an agricultural machine for separating crop seeds, fruits (apples, citrus fruit), grape stalks, potatoes, and so on by size. In the USSR size graders are produced for grading corn, sugar beet seeds, fruits, and grape stalks.
The primary working elements of the grader for separating corn and sugar beet seeds are screen mills fitted with screens with round or longitudinal holes of various sizes. The screens with round holes grade seeds by width, and those with longitudinal holes grade them by thickness into several groups. By using screens with the appropriate-sized holes, the machines can be used to grade sunflower seeds, castor beans, soybeans, kidney beans, peas, and other crops.
Size graders for sorting and grading round fruits by size or weight consist of a feeder to empty the boxes of ungraded fruits, a sorting roller conveyer along which sorting workers manually pick out nonstandard fruits, grading sections or devices, and storage trays. Band conveyers with holes of different sizes cut in the band are used in size graders for grading fruits by size. Size graders that divide fruits by weight use a grading device in the form of a conveyer with cups, into which a cellular conveyer places the fruit one at a time, and scales for weighing the cups containing the fruit. The graded fruits are carried to storage trays from which they are packed or poured into boxes.
Size graders for trimming grape stalks by length and grading them by diameter have two cutting devices, two grading rulers, and two trays set on opposite walls of the machine. In addition, the machine has compartments for picking out stalks with identical diameters; the diameter limits of the graded stalks are within 7-12 mm.
Potatoes are graded by potato-sorter assemblies and potatosorters.