6311-2RS bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-24

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 6311-2RS model number is decoded

In the 6300-series (diameter series 3 of ISO 15) the last two digits encode the bore: 6311 carries bore code 11 = 55 mm. Outside diameter 120 mm and width 29 mm come from the ISO 15 boundary-dimensions general plan. Suffix -2RS denotes two contact-type elastomer seals over a lifetime grease fill; the sealing lips add drag compared with open or shielded versions. For normal-load mounting with a rotating inner ring on a 55 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. SKF's contact-seal catalogue number is 6311-2RSH (older text: -2RS1), mapped here from the industry-neutral -2RS spelling.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Interference on a 55 mm shaft plus running heat consumes radial clearance: where the shaft runs hot or the fit is tight, order 6311 with C3 clearance and re-check the residual value after mounting.
• The 63xx medium section at 55 mm bore gains dynamic rating through larger rolling elements on a 120 mm OD; the penalty is mass and a lower limiting speed than the 6211 — do not specify it for speed-critical shafts.
• Contact seals add drag and heat: 6311-2RS runs slower and cooler-limited than the open 6311; rubber lips are generally limited to roughly 80–110 °C continuous depending on grease, and C3 clearance is the common hot-duty choice.
• Heat is the enemy of the sealed 6311-2RS: sustained running near the lip temperature limit hardens the rubber, after which grease escapes and dirt tracks in — watch the housing temperature in hot drives.
• Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 6300-series position can soften the mixture and leak — clean out the old fill before switching grease types.
• A 55 mm bore listing showing the right d/D/B but no standard or precision-class reference may be a loose-tolerance import; measure bore/OD spread before fitting it to a machined shaft.
• SKF catalogues the contact-sealed version as 6311-2RSH (older printings may read -2RS1); it is shipped pre-greased and its 3800 r/min limiting speed is set by seal-lip drag and grease life versus the open bearing's 12000 r/min thermal reference speed. The single-seal catalogue number is 6311-RSH, used where one shaft side needs external relubrication.
• A one-seal execution 6311-RSH exists for arrangements that lubricate through the open side; fitting 6311-2RSH instead means lifetime grease and no external oil supply — mixing the two in the same shaft can starve the sealed position.
• The 74.1/45 kN ratings here are SKF Explorer-class figures from catalogue PUB BU/P1 17000/1 EN (Oct 2018); SKF can revise internal geometry and ratings without changing the designation, so treat the catalogue version and date as part of the specification and re-verify for critical drives.