32018 bearing: complete specifications & equivalents
The 32018 is a ISO 355 radial bearing sized 90 x 140 x 32 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 90 mm |
| Outer diameter D | 140 mm |
| Width B | 32 mm |
| Seal / shield | open |
| Internal clearance | CN available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 1475 g |
| Standard | ISO 355 |
| Catalog version | iso355-geometry |
| Last verified | 2026-09-24 |
Source: ISO 15 boundary-dimensions standard · extracted 2026-09-24
Standard-interchange bearing: dimensions per ISO 15; CN clearance, P0 tolerance and a stamped-steel cage are catalogue defaults unless the supplier states otherwise, and mass is a geometry-derived estimate. Brand catalogue load ratings and limiting speeds for 32018 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 32000-series range
| Bore d | 3.543 in |
|---|---|
| Outer diameter D | 5.512 in |
| Width B | 1.26 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in 32000-series | 20 mm |
| Largest outer diameter in 32000-series | 225 mm |
| Width range across 32000-series | 15–48 mm |
| Bore position in 32000-series (smallest first) | 15 of 23 |
| Bore above smallest 32000-series size | 70 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32018 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 32018 model number is decoded
In the 32000-series the last two digits of 32018 encode the bore: code 18 = 90 mm (code × 5 from 04 upward). The ISO 355 envelope is 140 mm outside diameter and 32 mm total assembly width T over the separable cone and cup — 3.543 × 5.512 × 1.26 in, with a 25.0 mm radial section height. Tapered rollers carry combined radial and single-direction axial load; bidirectional thrust needs an opposed pair (X face-to-face or O back-to-back) adjusted at fit-up. With a rotating cone on a 90 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore, EP lubrication and a defined end-play setting — verify against the load direction and magnitude.
Typical equipment & failure modes
Common applications
- large conveyor drum pulleys
- crane travel wheels and winch drums
- railway axle boxes
- agricultural tractor axles
- truck and trailer wheel hubs
Known failure patterns
- false brinelling from vibration while the axle is stationary during transport
- fretting corrosion on a loose shaft seat when the cone is pressed to an interference that relaxes with wear
- cup creep and housing bore fretting when the outer ring is left without its specified press fit
- roller large-end smearing and scoring against the inner-ring guide rib from loss of the EP lubricant film
- raceway spalling at the roller-rib junction after the L10 life or sustained axial overload
Selection pitfalls — read before you substitute
- The large 90 mm-bore 32018 develops substantial mounting forces; heat the cone (induction heater, max 120 °C) and never tighten the adjusting nut to seat it — draw it up by torque, then back off to the mark, leaving roughly 0.05–0.20 mm end play on the 90 mm shaft.
- The 320 narrow series at 90 mm bore keeps the OD down to 140 mm for space-limited hubs; its 32 mm width carries less load than a 30218, so do not substitute it into a 302 application without re-rating.
- The 32 mm-wide 32018 ring seats against a shaft and housing shoulder whose fillet must clear the bearing chamfer: keep the corner radius small enough that the 90 mm bore and 140 mm cup seat square — an undercut beats an oversized radius, which lifts the ring and edge-loads the 25.0 mm section.
- When mounting 32018 to a 90 mm shaft, warm the cone to 80–100 °C and slide it dry to the shoulder; cooling shrinks it into its interference, whereas hammering a cold cone through a 140 mm assembly dents the tapered raceway before first run.
- Inspect the removed 32018 cone and cup as a pair: pitting on the 140 mm cup with a clean cone usually means seal failure and water ingress, while rib scoring on the 90 mm cone points to wrong preload or lost EP film — the two faults need different corrections.
- The sliding contact between roller large ends and the inner-ring rib needs extreme-pressure lubricant; use an EP gear oil or EP grease (GL-5 class in axles) rather than plain bearing grease or the rib will smear in the first heavy run.
- Tapered rollers accept virtually no misalignment; a deflected 90 mm shaft or a tilted housing shoulder concentrates load on one end of the 32 mm-wide roller row — align seats and verify housing perpendicularity.
Frequently asked questions
What are the dimensions of a 32018 tapered roller bearing?
A 32018 single-row metric tapered roller bearing per ISO 355 has a 90 mm bore, 140 mm outer diameter and 32 mm total assembly width (3.543 × 5.512 × 1.26 in), a 25.0 mm radial section and roughly 1475 g geometry-based estimated mass; catalogue masses vary with roller and cage design.
How does the 32018 bore code work?
The last two digits of 32018 are bore code 18, giving 18 × 5 = 90 mm bore — the same convention as 6xx ball bearings, starting at code 04 (20 mm). The 140 mm OD and 32 mm width come from the ISO 355 diameter and width series, not the bore code alone.
What is the cone and cup of 32018?
Tapered roller bearings are separable: the cone is the inner ring with the tapered rollers and cage, the cup is the outer ring. 32018 denotes a matched cone-and-cup set. They are fitted separately — cone pressed on the shaft, cup in the housing — and adjusted against each other.
How is the preload or clearance of 32018 set?
At fit-up the 90 mm-bore cone is tightened against the cup while the hub is rotated, seated, then backed off to the specified end play — a typical starting range of 0.05–0.20 mm for a 90 mm bore — and locked with shims, a locknut or a spacer. Too tight overheats and seizes the rib; too loose causes skid, noise and early wear. Confirm the exact figure in the hub or axle-maker procedure.
Can 32018 take axial load in both directions?
A single 32018 takes thrust in one direction only — the roller large ends bear against the inner-ring rib under load. Bidirectional axial load requires an opposed pair: X (face-to-face) tolerates misalignment slightly better, O (back-to-back) gives a wider load centre and more moment stiffness.
Reviewed & verified by the MPN Base engineering desk against source catalog iso355-geometry on 2026-09-24. Read our editorial & correction policy.