51328-M 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 51328-M model number is decoded

The 51300 series order number 51328 M is a SKF single-direction thrust ball bearing for a 140 mm seat, built to ISO 104, with a flat housing seating surface, 140×240×80 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 28 decodes to 140 mm (code 28 × 5) under the same 00/01/02/03-exception, ×5 rule SKF uses across its coded bearing ranges. the trailing M names a solid machined brass window cage centred on the balls rather than on a washer, the catalogue choice when size, speed or interrupted lubrication rules out sheet steel. Envelope 140×240×80 mm (5.512×9.449×3.15 in), 50.0 mm radial section, C 377 kN, C0 1220 kN, Pu 32.5 kN. reference speed 950 r/min (thermal) and limiting speed 1,300 r/min (mechanical), catalogue mass 15500 g. Bore-to-OD planning: OD 240 over bore 140 is a 1.71× step for this size, and the 80 mm height gives a bore/height ratio of 1.75; use these ratios when the housing recess around the 140 mm shaft is the first constraint. Section proportions: the 50.0 mm radial section compares with 140 mm of bore (section/bore ≈ 0.36) and the 80 mm height is 1.60× that section — the proportions that identify the 51300 envelope at a glance. Minimum-load arithmetic: with dm ≈ 190.0 mm and factor A 9.1, Fam ≈ A·(n·dm/1000)² at the 950 r/min reference speed is about 296.5 kN for 51328 M; below that preload the balls skid and smear the tracks. At the printed limiting speed of 1,300 r/min the mean pitch diameter dm ≈ 190.0 mm implies a dn value around 247k mm·r/min; the 950 r/min reference speed is the thermal-planning value under catalogue load. Pitch-diameter arithmetic: dm = (140+240)/2 = 190.0 mm; at the 1,300 r/min limiting speed that corresponds to roughly 247k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. Machined-cage order-number note: the M brass cage is a one-piece ball-centred window cage, chosen at the heavy end of the section for speed and shock duty; it is heavier and stiffer than the pressed-steel execution of the smaller sizes and tolerates interrupted lubrication far better, which is why the catalogue restricts the M suffix to the large bores. The M cage of 51328 M adds a small amount of mass and cage strength without changing the 140×240×80 mm ISO 104 envelope, so the pressed-cage execution drops into the same recess but should not be assumed equal under the 1,300 r/min ceiling.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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.
• 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 80 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 377/1220 kN and the available 240 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• The 51328 M is a pure axial bearing: it must never be subjected to radial load — any radial force on the 140 mm shaft has to be carried by a radial bearing mounted alongside it.
• The 377/1220 kN figures belong to 51328 M specifically (the single flat brass execution of 51328); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.