51409-SKF 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 51409-SKF model number is decoded

51409 is SKF's 45 mm-bore single-direction thrust ball bearing in the 51400 series to the ISO 104 dimension plan, with a flat housing seating surface, measuring 45×100×39 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 09 encode the bore as 45 mm (code 09 × 5), the standard SKF bore-code rule shared with radial bearings. with no cage suffix this is the standard execution with a stamped sheet-steel ball-cage assembly (pressed cage) — the light, quiet and economical cage for small and medium thrust-ball sizes. Envelope 45×100×39 mm (1.772×3.937×1.535 in), 27.5 mm radial section, C 124 kN, C0 240 kN, Pu 9 kN. reference speed 2,200 r/min (thermal) and limiting speed 3,000 r/min (mechanical), catalogue mass 1400 g. Pitch-diameter arithmetic: dm = (45+100)/2 = 72.5 mm; at the 3,000 r/min limiting speed that corresponds to roughly 218k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. Imperial cross-check for procurement drawings: 1.772 in bore, 3.937 in OD, 1.535 in height, and the 1400 g catalogue mass converts to 1.400 kg (49.4 oz). Light-load floor: Pu = 9 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 51409; the number is 7 % of the 124 kN dynamic rating. Sizing arithmetic on the 45 mm bore: 124 kN C over the 27.5 mm radial section gives 4.5 kN per section millimetre, and the 39 mm stack height is 1.42× that section — proportions typical of a 51400 thrust section. Static-first selection data: 240 kN C0 spread across the 39 mm stack gives 6.2 kN of static rating per height millimetre, and the 1400 g mass/C0 ratio is about 6 g per static kN — crane-hook and screw positions are normally sized on these two figures. Execution note for this order number: the flat housing seating surface must be machined square to the shaft axis and supported across the full washer face — unlike the sphered 53-series execution this pressed-cage 51-series bearing has no self-aligning capability at all, so seat squareness is checked at mounting, not compensated in service. Inspection after removal of a 39 mm-high stack means checking both washer faces: the loose housing washer often shows the first false-brinell marks under machine vibration even though the tight shaft washer carries the rotating load of 124 kN C.

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 51409 against two-way load lifts the loose washer off its raceway.
• Identify the washers before fitting: the shaft washer has the ground, smaller bore and takes an interference fit on the 45 mm shaft, while the housing washer bore is larger and runs loose; swapping them locks the ball set and burns the tracks.
• 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.
• When the housing seat cannot be machined square to the 45 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.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for 51409 as the single flat pressed steel execution; other order numbers of the 51409 size are different products and may carry different ratings or seating geometry — always quote the full designation when purchasing.