Adjustable cleaning system of soybean harvester

The invention relates to an adjustable cleaning system of a soybean harvester, and belongs to the technical field of agricultural machinery. A main shaft of a uniform flow fan of the system is provided with a reducing belt wheel and is in transmission connection with a driving belt wheel through a transmission belt with a tension adjusting mechanism; a front grid screen and a rear grid screen in a vibrating screen of the system respectively comprise screen pieces which are arranged in a frame and distributed at intervals; hinge holes and receding holes which are uniformly distributed at intervals are formed in side plates of the rear grid screen; the upper ends of screen pieces of the rear grid screens are hinged to the corresponding hinge holes, and the lower ends of the screen pieces of the rear grid screens stretch out of the corresponding receding holes and then are hinged to the corresponding holes of the outer connecting rods, so that a parallel four-connecting-rod mechanism is formed. And one of the sc