51211-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 51211-SKF model number is decoded

51211 is SKF's 55 mm-bore single-direction thrust ball bearing in the 51200 series to the ISO 104 dimension plan, with a flat housing seating surface, measuring 55×90×25 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 11 encode the bore as 55 mm (code 11 × 5), the standard SKF bore-code rule shared with radial bearings. with no cage suffix this is the standard execution with a stamped sheet-steel ball-cage assembly (pressed cage) — the light, quiet and economical cage for small and medium thrust-ball sizes. Envelope 55×90×25 mm (2.165×3.543×0.984 in), 17.5 mm radial section, C 58.5 kN, C0 134 kN, Pu 4.9 kN. reference speed 2,800 r/min (thermal) and limiting speed 4,000 r/min (mechanical), catalogue mass 590 g. At the printed limiting speed of 4,000 r/min the mean pitch diameter dm ≈ 72.5 mm implies a dn value around 290k mm·r/min; the 2,800 r/min reference speed is the thermal-planning value under catalogue load. Minimum-load arithmetic: with dm ≈ 72.5 mm and factor A 0.11, Fam ≈ A·(n·dm/1000)² at the 2,800 r/min reference speed is about 4.5 kN for 51211; below that preload the balls skid and smear the tracks. Capacity density: 58.5 kN C from 0.590 kg of bearing steel gives about 99.2 kN per kilogram; static density is correspondingly 227.1 kN/kg at C0 134 kN. Sizing arithmetic on the 55 mm bore: 58.5 kN C over the 17.5 mm radial section gives 3.3 kN per section millimetre, and the 25 mm stack height is 1.43× that section — proportions typical of a 51200 thrust section. Track-circle loading: per millimetre of mean track circumference the 58.5 kN dynamic rating corresponds to roughly 0.26 kN/mm of π·dm track, a useful comparison against the other dimension series of the 55 mm bore. 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 25 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 58.5 kN C.

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 58.5 kN track before first rotation.
• 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.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 58.5/134 kN and the available 90 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• 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 51211 against two-way load lifts the loose washer off its raceway.
• The 58.5/134 kN figures belong to 51211 specifically (the single flat pressed steel execution of 51211); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.