Design and development of tractor operated onion digger with cutter bar topping unit
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Date
2020-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
A tractor drawn onion digger with cutter bar topping unit which unites the benefits of topping and digging together, along with soil separation unit was designed and developed for onion crop. It comprised of a topping unit, digging unit, soil separation unit, power transmission unit, windrowing unit, main frame, and three point hitch. A standard reciprocating type cutter bar with a total cutting width of 750 mm was used as a topping unit. An inverted V- shaped blade of 650 mm was used as digging unit which was fixed to the base plate with nuts and bolts. For the conveyor a rectangular sieve with the overall dimensions of 700 × 550 mm was used for separating the onion from the soil. It was supported by two passive rollers made up of 50.8 mm diameter pipe and 550 mm length on which the canvas endless belt of 50 mm thickness was rotating over both the ends of the rollers. 20 × 55 mm MS flats are bolted perpendicular on the belt with a span of 250 mm gap between two successive flats which helps to pass the soil through the gap between the flats. A power transmission unit consisted of gear box, V- belts, shafts, and pulleys. Pulleys were used to transmit the power and maintain the speed ratio of 3:1 and 2.4:1 for conveying and topping unit respectively. The total weight of the onion digger with topper was 135 kg. The maximum stress, strain and deflection on digging unit in finite element analysis (FEA) using solid works software was found as 2.975×106 N m-2, 3.172×10-2 mm, 9.729×10-6 respectively. The physical and agronomical properties as found equatorial, polar diameter, shape index, bulk density, plant height and number of tillers per plant was measured and found to be 44.75 mm, 43.34 mm, 1.01, 561 kg m-3, 28.76 mm, 5 number respectively. Field evaluation of machine was conducted to optimize the independent parameters such as moisture content (9.5, 11.65, and 13.0%) (dry basis), rake angle (10,15, 20°) and speed of operation (2.5,3.25,4.0 km h-1) by using central composite design (CCD) in response surface methodology (RSM). The optimum conditions for maximum digging efficiency (93.76%), minimum damage percentage (6.44%) and topping efficiency (78.46%) were found at 11.39% (dry basis) moisture content, 15.12° rake angle and 3.11 km h-1 speed of operations respectively. For optimum values of independent parameters the theoretical field capacity, actual field capacity and field efficiencies were calculated 0.20 ha h-1, 0.17 ha ha-1, and 85% respectively. 4.94 hours were required to cover one hectare land using tractor operated onion digger with cutter bar topping unit that cost about rupees 2,284.88/- per ha which is 59.37 % less as compared with manual digging (Rs. 5,625/- per ha).