抄録
Utilizing the experimental results reported before, the bulblet harvester of the Chinese yam has been fabricated and demonstrated to ascertain its field performance. Its design concept includes simplicity for structure, size reduction for power transmission unit and lower cost. This laboratory experiments unveiled several findings as mentioned below.
1) The efficiency of harvest was greatly affected by the moisture content of dune sand exhibiting sharp decrease from 2% d.b. or so and unable to harvest at more than 2.8% d.b.. What is more, with the increase of peripheral speed under the limited range of 0.11 to 0.22m/s, the harvesting efficiency decreases and accelerates this tendency further when setting the working depth greater, i. e. from 2 to 5cm.
2) The percentage of dune sand passed through bucket is affected heavily by the moisture content of dune sand as well as the harvesting efficiency.
3) The moisture content of dune sand surface strata is desirable to keep less than 2% d.b. in terms of the stable operation unless forced oscillation of bucket type harvester is provided.
As a part of the subsequent studies following bucket type harvesting mechanism, the prototype being applicable in the form of attachment unit of a power tiller was designed and fabricated. Designing philosophy includes that the machine should be provided with simpler mechanism, less portion to be driven and reasonable cost.
The practicability of this machine was testified at the growing field of Chinese yam through performance test. Harvesting efficiency is heavily influenced by the undulating field surface, the amount of dead leaves and the moisture content of dune sand. Weather permitting, almost 90% of harvesting efficiency may be obtained under flat field and drier dune sand conditions as well.
