Gear box

Basics of how the Vespa gearbox works

• 1. The crank (1) is driven by the piston, this is directly connected to the clutch (2)

  2. The clutch (2) can connect and disconnect the crank force to a cog that drives the primary gear (3). When the clutch lever is pulled in by the rider, the clutch plates are lifted and the clutch spins freely without driving the primary gear. When the clutch lever is released by the rider, the clutch springs return the clutch plates pressure to driving the primary gear.

  3. The primary gear is part of a christmas tree of gears (4) which all spin as a solid mass.

  4. Another set of individual gears (5) mesh into the christmas tree and these ride freely on the output shaft (6). Within this shaft is a cruciform which slides up and down between the individiual gears when the rider changes gear. The cruciform locks into a single gear cog and to the output shaft together. So a gear ratio is obtained by a part of the christmas tree driving an individual output gear.

Below is a video from iowancamera on youtube