DEVELOPMENT AND PERFORMANCE EVALUATION OF A TRACTOR OPERATED TAPIOCA HARVESTER

Abstract

The harvesting of tuber crops is one of the serious bottlenecks in the tuber crop production value chain which requires immediate attention for developing appropriate mechanical harvesting technology. The conventional methods of harvesting tapioca using the bare hands with or without the use of indigenous tools are labour intensive, drudgery prone, time consuming and requires skilled labour. Therefore, a research work was undertaken to develop a tractor operated tapioca harvester considering soil, crop and machine parameters. The lab model of conveying unit was developed and evaluated to finalize the parameters such as chain conveyor speed and angle of chain conveyor to achieve maximum conveying efficiency for prototype of tapioca harvester. The developed machine comprises of main frame, power transmission system, digging unit, conveying unit and hydraulic drive system. The overall dimensions (L×W×H) of the developed unit was 2335×1800×1600 mm respectively. The performance evaluation of the developed unit was conducted and the operational parameters were standardized. The digging unit of the developed harvester was tested with different treatment combinations of blade geometries viz., Chisel type share, Crescent shaped and V-shaped blades at different rake angles of 15, 20 and 25° and at different forward speeds of 1.5, 2.0 and 2.5 km h -1 . The effects due to these parameters were optimized based on performances parameters viz., draft requirement, digging efficiency, percent damage and fuel consumption. The conveying unit of the harvester was tested with different treatment combinations of chain conveyor speed (2.1, 2.8 and 3.5 km h -1 ) and angle of chain conveyor (15, 20 and 25°). The operational parameters of the conveying unit were optimized based on the performance parameter, i.e., the conveying efficiency. The optimization of independent parameters was performed by numerical optimization technique to obtain optimum levels and the desirability index was found out and accordingly the best optimal solutions were separately found out for digging and conveying units of the harvester. The cost economics of developed harvester was found 142out in terms of break-even point, payback period and benefit-cost ratio. The saving in cost of operation of developed machine over conventional method of harvesting tapioca was also determined to predict the economic viability of the developed machine. The maximum conveying efficiency of 94.22 per cent was recorded for chain conveyor speed of 3.5 km h -1 and angle of chain conveyor of 15° with lab test of experimental model of the conveying unit. The maximum draft of 3725.95 N was recorded for crescent shaped blade while the minimum of 2513.64 N was obtained for chisel type share blade. The maximum digging efficiency of 96.17 per cent was noticed for chisel type share blade, whereas the lowest of 79.71 per cent was obtained for crescent shaped blade. The least percent damage of 0.79 per cent was obtained for chisel type share blade whereas highest of 5.54 per cent was recorded for V-shaped blade. Among the different types of blade geometry, the minimum fuel consumption of 4.75 L h -1 was obtained for chisel type share blade, whereas the maximum of 6.24 L h -1 was recorded for crescent shaped blade. The maximum conveying efficiency of 92.16 per cent was recorded for chain conveyor speed of 3.5 km h -1 and angle of chain conveyor of 15°, whereas least conveying efficiency of 84.87 per cent was obtained for chain conveyor speed of 2.1 km h -1 and angle of chain conveyor of 25°. The effective field capacity and field efficiency of the machine were noticed as 0.13 ha h -1 and 86.67 per cent respectively. The cost for development of the prototype tractor operated tapioca harvester was Rs. 93,000. The cost of operation of harvester was found out as Rs. 1033 h -1 and breakeven point, payback period and benefit cost ratio of the machine was 65.24 hours per annum, 1.50 years and 4:1 respectively. The savings in cost for harvesting of tapioca with harvester was Rs. 31806 ha -1 and 80.01 per cent when compared to manual harvesting by conventional method.