H-306 adapter sleeve: complete specifications & mounting data
The H-306 is an adapter sleeve sized 30 x 45 x 31 mm (tapered bore x sleeve OD x width) for a plain 25 mm metric shaft with M 30x1,5 thread supplied with the KM 6 lock nut at 95 g per ISO 2982-1. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 30 mm |
| Outer diameter D | 45 mm |
| Width B | 31 mm |
| Fits shaft diameter | 25 mm |
| Sleeve thread G | M 30x1,5 |
| Included lock nut | KM 6 |
| Included locking device | MB 6 |
| Material | Carbon_Steel |
| Mass | 95 g |
| Manufacturer designation | H 306 |
| Standard | ISO 2982-1 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 23.1 adapter sleeves for metric shafts |
| Last verified | 2026-09-30 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 23.1 adapter sleeves for metric shafts) · extracted 2026-09-30
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 23.1 adapter sleeves for metric shafts); 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 & H3-series range
| Bore d | 1.181 in |
|---|---|
| Outer diameter D | 1.772 in |
| Width B | 1.22 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 7.5 mm |
| Smallest bore in H3-series | 20 mm |
| Largest outer diameter in H3-series | 145 mm |
| Width range across H3-series | 28–77 mm |
| Bore position in H3-series (smallest first) | 3 of 18 |
| Bore above smallest H3-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| H | 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 H-306 model number is decoded
the sleeve wall is 7.5 mm thick at the small end — 25.0% of the 30 mm bore — thin enough to contract evenly onto the 25 mm shaft while keeping the seat round under the clamping load the KM 6 lock nut carries size index 6, matching the bore-code family of the 30 mm seat; the nut engages the M 30x1,5 sleeve thread over its full width at 95 g drive-up is still a hook-spanner job on the KM 6 nut slots, with feeler gauges checking clearance reduction rather than torque controlling the fit a width-to-bore ratio of 1.03 gives a 31 mm tapered contact length; the longitudinal slit lets the sleeve close down radially, so the grip on the 25 mm shaft is purely frictional mass 95 g is 3.2 g per mm of bore; the sleeve with its KM 6 nut and MB 6 washer forms the complete 31 mm-wide mounting assembly with a 25 mm shaft this sleeve serves the small-bearing end of the series — fans, small gearboxes and light conveyor rollers where a plain shaft keeps cost down H 306 is the classic nut-and-washer sleeve — the KM 6 nut drives the bearing up the taper and the MB 6 washer, keyed to the sleeve thread, locks the nut once a tab is bent into place as part of the medium-section H 3 range, the default seat for 13..K and 22..K self-aligning ball bearings and 222..K spherical roller bearings, this size keeps series-standard proportions: 31 mm width on a 30 mm bore, so the bearing lands at the catalogue axial position the KM 6 lock nut and the MB 6 locking washer ship in the kit, and no hydraulic accessory is required at the 25 mm shaft size typical applications include woodworking saw and planer spindles, rolling mill and steel plant roll seats and marine winch and deck machinery shafts adapter sleeves earn their place wherever a tapered-bore bearing must sit at any axial position on a plain shaft — here a 30 mm bore bearing on a 25 mm shaft in marine winch and deck machinery shafts the sleeve lets the designer use a plain, unstepped shaft and still locate the bearing positively; only one shoulder is needed, opposite the KM 6 nut ordering digest — H 306: 25 mm plain shaft to 30 mm tapered bore, sleeve 45 mm OD and 31 mm wide, thread M 30x1,5, supplied with KM 6 nut with MB 6 washer; listed mass is 95 g
Typical equipment & failure modes
Common applications
- conveyor pulley and drum bearing seats
- woodworking saw and planer spindles
- industrial fan and blower impeller shafts
- pump shafts in water and process plants
Known failure patterns
- greasing the tapered seat or shaft destroys the dry friction the joint relies on; a lubricated taper can let the whole sleeve spin under load
- driving the bearing via the outer ring during mounting loads the rolling elements; force is always applied through the lock nut on the inner ring
- misaligning the slit with the load zone or belt-pull direction concentrates stress on the split; orient the slit away from the main load
- mounting without a fixed abutment lets the bearing walk axially; the sleeve needs a shaft shoulder opposite the lock nut
- a fretted or corroded shaft seat cannot be rescued by a new sleeve — the thin wall conforms to the damage and clamping force collapses
Selection pitfalls — read before you substitute
- greasing the tapered seat or shaft destroys the dry friction the joint relies on; a lubricated taper can let the whole sleeve spin under load
- misaligning the slit with the load zone or belt-pull direction concentrates stress on the split; orient the slit away from the main load
- neglecting the catalogue axial displacement value leaves the bearing either loose on the taper or preloaded hot in service
Frequently asked questions
What shaft size does the H-306 adapter sleeve fit?
H 306 is listed for a 25 mm plain shaft; its tapered bore accepts 30 mm K-suffix bearings, the sleeve measures 45 mm OD and 31 mm wide.
What does the H 306 designation mean?
H 306: H-series metric adapter sleeve in the H3 dimension plan; the code resolves to a 30 mm tapered bore and a 25 mm shaft.
What is supplied with the H-306?
Supplied hardware is the KM 6 lock nut and MB 6 locking washer. No hydraulic tooling is listed for the 25 mm shaft size.
How much does the H-306 adapter sleeve weigh?
It weighs 95 g; the figure is the sleeve-only catalogue mass, with the KM 6 nut counted on the same product row but the hydraulic tool ordered separately.
How is the H-306 mounted on the shaft?
Slide the sleeve onto the 25 mm plain shaft against the abutment, fit the bearing, turn the KM 6 nut with a hook spanner until the measured clearance drop matches the table, and lock it with one MB 6 tab.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 23.1 adapter sleeves for metric shafts on 2026-09-30. Read our editorial & correction policy.