51115-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 51115-SKF model number is decoded

Listed in SKF 17000 chapter 5, 51115 is an ISO 104 single-direction thrust ball bearing, 75 mm bore and 100 mm OD on a flat housing seat, standing 19 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 15: bore 75 mm (code 15 × 5) for this single-direction size, via the standard exceptions 00/01/02/03 and ×5 above them. no cage suffix means the standard stamped steel retainer — a pressed sheet-metal ball-cage assembly that covers the bulk of the thrust-ball assortment. Envelope 75×100×19 mm (2.953×3.937×0.748 in), 12.5 mm radial section, C 44.2 kN, C0 134 kN, Pu 4.9 kN. reference speed 3,200 r/min (thermal) and limiting speed 4,300 r/min (mechanical), catalogue mass 400 g. Load balance: C0 134 kN against C 44.2 kN gives a 3.03 ratio — thrust ball bearings are chosen on static rating and F_a/C0 far more often than on L10 life, while Pu 4.9 kN enters the adjusted-life check. Speed planning separates the two ceilings mechanically: the pressed cage and balls tolerate 4,300 r/min while thermal balance under catalogue load sets the 3,200 r/min reference; at dm ≈ 87.5 mm the corresponding dn is approximately 376k mm·r/min. Capacity density: 44.2 kN C from 0.400 kg of bearing steel gives about 110.5 kN per kilogram; static density is correspondingly 335.0 kN/kg at C0 134 kN. Mass and section check: 400 g inside the 75×100×19 mm outline leaves a 12.5 mm radial section, and the 134 kN static rating is 3.03× the dynamic rating — plan static safety and minimum preload against those figures. Envelope economics: the 19 mm axial height over a 12.5 mm radial section yields 2.3 kN of dynamic capacity per height millimetre, and the bearing weighs 400 g for 44.2 kN C — about 9 g per rated kN. 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 19 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 44.2 kN C.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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.
• 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 19 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• 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 44.2 kN track before first rotation.
• Keep the applied thrust above Fam ≈ A·(n·dm/1000)² with the printed factor A 0.11; for 51115 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.
• The 44.2/134 kN figures belong to 51115 specifically (the single flat pressed steel execution of 51115); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.