The effects of disc and tilt angles on working parameters of the heavy duty disc harrow with independent spring mounted discs and its modeling with dimensional analysis

The objecitive of this reserach was to determine the design parametres of the heavy duty disk harrow with independent spring mounted discs in field conditions. For this purpose; the heavy duty disk harrow was operated at three tilt angles (15o, 18o and 22o) and three disc angles (20o, 23o and 27o) at different speeds (2.71, 3.51, 4.46 km/h) and draft, slip, fuel consumption, tillage depth and soil pulvarization index were measured to determine the optimum disk angles. Finally, from the data obtained, prediction models for specific draft and fuel consuptions were developed according to the soil constants and disk angles of the machine. Field experiments were conducted in the fields of Menemen Research and Application Farm of the Faculty of Agriculture, Ege University in sandy loam soil with 14.45 % moisture content. The study was planned in the form of a split parcel design and three replications were applied. According to the results; draft, slip, fuel consumption tillage depth and soil pulvarization index are affected by forward speed of the tractor and disc angles of the machine. All parameters, except forward speed effect on fuel consumption, were found statistically significant with a level of α:0.01. The tillage depth increases with increasing disc angles but decreasing with tilt angles of the machine. Minimum and maximum tillage depths were measured as 8.12 cm and 22.44 cm respectively. Draft requirement of the machine increased with increasing disk angles but reduced with tractor forward speed due to reaching optimum speed. Draft was measrued lowest as 27,91 kN at optimum forward speed of 4,46 km/h Low speeds required higher drafts. Slip of the tractor increased with increasing disk angles of the machine. The lowest slip was measured as 9.69% while the highest mesured was 20.75%. The fuel consumption of the tractor increased with increasing disc angles of the machine but decreased with forward speed due to reaching optimum speed. The lowest and highest values of fuel consumption were measured as 12 L/ha and 24.35 L/ha, respectively. Soil pulvarization index increased drastically with increasing disc angles of the machine and forward speeds of the tractor. Index was calculated lowest 0.58 at lowest disc angles and forward speed, and this value reached to highest level of 0.92 at highest disc angles and forward speed. Optimum disc angles that any heavy duty disc harrow with independet spring mounted should have depend on soil conditions, required tillage depth and soil pulvarization index. Disc and tilt angles should be 23º and 18º respectively when it is desired to have optimum tillage depth and pulvarization index in the field. Finally, from the data obtained, prediction models for specific draft and fuel consuptions were developed according to the soil constants and disk angles of heavy duty disc harrow with independet spring mounted with the accuracy of 97% and 98% respectively.