Main pulley rope falling prevention device for variable-amplitude trolley of tower crane

The invention discloses a main pulley rope falling prevention device for a variable-amplitude trolley of a tower crane. The main pulley rope falling prevention device comprises an upper rope blocking device, a lateral rope blocking device and rope falling prevention assemblies. The upper rope blocking device is fixed on the variable-amplitude trolley and stretches over a pulley, and a certain distance is reserved between the upper rope blocking device and the highest position of the pulley, wherein the distance is smaller than the diameter of a steel wire rope wound on the pulley. The lateral rope blocking device is fixed to the variable-amplitude trolley and stretches across the position where the steel wire rope is cut into the pulley, a gap is formed between the lateral rope blocking device and the pulley and is smaller than the diameter of the steel wire rope, and the rope falling prevention assemblies are arranged along the edge curve of the lower half portion of the pulley. The rope falling prevention a