Gear Ratio & Torque
Determine output speed, output torque, and mechanical advantage across two meshing gears.
The Iron Triangle of Gearing
In mechanical power transmission, you can trade speed for torque, or torque for speed, but you can never gain power. In fact, due to frictional losses, output power is always strictly less than input power.
Why We Gear Down
Standard AC induction motors natively run at high speeds (e.g., 1750 RPM or 3450 RPM) but generate relatively low torque. Most industrial machinery – from conveyors to mixers – requires the exact opposite: low speeds and massive torque to overcome inertia.
Efficiency Losses by Gear Type
| Gear Type | Est. Efficiency (Per Stage) |
|---|---|
| Spur Gears | 95% - 98% |
| Helical Gears | 94% - 98% |
| Bevel Gears | 93% - 97% |
| Worm Gears (High Ratio) | 40% - 60% |
Notice the severe efficiency penalty of worm gears, caused by the high sliding friction inherent in their design. However, they are often chosen for their inherent self-locking ability (cannot be back-driven).