Fundamental Studies on Tillage Machinery (I)

Basic Consideration on Soil Stress in Tillage and Various Kinds of Tillage Machinery

Abstract

Author has tried to find out new method to investigate tillage machinery with minimum resistance force, and took consideration on soil stress distribution in tillage and on the type of soil failure, on the ground that soil stress directly determines soil resistance.
In consideration of normal stress and shearing stress in plane of failure, there must be five types of soil failure, namely, compressive shear, simple shear, ten sile shear, rupture, breakage with cutting edge. Based upon Coulomb's equation and interlocking of soil particles, the resistance force in every type of failure was considered and came to the following conclusion; the smaller the normal stress in plane of failure, the less the resistance is. In soil cutting action, breaking resistance and frictional force are two main components of resistance force, therefore in order to reduce them, we must seek for tillage method in which the value of normal stress in plane of failure and on the plane of cutting blade is minimum.
Then, author tried to disclose the factors which greatly effect upon soil stress distribution in tillage, and classified various kinds of tillage implements on the base of these factors, finding that in spite of many various tillage machinery which have hitherto appeared, there can be other kinds of new tillage machinery.