HK2538ZWD bearing: complete specifications & equivalents
The HK2538ZWD is a ISO 3245 radial bearing sized 25 x 32 x 38 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 25 mm |
| Outer diameter D | 32 mm |
| Width B | 38 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 35 kN |
| Basic static load rating C0 | 65.5 kN |
| Fatigue load limit Pu | 8 kN |
| Limiting speed (mechanical) | 6500 rpm |
| Mass | 65 g |
| Manufacturer designation | HK2538ZWD |
| Standard | ISO 3245 |
| Catalog version | CAT. No. 2203-3/E 2024 |
| Last verified | 2026-09-25 |
Source: catalog reference (CAT. No. 2203-3/E 2024) · extracted 2026-09-25
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (CAT. No. 2203-3/E 2024); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & HK-series range
| Bore d | 0.984 in |
|---|---|
| Outer diameter D | 1.26 in |
| Width B | 1.496 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 3.5 mm |
| Smallest bore in HK-series | 3 mm |
| Largest outer diameter in HK-series | 58 mm |
| Width range across HK-series | 6–38 mm |
| Bore position in HK-series (smallest first) | 18 of 24 |
| Bore above smallest HK-series size | 22 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the HK2538ZWD model number is decoded
As an open-end drawn-cup needle roller bearing in the HK-series (ISO 3245), NTN HK2538ZWD is built around a thin hardened steel cup.Its printed envelope — 25 mm under-roller diameter, 32 mm outside diameter, 38 mm width — is fixed by ISO 3245; the 25 mm figure is the shaft journal itself, which carries the rollers directly. There is no separate inner ring — the thin-walled cup is drawn from sheet steel, hardened, and press-fitted into the housing, giving the smallest radial section of any rolling bearing at this shaft size. The ZW suffix marks two roller rows in the same cup, roughly doubling the dynamic rating of the width-equivalent single-row version at the cost of the extra width. Mid-size drawn cups like this appear throughout passenger-car and light-truck transmissions, pressed into cast housings where a machined ring would not fit. This size is specified in printing-press folder and cutter mechanisms, where the shaft is short, the loads are cyclical, and the thin cup lets the frame plates stay close together. When replacing this size, measure the housing bore with a plug gauge before pressing the new cup: a bore worn oversize by the previous bearing will not retain the new shell.
Typical equipment & failure modes
Common applications
- automotive manual transmission gear sets
- industrial gearbox lay shafts
- hydraulic pump and motor shafts
- shock-loaded start-stop service such as clutch and kick-starter mechanisms
Known failure patterns
- edge loading and needle skewing under shaft misalignment or deflection
- cage wear or fracture from sustained operation near the limiting speed
- cup cracking from an oval or tapered housing bore distorting the thin shell
Selection pitfalls — read before you substitute
- The two roller rows in HK2538ZWD share one cup: any shaft bending or housing-bore taper loads one row ahead of the other, so hold the 32 mm seat straight over the full 38 mm width and keep shaft deflection minimal.
- The 38 mm extra-wide section of HK2538ZWD (double-row or extended roller set) is the high-capacity option at 25 mm shaft; the wider cup is more sensitive to housing bore alignment, so check bore straightness over the full 38 mm width.
- Drawn-cup needle bearings carry radial load only: HK2538ZWD provides no axial shaft location — use separate thrust washers or a locating bearing for axial forces.
- The HK2538ZWD drawn cup is a thin shell that takes the shape of its housing: the housing bore must be machined to tolerance (typically N6/N7 for steel housings) — a worn or oval seat distorts the cup and cuts life.
- Mid-size cups like HK2538ZWD (25 mm shaft) inherit the shape of their seat: a scored or oval housing bore from the previous bearing will cut the new bearing's life short.
Frequently asked questions
What does Fw mean on a HK2538ZWD drawn-cup bearing?
Fw is the under-roller diameter — the diameter of the shaft journal on which the needle rollers run directly. For HK2538ZWD, Fw = 25 mm, so the shaft must be machined to 25 mm, hardened to 58–64 HRC and ground, unless a separate IR inner ring is fitted.
Can a HK2538ZWD needle roller bearing carry axial load?
No. Drawn-cup needle roller bearings like HK2538ZWD carry radial load only and provide no axial shaft location. Axial forces must be carried by separate thrust washers or a locating bearing in the arrangement.
Does HK2538ZWD need a hardened shaft?
Either the 25 mm shaft journal must be hardened to 58–64 HRC and ground to Ra ≤ 0.2 µm, or you can fit the matching inner ring (IR20x25x38.5) so a standard unhardened shaft can be used.
What duty conditions suit a HK2538ZWD drawn-cup bearing?
HK2538ZWD is typically specified for dirty environments where the open ends rely entirely on the housing seals; match the grease/oil speed limits (6500/9500 rpm) and radial load against the actual duty before finalizing.
What are the dimensions of a HK2538ZWD needle roller bearing?
A HK2538ZWD drawn-cup needle roller bearing has a 25 mm shaft diameter (Fw, under-roller diameter), 32 mm outside diameter and 38 mm width, per ISO 3245 boundary dimensions. It has no inner ring — the shaft journal serves as the raceway.
Reviewed & verified by the MPN Base engineering desk against source catalog CAT. No. 2203-3/E 2024 on 2026-09-25. Read our editorial & correction policy.