cage is machined from solid, ball-centred, and its heavier mass must be supported by genuine oil or grease flow at start-up — never mount an F bearing dry for a trial rotation. The F execution appears only at the 340 mm top end of the range: the 460 mm OD ball complement is large enough that cage centrifugal forces dictate a machined guide, which is also why the 3200 kN C0 figure dominates selection of this order number.

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 53; for 51268 F 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.
• The 51268 F is a pure axial bearing: it must never be subjected to radial load — any radial force on the 340 mm shaft has to be carried by a radial bearing mounted alongside it.
• Identify the washers before fitting: the shaft washer has the ground, smaller bore and takes an interference fit on the 340 mm shaft, while the housing washer bore is larger and runs loose; swapping them locks the ball set and burns the tracks.
• 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 605 kN track before first rotation.
• Ordering discipline for 51268: the catalogue page quotes 51268 F and its 605/3200 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.