| Size SleeveX | Max. Bore d1 / d2 mm | Outer Dia D mm | Hub Outer D1 Dia mm | Total Length L mm | Sleeve Length L1 mm | Hub Length l1 / l2 mm | Space Betⁿ Hubs l3 mm | l4 | l5 | No. of Teeth | Extra Long Hub Length l1 / l2 mm |
|---|---|---|---|---|---|---|---|---|---|---|---|
| M28 | 28 | 65 | 44 | 84 | 46 | 40 | 4 | 13 | 19 | 34 | 55 |
The M28 jumps from the 56 mm total length of the M24 up to 84 mm. This extra length provides significantly more "clamping" surface area on the shafts, making it the first model in the lineup truly suited for heavy-duty industrial cycles.
Extracted from the dimensional table for the M28 configuration:
| Specification | Metric Value |
| Max Bore Capacity (d1 / d2) | 28 mm |
| Outer Diameter (D) | 65 mm |
| Hub Outer Diameter (D1) | 44 mm |
| Total Length (L) | 84 mm |
| Sleeve Length (L1) | 46 mm |
| Standard Hub Length (l1 / l2) | 40 mm |
| No. of Teeth | 34 |
This model marks a departure from the "compact" series with several major upgrades:
High Tooth Density: With 34 teeth, this coupling offers much smoother power transmission and a higher torque-to-size ratio than the smaller models. More teeth mean the load is distributed more evenly across the elastomer.
Double the Hub Engagement: The standard hub length ($l1/l2$) jumps from 26 mm in the M24 to 40 mm in the M28. This provides a much more secure grip on the motor and driven shafts, reducing the risk of keyway wear under heavy loads.
Increased Sleeve Length: The sleeve reaches 46 mm, allowing for better absorption of shock loads and greater tolerance for angular misalignment.
Extra Long Hub Option: For specialized heavy-duty machinery, an Extra Long Hub of 55 mm is available, providing maximum shaft support.
| Feature | M24 | M28 | Change |
| Total Length (L) | 56 mm | 84 mm | +50% |
| Hub Length (l1) | 26 mm | 40 mm | +54% |
| Outer Dia (D) | 53 mm | 65 mm | +12 mm |
| Teeth Count | 28 | 34 | +6 Teeth |
Heavy Conveyor Drives: Where high-start torque requires the extra hub length to prevent shaft slippage.
Industrial Mixing Equipment: The 34-tooth design excels at dampening the vibrations of viscous fluids.
Large Gearbox Inputs: Fits standard 28 mm output shafts on mid-range industrial gear reducers.
Summary
The M28 is the "heavy-duty" entry point of the series. If your application requires more than just a simple connection—specifically if you need high vibration dampening and maximum shaft security—the M28 is the preferred choice.
