Gearbox

A gearbox, comprising a speed change device and a gear shifting control system, wherein the speed change device comprises a box body, a main shaft and a countershaft, the main shaft and the countershaft are mounted in parallel on the box body, at least one main shaft gear is mounted on the main shaft, and a countershaft gear meshing with the main shaft gear is mounted on the countershaft;

• a ratchet meshing with the main shaft gear is slidably mounted on the main shaft;
• the ratchet is in driving connection with the gear shifting control system;
• wherein the gear shifting control system comprises an elastic shift fork mechanism, a gear shifting guide groove drum rod for driving the elastic shift fork mechanism to move, a gear shifting control gear set for driving the gear shifting guide groove drum rod to rotate, and a gear shifting control mechanism for driving the gear shifting control gear set to rotate, and the gear shifting guide groove drum rod is rotatably mounted on the box body;
• wherein the elastic shift fork mechanism comprises a shift fork seat, a shift fork arm rotatably connected to the shift fork seat, and an elastic member for driving the shift fork arm to reset, and after the shift fork arm swings relative to the shift fork seat, the elastic member drives the shift fork arm to reset;
• and
• a gear shifting guide groove is provided on a circumferential surface of the gear shifting guide groove drum rod, and an upper end of the shift fork seat is provided with a shift fork convex column, the shift fork convex column is movably provided in the gear shifting guide groove, and a lower end of the shift fork arm is movably connected to the ratchet;
• wherein the speed change device further comprises a chain wheel mounted on the main shaft and cranks mounted at both ends of the main shaft;
• the shift fork arm is provided with a lower fork part, and each of inner sides of both ends of the lower fork part of the shift fork arm is provided with a shift pile, the shift pile is movably provided in a shift fork groove on a circumferential surface of the ratchet.