a machine for cleaning and sorting the grain. The operation of the grain-cleaning machine is based on differences in the width, thickness, and length of the grain, and in the aerodynamic properties, surface condition, shape, and specific weight.
Grain is sorted for thickness on screens with elongated holes; screens with round holes are used to sort for width. The screens are usually flat and oscillate; less frequently cylindrical revolving screens are used. Brushes, beaters, and other devices are used to remove particles stuck in the screens. Length separators are used to separate seeds by length and fans to separate them by aerodynamic properties; gravity and electromagnetic seed cleaners are used for separating by surface condition and shape, and pneumatic picking table separators are used to separate by specific weight. A distinction is made between simple and complex grain-cleaning machines. A simple machine has one or two working elements, and a complex machine has several, usually including fans, screens, and cylinder sorters.
Grain-cleaning machines can be mobile or stationary. Mobile machines are used on threshing floors; stationary machines are used at cleaning and drying stations and at plants with flow technology. In the agriculture of the USSR, grain is cleaned and sorted at grain-cleaning stations and cleaning and sorting stations using OS-4.5A and OVP-20 mobile units and OVS-10B and SVU-5 stationary machines. The cleaning and drying stations also use winnowers, length separators, electromagnetic machines, sorting machines, and dryers.
The OS-4.5A machine (see Figure 1) has an air-cleaning section, a sieve boot, two length separators, and loading and unloading conveyors. Its operating elements are driven by a
5.5-kilowatt (kW) electric motor. The grain, which is fed into the receiving chamber by the loading conveyor, is then processed in the aspiration ducts of the grain-cleaning section and on the screens, guided by a screw conveyor to the oat separator, and then from it to the cockle separator. The cleaned grain pours onto the unloading conveyor; light waste products are collected in bags, and heavy wastes fall to the ground. The machine has an output of up to 4.5 tons per hr. The OVP-20 machine (see Figure 2) has two sieve boots, an
air-cleaning section, loading and unloading conveyors, a self-propulsion mechanism, and three 10.8-kW electric motors to drive the working elements and the propulsion mechanism. With the machine moving along the bale at a speed of 0.1–0.3 m/min, the loading conveyor feeds grain into the receiving chamber, from which it enters the aspiration ducts and is acted upon by the air current. Light extraneous matter is separated from the grain and blown out of the machine through a pipe; the grain enters the sieve boots for cleaning coarse and fine impurities. The cleaned grain is removed from the machine by an auger and a conveyor. The impurities are removed by a pneumatic conveyor. The machine’s output is 10–20 tons per hr. The OVV-20 machine, in which impurities are removed by an air current, is also used on farms. Complex foreign-made grain-cleaning machines have similar designs and are equipped with screens, fans, and length separators.
REFERENCESKarpenko, A. N., and A. A. Zelenev. Sel’skokhoziaistvennye mashiny, 2nd ed. Moscow, 1968.
Sel’skokhoziaistvennye mashiny i orudiia, 2nd ed. Moscow, 1971.