The Development of a Forage Harvester Ensuring Two-Level Mowing of Tall Stalk Forage

Currently, in countries with warm climatic conditions, the average height of corn stalks during silage harvesting reaches 2.5 m. However, trailed forage harvesters are designed for mowing stalks not more than 1.5 m. That is why there is a demand to develop a compact forage harvester that can mow and shred tall stalks. This research proposes a two-level mowing method for tall stalks. According to the obtained analytical expressions, the technological distance between the vertical axes of the mowing rotors is determined to be 700 mm. A forage harvester is developed, equipped with a device that orientates itself by the length of stalks at the entrance to the shredding chamber and two mowing rotors designed for mowing tall stalks. Analytical expressions are obtained, which determine the required power for the mass transportation processes by the screw working device and the mass supply by the orienting drum into the chamber of the radial-knife blade shredding rotor. The required powers of the screw conveyor and the orienting drum are determined based on the obtained expressions; they are, respectively, equal to 0.42 kW and 0.11 kW. As a result of the conducted laboratory field tests, the required powers for mowing and for the general processes of mowing, shredding, and transporting the mass through the deflector are determined. The power balance of the harvester units is compiled. It is established that 75% of the consumed power is used for effective work, while 25% is for used for idling the harvester. During the mowing and shredding of corn stalks with a height of 2.9 m, the harvester’s productivity reaches 16.3 tons per hour, with a required power of 12.5 kW. During the tests, the harvester functioned without losses and without any violation of the technological process. The test proves the performance of the design and technological scheme and the accuracy of the obtained analytical expression determining the technological distance between the vertical axes of mowing rotors.