Low-cost wheel driven crop sprayer
Agriculture in Africa is an essential economic activity, employing about two-thirds of the continent's working population. Much of the agricultural activities are confined to subsistence farming; however, the machinery available to the majority of these subsistence farmers requires significant manual labour, causing farmers to accumulate health problems and experience low production capacity. Subsistence farmers engaged in crop spraying rely on knapsack sprayers, which leads to many of them citing back problems. High costs of alternatives, such as drone sprayers, prohibit their adoption. This study presents the design, fabrication, and testing of a low-cost crop spraying device. The device reduces the load carrying effort required. The user manually pushes a single-wheel frame carrying a tank and allows a gear-chain system to operate the pump's lever automatically. The performance of the prototype was characterized through experimental testing, revealing that the device can carry a 50-litre larger tank while requiring a manual equivalent to 32% of the load under firm mud conditions and staying below the 50% load limit for loose sand. Appropriate gear sizing was confirmed to enable the desired flow rate of 1.2 L/min while the user walks with a regular gait, e.g., an operational speed of 1.45 m/s.
Capstone Project submitted to the Department of Engineering, Ashesi University in partial fulfillment of the requirements for the award of Bachelor of Science degree in Mechanical Engineering, May 2022