Adapter sleeve is a tapered mounting accessory with a 1:12 external taper used to fix tapered bore bearings onto plain shafts or shafts with loose-fit tolerances, enabling axial position adjustment and easy disassembly without requiring precision shaft machining.
The adapter sleeve consists of three components: the tapered sleeve (with a longitudinal split allowing radial compression when tightened), the locknut (KM type), and the lockwasher (MB type) as standardized by SKF and Schaeffler. When the locknut is tightened, the sleeve is forced into the bearing's tapered bore, generating a clamping force that grips the shaft. See the complete guide to self-aligning bearings and their mounting systems at self-aligning bearing guide and browse spherical roller bearings with EK tapered bore compatible with adapter sleeves. The most common combination: self-aligning spherical roller bearing (SRB) series 22xxx/23xxx + adapter sleeve + KM locknut + MB lockwasher.
Key advantages over direct shaft-shoulder mounting: (1) shaft requires only h9 or h11 tolerance — no precision machining needed; (2) bearing removal is fast during scheduled maintenance without a press; (3) axial position can be adjusted after initial mounting; (4) replacing the adapter sleeve is simpler than regrinding the shaft.
Mounting Procedure and Clearance Verification
Standard mounting procedure for bearing 22220 EK/C3 (d = 100, D = 180, B = 46 mm, C = 365 kN) on adapter sleeve H320 (for shafts 95–100 mm):
- Clean shaft and sleeve thoroughly; apply a thin grease film on the taper surface
- Slide the sleeve onto the shaft; mount the bearing onto the sleeve
- Measure initial radial internal clearance with a feeler gauge before tightening — record the value
- Tighten the KM locknut clockwise. Check clearance after every 30° of rotation
- Stop when clearance has reduced by the amount specified in the catalog table (typically 15–25 µm for 22220)
- Fold the lockwasher MB tab into the locknut slot to lock
Practical example: bearing 22220 EK/C3 with initial C3 clearance of 35–55 µm, required clearance reduction of 20–25 µm. After correct tightening, remaining clearance is 10–30 µm — sufficient for operating temperatures up to 80°C.
| Adapter Sleeve | Compatible Bearing | Shaft Diameter | Clearance Reduction at Correct Tightening |
|---|---|---|---|
| H208 | 22208 EK | 35–40 mm | 10–15 µm |
| H2316 | 22316 EK | 75–80 mm | 18–23 µm |
| H320 | 22220 EK | 95–100 mm | 20–25 µm |
| H3128 | 23128 EK | 135–140 mm | 25–32 µm |