Rotary Shaft Oil Seals
O-Rings & Rotary Seals · 8 specs
Direct Answer
Radial rotary shaft oil seals retain lubricating grease/oil and exclude contaminants along rotating shafts, standardized under DIN 3760 / ISO 6194 by three boundary dimensions: Shaft Diameter (d_1), Housing Bore Diameter (d_2), and Seal Width (b).
Source: DIN 3760 Radial-Wellendichtringe / ISO 6194-1 · Last reviewed Aug 28, 2026
Specs
| Governing Standards | DIN 3760 / ISO 6194-1 / RMA OS-1 |
| Dimension Format | [Shaft Diameter d₁] × [Bore Diameter d₂] × [Width b] in mm (e.g. 25 × 40 × 7) |
| DIN 3760 Type A (ISO Form SC) | Elastomer-encased outer metal case, single sealing lip with garter spring |
| DIN 3760 Type AS (ISO Form TC) | Elastomer-encased outer metal case, primary sprung lip + auxiliary dust wiper lip |
| DIN 3760 Type B (ISO Form SB) | Exposed precision-ground metal outer diameter, pressed into cast iron housings |
| Garter Spring Material | Carbon spring steel (Standard) or AISI 302/316 Stainless Steel (Corrosion/Marine) |
| Shaft Surface Finish Requirement | Ra 0.2 to 0.8 µm (Rz 1.0 to 4.0 µm) plunge-ground without spiral machining lead |
| Shaft Hardness at Seal Track | 45 to 60 HRC minimum (prevents grooving under seal lip) |
Popular DIN 3760 Metric Rotary Shaft Seal Sizes
| Shaft Diameter (d_1) | Housing Bore (d_2) | Seal Width (b) | Standard DIN Type | Max Shaft Speed (NBR @ 80°C) | Typical Automotive / Industrial Application |
|---|---|---|---|---|---|
| 12 mm | 22 mm | 7 mm | Type AS (TC) | 10,000 RPM | Small electric motor, motorcycle shift shaft |
| 15 mm | 30 mm | 7 mm | Type AS (TC) | 8,000 RPM | Water pump shaft, small industrial gearbox |
| 20 mm | 35 mm | 7 mm or 8 mm | Type AS (TC) | 6,500 RPM | Motorcycle wheel hub, power tool output shaft |
| 25 mm | 40 mm | 7 mm or 8 mm | Type AS (TC) | 5,500 RPM | Automotive transmission output shaft |
| 30 mm | 47 mm | 7 mm or 8 mm | Type AS (TC) | 4,800 RPM | Automotive front wheel hub, pump spindle |
| 35 mm | 52 mm | 7 mm or 8 mm | Type AS (TC) | 4,200 RPM | Engine camshaft front seal, tractor PTO shaft |
| 40 mm | 55 mm or 62 mm | 8 mm | Type AS (TC) | 3,700 RPM | Automotive crankshaft front seal |
| 85 mm | 105 mm | 11 mm or 12 mm | Type AS (TC) | 1,800 RPM | Automotive rear main crankshaft seal |
Shaft Plunge-Grinding & Lead-In Chamfers
Rotary shaft seal longevity depends entirely on shaft preparation:
- No-Lead Plunge Grinding: The shaft seal track must be ground via plunge grinding without axial feed. If the shaft has spiral tool marks (lead) from turning, the rotating spiral acts as a micro-pump that pumps lubricating oil out of the housing or pulls exterior grit into the oil reservoir.
- Shaft Lead-In Chamfer: The shaft end must have a 15° to 30° lead-in chamfer with all burrs polished off. Installing a seal over a sharp shaft shoulder flips or cuts the delicate elastomeric lip, dislodging the garter spring.