6311-ZZ-FAG bearing: complete specifications & equivalents

Specification table

Source: catalog reference (HR 1 Rolling Bearings (Jan 2020)) · extracted 2026-09-25

Parameters extracted from the official FAG Rolling Bearings catalogue (HR 1 Rolling Bearings (Jan 2020)); FAG® is a trademark of Schaeffler Technologies AG & Co. KG, used here for identification only — mpnbase is not an authorized FAG/Schaeffler distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at schaeffler.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-ZZ-FAG 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 -ZZ denotes two non-contact metallic shields; they retain grease and block coarse debris but are not liquid-tight. 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. Schaeffler HR 1 catalogue order number: 6311-C-2Z (FAG suffix 2Z), two non-contact steel shields, mapped here from the industry-neutral -ZZ spelling.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Temperature rise and interference fits consume internal clearance on this 55 mm bore: a CN bearing on a tight, hot shaft can lose all residual clearance — size 6311 with C3 for those conditions.
• 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.
• ZZ shields are non-contact: 6311-ZZ-FAG blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 6311-2RS for that.
• Shielded 6311-ZZ-FAG units are typically greased for life; prying the shields out for regreasing usually bends them and leaves a gap that throws grease in service.
• Axial location must clamp the ring face, not the seal area: a shoulder or circlip bearing on the seal side of the 29 mm-wide ring of 6311-ZZ-FAG drags the lip and overheats it.
• 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.
• Schaeffler HR 1 lists the shielded version as 6311-C-2Z — FAG suffix 2Z, two non-contact steel shields. The industry-neutral page spelling is -ZZ; quote the FAG order number when buying through a Schaeffler channel.
• At 7200 r/min mechanical limiting speed (thermal reference speed 7800 r/min), 6311 covers medium-duty industrial drives; the open or shielded execution can run continuously here on standard lithium grease.
• At 55 mm bore 6311 is in Schaeffler's upper general-purpose range; the pressed steel cage is standard but mid-section 63xx sizes at this bore can be ordered with a machined brass cage (suffix M) for shock or very-low-speed duty — confirm cage material with the Schaeffler channel if the application sees impact loads.
• At 83 kN dynamic load rating (C) and 47.5 kN static (C0), 6311 is a heavy-load FAG bearing for industrial gearboxes and large conveyors; Schaeffler expects a machined brass cage (suffix M) at this rating for shock duty, and C0 must be checked against mounting or lifting loads.
• At 1370 g (1.4 kg), 6311 needs mechanical handling for mounting; Schaeffler recommends induction heating the inner ring (max 120 °C) rather than pressing cold, and a lifting provision if the housing is pre-assembled.
• The 55×120×29 mm envelope of 6311 gives a D/d ratio of 2.18 and 32.5 mm radial section height — a heavy FAG section for high-load, lower-speed duty; specifying it in a high-rpm motor generates excess heat and shortens grease life, so prefer a 62/63-series there.
• The 83/47.5 kN load ratings, mass 1370 g here are Schaeffler HR 1 Rolling Bearings (Jan 2020) catalogue figures for 6311-C-2Z on the 55×120×29 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6311 in a rated drive. Where FAG has since released an X-life version of this size, its expanded C/C0 ratings supersede the HR 1 print values quoted here.
• For hot shafts above roughly 100 °C continuous, consult Schaeffler about seal material and grease options for the 2RSR execution of 6311; the standard NBR lip is the economical general-duty choice, not the high-temperature one.
• Mixing old and new FAG generations of the same designation in one arrangement is dimensionally acceptable, but where ratings matter — preloaded or matched sets — order both positions from the same generation and lot.