Correct maintenance of harvesters

Harvester maintenance must be seen by producers as an important and necessary step to keep the equipment up to date, ready to perform its function efficiently and without unpleasant surprises. 

Agricultural machines and implements show natural wear and tear throughout their useful lives, resulting from the execution of agricultural operations. This wear and tear can be accentuated when such operations and/or crop characteristics require extreme efforts or provide inadequate conditions for the normal functioning of machines such as, for example, self-propelled grain harvesters, used to harvest irrigated rice.

According to Gastão Moraes da Silveira (2001), well-performed maintenance is the most effective way to obtain maximum performance, and maintenance costs, including labor and spare parts, are considerably low compared to the benefits achieved. , which are expressed through lower operating costs.

Self-propelled grain harvesters have numerous components that require continuous review through a set of procedures that aim to keep them in the best conditions of use and operation. Initially, maintenance can be classified as periodic and corrective, the first being carried out according to a schedule pre-established by the machine manufacturer, generally based on a certain number of working hours. Corrective maintenance, as the name suggests, aims to correct or repair a component that has suffered excessive wear or breakage resulting from extreme operating conditions or particularities of the crop.

The post-harvest period, or off-season, is considered the ideal time to carry out harvester maintenance, as all the problems presented during the previous harvest are known. After being reviewed, it can be stored and will be ready for harvesting the next harvest.

The big problem with these machines being stored without proper maintenance comes from forgetting certain problems that occurred in the previous harvest, and when the machine goes into operation, these problems will appear again. Furthermore, the maintenance carried out moments before starting the harvest often does not include all the items that need to be reviewed, both for periodic maintenance and for corrective maintenance.

It is pertinent to point out that harvesters do not “break” when stopped, but rather when they are in operation. Undesirable stops cause serious problems, especially those related to agricultural mechanization planning, causing delays in harvesting and, consequently, huge losses to the farmer.

Below we will describe the main items that must be observed during the maintenance of a self-propelled grain harvester, during the off-season, taking into account the working hours, as established by the manufacturers' manuals and wear of some of the main components.

CUTTING PLATFORM

The cutting deck is one of the most important components of a harvester. According to Embrapa (2014), between 80% and 85% of grain losses during harvest occur due to the action of the mechanisms that make up the platform (reel, cutting bar and transverse conductor). The correct maintenance of mechanical elements is of fundamental importance, as it will interfere with the progress of the harvest and will also contribute to reducing losses. The cutting bar suffers natural wear caused by direct friction with the crop, as well as accumulation of soil between the knives or knives and counter knives, accentuating the wear process. It is recommended to check the gaps between the knives and counter knives, as if these are small there will be excessive wear on these components and if the gaps are large there will be an increase in the vibration of the assembly. If knives and counter knives have broken or worn parts, they must be replaced.

The transverse conductor, also known as snail, is considered another element that suffers wear, especially in irrigated rice harvesting, due to the abrasive action of straw and grains. This wear reduces feeding capacity, in addition to throwing grains and/or entire plants off the cutting platform. This occurs due to the formation of protrusions at the ends, and it is recommended to change the helicoid in these cases. Some elements such as bearings, cutting bar drive box, hoses, hydraulic cylinders, drive shaft, retractable fingers, must also be inspected, as well as the lower part of the platform (plate and sliding shoes), which often go unnoticed. by farmers. In the case of platforms draper, Likewise, a rigorous inspection of all its components is recommended.

LONGITUDINAL CONDUCTOR

The longitudinal conductor, known as the “neck” of the harvester, also shows wear. Due to this, it is necessary that the cylinders and hydraulic drive hoses, chain tension, integrity of the bars and the space between the conductive belt and the bottom of the feeder channel are inspected. It is common to observe that after a few harvests, a natural process of wear occurs on the metal sheets on the lower part of the conductor, mainly caused by abrasiveness, in the case of irrigated rice cultivation.

TRACKING, SEPARATION AND CLEANING SYSTEM

The threshing, separation and cleaning system constitutes the main unit of the harvester and has a series of elements that require frequent inspections and maintenance. In both the radial and axial track systems, some components show wear, such as bars or teeth on the track cylinder. Inspections of bearings, seals and belts are also an extremely important action, as the breakage or rupture of one of these elements in the machine may cause the entire harvesting operation to stop. Both belts and bearings work under continuous load, heat up and are exposed to dust and heat, causing their useful lives to be significantly reduced.

With regard to bearings, they must not present noise or excessive heating, and need to be replaced when they are in these situations. This opportunity should be used to clean the lubrication points (grease pins), if any, as they could eventually be the cause of the problem due to poor lubrication.

Belts that show cracks and chains with visible wear must also be replaced, as if this occurs during harvesting the machine will be stopped for hours until the repair is carried out. The sieves and fan must also be inspected to find possible cracks, breaks and/or corrosion.

The clean grain elevator and the tailing elevator are the components that show the greatest wear in the system. Damage normally occurs in the internal division and on the sides of the elevators due to wear arising from the flow of grain, requiring repairs to be carried out by professionals in the field. Similar damage also occurs on conveyor chains, requiring appropriate maintenance.

The screw conveyors, which receive the grains from the lower sieve or the tailings, as well as the spreader located inside the grain tank and discharge tube, have little durability, especially when the harvester is used in rice fields, due to the excessive wear caused by culture.

When the farmer has qualified and specialized labor on the property, helicoids can be replaced, reusing the original axles, however, in most cases, the entire set is replaced, increasing maintenance costs.

When it is necessary to carry out some type of repair using electric welding, extra attention must be paid. If it is not possible to remove the part with problems to carry out the service, the electronic modules and/or battery cables must be disconnected by a specialized professional. Otherwise, the electric current formed when the welding arc closes could damage the electrical and electronic system, especially in modern harvesters.

ENGINE, TRANSMISSION SYSTEM AND HYDRAULIC SYSTEM

The engine, transmission and hydraulic systems of grain harvesters strictly follow the periodic maintenance schedule, complying with a certain number of working hours. Therefore, each manufacturer makes its recommendations, specifying all the intervals at which oil changes for the hydraulic and transmission systems should be carried out, also including final reduction and engine oil changes. Most often, manufacturers recommend changing filter elements (filters), including those in the air and fuel supply system. If the machine has not reached the predetermined number of hours for oil and filter changes to be carried out, simply check its minimum and maximum levels.

FINAL CONSIDERATIONS

Maintaining the grain harvester is considered an important step and must be carried out in accordance with the maintenance plan specified by the manufacturer. It is based on technical and organizational criteria, thus guaranteeing a normal progress of the harvesting activity, and any problem arising from lack of maintenance will cause a delay in the property's planning, considerably increasing production costs.

Alexandre Russini and Eloir Missio, Unipampa – Campus Itaqui; José Fernando Schlosser, Marcelo Silveira Farias and Juan Paulo Barbieri, Nema – UFSM

Article published in issue 148 of Cultivar Máquinas.