Forward or reverse motion of the vehicle is obtained by placing the selector lever in Drive or Reverse.
In Drive, a synchronizer assembly connects the magnetic clutch directly to the primary pulley of the variable transmission.
In Reverse, the drive is transmitted through a reverse idler. It changes the direction of rotation of the primary pulley, and the transmission.
A steel vee belt connects the primary pulley to the secondary. The pulleys are split to allow their contact radius or groove width to be varied.
Hydraulic pressure from an engine driven pump, and a computerized hydraulic-control system, moves one side of each pulley inward or outward.
This widens or narrows the pulleys, but the vee belt stays taut at all times.
In a widened pulley, the belt rides down to the bottom of the groove.
When the pulley is narrowed, it rides up to the top.
This creates different size pulleys, which act like gears of different sizes, to provide varying gear ratios.
When the primary, or drive pulley is widest, and the secondary or driven pulley is narrowest, it creates a low ratio of approximately 2.5 to 1.
When the pulleys are the same size, a 1 to 1 direct drive gear ratio is created.
With the drive pulley narrowest and the driven pulley widest, an overdrive ratio of about 0.5 to: 1 is created.
Between these extremes, the variation in pulley widths provides a stepless range of gear ratios which is not linear, as in a manual transmission. It is expressed as the region bound by the maximum and minimum pulley ratio.
This allows the engine to run in its most efficient speed range for fuel consumption and maximum torque output.
