HK4012 bearing: complete specifications & equivalents
The HK4012 is a ISO 3245 radial bearing sized 40 x 47 x 12 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 47 mm |
| Width B | 12 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 13.4 kN |
| Basic static load rating C0 | 24.5 kN |
| Fatigue load limit Pu | 2.8 kN |
| Reference speed (thermal) | 6300 rpm |
| Limiting speed (mechanical) | 7000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 30 g |
| Manufacturer designation | HK 4012 |
| Standard | ISO 3245 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & HK-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 1.85 in |
| Width B | 0.472 in |
| ISO bore code | 12 |
| Radial section height (D−d)/2 | 3.5 mm |
| Smallest bore in HK-series | 3 mm |
| Largest outer diameter in HK-series | 68 mm |
| Width range across HK-series | 6–38 mm |
| Bore position in HK-series (smallest first) | 22 of 26 |
| Bore above smallest HK-series size | 37 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| HK4012 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
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 HK4012 model number is decoded
The drawn cup bearing HK 4012 gives the smallest radial section of any caged needle bearing with its own outer ring: 40 mm Fw, 47 mm OD and 12 mm width, the shell pressed directly into the housing bore. Reading the code: HK marks the open-end drawn cup series, the first two digits (40) give the 40 mm under-roller diameter Fw, the last two (12) the 12 mm width; the 47 mm OD follows the ISO 3245 plan. Open caged execution: the standard HK drawn cup with steel cage, relubricable through the shaft where the housing allows. Drawn cups exist open (basic HK), sealed (2RS, with contact seals and grease fill) and with polymer TN cage; each is a separate order number with its own ratings, not a field conversion. Minimum load matters: below roughly 0.02·C the rollers skid and smear; preloading the pivot or specifying a heavier execution avoids the glazing that pure oscillation produces on these raceways. Mounting: press the cup in with a shouldered mandrel against the stamped end face only — through-the-rollers pressing brinells both raceways; the housing bore takes a firm press fit and the shaft slides in after.
Typical equipment & failure modes
Common applications
- clutch release mechanisms and cable pulleys
- office equipment and power tool gear trains
- steering column and pedal-box pivots in passenger cars
- idler gears and pulleys in small appliance drives
Known failure patterns
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- fretting corrosion of the cup outside diameter in a soft or oversized housing bore
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- corrosion pitting from condensation in intermittently operated machinery
Selection pitfalls — read before you substitute
- At 40 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 40 mm seats can bend past the compensation range long before the load rating is exhausted.
- Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.
- Do not interchange envelope-identical needle families blindly: HK 4012 shares its 40×47×12 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- The 13.4/24.5 kN ratings and 30 g mass are SKF catalogue values transcribed from ch. 7.2 of PUB BU/P1 17000 (PDF table page 624); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Which dimensions does the HK 4012 have?
A HK 4012 measures 40 mm bore/Fw × 47 mm outside diameter × 12 mm width (1.575 × 1.85 × 0.472 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 13.4 kN, static C0 24.5 kN, fatigue limit Pu 2.8 kN, limiting speed 7,000 r/min, reference speed 6,300 r/min, mass about 30 g.
What does HK 4012 mean in SKF part numbering?
HK = open-end drawn cup needle roller bearing (ISO 3245); the first two digits give Fw 40 mm, the last two the width 12 mm, the shell OD 47 mm follows the plan. 2RS adds both-side contact seals, TN the polymer cage.
Does the HK 4012 need a hardened and ground shaft?
No. In this execution the 40 mm shaft journal is the inner raceway: it must be ground and hardened to 58–64 HRC (with matching housing bore quality on the outside). If the shaft cannot meet that, order the inner-ring sibling (NKI/NA execution) plus its ground inner ring instead.
What mounting mistakes ruin a HK 4012?
Press the cup in with a shouldered mandrel bearing on the stamped face, into a housing bore sized for a firm press fit; never hammer it or press through the rollers. Then slide the hardened shaft in. For 2RS executions the seals and grease are already in place — no additional sealing is needed.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings on 2026-09-26. Read our editorial & correction policy.