| 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| M38 | 38 | 83 | 58 | 84 | 48 | 40 | 4 | 13 | 18 | 44 | 60 |
The M38 is the "heavy hitter" of the mid-range sizes. It maximizes the 84 mm total length by expanding the hub and outer diameters, providing the structural mass required for larger motor frames.
Extracted from the dimensional table for the M38 configuration:
| Specification | Metric Value |
| Max Bore Capacity (d1 / d2) | 38 mm |
| Outer Diameter (D) | 83 mm |
| Hub Outer Diameter (D1) | 58 mm |
| Total Length (L) | 84 mm |
| Sleeve Length (L1) | 48 mm |
| Standard Hub Length (l1 / l2) | 40 mm |
| No. of Teeth | 44 |
The M38 is designed for high-inertia starts and continuous heavy-duty operation:
Maximum Tooth Count (44 Teeth): This model features the highest tooth count in the standard metric "M" range. This high resolution ensures that torque is distributed across the maximum possible surface area, reducing wear on the elastomeric sleeve and providing superior vibration dampening.
Beefed-up Hub (58 mm): The Hub Outer Diameter ($D1$) has been increased to 58 mm to maintain safety factors around the 38 mm bore. This ensures the hub can withstand the high keyway pressures associated with 7.5 kW to 11 kW motors.
Standardized Axial Space: Like the M28 and M32, the Total Length remains 84 mm. This allows engineers to upgrade motor sizes (and thus shaft sizes) without having to redesign the baseplate or move the driven equipment.
Extra Long Hub Option: For high-torque applications where shaft stability is paramount, an Extra Long Hub of 60 mm is available.
| Feature | M32 | M38 | Change |
| Max Bore | 32 mm | 38 mm | +18.5% |
| Outer Dia (D) | 75 mm | 83 mm | +8 mm |
| Teeth Count | 40 | 44 | +4 Teeth |
| Hub Outer (D1) | 50 mm | 58 mm | +8 mm |
Large Industrial Fans: The 44-tooth design is ideal for managing the high rotational inertia of large fan blades.
Conveyor Head-Drives: Used in mining and aggregate sectors where 38 mm shafts are common on gear reducer inputs.
Heavy-Duty Process Pumps: Specifically those used in slurry or high-viscosity fluid transport.
Summary
The M38 is the peak of the 84 mm length series. It offers a 38 mm bore and 44 teeth, making it the most torque-capable model before the series jumps to the larger M42 chassis (88 mm length).
