HK3012CT bearing: complete specifications & equivalents
The HK3012CT is a ISO 3245 radial bearing sized 30 x 37 x 12 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 30 mm |
| Outer diameter D | 37 mm |
| Width B | 12 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 12.3 kN |
| Basic static load rating C0 | 18.2 kN |
| Fatigue load limit Pu | 2.22 kN |
| Limiting speed (mechanical) | 5500 rpm |
| Mass | 24 g |
| Manufacturer designation | HK3012CT |
| 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 | 1.181 in |
|---|---|
| Outer diameter D | 1.457 in |
| Width B | 0.472 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) | 20 of 24 |
| Bore above smallest HK-series size | 27 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the HK3012CT model number is decoded
As an open-end drawn-cup needle roller bearing in the HK-series (ISO 3245), NTN HK3012CT is built around a thin hardened steel cup.Its printed envelope — 30 mm under-roller diameter, 37 mm outside diameter, 12 mm width — is fixed by ISO 3245; the 30 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 trailing code letters mark a production-variant shell or cage execution; the boundary dimensions match the base HK size, so interchange checks should rely on the printed Fw/D/C values. In this class the limiting factor is rarely the rating table — a poorly supported or out-of-round seat will end the bearing long before fatigue does. Model and hobby drivetrains, from RC cars to small robotics, use this size because the thin cup lets designers shrink the gearbox around the gears rather than around the bearing. For low-temperature service, verify the grease is rated for the minimum ambient — a standard lithium grease in this cup will stiffen and starve the rollers on a cold start.
Typical equipment & failure modes
Common applications
- construction equipment swing pivots
- printing press cylinder journals
- machine tool feed drive supports
- lightly loaded high-speed idler positions where roller skidding must be watched
Known failure patterns
- cage wear or fracture from sustained operation near the limiting speed
- cup cracking from an oval or tapered housing bore distorting the thin shell
- fretting of the cup outer surface in a soft or worn housing seat
Selection pitfalls — read before you substitute
- The HK3012CT 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.
- Pressing HK3012CT (30 mm shaft) home needs real force: keep the cup square with a guided mandrel, because a tilted cup overloads the roller row nearest the shoulder.
- HK3012CT carries a maker-specific variant code after the size: when substituting another brand, match the printed 30×37×12 mm boundary dimensions and load ratings rather than the suffix letters, which are not standardized across makers.
- The 12 mm standard width of HK3012CT is the general-purpose section at 30 mm shaft; wider HK variants in the same 30×37 mm envelope carry more load and are not interchangeable if the housing width is fixed.
Frequently asked questions
Does HK3012CT need a hardened shaft?
Either the 30 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 (IR25x30x12.5) so a standard unhardened shaft can be used.
What are the dimensions of a HK3012CT needle roller bearing?
A HK3012CT drawn-cup needle roller bearing has a 30 mm shaft diameter (Fw, under-roller diameter), 37 mm outside diameter and 12 mm width, per ISO 3245 boundary dimensions. It has no inner ring — the shaft journal serves as the raceway.
What does Fw mean on a HK3012CT drawn-cup bearing?
Fw is the under-roller diameter — the diameter of the shaft journal on which the needle rollers run directly. For HK3012CT, Fw = 30 mm, so the shaft must be machined to 30 mm, hardened to 58–64 HRC and ground, unless a separate IR inner ring is fitted.
Can a HK3012CT needle roller bearing carry axial load?
No. Drawn-cup needle roller bearings like HK3012CT 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.
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.