Calculate simple and compound four-gear ratios, shaft speeds, torque, power, efficiency, geometry, rotation direction, and practical transmission results quickly and clearly.
| Gear | Teeth | Pitch Diameter | Pitch-Line Speed |
|---|---|---|---|
| Gear 1 | — | — | — |
| Gear 2 | — | — | — |
| Gear 3 | — | — | — |
| Gear 4 | — | — | — |
Center distances will appear after calculation.
A four-gear train changes rotational speed, torque, and direction between shafts. In a simple train, all four gears mesh in sequence. The middle gears mainly transmit motion and alter rotation direction. The overall speed ratio depends on the first and last gears. In a compound train, gears two and three share one shaft. That arrangement creates two useful ratio stages. Each stage multiplies the other, allowing large reductions inside compact mechanisms.
Gear reduction lowers output speed while increasing ideal output torque. Overdrive does the opposite. Real mechanisms lose energy through tooth friction, bearings, lubrication, and alignment errors. This calculator applies either one total efficiency value or one efficiency value per active mesh. Output power therefore remains below input power whenever efficiency is below one hundred percent. Calculated power loss shows the difference clearly.
Pitch diameter determines how mating gears fit together. Metric gears commonly use module, while imperial gears often use diametral pitch. Meshing gears must share compatible tooth geometry and pressure angle. The calculator estimates pitch diameters, center distances, and pitch-line speeds for quick engineering checks. Very small tooth counts can increase undercut risk, especially with common involute profiles. Always confirm detailed gear strength, material limits, backlash, lubrication, and bearing loads before manufacturing.
A ratio above one indicates reduction when the calculator reports input speed divided by output speed. A ratio below one indicates overdrive. For compound systems, multiply both stage reductions. Direction depends on the number of external meshes. Each external mesh reverses rotation. The exported CSV stores the numerical results for spreadsheets, while the PDF creates a compact engineering record. This tool is useful for education, prototypes, machinery planning, motor drives, robotics, and general transmission analysis. Always verify critical designs before fabrication or operation.
| Gear | Teeth | Shaft RPM | Role |
|---|---|---|---|
| Gear 1 | 20 | 1200 | Driver |
| Gear 2 | 60 | 400 | Driven |
| Gear 3 | 15 | 400 | Compound driver |
| Gear 4 | 45 | 133.33 | Output |
For this compound example, R = (60/20) × (45/15) = 9. The output speed is about 133.33 RPM.
It compares input shaft speed with output shaft speed through four meshing gears.
They change direction and spacing, but the first and last tooth counts set the overall simple ratio.
Two gear pairs act as separate stages, so their individual ratios multiply together.
Input torque is multiplied by the reduction ratio and drivetrain efficiency.
It applies the chosen efficiency repeatedly across each active gear mesh.
Use one geometry system consistently for a given gear set.
No. Strength, bending stress, contact stress, fatigue, and bearing loads require separate engineering checks.
Yes. Use the CSV and PDF buttons above the calculator form.
Use these results as engineering estimates and verify critical designs independently.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.