How Does a Variator Work?

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    • The variator transmission consists of two pulleys connected by a drive belt. One pulley is driven by the rotation of the main crankshaft, while the belt connects it to a second pulley, called the "Driven" pulley. A single standard length belt has a V groove design that allows it to ride in the pulley bevels without any slippage because it stays in constant contact with the pulleys.

    Front Pulley

    • The front driving pulley consists of two halves, a front half and a rear half. The rear half of the pulley mechanism is a hollow shell equipped with compartment ramps, and rounded weights that sit inside the compartments. As the motor spins, so does the rear half of the pulley, which forces the weights to travel in an outward direction due to centrifugal force. As the weights push against the interior plates, the rear half of the pulley moves toward the front half of the pulley, closing the gap and raising the belt position up into a higher gear.

    Rear Pulley

    • The rear pulley has two divisions just like the front pulley, a front half and rear half. Only the shaft the pulley rides on has a stiff center spring. The spring forces the two halves together, which holds the belt outward in a low gear position. When acceleration or torque is applied, the two halves move away from each other, allowing the belt to slip downward into a higher gear, changing the diameter or gear ratio of the pulley. The tautness of the spring governs how fast the pulley halves separate, and when the acceleration is decreased, the spring acts to close the pulley halves.


    • The centrifugal clutch which connects to the outside of the rear pulley does not engage the drive shaft unless torque or acceleration is provided. It allows the transmission to sit in neutral at idle, without any driving force. When acceleration is applied, the spring weights inside the clutch housing compress against the clutch shell which is connected to the drive gear shaft. The clutch engages first, transmitting rotational speed, then the variator actuates to close the pulley halves, raising the gear. The gradual closing of the pulley halves provides a smooth, up-shift transition from a slower speed to a higher speed.

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