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Performance Study of Locally Manufactured Power Threshers for Threshing Boro Rice

M.A. Rabbani
Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh

Khadija Afroja
Assistant Engineer
BMDA, Poba, Rajshahi

R.I. Sarker
Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh

Abstract/ Executive Summary:

This research work has been undertaken to study the operation and performance of the locally made selected power threshers. 'Four locally made power threshers including one "hold-on" and three "throw- in" types were tested for their performance in different places during the Boro season, 2002, ranging from May, 20 to June, 10. Three ''throw-in'' type threshers (i) Alim (ii) Rahman and (iii) Ishkhan were evaluated for threshing paddy harvested at a straw length of 50 cm. The Rahman open-drum (Hold-on) thresher was evaluated for threshing paddy harvested at a straw length of 75 cm, randomized with three replications. The mean threshing capacity of Alim thresher was 573 kglhr compared to those of 522, 540 and 464 kg/hr for Rahman closed-drum, Ishakhan and Rahman open-drum thresher respectively, where as in manual threshing it was about 66 kg/hr only. The average threshing losses of Alim, Rahman closed-drum, Ishakhan and Rahman open-drum threshers were 1.84, 1.71, 1.30 and 20.3 percent respectively, whereas in manual threshing about 7% grain is lost. The labour requirements of the selected threshers were 3.49, 3.83, 3.7 and 6.48 man-hr/ton respectively. Power requirement of the selected power threshers were 10.5, 12.83, 11.11 and 7.94 kW-hr/ton respectively. The threshing efficiencies of the Ishakhan thresher was 98.69 percent compared to that of 98.22, 98.32 and 97.98 percent for Alim, Rahman closed-drum and Rahman open-drum threshers respectively.

Keywords: Closed-drum, Open-drum and Power threshers

Location:

Start Date: 01-05-2002

End Date: 01-06-2002

Program Area: Farm Mechanization

Commodity: Performance evaluation

Objectives:

To study the threshing performance of locally developed power threshers (manufactured by Alim, Rahman and Ishakhan) for threshing rice (ii) To make suggestions for improvement

Methodology:

A number of different types of power-driven threshers have been developed by different government and non-government organizations in Bangladesh and some of these are being used by the farmers. For this study axial flow, throw-in type power thresher manufactured by Alim Industries Limited, Sylhet; axial flow rice-wheat thresher (TH-7) and axial flow, hold-on type power thresher manufactured by Rahman Engineering Workshop, Kushtia; axial flow, throw-in type power thresher manufactured by MIS. Ishakhan Engineering Works, Kishoregonj were selected for performance test. The experiments were conducted at the Farm Machinery Workshop of Farm Power and Machinery Department, Bangladesh Agricultural University, Farm of Bangladesh Agricultural University and BADC Seed storage, Modhupur, Tanqail. The performance test was carried out during May 20 to June 10, 2002 on Boro paddy (BR-28). Cleaning efficiency gives an indication of amount of foreign materials mixed in threshed grain. After each test, the weight of foreign materials and grain obtained from main outlet were recorded. The cleaning efficiency was calculated from the following expression

Source of Information: Bangladesh j. crop sci. 2006, 17 (1): 211-220

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

To increase the performance of the threshers as well as reduce the threshing cost, farmers and operators should be trained. Rahman closed-drum thresher has the highest cleaning efficiency of about 89.2 percent, which indicates the presence of a large amount of chaffs in the output grain. By using a 12 Hp engine and by designing the blower properly, this problem can be eliminated. The local manufactures should make more and more demonstrations of the power threshers at farmer's level to create awareness about the benefits of the power threshers as well as for appropriate adoption of the power threshers in the country. To increase the thrashing capacity of the closed drum thresher, the farmers and manufacturers should use 12 Hp prime mover or engine. This will also reduce the clogging of the closed-drum threshers. The spacing between the spike tooth should be around 10 cm. For maximum output without clogging, the diameter of the spike should be 1/2 inch or 5/8 inch instead of 3/8 inch diameter rod. This will increase the strength of the teeth. Beating action will be increased if deformed bar is used instead of plain bar. The clearance between the concave and the threshing drum should be between 0.5 to 1 cm. The presence of chaffs in the threshed grain should be reduced by increasing the rpm of the blower or fan. Threshing the paddy at optimum moisture content may also increase the cleaning efficiency of the threshers. To avoid bending action and control vibration, an extra bearing can be incorporated at the middle of the shaft of open-dram thresher. To prevent the bending of the drum shaft, the diameter of the shaft may be increased to 50 mm

Knowledge Management: Journal