Grains of grain fall on a sieves made of steel wire. The air draft, which comes absorbed from under the sief, gently floats the wheat that has spread over the sief. The boundary of separation is precisely revealed. The amount of air draft and the tilt angle of the sie wheel can be adjusted. Through these two settings, it is possible to adjust the degree of separation according to the type of wheat, the amount of stone it contains. Air pressure is adjusted with a special indicator. The fact that the air distribution on the entire sief surface is equal and uniform, allowing a very uniform wheat distribution of vibration to be provided by the vibrator, has maximized the separation accuracy.