A gear arrangement that places multiple gears on a single shaft is called a

• A. Simple gear drive
• B. Compound gear drive
• C. Planetary gear set
• D. Differential gear

Answer: (B)

This is about a compound gear drive, where multiple gears are fixed to the same shaft and rotate together. When two gears share the same shaft, they turn as a unit, which lets you change the overall gear ratio between input and output more flexibly while keeping the mechanism compact. In a simple gear drive, each gear sits on its own shaft and meshes with a gear on another shaft, so you don’t have multiple gears tied to one shaft. A planetary gear set is a more complex arrangement with a sun gear, planet gears on a carrier, and a ring gear, designed for high reduction in a compact form, not simply multiple gears on one shaft. A differential uses a set of gears to split torque between two output shafts, not to create a train with several gears mounted on a single shaft.