Tractor maintenance

Proper maintenance of tractors and agricultural machinery helps reduce mechanization costs, as well as avoiding unnecessary downtime and reducing the useful life of equipment.

Among the most effective measures to reduce the cost of agricultural mechanization in different production systems is the adequate maintenance of tractors. As complex mechanical systems, these machines are made up of components that require specific care, at appropriate times, for correct operation.

Maintenance can be generically termed as the set of care adopted for the continuous and indefinite operation of machines, tools, equipment and structures. For tractors, these precautions are necessary to avoid, in addition to direct costs, related to breakdowns and replacement of parts, indirect costs, which are costs due to the unavailability of the equipment at the time when its use is necessary. An example would be the interruption of work due to an oil leak, the solution of which is generally cheap to resolve, however, if this has to be done during the sowing operation, the delay can have a major impact on productivity and profit.

TYPES OF MAINTENANCE

When equipment is repaired that performs below expectations or is unable to operate (breaks), corrective maintenance is carried out. This type of maintenance can be planned or unplanned, and what characterizes it is action after an event has already occurred, making it necessary, therefore, to restore operating conditions. Unplanned corrective maintenance must be avoided by all means, given the impacts on the work that is not carried out in the field. Preventive maintenance can be understood as action aimed at reducing or avoiding failure or decline in equipment performance. It follows a previously prepared plan in which there are defined intervals in each machine subsystem.

In production units with mechanized systems containing many machines, the practice of predictive maintenance is common. In this there is a systematic monitoring of performance parameters and indicators that allow defining the time for changing components and materials such as oil and filters. This type of maintenance allows changes to be carried out only when necessary and before any failure occurs, however, it is not viable if the number of equipment is small, not justifying the investments in the necessary structure.

Agricultural tractors require continuous maintenance throughout their useful life, defined by the manufacturers and presented in the manuals, the so-called maintenance plans that specify the actions to be carried out from daily intervals to thousands of hours of use. Due to differences in design, which may even be decisive in choosing one model or another, there is some fluctuation in maintenance intervals for the same systems on agricultural tractors. Manufacturers seek to increase these ranges to maximize uptime and availability through more advanced designs and components. Following the procedures described in the instruction manual means following the procedures defined by the manufacturer, thus avoiding breakages and premature wear.

PROPER MAINTENANCE

Machine wear is closely associated with the rise in temperature due to the generation of friction between its components. Carrying out adequate maintenance on the systems that prevent impurities from entering the machines significantly increases their useful life. In the air supply system, maintaining clean filters, hoses and clamps intact prevents dust from entering the engine, preventing premature wear and loss of power. Additionally, cleaning and changing diesel filters prevents the entry of impurities that cause clogging and wear in the fuel system and internal engine components, in addition to loss of power with a consequent increase in fuel consumption. Adequate lubrication, through changing the oil in the engine, hydraulic system and transmission, is essential to prevent premature wear of parts that have intimate contact and are exposed to extreme loads and conditions. But not only changing filters and lubricants prevents such problems, care such as cleaning the tractor is essential to facilitate the detection of leaks, cracks and various damages. During washing, care must be taken to prevent water from entering through the transmission breathers, as well as water accumulating on the electronic components. There is little point in changing the oil and keeping the hydraulic system leak-free if the quality of the oil and the presence of impurities in the oil of the implements that are driven by the tractor are not observed. The maintenance of tractors therefore involves the maintenance of equipment that is hydraulically driven by them. In the case of lubrication using grease, which is necessary in many pieces of equipment, it must be carried out periodically according to the interval presented in the manual, and it is essential to pay attention to the conditions of use. In this aspect, although the manuals provide a recommendation, depending on conditions such as: flooded terrain, dust, straw, high temperatures, among others, there may be variations. A typical example is the need to frequently clean radiators when there is dust or chaff during harvesting, preventing adequate heat exchange and, therefore, raising the temperature of the engine and hydraulic system oil, which can cause severe damage. . Another example is movement through flooded land, such as in rice production.

WHEELS

Although wheelsets usually receive little attention, they are essential for transferring the tractor's power to the driven equipment. The tightening of the fixing nuts must be checked weekly, as well as the tire pressure and the presence of cuts or damage that can be repaired before they become irrecoverable.

In addition to ensuring the availability of tractors, maintenance also contributes to increasing the value of the equipment, which can be sold at the end of its useful life more easily. Such as the use of original parts, which are more durable and ensure correct functioning without causing damage to other components.

 

STREAMING

The tractor transmission system is responsible for transforming the power generated in the engine into combinations of travel speed and traction force. It is a system in which there is great constructive diversity between manufacturers, ranging from models with fully mechanical and manual gearboxes to fully automated hydraulic ones. Due to the fact that there are a large number of components subjected to high stress, it is essential to ensure correct lubrication in this system. However, there are errors such as the use of low quality oil or inadequate specification, as well as changes at intervals well above those recommended by the manufacturer. Furthermore, the moment of change is often defined based on visual inspection, an error, given that the changes that occur through use are effectively quantified only through specific instruments. Contamination of the oil through the entry of impurities through the breather must deserve special attention. When changing the oil, it is important that the transmission is at operating temperature, which facilitates drainage and provides adequate removal of impurities generally deposited at the bottom of reservoirs and casings.

ELECTRONIC MOTORS

Modern engines with electronic control allow greater precision in fuel injection. Such engines favor more adequate dosage and burning of diesel in the combustion chamber, employing a single duct to maintain the fuel under high pressure, solenoid valves, a range of sensors and a control center. The electronic systems also allow the adjustment of the engine's working regime depending on the operating characteristics, reducing fuel consumption in lighter operations and increasing power in those where the effort is maximum.

The National Environmental Council (Conama), through the Air Pollution Control Program from Motor Vehicles (Proconve). Proconve MAR – 1 (MAR – Agricultural and road machinery), established requirements that will have an impact on the adoption of cleaner engines and electronic engines will be one of the strategies to meet the criteria. The legislation will come into force in a staggered manner, so that from 2017 onwards, models sold with power above 101 hp must be suitable and, from 2019 onwards, those below this power range. For these new engines there are solutions such as Exhaust Gas Recirculation (EGR), through which the exhaust gas returns to the engine's combustion chamber, reducing the combustion temperature and the formation of nitrogen oxides, making changes to the engine necessary. forced feeding system. Selective Catalytic Reduction (SCR) is another strategy in which a liquid reagent (“Arla”, “adblue”) is sprayed into the exhaust, causing a chemical reaction to occur in a catalyst that neutralizes the generation of nitrogen oxides. Consumption around three liters for every 100 liters of diesel. Both systems, EGR and SCR, employ additional components, and for their use it is necessary to use fuel with a lower sulfur content. The use of inappropriate fuel can cause damage to the engine and changes to circumvent the need to use Arla will void the warranty. Although adoption is gradual and is still one step below Tier4, already present abroad, the user of agricultural machinery must be aware of the quality of the fuel and the additional maintenance required and specified by the manufacturer.

As much of the behavior of these new engines is subject to electronic control, maintenance cannot always be carried out on the farm, given that diagnosis also requires electronic tools. In this case, it is essential to rely on a reseller or a good service provider who must be prepared to offer diagnostic and repair services appropriately.

Tractor maintenance intervals

Variation in maintenance intervals for different tractor components

Leandro M. Gimenez, Marcos Milan and Thiago L. Romanelli, Esalq/USP

Article published in issue 162 of Cultivar Máquinas.