MPNbase

55×120×29 mm bearings

51 models from 4 brands across 5 types share this ISO 15 envelope: 55 mm bore, 120 mm outside diameter, 29 mm width (2.165×4.724×1.142 in), 32.5 mm radial section.

51 models fit this space 4 brands 51 with catalogue C rating

Dimensional interchange — verify before substituting

These bearings are interchangeable on boundary dimensions per ISO 15 — same bore, OD and width. They are not guaranteed drop-in equivalents: compare load ratings, seals, clearance, cage, precision and axial-locating design for the specific duty. Models without a catalogue C rating on this site carry ISO 15 geometry only; request the manufacturer table before a load-critical replacement.

Model Type Brand Seal Clearance C (kN) C0 (kN) Mass (g)
1311 Self-Aligning Ball NTN open — 51.5 17.9 1600
1311-EKTN9 Self-Aligning Ball SKF open CN 50.7 18 1600
1311-ETN9 Self-Aligning Ball SKF open CN 50.7 18 1600
1311K Self-Aligning Ball NTN open — 51.5 17.9 1600
21311 Spherical Roller SKF open CN 159 166 1700
21311-EK Spherical Roller SKF open CN 159 166 1950
21311-NTN Spherical Roller NTN open CN 161 163 1710
21311K Spherical Roller NTN open CN 161 163 1690
311 Deep Groove Ball SKF open CN 79.2 67 1500
311-ZZ Deep Groove Ball SKF ZZ CN 79.2 67 1500
6311 Deep Groove Ball SKF open CN 74.1 45 1350
6311-2RS Deep Groove Ball SKF 2RS CN 74.1 45 1400
6311-2RS-FAG Deep Groove Ball FAG 2RS CN 83 47.5 1370
6311-2RS-NSK Deep Groove Ball NSK 2RS CN 78.5 44.5 1370
6311-2RS-NTN Deep Groove Ball NTN 2RS CN 79.5 45 1370
6311-FAG Deep Groove Ball FAG open CN 83 47.5 1330
6311-M Deep Groove Ball SKF open CN 74.1 45 1650
6311-NSK Deep Groove Ball NSK open CN 78.5 44.5 1370
6311-NTN Deep Groove Ball NTN open CN 79.5 45 1370
6311-RSR Deep Groove Ball NSK RSR CN 78.5 44.5 1370
6311-RSR-NTN Deep Groove Ball NTN RSR CN 79.5 45 1370
6311-ZZ Deep Groove Ball SKF ZZ CN 74.1 45 1400
6311-ZZ-FAG Deep Groove Ball FAG ZZ CN 83 47.5 1370
6311-ZZ-NSK Deep Groove Ball NSK ZZ CN 78.5 44.5 1370
6311-ZZ-NTN Deep Groove Ball NTN ZZ CN 79.5 45 1370
7311 Angular Contact Ball SKF open CN 79.3 55 1400
7311-ACCBM Angular Contact Ball SKF open CN 96.5 67 1400
7311-BECBM Angular Contact Ball SKF open CN 85 60 1400
7311-BECBP Angular Contact Ball SKF open CN 85 60 1400
7311-BECBPH Angular Contact Ball SKF open CN 85 60 1400
7311-BECBY Angular Contact Ball SKF open CN 90 65.5 1400
7311-BEP Angular Contact Ball SKF open CN 79.3 55 1400
7311-NTN Angular Contact Ball NTN open CN 95 61.5 1390
7311B Angular Contact Ball NTN open CN 87 56.5 1420
N311 Cylindrical Roller NTN open CN 123 111 1420
N311-ECP Cylindrical Roller SKF open CN 156 143 1450
N311EA Cylindrical Roller NTN open CN 162 143 1430
NF311 Cylindrical Roller NTN open CN 123 111 1420
NF311EA Cylindrical Roller NTN open CN 162 143 1430
NJ311 Cylindrical Roller NTN open CN 123 111 1420
NJ311-ECP Cylindrical Roller SKF open CN 156 143 1500
NJ311EA Cylindrical Roller NTN open CN 162 143 1430
NU311 Cylindrical Roller SKF open CN 156 143 1450
NU311-NTN Cylindrical Roller NTN open CN 123 111 1420
NU311EA Cylindrical Roller NTN open CN 162 143 1430
NUP311 Cylindrical Roller NTN open CN 123 111 1420
NUP311-ECP Cylindrical Roller SKF open CN 156 143 1500
NUP311EA Cylindrical Roller NTN open CN 162 143 1430
QJ-311-MA Angular Contact Ball SKF open CN 137 118 1750
QJ-311-N2MA Angular Contact Ball SKF open CN 137 118 1750
QJ311 Angular Contact Ball NTN open CN 118 170 1760

