الفهرس 
Introduction
Coefficient of frictionOnly 14 pages are availabe for public view
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Abstract
Studying and investigating the main physical and mechanical properties of watermelon fruits and seeds have been carried out in the present research to use this date for designing and fabricating a locally prototype to separate the watermelon seeds. This study also aimed test and evaluate the performance of the fabricated prototype under different field conditions. Four feed rates of watermelon fruits namely: 60, 70, 80 and 90 kg/min, four drum speeds namely: 4.71, 7.07, 9.43 and 11.79 m/s, four drumknives number namely: 2, 4, 6 and 8 knives, three drumconcave clearances namely: 24, 32 and 40 mm and three separating intervals after harvesting time namely: 3, 5 and 7 days were used during the performance operation of the fabricated prototype. While, four brush speeds namely: 2.36, 3.14, 3.93 and 4.71 m/s in addition to two brushes number namely: 4 and 8 brushes were taken at measuring the cleaning efficiency of the separating prototype. The results can be summarized as following: (1) the combination of 90 kg/min feed rate, 4.71 m/s drum speed, 2 drum knives number, 40 mm drumconcave clearance and three days timespan after harvesting achieved the minimum values of visible and invisible seed damage of 0.07 and 1.11% respectively. (2) the combination of 60 kg/min feed rate, 4.71 m/s drum speed, 4 drumknives number, 24 mm drumconcave clearance and seven days timespan after harvesting achieved the minimum values of seed losses 1.95%. Vise versa the 90 kg/min feed rate, 4.71 m/s drum speed, 4 drumknives number, 24 mm drumconcave clearance and seven days timespan after harvesting achieved the maximum values of machine productivity 262 kgw/h. (3) the maximum values of 94.47% of cleaning efficiency were achieved with the 60 kg/min feed rate, 4.71 m/s drum speed, 4.71 m/s brush speed, 8 brushes number and time of extracting after seven days from the watermelon harvesting. (4) the minimum and maximum values of 8.57 and 16.83 kW power consumed at 60 and 90 kg/min feed rate, 4.71 and 11.79 m/s drum speed with 2 and 8 knives number respectively. (5) the extraction of watermelon seeds using the developed equipment save the extraction cost and time by 50 and 62% compare to the manual extraction method.