Linear and pure-gear transmission stepless gearbox

The invention relates to a stepless gearbox, which is the first pure-gear transmission stepless gearbox without friction, hydraulic system, computer control system and other auxiliary speed regulating equipment, and radically solves the problems of small driving torque, complicated structure and complex speed regulation because the conventional stepless gearbox transmits power by means of hydraulic pressure and static friction. The stepless gearbox is as simple as pushing and pulling a bellows. In the whole stepless speed change process, the power is transmitted through gears, so the gearbox can realize high-power transmission. The simplest gearbox is only provided with dozens of parts, and can be used in all places requiring speed change such as motorcycles, automobiles, steamships, machine tools and the like.