51276-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 51276-F model number is decoded

51276 F is SKF's 380 mm-bore single-direction thrust ball bearing in the 51200 series to the ISO 104 dimension plan, with a flat housing seating surface, measuring 380×520×112 mm. The separable set comprises a shaft washer (ground bore, tight fit on the shaft), a loose-bore housing washer and one ball-cage assembly, reacting axial force in one direction and carrying no radial load. in the 51xxx designation the first 1 marks a single-direction bearing with a flat housing seating surface; the third digit 1–4 grades the dimension series from the light 511 section through the heavy 514 section. the final two digits 76 encode the bore as 380 mm (code 76 × 5), the standard SKF bore-code rule shared with radial bearings. suffix F identifies a machined steel cage, ball-centred: fitted to the largest sizes of the assortment where the ball complement and centrifugal forces exceed what the stamped sheet-steel execution can guide. Envelope 380×520×112 mm (14.961×20.472×4.409 in), 70.0 mm radial section, C 728 kN, C0 4150 kN, Pu 72 kN. reference speed 500 r/min (thermal) and limiting speed 700 r/min (mechanical), catalogue mass 73000 g. Bore-to-OD planning: OD 520 over bore 380 is a 1.37× step for this size, and the 112 mm height gives a bore/height ratio of 3.39; use these ratios when the housing recess around the 380 mm shaft is the first constraint. Mass and section check: 73000 g inside the 380×520×112 mm outline leaves a 70.0 mm radial section, and the 4150 kN static rating is 5.70× the dynamic rating — plan static safety and minimum preload against those figures. Rating split for documentation: dynamic 728 kN (L10 life), static 4150 kN (safety factor s0), fatigue limit 72 kN (adjusted life) — three different uses of three different numbers for 51276 F, none interchangeable with another. Sizing arithmetic on the 380 mm bore: 728 kN C over the 70.0 mm radial section gives 10.4 kN per section millimetre, and the 112 mm stack height is 1.60× that section — proportions typical of a 51200 thrust section. Imperial cross-check for procurement drawings: 14.961 in bore, 20.472 in OD, 4.409 in height, and the 73000 g catalogue mass converts to 73.000 kg (2575.0 oz). 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. Mounting note for the 112 mm F stack: induction-heat the shaft washer only — the machined steel cage rides the balls and must never be tapped, and first rotation should be a slow unloaded bedding run before the working thrust goes on.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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 728 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 112 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• 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.
• 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 51276 against two-way load lifts the loose washer off its raceway.
• The 728/4150 kN figures belong to 51276 F specifically (the single flat machined steel execution of 51276); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.