18790-18720 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 18790-18720 model number is decoded

The 17.1 mm radial section height ((85−50.8)/2) and 370 g catalogue mass frame a 50.8 mm bore bearing rated at 62.1 kN C — roughly 1.22 kN of dynamic capacity per millimetre of bore before application factors. A single 18790 locates the shaft in one axial direction only; mount it against a second bearing in O (back-to-back) or X (face-to-face) arrangement, and set the running clearance by the mounting procedure — not by feel. Journal and housing interface: the 50.8 mm bore takes a k5 shaft seat (upper deviation ~0.102 mm for this diameter range) and the 85 mm outside diameter pairs with an H7 housing bore tolerance band of 85.000/85.020 mm; the 17.462 mm width defines the shoulder depth, and the 370 g cone-plus-cup assembly is the dead load on the shaft during thermal expansion calculations. From a specification standpoint the 18720 cup is the controlling half of 18790 for housing design — it sets the 85 mm OD and the outer abutment diameter — while the 18790 cone controls shaft fit at the 50.8 mm bore; the 17.462 mm width is the result of the two together.SKF 18790/18720 belongs to the SKF single-row tapered roller range — the 50.8 mm bore entry in the inch 18700-series, dimensioned 85 mm OD and 17.462 mm wide.The 18700-series series assigns 50.8 mm bore, 85 mm OD and 17.462 mm width to 18790; the cone and cup references are not interchangeable with other inch-series pairs even when the bore matches, because the cup profile and rib geometry are series-specific. SKF lists the plain number as the basic execution; letter suffixes such as B denote a steeper contact angle and are different order numbers.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• On this 50.8 mm bore, interference and temperature rise consume clearance inside a preloaded pair; calculate the residual clearance after mounting and at operating temperature — an over-tight 18790 pair heats, loses setting control and smears the roller-rib contact.
• The 18700-series inch series at 50.8 mm bore (85×17.462 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.
• Setting is a design value, not an assembly feel: excessive preload in the 18790 pair raises operating temperature and can trigger thermal runaway, while too little lets the rollers skid and smear the raceway under light load.
• O (back-to-back) pairs are stiffer against moments, X (face-to-face) pairs tolerate misalignment and thermal growth better; choosing the arrangement from the 2D drawing rather than the actual shaft thermal expansion is a common 18790 mounting error.
• Shaft and housing fillets must clear the bearing chamfer so the 17.462 mm-wide cup seats square; use an undercut or withdrawal groove rather than an oversized radius that locks on the ring face.
• The 62.1/65.5 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 18790 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 18790/18720 designation when purchasing and match the execution to the mounting arrangement.