Maintenance and Inspection of Cooling Components for Caterpillar 336 Excavator
During the use of the Caterpillar 336D excavator, it is important to pay attention to the inspection and maintenance of the engine radiator, hydraulic oil cooler, and related components. Otherwise, it will reduce the engine's heat dissipation efficiency, cause an increase in oil temperature and water temperature, resulting in a decrease in power and increased wear. In severe cases, it can lead to early engine damage accidents. Therefore, the inspection and maintenance of these components cannot be ignored.
The heat dissipation of the hydraulic excavator engine adopts suction air cooling, which can achieve good distribution of air passing through the radiator core. To ensure the original heat dissipation effect of the hydraulic excavator engine during use, it is necessary to ensure the integrity of the heat dissipation related components. There are several aspects that affect the heat dissipation effect:
1. Prevent the backflow of hot air during use
The filling around the radiator is commonly known as "sponge". But it cannot be replaced by any 'sponge'. The requirements for hydraulic excavators are good corrosion resistance, temperature resistance, and poor ventilation, as their main function is to prevent hot air reflux. To prevent the cold air drawn in from the front of the radiator from rising in temperature and entering the rear of the radiator (engine compartment), it cannot flow back to the front of the radiator. If some high-temperature gas flows back to the radiator, it will inevitably reduce the system's heat dissipation effect, causing an increase in oil and water temperature, which will prevent the engine from working properly and result in early damage. Therefore, during the use of hydraulic excavators, it is essential not to neglect the inspection and repair of the "sponge" around the radiator, and the damaged parts should be replaced in a timely manner.
2. Ensure smooth discharge of hot air
① The partitions in the engine compartment behind the radiator cannot be dismantled or discarded at will, otherwise it will cause vortices to form during the circulation of hot air, affecting the exhaust of hot air The exhaust holes in the engine compartment must be kept unobstructed, especially the exhaust holes of the lower protective plate of the engine and oil pump, which must not be blocked or placed with objects, otherwise it will hinder the exhaust of hot air. The decrease in intake air volume leads to an increase in cabin temperature, which in turn causes an increase in intake air temperature. Electrical components are damaged due to early aging caused by high temperatures.
3. Ensure the air circulation area of the heat dissipation part
The ventilation area of the radiator core is prone to blockage during the use of hydraulic excavators due to air flow and various reasons. If there is a protective net, the blockage should be cleaned up in a timely manner. If there is no protective net, the external pollution of the radiator should be cleaned and washed in a timely manner according to the changes in the environment and construction conditions. Otherwise, the blockage of the air flow channel will reduce the ventilation area and inevitably lower the heat dissipation efficiency. It is more important to prevent contamination inside the radiator. During use, it is necessary to strictly follow the random technical documents, regularly replace the antifreeze and clean it, and do not add contaminated water to replace the antifreeze. If it causes blockage of the internal liquid flow channel, it is difficult to inspect and clean, and the only solution is to replace the radiator.
4. Ensure the intake air volume of the heat dissipation part
The most important factors affecting the air intake, besides preventing hot air reflux and ventilation area, are the air guide hood and fan. At present, there are mainly three types of air deflectors: Wenduli type, ring type, and box type. There are strict requirements for the installation position of the fan and air guide cover, as well as the distance between the fan and the engine. Because air deflectors are usually used to improve fan efficiency, distribute air more evenly on the radiator core, and prevent hot air from flowing back into the engine compartment. According to the recommended installation requirements for Cummins engines: ① The distance between the fan and the radiator core is 50.8-101.6mm. ② The maximum linear velocity of the fan blade tip is limited to the range of 4000-5200 meters per minute The gap between the fan blade tip and the air guide hole is 1.5% of the fan diameter. The smaller the gap, the higher the efficiency. When the gap is greater than 2.5%, the fan's air supply will sharply decrease. Therefore, during the use, maintenance, and repair process, the size and geometric shape of the air guide cover and fan cannot be changed, nor can the installation position of the radiator and fan be changed, otherwise the original heat dissipation effect and reliability cannot be guaranteed. Especially for fans, most of them are made of non-metallic materials and will deform when exposed to high temperatures. If there is deformation, it will reduce the air supply of the fan.
5. To ensure that the intake resistance and intake temperature are within the standard range (Cummins 6BT5.9 engine intake resistance standard is ≤ 15inH0o, engine power decreases by 1% and heat dissipation increases by 1.5% for every 6 ℃ increase in intake temperature above 38 ℃)
The main factors that increase intake resistance during use are contamination of the intake filter, swirl filter, and air filter element. It is easy to clean and wash the swirl filter and inlet filter in a timely manner, but it is not so easy to choose the air filter element because sometimes it cannot be directly purchased from the engine manufacturer due to various reasons, and it is difficult to determine whether the purchased air filter element can meet the needs of the engine when purchased from other distributors. If the replaced paper filter cannot meet the needs of the engine, it will directly affect the reliability of the engine and reduce its service life. This requires understanding and mastering the relevant performance and parameters of the paper filter, as well as the air filtration accuracy required by the engine. It should be noted that the engine has strict requirements for air filtration accuracy and intake resistance. Imported diesel engines require an air filtration accuracy of 5um, while domestic diesel engines also require an air filtration accuracy of less than 20um. However, domestic filter paper has a filtration accuracy of only 80um, imported ordinary filter paper has a filtration accuracy of 30um, and imported high-efficiency filter paper has a filtration accuracy of 2um. So the selected air filter must match the power, economy, and reliability of the original engine; The filter paper should have requirements such as thickness, tensile strength, original air intake resistance, and filtration accuracy. The performance test of filter cartridge mainly includes the following four aspects: ① Flow resistance test, which measures the pressure loss of air flow. ② The original filtration efficiency test can calculate the dust collection efficiency of the filter element. The dust removal rate of a normal filter element should be above 99% Dust storage capacity test and cumulative efficiency test showed that excessive dust accumulation in the filter element caused blockage and increased intake resistance. The intake resistance when the engine power decreases by 5% or the fuel consumption increases to 5% is a limit value, and when this value is reached, the filter element must be cleaned or replaced The original intake resistance test shows that the pressure difference at the inlet and outlet when the rated intake volume passes through the filter element (the rated intake volume of the filter element should be greater than the required intake volume of the engine) should not exceed 3.2kPa, otherwise the filter element cannot meet the needs of the engine. The intake temperature is closely related to the position of the intake port and the temperature of the cabin. The intake pipe and intake port need to be isolated from high-temperature components or kept as far away as possible to prevent high-temperature gases from entering the intake port. At the same time, it is necessary to ensure smooth exhaust of hot air from the cabin and minimize the temperature of the cabin. The engine is the power source of hydraulic excavators. Whether the normal operation of the engine can be guaranteed depends not only on the design and manufacturing quality of the engine itself, but also on the maintenance, inspection, and scientific and reasonable repair of the engine during use. This scientific and reasonable maintenance is to predict preventive inspections and conduct preventive maintenance based on the actual working conditions of the engine. During the maintenance process, it is necessary to analyze the four aspects of the engine system: heat dissipation, intake, exhaust, and lubrication. By analyzing the interactions and influencing factors of these four aspects, it is determined whether each component needs to be repaired or replaced, in order to restore the original reliability and extend the service life of the engine.
The upper rotating platform located on the lower walking body of the hydraulic excavator is as important as the head and torso of the human body.
Although its structure is difficult to see from the outside, if the engine and various hydraulic devices installed inside fail or are overloaded, it will affect the overall state of the machine, reduce performance, and ultimately lead to machine failure.
