Drum gear couplings and diaphragm couplings are often compared, but they serve different ranges — not substitutes, but division of labor.
| Aspect | Drum gear coupling | Diaphragm coupling |
|---|---|---|
| Torque | High (630–25000 N·m typical) | Medium (hundreds–few thousand N·m; large sizes costly) |
| Misalignment | Angular+axial+radial, large | Mostly angular/axial, small radial |
| Lubrication | Oil/grease required | None (metal diaphragm) |
| Speed | Usual (1300–4000 rpm) | High / very high speed |
| Maintenance | Teeth replaceable, long life | Membrane fatigues, replace whole |
| Use | Mill/mining/crane/wind (heavy) | Turbine/compressor/high-speed pump |
Verdict: heavy, high-torque, high-misalignment, remote duty → drum gear is steadier; pure high-speed, lube-free turbine duty → diaphragm fits better.