Abstract
Using the experimental method described in the previous report, a series of factor tests were carried out and obtained data were analyzed. The main results are following: 1) Although the fluctuation of measured value of soil stress is considerably large and obtained data may be considered as only qualitative data, soil stress measurement is very useful for studying real reasons of resistance force change. 2) The stress theory has been proved to be right and useful for studying new tillage method with minimum resistance force. 3) In the case of discontinuous blades, the horizontal resistance force component is less than that of continuous blade. This is thought to be caused by the stress reduction at the slit as well as the reduction of frictional, shearing and cutting resistance near the slit. 4) Minus curved blades have been proved to need less draft than plus blades.
This is caused from the less soil compressing character of minus blades. 5) With the increase of cutting angle as well as cutting velocity, the compressive tendency of furrow slice is strengthened, therefore the resistance increases. 6) Degree of freedom of blade motion causes stress relaxation in furrow slice, consequently the horizontal resistance decreases. But because of the vertical compressive action near the lower part of disc blade, the vertial component increases considerably.
