Effect of velocity ratio on performance characteristics of an active-passive combination tillage implement

Abstract

A study was conducted to investigate the effect of velocity ratio (ratio of peripheral velocity to the forward velocity of tillage tool) on the performance of an active-passive combined offset disc harrow. This implement unites the benefits of powered discs and combination tillage to reduce draft requirements, wheel slip, and gross fuel consumption. The test parameters consisted of forward velocities (3.46, 4.55, and 6.82 km h−1) and rotational velocities of front gang axle, NFGA (95, 133, and 150 rpm) to ultimately vary the velocity ratio from 1.48 to 4.59. Tests were conducted in freshly harvested paddy fields with sandy clay loam soil having moisture content and cone index of 11 ± 0.75% (dry basis) and 975 ± 50 kPa, respectively. The results indicate that increase in velocity ratio from 1.48 to 3.49 helped to reduce both draught and torque requirement with negligible reduction observed when velocity ratio was increased beyond 3.49. At a velocity ratio of 2.91, the specific energy consumption was minimum. Attempts were made to select a suitable velocity ratio based on tillage performance index considering both fuel energy input and tillage effectiveness parameters such as crop residue burial efficiency and soil pulverization. It is suggested to operate this type of implement at velocity ratio of 3.09 (forward velocity 4.55 km h−1, NFGA 133 rpm) and 4.06 (forward velocity 3.46 km h−1, NFGA 133 rpm) during the first pass and the second pass, respectively to obtain maximum tillage performance with minimum energy consumption.