Development and experiment of self-propelled cabbage harvester

Abstract: Development of a cabbage harvester is an efficient approach to change the traditional way of harvesting cabbage in China. In order to satisfy the ascending demand for agricultural machinery, a self-propelled cabbage harvester was developed and its field working performance was tested. To achieve this project, the investigation of the physical properties of cabbage in Zhejiang and Jiangsu Province became the primary task providing the reference for the design. Then the once-over harvester attached to a self-propelled crawler tractor was designed and manufactured, which included the picking and lifting mechanism, dual-disc cutter, leaf separator and collection device. All parts of the harvesting system were powered hydraulically. The picking device consists of a couple of picking shovels and a reel, and the picking shovels pull the cabbage out of the soil using the forward speed of the harvester while the reel pushes the cabbage at the entrance of lifting mechanism. The lifting mechanism takes a kind of transverse-belt clamping way, which means 2 belts are used to clamp and convey the cabbage to the cutting device. The dual-disc cutter, with 2 contra rotating cutting discs, cuts off the root at the connection area between the corm and the root as well as avoids the unbalance of cutting force. Then, the corm and loose leaves remain up to the leaf separator and the root is discarded after the cutting process. The leaf separator is composed of a leaf-separating belt and a leaf-separating roller. The loose leaves are separated from the corm through the rubbing action and inter-collision between the cabbage and leaf-separating roller. Finally, the cabbage corm is conveyed into the box and the whole harvesting process is finished. The harvesting field tests were conducted in 3 regions including the greenhouse in February, 2015 and the outdoors in April and May, 2015, a total of 5 times. Because of the non-standard planting, 60 cabbages were mainly harvested individually or consecutively for several. The results demonstrated that the harvester exhibited a good capability, feasibility and productivity, which met the preliminary requirements of mechanized harvesting. When operating at the speed of 0.3 m/s, the picking rate of harvester in 2nd field test was 86.7% in the outdoor field, much better than the results in 1st field test in the greenhouse because of the soil humidity. The transverse-belt lifting mechanism presented the stable performance with a success delivery rate of 93.3%. However, the qualified cutting rate was 75% as a consequence of the cabbage size diversity in different mature periods, giving rise to the excessive and insufficient cutting. Furthermore, the qualified leaf-separating rate was 81.7%, and the working parameters of the leaf separator including leaf-separating belt and leaf-separating roller should be optimized based on orthogonal tests. The other 3 field tests with finger-type picking device presented the similar results to the 2nd field test. This task has also urged a new standard to be established for cabbage harvester to test the performance in China. Last but not least, to make the standard of cabbage agronomy is equally important to realize the promise of mechanized harvesting cabbage, such as planting normalization and maturity consistency. The results above revealed the feasibility of design scheme, and the self-propelled cabbage harvester had the ability to harvest cabbages individually, which would be a breakthrough for mechanized harvesting cabbage in China after the further optimization and tests of the prototype.