🔍 Key Concepts

• How power from two engines is combined to drive one shaft • Difference between single input and double input reduction gears • Why double reduction and planetary gears are used (very high speed vs medium‑speed engines)

💭 Think About

• Which option(s) clearly allow power from two separate engines to go into one gear box/one output shaft? • For medium‑speed diesels, do you usually need very large speed reduction (double reduction) or a more modest reduction (single reduction)? • Which designs are more common in standard commercial twin‑engine, single‑shaft arrangements rather than in very high‑power or special applications?

✅ Before You Answer

• Identify which choices are single input vs double input and eliminate any that physically cannot accept two engine inputs. • Decide whether planetary or articulated double reduction gears are typically associated with very high‑speed or gas turbine applications rather than ordinary medium‑speed diesels. • Confirm that the chosen gear type can both merge power from two engines and provide the typical reduction ratio needed from medium‑speed engines to propeller RPM.