51105-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 51105-SKF model number is decoded

The 51100 series order number 51105 is a SKF single-direction thrust ball bearing for a 25 mm seat, built to ISO 104, with a flat housing seating surface, 25×42×11 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 05 decodes to 25 mm (code 05 × 5) under the same 00/01/02/03-exception, ×5 rule SKF uses across its coded bearing ranges. the suffix-free listing carries the catalogue default: a pressed (stamped sheet-steel) ball-cage assembly, light and quiet, used across the small and medium sizes. Envelope 25×42×11 mm (0.984×1.654×0.433 in), 8.5 mm radial section, C 18.2 kN, C0 39 kN, Pu 1.43 kN. reference speed 6,300 r/min (thermal) and limiting speed 9,000 r/min (mechanical), catalogue mass 56 g. Mass and section check: 56 g inside the 25×42×11 mm outline leaves a 8.5 mm radial section, and the 39 kN static rating is 2.14× the dynamic rating — plan static safety and minimum preload against those figures. Light-load floor: Pu = 1.43 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 51105; the number is 8 % of the 18.2 kN dynamic rating. Imperial cross-check for procurement drawings: 0.984 in bore, 1.654 in OD, 0.433 in height, and the 56 g catalogue mass converts to 0.056 kg (2.0 oz). Load balance: C0 39 kN against C 18.2 kN gives a 2.14 ratio — thrust ball bearings are chosen on static rating and F_a/C0 far more often than on L10 life, while Pu 1.43 kN enters the adjusted-life check. Preload at the mechanical ceiling: repeating Fam ≈ A·(n·dm/1000)² with factor A 0.0079 at the 9,000 r/min limiting speed raises the required axial preload to about 718 N; the reference-speed value 352 N 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. On this 25 mm size the pressed cage and separable washers make the bearing interchangeable across brands on the ISO 104 plan, but the SKF ratings 18.2/39 kN are this catalogue's figures — confirm the replacement order's ratings rather than swapping on envelope alone.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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 18.2 kN track before first rotation.
• When the housing seat cannot be machined square to the 25 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.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 18.2/39 kN and the available 42 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• 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 51105 against two-way load lifts the loose washer off its raceway.
• The 18.2/39 kN figures belong to 51105 specifically (the single flat pressed steel execution of 51105); suffixed, sphered and counterpart-series order numbers are separate articles, so write the complete designation on the order and the maintenance record.