What’s inside?

Its time again for another installation of everyones favorite show “What’s inside?” My curiosity about how things work often gets me into trouble,however when I decided to crack open the transmission on my Kymco People150 there was no problem at all. The Kymco, and pretty much all automatic scooters, have a CVT transmission. This type of transmission has two pulleys, each made up of two conical pulley halves, a belt, a variator and a clutch. Inside the variator are roller weights, as the engine speeds up centripetal force causes the rollers to move outward. This forces the front pulley halves together. Since the pulley halves are conical the belt is forced to run further out on the pulley half effectively
making the pulley bigger.

The rear pulley is also made of two conical pulley halves. The rear pulley halves are held together by a spring. As the belt tightens up on the rear pulley, due to the expanding front pulley, the rear pulley halves are forced apart against the spring tension, effectively making the pulley smaller.

The clutch is mounted to the rear pulley. The clutch has two or three brake shoes that spin out with centripetal force to grip the clutch bell which is connected to the final reduction, then the rear wheel. (the clutch bell is what you see in the photo, the clutch is inside it) When the spinning clutch engages the clutch bell the rear wheel turns. When you let off the throttle the motor slows and the clutch no longer engages the clutch bell allowing the rear wheel to coast until you apply the break otherwise the inertia of the bike would cause the engine to turn over (engine breaking). Now that I’ve gotten you really confused, heres a little movie.

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