Gear connecting structure of gearbox

The utility model discloses a gear connecting structure of a gearbox, which comprises a gearbox shell, the gearbox shell comprises a main shell, a lower mounting shell part extending downwards is formed on the right side of the main shell, a box cover is fixed on the bottom surface of the lower mounting shell part, and a duplicate gear shaft and an input shaft are arranged between the box cover and the lower mounting shell part; the upper end of the input shaft is hinged to a top plate of the lower mounting shell part, and the lower end of the input shaft is hinged to a bottom plate of the box cover; the outer side wall of the upper end of the duplicate gear shaft is fixed to the inner side wall of an inner ring of an upper tapered roller bearing, a mounting groove is formed in the bottom face of a top plate of the lower mounting shell part, and an outer ring of the upper tapered roller bearing is fixed to the inner side wall of the mounting groove. An upper tapered roller bearing and a lower tapered roller b