40×68×19 mm bearings
3 models from 3 brands across 3 types share this ISO 15 envelope: 40 mm bore, 68 mm outside diameter, 19 mm width (1.575×2.677×0.748 in), 14 mm radial section.
3 models fit this space 3 brands 3 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) |
|---|---|---|---|---|---|---|---|
| 32008 | Tapered Roller | FAG | open | CN | 63 | 71 | 279 |
| 51208 | Thrust Ball | NTN | open | — | 47 | 98.5 | 276 |
| 81208-TN | Cylindrical Roller Thrust | SKF | open | CN | 83 | 255 | 250 |
Substitution verification checklist
- Load rating. Check C (dynamic) and C0 (static) against the original life calculation — the table above shows which models carry verified catalogue values.
- 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.
- 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.
- Cage and precision. Stamped steel, machined brass and polymer cages, and P0/P6/P5 tolerance classes, carry different speed and shock limits.
- 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 40 mm bore bearings for wider or narrower sections, or open a model page for naming-rule decode, applications and graded cross references: 32008, 51208, 81208-TN.
Frequently asked questions
Are all 40×68×19 mm bearings interchangeable?
They share the same ISO 15 boundary dimensions — 40 mm bore, 68 mm OD, 19 mm width (1.575×2.677×0.748 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 3 models listed here and must be checked against the duty before substitution.
Is it a drop-in replacement if two bearings both measure 40×68×19?
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 40×68×19 mm in inches?
40×68×19 mm converts to 1.575×2.677×0.748 in, with a 14 mm (0.551 in) radial section height. These are the ISO 15 general-plan envelope dimensions shared across manufacturers, which is why models such as 32008, 51208, 81208-TN mount in the same space despite different internal designs.