H-311 adapter sleeve: complete specifications & mounting data
The H-311 is an adapter sleeve sized 55 x 75 x 45 mm (tapered bore x sleeve OD x width) for a plain 50 mm metric shaft with M 55x2 thread supplied with the KM 11 lock nut at 320 g per ISO 2982-1. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 55 mm |
| Outer diameter D | 75 mm |
| Width B | 45 mm |
| Fits shaft diameter | 50 mm |
| Sleeve thread G | M 55x2 |
| Included lock nut | KM 11 |
| Included locking device | MB 11 |
| Associated hydraulic nut | HMV 11 E |
| Material | Carbon_Steel |
| Mass | 320 g |
| Manufacturer designation | H 311 |
| 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 | 2.165 in |
|---|---|
| Outer diameter D | 2.953 in |
| Width B | 1.772 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 10 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) | 8 of 18 |
| Bore above smallest H3-series size | 35 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-311 model number is decoded
the sleeve wall is 10 mm thick at the small end — 18.2% of the 55 mm bore — thin enough to contract evenly onto the 50 mm shaft while keeping the seat round under the clamping load the KM 11 lock nut carries size index 11, matching the bore-code family of the 55 mm seat; the nut engages the M 55x2 sleeve thread over its full width the annular envelope between 55 mm bore and 75 mm OD is about 2,042 mm² in cross section, which sets the 320 g mass at steel density for the 45 mm-long slit bush a width-to-bore ratio of 0.82 gives a 45 mm tapered contact length; the longitudinal slit lets the sleeve close down radially, so the grip on the 50 mm shaft is purely frictional mass 320 g is 5.8 g per mm of bore; the sleeve with its KM 11 nut and MB 11 washer forms the complete 45 mm-wide mounting assembly with a 50 mm shaft this sleeve covers the most frequently replaced bearing seats, where using a plain shaft and sleeve avoids the cost of a stepped, ground shaft the un-suffixed H catalogue number means the standard execution; the M 55x2 thread, the KM 11 nut and the MB 11 washer are dimensioned as one matched assembly for this seat the H3 designation block places it in 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 — every sleeve in the block uses the same bore-code logic, and here the 55 mm tapered bore matches the K-suffix bearing it is ordered for the KM 11 lock nut and the MB 11 locking washer ship in the kit; controlled drive-up uses the HMV 11 E hydraulic nut rather than a spanner typical applications include quarry conveyor head and tail drums, conveyor pulley and drum bearing seats and printing press cylinder journals adapter sleeves earn their place wherever a tapered-bore bearing must sit at any axial position on a plain shaft — here a 55 mm bore bearing on a 50 mm shaft in printing press cylinder journals the sleeve lets the designer use a plain, unstepped shaft and still locate the bearing positively; only one shoulder is needed, opposite the KM 11 nut ordering digest — H 311: 50 mm plain shaft to 55 mm tapered bore, sleeve 75 mm OD and 45 mm wide, thread M 55x2, supplied with KM 11 nut with MB 11 washer, drive-up tool HMV 11 E; listed mass is 320 g
Typical equipment & failure modes
Common applications
- rolling mill and steel plant roll seats
- quarry conveyor head and tail drums
- textile machine roller shafts
- woodworking saw and planer spindles
Known failure patterns
- over-driving the taper eliminates bearing internal clearance entirely; clearance reduction must be measured with feeler gauges, not estimated from nut torque
- the shaft must be within h9 tolerance and free of scoring; an oversize or rough shaft stops the slit sleeve closing down and leaves the grip to the thread alone
- a fretted or corroded shaft seat cannot be rescued by a new sleeve — the thin wall conforms to the damage and clamping force collapses
- 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
- mounting without a fixed abutment lets the bearing walk axially; the sleeve needs a shaft shoulder opposite the lock nut
Selection pitfalls — read before you substitute
- over-driving the taper eliminates bearing internal clearance entirely; clearance reduction must be measured with feeler gauges, not estimated from nut torque
- a fretted or corroded shaft seat cannot be rescued by a new sleeve — the thin wall conforms to the damage and clamping force collapses
- reusing a stretched locking washer tab invites fatigue failure; the bent tab snaps off and the nut backs off undetected
Frequently asked questions
What shaft size does the H-311 adapter sleeve fit?
H 311 is listed for a 50 mm plain shaft; its tapered bore accepts 55 mm K-suffix bearings, the sleeve measures 75 mm OD and 45 mm wide.
What does the H 311 designation mean?
H 311: H-series metric adapter sleeve in the H3 dimension plan; the code resolves to a 55 mm tapered bore and a 50 mm shaft.
What is supplied with the H-311?
Supplied hardware is the KM 11 lock nut and MB 11 locking washer. Drive-up is done with the HMV 11 E hydraulic nut.
How much does the H-311 adapter sleeve weigh?
It weighs 320 g; the figure is the sleeve-only catalogue mass, with the KM 11 nut counted on the same product row but the hydraulic tool ordered separately.
How is the H-311 mounted on the shaft?
Slide the sleeve onto the 50 mm plain shaft against the abutment, fit the bearing, turn the KM 11 nut with a hook spanner until the measured clearance drop matches the table, and lock it with one MB 11 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.