51144-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 51144-M model number is decoded

51144 M is SKF's 220 mm-bore single-direction thrust ball bearing in the 51100 series to the ISO 104 dimension plan, with a flat housing seating surface, measuring 220×270×37 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 44 encode the bore as 220 mm (code 44 × 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 220×270×37 mm (8.661×10.63×1.457 in), 25.0 mm radial section, C 178 kN, C0 800 kN, Pu 19 kN. reference speed 1,300 r/min (thermal) and limiting speed 1,900 r/min (mechanical), catalogue mass 4600 g. Mass and section check: 4600 g inside the 220×270×37 mm outline leaves a 25.0 mm radial section, and the 800 kN static rating is 4.49× the dynamic rating — plan static safety and minimum preload against those figures. Static-first selection data: 800 kN C0 spread across the 37 mm stack gives 21.6 kN of static rating per height millimetre, and the 4600 g mass/C0 ratio is about 6 g per static kN — crane-hook and screw positions are normally sized on these two figures. Capacity density: 178 kN C from 4.600 kg of bearing steel gives about 38.7 kN per kilogram; static density is correspondingly 173.9 kN/kg at C0 800 kN. Washer-annulus check: the π/4·(D²−d²) contact annulus of 51144 M covers about 19,242 mm², distributing C0 800 kN over a mean track circle of π·dm ≈ 770 mm. Sizing arithmetic on the 220 mm bore: 178 kN C over the 25.0 mm radial section gives 7.1 kN per section millimetre, and the 37 mm stack height is 1.48× that section — proportions typical of a 51100 thrust section. 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 4600 g the machined brass cage represents a meaningful fraction of total mass; balancing checks on high-speed 220 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

• Identify the washers before fitting: the shaft washer has the ground, smaller bore and takes an interference fit on the 220 mm shaft, while the housing washer bore is larger and runs loose; swapping them locks the ball set and burns the tracks.
• Keep the applied thrust above Fam ≈ A·(n·dm/1000)² with the printed factor A 3.3; for 51144 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 220 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.
• 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 37 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• The 178/800 kN figures belong to 51144 M specifically (the single flat brass execution of 51144); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.