# The Development of a Forage Harvester Ensuring Two-Level Moving of Tall Stalk Forage
## 3 Materials and Methods of Research
In countries with warmer climatic conditions, the height of corn stalks reaches 2.5 m.  
For instance, in the Southern region of the Republic of Kazakhstan during corn silage harvesting, the average height of corn reaches 2.43 m [22]. Currently, forage harvesters are equipped with rotary headers for harvesting tall stalks. The use of such headers in the design of trailed harvesters, therefore, complicates the design and increases the cost of the machines. In recent years, trailed harvesters have been equipped with moving rotors with L-shaped knives and a radial-blade shredding unit. The main advantage of these machines is that the moving rotor ensures both grass mowing and window pickup. Nevertheless, they are unable to facilitate moving of corn stalks with a height of more than 2.0 m, leading to significant losses. Therefore, such machines are not recommended for harvesting tall stalks. For example, the technical specifications of the KSD-2 forage harvester indicate that its use is not recommended for moving tall-stemmed plants exceeding 1.5 m in height [15]. To clarify the rationale behind this recommendation, a conceptual model illustrating the mowing process of plants with varying stem heights by a single-rotor forage harvester is presented (Figure 1). The figure illustrates the process of moving stalks with heights of 1.5 m and 2.5 m. Line A1D represents the moving trajectory of a 1.5 m tall stalk as it encounters the cutting blades. Initially, the stalk is cut at point C and captured by the L-shaped blade, then rotated upward relative to the front bar, i.e., around point B. Under the influence of centrifugal force (F), the stalk is directed into the moving rotor chamber. After rotating around point B, the stalk is cut a second time. These technological processes of stalk fragmentation have been described in previous studies [21]. The resulting stalk particle lengths were measured as follows: BC = 0.208 m; CD = 0.337 m; BD = 0.545 m. This shows that the lower part of the stalk with a length of 0.545 m is initially cut. When moving 1.5 m tall stalks (as indicated by line A1D in the diagram), the outer portion of the stalk extending beyond the moving rotor chamber is 0.955 m long, and its center of gravity is located 0.477 m from the front bar. Before the next cut of the lower portion, the stalk continues to move toward the moving rotor chamber due to the centrifugal force (F). The formula used to determine this velocity is provided in [21]. In addition, the forward motion of the unit increases the stalk's entry speed into the moving rotor chamber. Therefore, it can be assumed that the outer portion of the stalk, measuring 0.955 m, can enter the rotor chamber freely before falling to the ground. Figure 1: Diagram demonstrating moving of stalks with heights of 1.5 m and 2.5 m.  
The figure also shows the position of the outer portion of a stalk with a height of 2.5 m. When the lower part of the stalk is moved, the remaining outer portion is 0.1955 m, with its center of gravity located 0.977 m from the front bar. In this case, it is unlikely that a stalk nearly 2.0 m long can fully enter the moving rotor chamber. Thus, moving stalks taller than 1.5 m may result in significant losses. To address this issue, we initiated the design of a compact dual-rotor forage harvester capable of performing two-level moving of tall-stemmed crops. Upon analyzing existing forage harvester designs and reviewing published studies, we found no existing design of a dual-rotor harvester capable of two-level moving of tall stalks. The design process began by ensuring that each rotor, operating independently, could move and chop stalks shorter than 1.5 m. Based on this requirement, the installation height of the upper rotor's horizontal axis was determined. The upper rotor mows and chops the upper portion of the stalks located at heights above approximately 1.2-1.3 m. Assuming the average height of maize stalks is 2.5 m, each rotor is designed to move and process a 1.25 m section of the stalk.