51260-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 51260-M model number is decoded

The 51200 series order number 51260 M is a SKF single-direction thrust ball bearing for a 300 mm seat, built to ISO 104, with a flat housing seating surface, 300×420×95 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 60 decodes to 300 mm (code 60 × 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 300×420×95 mm (11.811×16.535×3.74 in), 60.0 mm radial section, C 585 kN, C0 3000 kN, Pu 57 kN. reference speed 630 r/min (thermal) and limiting speed 850 r/min (mechanical), catalogue mass 42000 g. Envelope economics: the 95 mm axial height over a 60.0 mm radial section yields 6.2 kN of dynamic capacity per height millimetre, and the bearing weighs 42000 g for 585 kN C — about 72 g per rated kN. Minimum-load arithmetic: with dm ≈ 360.0 mm and factor A 47, Fam ≈ A·(n·dm/1000)² at the 630 r/min reference speed is about 2417.6 kN for 51260 M; below that preload the balls skid and smear the tracks. Sizing arithmetic on the 300 mm bore: 585 kN C over the 60.0 mm radial section gives 9.8 kN per section millimetre, and the 95 mm stack height is 1.58× that section — proportions typical of a 51200 thrust section. Load balance: C0 3000 kN against C 585 kN gives a 5.13 ratio — thrust ball bearings are chosen on static rating and F_a/C0 far more often than on L10 life, while Pu 57 kN enters the adjusted-life check. Mass and section check: 42000 g inside the 300×420×95 mm outline leaves a 60.0 mm radial section, and the 3000 kN static rating is 5.13× the dynamic rating — plan static safety and minimum preload against those figures. 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. At 42000 g the machined brass cage represents a meaningful fraction of total mass; balancing checks on high-speed 300 mm vertical shafts should use the actual M-execution weight, not the lighter pressed-cage catalogue value.

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 51260 against two-way load lifts the loose washer off its raceway.
• 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 95 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• Keep the applied thrust above Fam ≈ A·(n·dm/1000)² with the printed factor A 47; for 51260 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.
• When the housing seat cannot be machined square to the 300 mm shaft, the sphered 53-series execution of this size with its U seat washer is the self-aligning counterpart of this flat 51200 bearing.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for 51260 M as the single flat brass execution; other order numbers of the 51260 size are different products and may carry different ratings or seating geometry — always quote the full designation when purchasing.