REVERSE-ROTATIONAL ROTARY TILLER FOR REDUCED POWER REQUIREMENT IN DEEP TILLAGE

In this paper details of rotary tillage regarding the movement of till ed soil are presented. A noticeable reduction of tillage power require ment was achieved during rotary tillage. The soil movement depended up on the direction of rotation and the ratio of tilling depth (H) to bla de radius (R). With the differences in the soil movement, four kinds o f rotary tilling patterns were determined. Increase in operating power generally resulted when a large amount of tilled soil was re-tilled i n the zone of blade rotation. Improvement of backward throwing of the soil was required for power reduction, especially in deep tillage. A b ackward throwing model of soil by the blade was developed on the basis of trochoidal motion of the blade and sliding motion of the soil over a scoop-surface on the horizontal portion of the blade. The throwing model estimated the conditions for avoiding re-tillage, such as direct ion of rotation and shape of scoop-surface. The throwing model was app lied to the design of the shape of the scoop-surface which enabled max imum backward throwing of the soil sufficient to avoid re-tilling. At tilling depths greater than 300 mm, reverse rotation with the new shap ed blades brought about a tillage power reduction by about a half comp ared to forward or reverse rotation with conventional blades.