6311-RSR bearing: complete specifications & equivalents
The 6311-RSR is a ISO 15 radial bearing sized 55 x 120 x 29 mm (bore x OD x width) with RSR sealing. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NSK |
| Bore diameter d | 55 mm |
| Outer diameter D | 120 mm |
| Width B | 29 mm |
| Material | GCr15 |
| Seal / shield | RSR |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 78.5 kN |
| Basic static load rating C0 | 44.5 kN |
| Mass | 1370 g |
| Manufacturer designation | NSK 6311VV |
| Standard | ISO 15 |
| Catalog version | NSK Rolling Bearings E1103 Part C |
| Last verified | 2026-09-24 |
Source: catalog reference (NSK Rolling Bearings E1103 Part C) · extracted 2026-09-24
Dimensions in inches & 6300-series range
| Bore d | 2.165 in |
|---|---|
| Outer diameter D | 4.724 in |
| Width B | 1.142 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 32.5 mm |
| Smallest bore in 6300-series | 10 mm |
| Largest outer diameter in 6300-series | 500 mm |
| Width range across 6300-series | 11–95 mm |
| Bore position in 6300-series (smallest first) | 12 of 34 |
| Bore above smallest 6300-series size | 45 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6311 | ISO-INTERCHANGE | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | ISO 15 envelope interchange; NSK suffix VV maps to industry-neutral RSR. Verify seal design, grease and speed rating per brand catalogue. |
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-RSR model number is decoded
In the 6300-series (ISO 15 diameter series 3) 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 -RSR denotes two low-friction non-contact elastomer seals; they keep coarse debris out with minimal drag 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.
Typical equipment & failure modes
Common applications
- conveyor drives
- material-handling equipment
- industrial fans
- industrial electric motors
Known failure patterns
- ingress of fine dust or moisture past the non-contact lip in dirty or wet duty (RSR is not liquid-tight)
- lip-lubricant starvation if the bearing runs dry for extended periods
- raceway smearing under marginal lubrication at start-up
- edge loading from shaft deflection or housing misalignment
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 series gains rating at 55 mm bore through a 120 mm OD and 29 mm width; the heavier rolling elements also trade away some speed versus a 6211.
- RSR low-friction seals on 6311-RSR run faster than contact-seal 6311-2RS but let fine dust and moisture past the non-contact lip; in dirty or wet duty specify 6311-2RS instead.
- The non-contact lip of 6311-RSR does not retain a lifetime grease fill the way a contact seal does; confirm the regreasing interval for the 55 mm bore position before relying on it as sealed-for-life.
- Assign fits by which ring rotates: an interference shaft fit for a rotating inner ring; if the outer ring rotates instead, reverse the logic — a loose rotating ring creeps and frets its seat.
- NSK catalogues this low-friction non-contact seal as 6311VV (suffix VV), the NSK equivalent of the industry-neutral -RSR spelling on this page. VV is not liquid-tight; NSK's contact-seal suffix DDU (industry-neutral -2RS) is the choice for wet or fine-dust duty.
- The 78.5/44.5 kN ratings, mass 1370 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6311VV; this seal/size combination has no counterpart in the SKF 17000 extract used elsewhere on this site, so the page rests on a single manufacturer source — internal geometry and ratings legitimately differ between brands, so re-verify before substituting in a rated drive.
Frequently asked questions
What are the dimensions of a 6311-RSR bearing?
A 6311-RSR deep-groove ball bearing has a 55 mm bore, 120 mm outer diameter and 29 mm width (2.165 × 4.724 × 1.142 in), per ISO 15 boundary dimensions. It is fitted with two low-friction non-contact rubber seals.
How does the 6311 bore code work?
The last two digits of 6311 are bore code 11, giving 11 × 5 = 55 mm bore. The 120 mm outside diameter and 29 mm width follow the ISO 15 diameter series, not the bore code alone.
What does the RSR suffix on 6311-RSR mean?
RSR means two low-friction non-contact rubber seals. They keep coarse debris out with minimal drag (speed close to the open bearing) but are not liquid-tight; use -2RS contact seals for wet or fine-dust environments.
How does the 6300 compare with other series at the same 55 mm bore?
The '3' is the medium diameter series: 120×29 mm, 32.5 mm radial section at 55 mm bore, carrying more load than a 6211 but needing a larger housing bore and giving up some speed.
What is the NSK designation and catalogue data for 6311-RSR?
In the NSK Rolling Bearings catalogue (E1103 Part C) this size is listed as 6311VV — two low-friction non-contact rubber seals (NSK suffix VV), 55×120×29 mm per ISO 15. Quoted values: C 78.5 kN, C0 44.5 kN, mass 1370 g. The industry-neutral page spelling 6311-RSR follows the seal-suffix convention used across this site, not NSK order-number spelling. Reference and limiting speeds are not tabulated in the E1103 dimension tables used here; consult NSK speed tables before high-speed service.
Reviewed & verified by the MPN Base engineering desk against source catalog NSK Rolling Bearings E1103 Part C on 2026-09-24. Read our editorial & correction policy.