Design, Construction, and Evaluation of a Precision Vegetable Reaper to Use in Small Plots

In this study, a miniature and lightweight reaper that can harvest vegetable in small plots and does not damage the dedicated stems and roots of plants were designed and constructed.

For the design of the vegetable reaper, an initial step involved the calculation of the resisting forces for blade movement. Determination of engine power and the pully size of the simple power transmission system were conducted based on knife speed and the required cutting power. To evaluate machine performance, three important performance variables including effective field capacity (EFC), cutting efficiency (CE), and plant damage (PD) were assessed under field conditions. In this evaluation, three variables of forward speed (0.8, 1.2, and 1.8 km/h), knife speed (3 and 4 m/s), and cutting height (3 and 5 cm) were assessed.

The results indicated that the forward speed had a significant effect on all three performance variables of the machine. Although the highest EFC was achieved at a speed of 1.8 km/h, the optimum values of CE and PD were obtained at the forward speed of 0.8 km/h. A cutting height of 3 cm and a blade speed of 4 m/s were chosen for this machine. To have a continuous rotation of the star-wheels, 5 teeth star-wheel provided the best performance compared with other shapes.

Using the light-weight vegetable reaper can reduce the crushing or damaging of the roots or stems as well as easing the harvesting process compared to manual methods. Because the vegetable plots are very small and the machine could be moved by the operator, eliminating the gearbox greatly reduced the slippage of the driving wheels and reduced damage to the dedicated stems.