The objective of this study was to analyze characteristics
and measure dynamic resistance forces acting on three types of
rotary blade ,i.e., L-shaped, C-shape and mixed type blades. The
experimental method of this study was to measure resistance
forces and a moment at one blade while cutting sand in the bin.
The rotational speed of rotary shaft was 120 rpm with the cutting
length are 3, 6 and 9 cm. The tilling depth was 12 cm and the
density of sand was about 2.8 kgf/cm2 at 12 cm depth. The
results were shown that maximum resultant forces acted upon
the three-type blades occurred at the cutting length 9 cm. The
magnitudes of these forces are 300 N, 250 N and 350 N at the
tilling depth 5.27 cm, 11.7 cm and 11.2 cm for L-shaped, Cshaped
and mixed type blades, respectively. These
characteristics of dynamic resistance forces which directly act on
rotary blades were firstly studied. These technical information and
phenomena will be used to explain operating conditions of rotary
tiller and design suitable shape of rotary blade.