51122 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 51122 model number is decoded

The 51100 series order number 51122 is a SKF single-direction thrust ball bearing for a 110 mm seat, built to ISO 104, with a flat housing seating surface, 110×145×25 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 22 decodes to 110 mm (code 22 × 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 110×145×25 mm (4.331×5.709×0.984 in), 17.5 mm radial section, C 83.2 kN, C0 285 kN, Pu 9.5 kN. reference speed 2,200 r/min (thermal) and limiting speed 3,200 r/min (mechanical), catalogue mass 1050 g. Selection figures for 51122: the C0/C ratio is 3.43, Pu 9.5 kN is about 11 % of C, and the catalogue mass works out to roughly 10 g per millimetre of bore; the printed minimum-load factor is A 0.52. Preload at the mechanical ceiling: repeating Fam ≈ A·(n·dm/1000)² with factor A 0.52 at the 3,200 r/min limiting speed raises the required axial preload to about 86.6 kN; the reference-speed value 40.9 kN is the thermal design point. Stack/annulus proportions: the 25 mm axial stack over the 7,010 mm² washer annulus gives 3.57 mm of height per annular square millimetre ×10⁻³, and at 1050 g the bearing holds about 271.4 kN of C0 per kilogram. Sizing arithmetic on the 110 mm bore: 83.2 kN C over the 17.5 mm radial section gives 4.8 kN per section millimetre, and the 25 mm stack height is 1.43× that section — proportions typical of a 51100 thrust section. Speed planning separates the two ceilings mechanically: the pressed cage and balls tolerate 3,200 r/min while thermal balance under catalogue load sets the 2,200 r/min reference; at dm ≈ 127.5 mm the corresponding dn is approximately 408k mm·r/min. 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 83.2 kN C.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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 51122 against two-way load lifts the loose washer off its raceway.
• 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 83.2 kN track before first rotation.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 83.2/285 kN and the available 145 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• The 51122 is a pure axial bearing: it must never be subjected to radial load — any radial force on the 110 mm shaft has to be carried by a radial bearing mounted alongside it.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for 51122 as the single flat pressed steel execution; other order numbers of the 51122 size are different products and may carry different ratings or seating geometry — always quote the full designation when purchasing.