This study was conducted to develop a prototype potato harvester which performs digging and collecting operation continuously. In this study major design factors of a prototype potato harvester were verified and the performance of the prototype harvester was evaluated. The results obtained in this study were summarized as follows.

1. The clod breaking ratio was influenced by shape of blade(straight, central wedge and bilateral wedge). The clod breaking ratio with bilateral wedge type was higher than that with straight or central wedge type.

2. The damage ratio and the debris mixing ratio were affected by three levels (0.3, 0.4, and 0.5 m/s) of conveyor speed. The damage ratio increased at conveyor speed of 0.5 m/s. At 0.5 m/s, potato was damaged because of collision with chain conveyor. Horizontal speed of conveyor was slower than working speed at 0.3 m/s. Therefore, the debris mixing ratio was increased at level of 0.3 m/s.
3. The debris removal part was designed with belt conveyor which rotates reversely. Effects of three levels of inclination of conveyor(0, 5, and 10°) on the debris removal ratio and the potato collection ratio were analyzed. The soil and grass removal ratio were not affected by the inclination of conveyor within 0 to 10°. The stone removal ratio at 10° decreased 16.1% than that at 5°. The potato collection ratio increased with increasing inclination ranged from 0° to 10°.

4. Performance of the prototype potato harvester with bilateral wedge type blades, the speed of chain conveyor of 0.4 m/s, and the inclination of belt conveyor of 5° was improved.

5. Effect of three levels (0.2, 0.24 and 0.28 m/s) of working speed on the performance of prototype harvester was investigated. At 0.28 m/s, the damage ratio, the debris mixing ratio and the loss ratio increased and there was no significant difference between 0.2 and 0.24 m/s. Therefore, it was concluded that 0.24 m/s was optimal working speed that resulted in improved working capacity.

6. Performance of the prototype potato harvester with working speed of 0.24 m/s was the digging of 99.4%, the damage of 2.7%, the debris mixing of 4.1% and the loss ratio of 3%, respectively. Working capacity of the prototype potato harvester was 1.3 h/10a.

7. Further studies about soil separation are required to improve the performance of the prototype harvester. Firstly, interval of round bar behind of digging blade needs to be expanded for soil emission. Secondly, vibration of chain conveyor is required and experiment about relationship between potato damage and soil separation will be needed. Thirdly, width of belt conveyor of debris removal part should be expanded same as width of chain conveyor of vertical conveying part to prevent potato congestion. Lastly, this study was conducted on the test field with soil texture of silk loam(SL). Thus, further studies on the different field conditions such as soil texture of clay type are needed to improve the adaptability of the prototype harvester developed in this study.