Optimisation of machine parameters of a pedal-operated paddy thresher using RSM

A pedal-operated paddy thresher (the VL paddy thresher) was designed and developed at VPKAS, Almora, Uttrakhand, India. The machine performance was evaluated for optimal design parameters, viz., wire loop spacing 39.1 mm, wire loop tip height 60.6 mm and threshing drum speed 339.46 m min−1. The corresponding threshing capacity and efficiency were 64.6 kg h−1 against predicted 66.8 kg h−1 and 96.4% against predicted 98.3%, respectively, for variety Thapa Chini. Comparative performance tests between the newly developed thresher and the old pedal thresher were conducted to test the effects optimisation. Test results indicated that the VL paddy thresher performed better compared to the existing pedal thresher with rice varieties VL-62, Thapa Chini, China-4, VL-85 and VL-61. It was inferred that the wire loop geometry and drum speed have major effect on the threshing performances of paddy threshers. The weight and cost (32 kg and INR 3500 or 88 US$) of the VL paddy thresher were lower than the existing pedal thresher (50 kg and INR 5500 or 138 US$). The power source for operating the thresher is either one person or a 0.373 kW electric motor.