1962 年 24 巻 2 号 p. 81-84
Authors carried out an experiment on the distribution of threshed materials under the concave-sieve of a double cylinder type threshing machine, and discussed the influence of the secondary cylinder on the resultant distribution of threshed materials.
The secondary cyinder scatters centrifugally the threshed material fed from the primary cylinder, which shows W figured distribution at one man operating, so that the center peak of distribution seen in the case of single cylinder type machines (Fig. 2, (c)) disappears as in Fig. 2, (a) and (b). By this scattering action of the secondary cylinder, the threshed materials of this machine form U figured distribution both at one man operating and at two men operation (Fig. 2) (d) (e), and show rougher distribution than those of single cylinder type machines.
As mentioned above, the mass of distributed materials on each section of the concave-sieve may decrease or increase as its location differs. In addition to that, authors showed that the mass destributed per a second may vary and that the composition of distributed materials also may vary as the time passes.
It was found out that the heavier of materials such as paddy fell at first, and that the quantities of lighter materials such as straw containd in distributed materials increased as the time passed.
As a threshing machine can do threshing and winnowing at the same time, it is important to pay big attention to the matching between the distribution of wind velocity from the winnower and that of threshed materials fallen down through concave-sieve, in order to make separation of grains from foreign materials such as chaff completely and effectively.