51156-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 51156-M model number is decoded

Listed in SKF 17000 chapter 5, 51156 M is an ISO 104 single-direction thrust ball bearing, 280 mm bore and 350 mm OD on a flat housing seat, standing 53 mm high before installation. The bearing is delivered as separate, interchangeable parts: a ground-bore shaft washer, a loose-bore housing washer and the ball-cage assembly between them, designed for one axial load direction only. 51xxx breaks down as 5 for thrust ball, 1 for one load direction on a flat seat, a section digit 1–4 light-to-heavy, then the two-digit bore code. reading the ending 56: bore 280 mm (code 56 × 5) for this single-direction size, via the standard exceptions 00/01/02/03 and ×5 above them. M-cage execution: brass machined from solid and ball-centred, giving heavier guidance than the standard pressed retainer at the top end of the thrust-ball range. Envelope 280×350×53 mm (11.024×13.78×2.087 in), 35.0 mm radial section, C 319 kN, C0 1460 kN, Pu 30.5 kN. reference speed 950 r/min (thermal) and limiting speed 1,300 r/min (mechanical), catalogue mass 12000 g. Pitch-diameter arithmetic: dm = (280+350)/2 = 315.0 mm; at the 1,300 r/min limiting speed that corresponds to roughly 410k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. Stack/annulus proportions: the 53 mm axial stack over the 34,636 mm² washer annulus gives 1.53 mm of height per annular square millimetre ×10⁻³, and at 12000 g the bearing holds about 121.7 kN of C0 per kilogram. Section proportions: the 35.0 mm radial section compares with 280 mm of bore (section/bore ≈ 0.13) and the 53 mm height is 1.51× that section — the proportions that identify the 51100 envelope at a glance. Light-load floor: Pu = 30.5 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 51156 M; the number is 10 % of the 319 kN dynamic rating. Preload at the mechanical ceiling: repeating Fam ≈ A·(n·dm/1000)² with factor A 11 at the 1,300 r/min limiting speed raises the required axial preload to about 1844.6 kN; the reference-speed value 985.1 kN is the thermal design point. 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 51156 M adds a small amount of mass and cage strength without changing the 280×350×53 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

• 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 319 kN track before first rotation.
• Keep the applied thrust above Fam ≈ A·(n·dm/1000)² with the printed factor A 11; for 51156 M a spring preload or the rotor weight is part of the selection at light load and high speed, because unloaded balls skid rather than roll.
• 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 51156 against two-way load lifts the loose washer off its raceway.
• When the housing seat cannot be machined square to the 280 mm shaft, the sphered 53-series execution of this size with its U seat washer is the self-aligning counterpart of this flat 51100 bearing.
• The 319/1460 kN figures belong to 51156 M specifically (the single flat brass execution of 51156); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.