51415-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 51415-M model number is decoded

51415 M is SKF's 75 mm-bore single-direction thrust ball bearing in the 51400 series to the ISO 104 dimension plan, with a flat housing seating surface, measuring 75×160×65 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 15 encode the bore as 75 mm (code 15 × 5), the standard SKF bore-code rule shared with radial bearings. suffix M identifies a one-piece machined brass cage, ball-centred: the large-size and heavy-section option for higher speeds, shock loads and thin-film lubrication where a pressed cage would distort. Envelope 75×160×65 mm (2.953×6.299×2.559 in), 42.5 mm radial section, C 251 kN, C0 610 kN, Pu 20.8 kN. reference speed 1,300 r/min (thermal) and limiting speed 1,800 r/min (mechanical), catalogue mass 6750 g. Sizing arithmetic on the 75 mm bore: 251 kN C over the 42.5 mm radial section gives 5.9 kN per section millimetre, and the 65 mm stack height is 1.53× that section — proportions typical of a 51400 thrust section. Stack/annulus proportions: the 65 mm axial stack over the 15,688 mm² washer annulus gives 4.14 mm of height per annular square millimetre ×10⁻³, and at 6750 g the bearing holds about 90.4 kN of C0 per kilogram. Speed planning separates the two ceilings mechanically: the pressed brass cage and balls tolerate 1,800 r/min while thermal balance under catalogue load sets the 1,300 r/min reference; at dm ≈ 117.5 mm the corresponding dn is approximately 212k mm·r/min. Light-load floor: Pu = 20.8 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 51415 M; the number is 8 % of the 251 kN dynamic rating. Minimum-load arithmetic: with dm ≈ 117.5 mm and factor A 1.9, Fam ≈ A·(n·dm/1000)² at the 1,300 r/min reference speed is about 44.3 kN for 51415 M; below that preload the balls skid and smear the tracks. 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 51415 M adds a small amount of mass and cage strength without changing the 75×160×65 mm ISO 104 envelope, so the pressed-cage execution drops into the same recess but should not be assumed equal under the 1,800 r/min ceiling.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• When the housing seat cannot be machined square to the 75 mm shaft, the sphered 53-series execution of this size with its U seat washer is the self-aligning counterpart of this flat 51400 bearing.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 251/610 kN and the available 160 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• 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 251 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 51415 against two-way load lifts the loose washer off its raceway.
• Ordering discipline for 51415: the catalogue page quotes 51415 M and its 251/610 kN ratings as one exact article; bare-number substitutions from another series or brand need a fresh dimension and rating check, not a like-for-like assumption.