Theoretically, the setting of the combine harvester is given in the instruction manual. However, these are only output data to carry out detailed adjustments decided by the machine operator. It is up to his knowledge and experience to obtain satisfactory work results, to which undoubtedly are purely threshed, undamaged grains and the smallest possible losses.
The detailed data of individual settings are given in the operating instructions for specific machine models, and in modern machines information on how to adjust individual elements are also given on-board computers. On some machines such adjustments can be made fully automatically. Regardless of this, the parameters given by the manufacturer should be treated only as output, because many factors influence the necessity of making corrections. The most important ones include: the variety of the plant, the humidity of the field (which changes significantly even during the day), the date of harvesting and weed infestation. Differences may also result from the cultivation technology itself - the type and amount of fertilizers used and chemical care of the field. Therefore, it is a mistake to think that in the most modern combines, it is enough to "get in and go" and the rest will be done by a computer. There is a reason why experienced combine harvesters are by service providers and large farms sought-after and well-paid.
PERFECT COLLECTION DOES NOT EXIST
It is necessary to know the construction and principles of operation of individual components to perform the adjustment of the machine's operating parameters. It is important to know the cause-and-effect mechanism of the processes taking place in the machine. The general rule for the construction of threshing units for all combine harvesters is the same and is based on a transverse drum or one / two longitudinal drums, or a combination of these systems, i.e. hybrids. Similarly with cleaning systems.
The most important settings include the rotational speed of the threshing drum, the threshing gap between the concave and the drum at the inlet and outlet, the type and setting of the top and bottom sieve and the fan rotation speed. In the case of cereals such as wheat, rye and barley, the initial adjustments are similar. For oats, a larger screen opening and a lower fan speed are used.
It is not possible to set the machine perfectly, guaranteeing at the same time the highest efficiency and quality of the grain without losing it. Always one of the parameters has priority. If you want a quick harvest, for example due to poor weather conditions, you have to reckon with increased grain losses and damage. In turn, the smallest losses will be obtained with a decrease in efficiency. For example, those who produce reproductive material will choose such a setting.
GRAIN WITHOUT DAMAGE
The threshing system is responsible for separating the grain from ears of ears, which in conventional wheel combines consists of two basic elements: a drum and a concave. At this point, at least 90 percent should be separated. seeds. Further on the shakers there is actually only the recovery of "tangled" grain in the straw. Increasingly, behind the threshing machine, various types of active separators (mainly drums) are used, which support this process. The heavier ears, in which the seeds remain, hit the inertia of the auger directing them to the ear conveyor, which in turn transports them to the threshing drum, dropping a narrow stream. If there are too many ears, the load on the shaft increases and the risk of breaking the grains (the place where the ears fall on the shaft can be seen after increased consumption). This is one of the causes of seed damage. In this particular case, the gap between the shaft and the concave should be reduced or the shaft rotation slightly increased, so that the grain is better paid even with the first approach of the ears.
A common mistake - if you notice significant amounts of damaged grains in the tank - is to increase the threshing gap. Meanwhile, the first step should be to increase your speed. This causes a larger amount of straw to flow through the threshing chamber, which creates a specific buffer zone for the seeds. If this solution does not bring the expected effect or significantly increase the loss of seeds (although in this case, losses can be generated largely by small or broken seeds, so you can gain the quality of grain in the tank), you have to reduce the drum speed, which strikes seeds, has a much greater impact on their "beating" than the gap between the concave and the drum. Increasing the gap under the drum should be carried out further. The general rule is that the lower the drum speed, the smaller the percentage of damaged seeds.
EFFICIENT OR WITHOUT LOSS?
Both due to the weather conditions and the need to use the combine as intensively as possible, to "earn a living", the machine should be operated on 100 percent. your possibilities. What does it mean? It turns out that the full use of a combine for one will mean harvesting grains with almost zero losses at the expense of reduced productivity, for another - threshing as fast as possible with an increased, acceptable level of grain "loosing". From the economic point of view, the first solution is a mistake. When the combine is correctly positioned and, for example, at a speed of 2 km / h, the losses can be reduced to 0.1-0.2%, but at the same time when operating at 5 km / h and at a loss level of 1%. efficiency will more than double, and the engine will use less fuel. In addition, too low speed means a greater risk of grain damage due to the small filling of the threshing machine with straw, which also loses on quality because it undergoes aggressive impact of flails. It is worth noting that grain losses are largely generated by broken seeds and bottoms.
Everyone should therefore develop their "golden mean" in this respect. If the combine is not equipped with a grain loss sensor, according to the literature ("Principles of preparing combine for harvesting cereals and rape", Dr. Aleksander Lisowski) can be determined, for example, by taking 10 ears from a straw roll behind the combine and counting the remaining there are grains in them. If 3 seeds are found, assuming that there are 30 grains in the head, this corresponds to a loss of 1%.