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Preventive Measures against Burning Damage of Diesel Engine Bearings

by:JNSN     2021-12-27
Early damage to sliding bearings is much more common than burning bearings, so it is important to prevent early damage to sliding bearings. The correct maintenance of sliding bearings is an effective way to reduce the early damage of the bearing, and it is also a reliable guarantee for extending the life of the bearing. Therefore, in the daily maintenance and repair of the engine, you must pay attention to the appearance and shape of the alloy surface, back, end and edge corners of the bearing. Measures to improve the working conditions of the bearing and pay attention to the prevention of early damage to the sliding bearing. ①Strictly measure the coaxiality and roundness of the main bearing hole of the diesel engine block. For the measurement of the coaxiality of the main bearing hole of the body, the coaxiality size of the diesel engine body must be measured more accurately, and the runout of the crankshaft must be measured at the same time, so as to select the thickness of the bearing bush to make the oil lubrication clearance consistent in each axis position. . For diesel engines that have suffered from shingle rolling, runaway, etc., the coaxiality of the main bearing hole of the body must be tested before assembly. The full length of the ductile iron crankshaft is not more than 0.14mm, and the full length of the steel crankshaft is not more than 0.12mm. The roundness and cylindricity are also required. If it exceeds the limit, it is prohibited. If it is within the limit, use the grinding method (that is, apply an appropriate amount of red lead powder on the bearing bush, install it in the crankshaft and rotate it, and then remove the bearing cover to inspect the bearing bush. After scraping the parts, measure the change in size to ensure the reliability of use. ②Improve the maintenance and assembly quality of the bearing, strictly control the qualification rate of the connecting rod. Improve the quality of the bearing hinge, and ensure that the back of the bearing is smooth and free Spots and positioning bumps are intact and undamaged; the self-bounce amount is 0.5~1.5mm, which can ensure that the bearing bushes fit tightly with the bearing housing hole by its own elastic force after assembly; the new and old connecting rods are required to measure their parallelism and distortion It is forbidden to get on the car for unqualified connecting rods; each end of the upper and lower bearing shells installed in the bearing seat should be 30-50mm higher than the bearing seat plane, and the higher amount can ensure that the bearing cap bolts are tightened according to the specified torque. It is closely matched with the bearing seat to generate sufficient friction and self-locking force, the bearing will not loosen, and the heat dissipation effect is good, which prevents the bearing from ablation and wear; the working surface of the bearing cannot be measured by the method of scraping to reach 75%-85% of the contact mark , The matching clearance between the bearing and the journal should meet the requirements without scraping. In addition, pay attention to checking the processing quality of the crankshaft journal and the bearing during assembly, and strictly implement the repair process specifications to prevent improper installation due to improper installation methods. And the torque of the bearing bolts is uneven or does not meet the requirements, resulting in bending deformation and stress concentration, leading to early damage to the bearing. Sampling of the purchased new bearing bushes. Focus on the thickness difference of the bearing bush and the size of the free opening to measure, and the appearance of the surface inspection Quality. After cleaning and testing the old bearings in good condition, implement the original body, the original crankshaft, the original bearing, and the in-situ assembly. Ensure the cleanliness of the diesel engine assembly and the oil. Improve the performance of the cleaning equipment, strictly control the cleaning quality, and improve The cleanliness of each part of the diesel engine. At the same time, the assembly site environment is purified, and the cylinder liner dust cover is made, so that the cleanliness of the diesel engine assembly has been significantly improved. ③ Reasonable selection and filling of lubricating oil. During use, the oil film surface tension should be small. The lubricating oil can reduce the impact of the oil flow when the bubble is collapsed, which can effectively prevent bearing cavitation; the viscosity level of the lubricating oil cannot be increased at will, so as not to increase the coking tendency of the bearing; the oil level of the engine’s lubricating oil The lubricating oil and lubricating tools must be cleaned to prevent any dirt and water from entering, while ensuring the sealing effect of all parts of the engine. Pay attention to regular inspection and replacement of lubricating oil; the place where lubricating oil is filled should be free of pollution, There is no wind and sand to prevent the intrusion of all pollutants; it is forbidden to mix lubricating oils of different qualities, different viscosity grades and different types of use. The precipitation time before lubricating oil filling should generally not be less than 48h. ④ Use and maintain the engine correctly. When installing bearings , The moving surface of the shaft and bearing should be coated with clean oil of the specified brand. After the engine bearing is installed, the fuel switch should be turned off before the first start, and the starter should be used to drive the engine to idling several times, and then wait until the engine oil pressure gauge shows Turn on and turn on the fuel switch, and place the throttle in the middle and low speed position, start the engine and observe the operation. Speed u200bu200brunning time cannot exceed 5min. Do a good job in the running-in operation of the engine during the running-in period of the new engine and after the overhaul. During the running-in period, it is forbidden to work for a long time under the condition of rapid load increase and decrease and high speed. It can be stopped after running at medium and low speed for 15 minutes, otherwise the internal heat will not be dissipated. Strictly control the start-up temperature of the locomotive and increase the start-up fuel supply time. In winter, in addition to strictly controlling the starting temperature of the locomotive, the fuel supply time should also be increased to ensure that the oil reaches the friction pairs of the diesel engine and minimize the mixed friction of the friction pairs when the diesel engine starts. Replacement of the oil filter. When the pressure difference between the front and rear of the oil filter reaches 0.8MPa, replace it. At the same time, in order to ensure the filtering effect of the oil, the oil filter is replaced regularly to reduce the impurity content in the oil. Strengthen the cleaning and maintenance of the oil filter and crankcase ventilation device, and replace the filter element in time according to the instructions; ensure the normal operation of the engine cooling system, control the normal temperature of the engine, prevent the radiator from 'boiling;
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