This page covers the 55 mm bore size of H3 Series Adapter Sleeves to ISO 2982-1 / DIN 5415. It reproduces the dimensional row, then works outward from it: the fit for the load case, the internal clearance group, the shoulder and fillet the corner radius allows, and where this bearing type should and should not be used.
55 mm Bore Dimensional Row (ISO 2982-1 / DIN 5415)
| Designation | Shaft diameter d (mm) | Bore d1 (mm) | Thread | Taper | For bearing series |
|---|---|---|---|---|---|
| H312 | 55 | 60 | M60x2 | 1:12 | 1312 K, 2212 K, 22212 K |
What a H3 Series Adapter Sleeves Does
This is a mounting part rather than a bearing: it exists to locate, clamp or seal a bearing. It carries no rating of its own, and the bearing it serves sets the speed, the load and the temperature the assembly can take.
Radial load. Axial load has to be carried by another element in the assembly.
Speed at 55 mm Bore
No limiting speed is tabulated for this product. Where speed matters, the figure to work to is the one the bearing supplier states for the exact design, cage and lubricant supplied — not a family value.
Mounting a 55 mm Bore H3 Series Adapter Sleeves
This bearing is mounted on a tapered adapter sleeve rather than on a machined interference seat. The sleeve is drawn up the shaft by its lock nut and the tapered bore expands the inner ring onto it, so the fit is created by how far the bearing is driven up the taper — measured as a reduction in radial internal clearance or as an axial drive-up distance — and the shaft itself only needs a commercial tolerance. Never judge the fit by feel: a bearing driven too far up the sleeve loses its clearance and runs hot from the first minute.
Lubrication & Relubrication
This part carries no lubricant of its own. The bearing it works with sets the lubrication regime for the assembly.
Where a 55 mm Bore H3 Series Adapter Sleeves Is Used
At a 55 mm bore, h3 series adapter sleeves are typically found in industrial gearboxes, fans and blowers, conveyor drives, pump and compressor shafts and machine tool spindles, where the load and the heat generated both start to decide the arrangement.
Failure Modes and What They Look Like
- Subsurface fatigue (spalling) — a flake of raceway lifts out and the bearing gets noisy and rough. This is the failure the L10 life calculation predicts — if it arrives near the calculated life the bearing did its job, and if it arrives early the load, the fit or the lubrication was not what the calculation assumed.
- Inadequate lubrication — a polished, then discoloured, then torn raceway, running hot with a darkened grease. It is the most common cause of early failure by a wide margin, and the interval, not the grease, is usually what was wrong.
- Contamination — dents in the raceway with raised edges, then premature spalling from those dents. Wear particles, casting sand and washdown water all do it; sealing and filtration are what prevent it.
- False brinelling and fretting — evenly spaced dull marks at ball or roller pitch, produced by vibration while the shaft is stationary — a machine that travels on a truck, or a standby pump beside a running one. It is not caused by overload and cannot be cured by fitting a bigger bearing.
Where NOT to Use a H3 Series Adapter Sleeves
- Do not rate this part as though it were the bearing it serves. Its function is to locate, clamp or seal; the bearing next to it sets the load, speed and temperature limits of the assembly.
