The type of gearbox that uses both planetary and spur gears for torque conversion is typically called a compound planetary gearbox (or compound gear train gearbox).
⚙️ 1. Planetary Gearbox
- Uses sun gear, planet gears, planet carrier, and ring gear.
- Provides high torque density in a compact size.
- Common in automatic transmissions, aerospace, and industrial machinery.
⚙️ 2. Spur Gear Stage
- Spur gears are simple parallel-axis gears that provide direct torque transfer.
- Often used as an input or output stage to modify speed or torque before or after the planetary stage.
⚙️ 3. Combined (Compound Planetary Gearbox)
Combines planetary and spur gears to achieve:
- Higher torque multiplication
- Multiple gear ratios
- Efficient power transmission
Example:
Automotive automatic transmissions or aerospace gearbox systems (e.g., turboprop reduction gearbox).
The gearbox that uses planetary and spur gears together for torque conversion is known as a compound planetary gearbox (or sometimes a planetary–spur combination gearbox).