When the drive pulley is small and the driven pulley is large, you get a low ratio for accelerating from a stop; swapping pulley sizes provides an appropriate cruising ratio.
12.
The power input to a gear train with a torque " T A " applied to the drive pulley which rotates at an angular velocity of " ? A " is " P = T A ? A ".
13.
From this two forward gears were provided by belts to either of the rear wheels with ratios selected by clutches on different diameter pulleys on either end of the countershaft . Braking was by blocks bearing on the drive pulleys.
14.
Computerized sensors constantly adjust the diameters of pulleys _ the drive pulley from the engine and the driven pulley that sends power to the wheels _ at each end of a steel drive belt, pushing the belt closer or farther away from the center of each pulley.