Investigations on effect of cylinder configuration of rectangular spiked tooth thresher on threshing performance of wheat crop

Nearly 90% of wheat threshers are spike tooth type and majority of them are operated by a prime mover of 3-4 kW. These threshers available in the market have cylinder and blower on the same shaft and hence are not suitable for threshing other crops. The machine factors which affect the quality and efficiency of threshing are feeding chute angle, spike shape, size and numbers, cylinder type, cylinder diameter, concave size, shape and clearance. In the threshing, standardization and improvement of critical component viz threshing cylinder configuration can bring down the total power consumption to 2/3. Therefore investigation was taken for manufacturing of threshing cylinders with different configuration and their testing for standardization. The threshing cylinder of rectangular spike of 6 mm thickness and 600 mm tip diameter yielded maximum output capacity (372 kg/h) with minimum specific power consumption (0.971 kWh/q) at maximum feed rate ((780 kg/h). The maximum threshing efficiency (99.91%) and minimum wheat straw length (21 mm) was obtained corresponding to the same configuration and feed rate. The minimum broken grain (0.20%) and total loss (0.43%) were at tip diameter of 500 mm and spike thickness of 6 mm corresponding to maximum feed rate (780 kg/h). The output capacity was above 300 kg/h at maximum feed rate (780 kg/h) for all the tip diameter and   spike thickness. The maximum wheat straw split (88.60%) was at 780 kg/h feed rate corresponding to tip diameter of 550 mm and spike thickness of 6 mm. The maximum cleaning efficiency (99.52%) was at maximum feed rate (780 kg/h) corresponding to tip diameter of 550 mm and spike thickness of 6 mm. The wheat straw size for maximum output capacity and threshing efficiency were 22.43 mm at tip diameter of 600 mm and spike thickness of 6 mm corresponding to maximum feed rate (780 kg/h). For higher threshing efficiency, fine straw quality and minimum specific power consumption, rectangular spiked threshing cylinder of 600 mm tip diameter and spike thickness of 6 mm gave best performance results with total grain loss within permissible limit.