51210-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 51210-SKF model number is decoded

The 51200 series order number 51210 is a SKF single-direction thrust ball bearing for a 50 mm seat, built to ISO 104, with a flat housing seating surface, 50×78×22 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 10 decodes to 50 mm (code 10 × 5) under the same 00/01/02/03-exception, ×5 rule SKF uses across its coded bearing ranges. the suffix-free listing carries the catalogue default: a pressed (stamped sheet-steel) ball-cage assembly, light and quiet, used across the small and medium sizes. Envelope 50×78×22 mm (1.969×3.071×0.866 in), 14.0 mm radial section, C 49.4 kN, C0 116 kN, Pu 4.3 kN. reference speed 3,400 r/min (thermal) and limiting speed 4,500 r/min (mechanical), catalogue mass 370 g. Speed planning separates the two ceilings mechanically: the pressed cage and balls tolerate 4,500 r/min while thermal balance under catalogue load sets the 3,400 r/min reference; at dm ≈ 64.0 mm the corresponding dn is approximately 288k mm·r/min. Bore-to-OD planning: OD 78 over bore 50 is a 1.56× step for this size, and the 22 mm height gives a bore/height ratio of 2.27; use these ratios when the housing recess around the 50 mm shaft is the first constraint. Section proportions: the 14.0 mm radial section compares with 50 mm of bore (section/bore ≈ 0.28) and the 22 mm height is 1.57× that section — the proportions that identify the 51200 envelope at a glance. Light-load floor: Pu = 4.3 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 51210; the number is 9 % of the 49.4 kN dynamic rating. Static-first selection data: 116 kN C0 spread across the 22 mm stack gives 5.3 kN of static rating per height millimetre, and the 370 g mass/C0 ratio is about 3 g per static kN — crane-hook and screw positions are normally sized on these two figures. 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. On this 50 mm size the pressed cage and separable washers make the bearing interchangeable across brands on the ISO 104 plan, but the SKF ratings 49.4/116 kN are this catalogue's figures — confirm the replacement order's ratings rather than swapping on envelope alone.

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 49.4 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 51210 against two-way load lifts the loose washer off its raceway.
• When the housing seat cannot be machined square to the 50 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.
• The 51210 is a pure axial bearing: it must never be subjected to radial load — any radial force on the 50 mm shaft has to be carried by a radial bearing mounted alongside it.
• The 49.4/116 kN figures belong to 51210 specifically (the single flat pressed steel execution of 51210); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.