In the transmission system, the belt is connected to two disks. The disk on the left is called the driving disk here, and the disk on the right is called the driven disk. The driving disk consists of two disks, the outer disk with blades is the fixed disk and the inner disk is the Puli disk (also called the rotating disk, which can move axially). Puli beads (also called moving beads, which can move radially) are accessories of Puli plate, and there are six in total, which are installed in six chutes respectively. Prickly disc is affected by engine speed. When the speed is gradually increased, the split bead is subjected to outward centrifugal force and moves radially along the chute to squeeze the split disc, thereby reducing the distance between the fixed disc and the split disc. Because the shape between the two disks is like a dovetail groove, which is narrow inside and wide outside. We must slide to the outer edge of the disc to increase the diameter of the driving disc, while the length of the belt is constant. When the diameter of the driving disk increases, the diameter of the driven disk decreases, thus increasing the transmission ratio (transmission ratio is the ratio of the diameter of the driving disk to the diameter of the driven disk). At this time, the speed of the motorcycle will increase, but the speed of the engine will decrease, the Pritzker will move radially to the axis, the strength of the belt pressed by the two disks will decrease, the belt will move to the center of the disks, the diameter of the driving disk will decrease, and the diameter of the driven disk will also decrease.