51315-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 51315-SKF model number is decoded

Listed in SKF 17000 chapter 5, 51315 is an ISO 104 single-direction thrust ball bearing, 75 mm bore and 135 mm OD on a flat housing seat, standing 44 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 75×135×44 mm (2.953×5.315×1.732 in), 30.0 mm radial section, C 163 kN, C0 390 kN, Pu 14 kN. reference speed 1,700 r/min (thermal) and limiting speed 2,400 r/min (mechanical), catalogue mass 2600 g. Light-load floor: Pu = 14 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 51315; the number is 9 % of the 163 kN dynamic rating. Section proportions: the 30.0 mm radial section compares with 75 mm of bore (section/bore ≈ 0.40) and the 44 mm height is 1.47× that section — the proportions that identify the 51300 envelope at a glance. Sizing arithmetic on the 75 mm bore: 163 kN C over the 30.0 mm radial section gives 5.4 kN per section millimetre, and the 44 mm stack height is 1.47× that section — proportions typical of a 51300 thrust section. Speed-ratio note for this exact unit: the reference speed is 1,700 r/min against a 2,400 r/min limiting speed, a reference-to-limit ratio of 0.71. Preload at the mechanical ceiling: repeating Fam ≈ A·(n·dm/1000)² with factor A 0.79 at the 2,400 r/min limiting speed raises the required axial preload to about 50.2 kN; the reference-speed value 25.2 kN is the thermal design point. 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 44 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 163 kN C.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Keep the applied thrust above Fam ≈ A·(n·dm/1000)² with the printed factor A 0.79; for 51315 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.
• 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 51315 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 44 mm stack; thrust-ball bearings on horizontal shafts should have the shaft washer (the tight one) against the rotating element.
• 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.
• Ordering discipline for 51315: the catalogue page quotes 51315 and its 163/390 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.