Abstract
The action forces on model mole Piercers (the ball type), when they pierce through the sandy loam and clay loam was measured. The results were as follows.
(1) In the case of deep penetrating, the horizontal forces of the ball whose extreme angle is 30 degrees are smaller than the ones whose extreme angles are 45 and 60 degrees respectively.
But when they pierce through shallow layer and have long skirt, there is not any difference of the horizontal forces between the small and the large angled ball.
(2) Large downward force acts upon the small angled ball, and this tendency is remarkable as skirt length increases. Upward force acts on the balls of 45 and 60 degrees when the skirts are short or nothing.
(3) The compound force on the ball is the largest when extreme angle is 30 degrees, and is the smallest when it is 45 degrees.
(4) On the clay loam, the upward force and the horizontal force increase, when compared with that on sandy loam. But it seems that whole tendency is the same both at clay and sandy loam.
(5) It appears that the horizontal force increases in proprotion to the diameter of ball.
(6) The horizontal action force incleases when the pierce speed exceeds 0.37m/s, but the vertical action force has nothing to do with pierce speed.
