Design and test of the key components for a combing-type tobacco harvester

The main design for a commercial tractor is safety and a rollover protection structure has gradually been equipped on tractor. The purpose of this study is to experiment the sideways overturning behaviour of a commercially available tractor in China with rollover protection structure. The object vehicle is a small-size tractor which weights near 1200 kg and was widely used in Chinese farm work. The cases of sideways overturning accident with no travelling speed and with idling speed with first gear were considered. Two gyroscopes were attached to the left and right fender on the rear wheels to measure the dynamic of this tractor. The rollover protection structure for the object tractor has been assembled to laterally contact the ground ahead of any side parts on this tractor, and a weight sensor was assembled at the lateral contact point of the rollover protection structure. The result shows that the sideways overturning behaviour of no traveling speed case was similar to that of idling speed case. Moreover, the result of measured impact force is significant while the rollover protection structure for a small-size commercially available tractor in China was designed.

In a vegetable transplanting operation, if the seedling picking mechanism extracts the whole row of seedlings, the seedling separating mechanism needs to place the seedlings in groups. In this study, a seedling separating mechanism based on a fixed seedling cup was proposed to realize faster seedling grouping in a smaller volume. A collision model between the pot and the wall of the seedling dropping cylinder during the seedling dropping process was established. The duration of seedling dropping at different positions was analyzed. Subsequently, the calculation equations between the installation angle and the cam rotation speed and the dropping duration were derived. The net dropping duration of seedlings at different positions was measured. According to the measurement results, the installation angles of the driving cam at each position were calculated as 0°, 72°, 150°, 216°, and 288°, respectively. The seedling uniformity test was conducted according to the optimized installation angles. The test results revealed that the success rate of dropping seedlings was 100%, the coefficient of variation in dropping seedling interval at different positions was 6.25%, and the matrix damage rate was less than 10%, which verified the reliability of the dropping seedling principle. Finally, the stability tests results showed that the mechanism was able to complete the uniform seedling drop operation at a seeding frequency of 75~108 plants/(min · row) under the existing installation conditions. Therefore, the research results can provide a reference for the design and research of a subsequent traction-based automatic pot seedling transplanting machine.