Chain tightness self-adjusting structure

The utility model discloses a chain tightness self-adjusting structure which comprises a transverse shaft connected between a main center shaft of a main gear and a driven center shaft of a driven gear, the main gear is in transmission connection with the driven gear through a chain, and a tightness adjusting rod assembly is arranged on the transverse shaft. The fixed end of the tightness adjusting rod assembly is connected to the transverse shaft, the tightness adjusting end of the tightness adjusting rod assembly is provided with a longitudinal shaft, the two ends of the longitudinal shaft are provided with guide chain wheels, the guide chain wheels and the main gear are located on the same vertical plane, and the guide chain wheels are meshed with the chain. According to the utility model, the tensioning degree of the chain of the ballast collecting mechanism can be automatically adjusted when the chain is in a loose state, so that the chain is always in a tensioned state, the risk that the chain falls off