Note: catalogue dynamic load ratings for this envelope span 50.7– 162.0 kN — a 220% spread between designs in the very same 55×120×29 mm space. The higher-rated unit is not an upgrade for every duty (it may run at lower limiting speed), but ignoring the gap will over- or under-life the replacement.

Substitution verification checklist

  1. Load rating. Check C (dynamic) and C0 (static) against the original life calculation — the table above shows which models carry verified catalogue values.
  2. Sealing. Open, -ZZ shields and -2RS contact seals are not equivalent in friction, speed or contamination protection; match the housing environment, not just the suffix on the old box.
  3. Internal clearance. CN/C3/C4 changes with fit and operating temperature; an interference inner-ring mount commonly needs C3 where the bench bearing ran CN.
  4. Cage and precision. Stamped steel, machined brass and polymer cages, and P0/P6/P5 tolerance classes, carry different speed and shock limits.
  5. Locating behaviour. Within one envelope an NU cylindrical roller floats axially while an NJ/NUP locates; ball designs take thrust that roller locating schemes do not. Preserve the shaft's locating arrangement.

Browse all 55 mm bore bearings for wider or narrower sections, or open a model page for naming-rule decode, applications and graded cross references: 1311, 1311-EKTN9, 1311-ETN9, 1311K, 21311, 21311-EK, 21311-NTN, 21311K, 311, 311-ZZ, 6311, 6311-2RS, 6311-2RS-FAG, 6311-2RS-NSK, 6311-2RS-NTN, 6311-FAG, 6311-M, 6311-NSK, 6311-NTN, 6311-RSR, 6311-RSR-NTN, 6311-ZZ, 6311-ZZ-FAG, 6311-ZZ-NSK, 6311-ZZ-NTN, 7311, 7311-ACCBM, 7311-BECBM, 7311-BECBP, 7311-BECBPH, 7311-BECBY, 7311-BEP, 7311-NTN, 7311B, N311, N311-ECP, N311EA, NF311, NF311EA, NJ311, NJ311-ECP, NJ311EA, NU311, NU311-NTN, NU311EA, NUP311, NUP311-ECP, NUP311EA, QJ-311-MA, QJ-311-N2MA, QJ311.

Frequently asked questions

Are all 55×120×29 mm bearings interchangeable?

They share the same ISO 15 boundary dimensions — 55 mm bore, 120 mm OD, 29 mm width (2.165×4.724×1.142 in) — so they fit the same shaft, housing bore and axial space. Interchangeability ends at the envelope: dynamic load rating, seal arrangement, internal clearance, cage and precision class differ between the 51 models listed here and must be checked against the duty before substitution.

Is it a drop-in replacement if two bearings both measure 55×120×29?

Only after verification. Confirm five things in order: (1) the C/C0 load ratings meet the original life calculation, (2) the seal type is equivalent or acceptable for the contamination level (open vs -ZZ vs -2RS), (3) internal clearance matches (CN/C3/C4 — an interference fit changes residual play), (4) cage material and precision class suit the speed, and (5) the axial-locating behaviour is the same (for example an NU cylindrical roller floats while an NJ locates one way). Same dimensions alone never guarantee equal performance.

What is 55×120×29 mm in inches?

55×120×29 mm converts to 2.165×4.724×1.142 in, with a 32.5 mm (1.280 in) radial section height. These are the ISO 15 general-plan envelope dimensions shared across manufacturers, which is why models such as 1311, 1311-EKTN9, 1311-ETN9 mount in the same space despite different internal designs.