Longitudinal axial flow drum structure having adjustable threshing diameter

A longitudinal axial flow drum structure having an adjustable threshing diameter, the longitudinal axial flow drum structure comprising a threshing drum, a transmission mechanism and a diameter regulating mechanism,

• wherein the diameter regulating mechanism comprises a plurality of regulating turntables, a plurality of crank linkages and an adapter sleeve, the threshing drum comprises a drum shaft, and a feeding wheel, a front supporting plate, a middle supporting plate and a rear supporting plate that are installed in the drum shaft in sequence along a feeding direction from front to rear, and a plurality of threshing tooth rods;
• the middle supporting plate is provided with a plurality of U-shaped grooves in a periphery thereof, the front supporting plate, both sides of the middle supporting plate and the rear supporting plate are installed with the regulating turntables that are fixedly connected to each other through the adapter sleeve sleeved over the drum shaft, the middle supporting plate is bored with a plurality of through holes, the regulating turntables arrayed along the both sides of the middle supporting plate are connected via bolts passing through the through holes;
• one end of each of the crank linkages is fixed in a corresponding one of the regulating turntables, the other end of each of the crank linkages is connected with a respective one of the threshing tooth rods inserted into a respective one of the U-shaped grooves;
• the transmission mechanism, serving as a power source of the diameter regulating mechanism, is fixed on the front supporting plate.