6581X-6535 bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB) · extracted 2026-09-28

Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB); 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 6581X-6535 model number is decoded

For a 90 mm shaft carrying combined load, SKF lists 6581X under catalogue execution SKF 6581 X/6535: one open single-row tapered roller bearing in the inch 6500-series.Reading the designation: 6581X follows the Timken-style inch convention — the cone (inner ring with rollers) and cup (outer ring) are quoted as a pair separated by a slash, and the 6500-series code identifies the dimensional series. The 90 mm bore, 161.925 mm OD and 53.975 mm width are the metric equivalents of the inch boundary dimensions. In SKF suffix language a bare 6581X is the standard execution; B marks a larger contact angle and Q or J2 mark clearance/cage variants, all quoted separately. The 36.0 mm radial section height ((161.925−90)/2) and 4750 g catalogue mass frame a 90 mm bore bearing rated at 404 kN C — roughly 4.49 kN of dynamic capacity per millimetre of bore before application factors. Because the contact line is tapered, one 6581X reacts thrust in a single direction; bidirectional shafts need an O or X pair, and a rotating cone on a 90 mm shaft typically takes a k5 seat with an H7 housing bore. Dimensional interchange map: within the 65800 series at 90 mm bore, the 161.925 mm OD and 53.975 mm width are fixed by the ISO 355 plan, so any same-code bearing from another brand shares the mounting envelope; the 36.0 mm section height distinguishes this family from a 302 or 322 of the same bore, and the 4750 g mass is the minimum—sealed or snap-ring executions add rotating weight above that catalogue baseline. Two catalogue entries share the 6581 X cone but use different cups; this one, 6581X, takes the 6535 cup and is ground for the resulting 161.925 mm OD / 53.975 mm width envelope. Selecting a sibling cup produces a different boundary plan and a different order number, so the full designation is required at purchase.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Mount the 90 mm bore 6581X by induction heating of the cone (max 120 °C — the pressed-steel cage sets the ceiling, not the steel); driving it home through the cup or rollers brinells the tapered raceway.
• The 6500-series inch series at 90 mm bore (161.925×53.975 mm) follows the Timken cone/cup convention; substitutions must match both the cone and cup reference exactly — interchanging with another series or a metric 3xxxx bearing of the same bore changes OD, width and contact angle, so re-run the pair setting and shoulder-diameter checks before swapping.
• The tapered contact angle creates an induced axial load under pure radial force; include it in the 6581X rating calculation (and account for it in both bearings of a pair) or the unloaded bearing skids its rollers.
• Setting is a design value, not an assembly feel: excessive preload in the 6581X pair raises operating temperature and can trigger thermal runaway, while too little lets the rollers skid and smear the raceway under light load.
• Catalogue reference speed and limiting speed are different limits: the 3,200 r/min reference is a thermal criterion under load, while the 4,000 r/min limiting value is the mechanical ceiling — observe both.
• The 404/510 kN ratings are SKF catalogue 17000 values for the basic execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
• SKF lists several executions of 6581X (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 6581 X/6535 designation when purchasing and match the execution to the mounting arrangement.