MPNbase

90×125×18 mm bearings

5 models from 3 brands across 2 types share this ISO 15 envelope: 90 mm bore, 125 mm outside diameter, 18 mm width (3.543×4.921×0.709 in), 17.5 mm radial section.

5 models fit this space 3 brands 4 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)
61918 Deep Groove Ball SKF open CN 33.2 31.5 590
61918-2RS Deep Groove Ball NSK 2RS CN 36 31.5 585
61918-RSR Deep Groove Ball NSK RSR CN 36 31.5 585
61918-ZZ Deep Groove Ball NSK ZZ CN 36 31.5 585
71918 Angular Contact Ball GENERIC-ISO open CN — — 543

Note: catalogue dynamic load ratings for this envelope span 33.2– 36.0 kN — a 8% spread between designs in the very same 90×125×18 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 90 mm bore bearings for wider or narrower sections, or open a model page for naming-rule decode, applications and graded cross references: 61918, 61918-2RS, 61918-RSR, 61918-ZZ, 71918.

Frequently asked questions

Are all 90×125×18 mm bearings interchangeable?

They share the same ISO 15 boundary dimensions — 90 mm bore, 125 mm OD, 18 mm width (3.543×4.921×0.709 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 5 models listed here and must be checked against the duty before substitution.

Is it a drop-in replacement if two bearings both measure 90×125×18?

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 90×125×18 mm in inches?

90×125×18 mm converts to 3.543×4.921×0.709 in, with a 17.5 mm (0.689 in) radial section height. These are the ISO 15 general-plan envelope dimensions shared across manufacturers, which is why models such as 61918, 61918-2RS, 61918-RSR mount in the same space despite different internal designs.