OPTIMIZATION OF ANIMAL DRAWN TILLAGE IMPLEMENTS .1. PERFORMANCE OF A CURVED TILLAGE IMPLEMENT

The effects of design and operational parameters such as speed, tail angle, side rake angle and radius of curvature of a curved soil tillage implement on horizontal and vertical forces have been investigated under laboratory conditions. Seven different wings of different radii of curvature (150, 200, 250, 300, 350, 400 and 450 mm) were designed. To minimize the effect of physical size, all the curves were made to have equal dimensions before bending them to the required curvature, The ranges of tail angle, side angle and speed used for the investigation were 32 degrees to 54 degrees, 40 degrees to 65 degrees and 0.5 m/s to 2 m/s respectively. The effect of radius on the horizontal force was different for different tail angles used, However, no great effect of radius on the horizontal force was observed, A radius of about 270 mm was found to be optimum for a curved implement, For the vertical force (directed downward), it was observed that, for all tail angles used, the force increased with decreasing radius, A considerable effect of tail angle on both horizontal and vertical forces was observed. Both the horizontal and the vertical forces increased with an increase of tail angle. Experimental investigation showed that both speed and radius affect the relation between side rake angle and force. Equations have been developed to predict the forces that result during interaction of a curved implement with soil and attempts made to fit these equations to the experimental data. (C) 1995 Silsoe Research Institute