Development of cowpea thresher

A cowpea thresher that uses petrol engine was developed to overcome drudgery of threshing with manually operated thresher and also to replace motorized cowpea thresher that cannot be used in areas where there is no supply of electricity. The performance tests on the machine were replicated three times using 10000, 8000 and 6000 grams of kannanado cowpea pods at the threshing cylinder speed of 700, 800 and 900 rpm each and moisture contents of 11.05%, 13.65% and 14.75% respectively based on the following parameters; Threshing efficiency, throughput capacity and percentage seed damage. The findings of the tests showed that the thresher had highest threshing efficiency of 98% at moisture content of 11.05%, threshing cylinder speed of 900 rpm and feed rate of 6 kg/hr. The maximum throughput capacity was observed to be 46.18 kg/hr at the feed rate of 10 kg/hr, 11.05% grain moisture content and threshing cylinder speed of 900 rpm. A highest cleaning efficiency and grain damage of 93.06% and 4.90% respectively were observed. This revealed that as the cylinder speed increased the threshing and cleaning efficiency and the throughput capacity also increased whereas feed rate and moisture content were decreased. The test also showed that high moisture content has a tendency to reduce the mechanical seed damage for the variety (kannanado) of cowpea investigated. Therefore, cowpea moisture contents of 11.05 % and threshing cylinder speeds of 900 rpm are the crop-machine parameters combination for optimum thresher performance. The performance of the machine is satisfactory; small-scale farmers will find more comfort in using it for threshing.