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Preventive measures for diesel engine bearing burning

Preventive measures for diesel engine bearing burning


Early damage of sliding bearings is much more common than burning them down, so it is important to prevent it.Correct maintenance of plain bearings is an effective way to reduce the early damage of bearings and a reliable guarantee to prolong the life of bearings.Therefore, in the daily maintenance and repair of the engine, must pay attention to the bearing surface of the alloy, the back end and the appearance of edge angles in shape, if there is any abnormal or half signs of wear and tear, to seriously investigate the cause, and take appropriate measures to improve the bearing of the working conditions, pay much attention to the prevention of early damage of the sliding bearing.

Strictly measure the coaxiality and roundness of the main bearing hole of the diesel engine body.To measure the coaxiality of the main bearing hole of the engine body, the coaxiality dimension of the diesel engine body must be measured accurately, and the runout quantity of the crankshaft must be measured at the same time.The coaxiality of the main bearing hole of the engine body must be tested before assembly. The total length of the nodular iron crankshaft should not be greater than 0.14mm, and the total length of the steel crankshaft should not be greater than 0.12mm. At the same time, roundness and cylindricity of the bearing hole of the engine body are also required.If it exceeds the limit, it shall be forbidden. If it is within the limit, the grinding method shall be adopted (that is, coating the bearing bush with appropriate amount of red and red powder, rotating it after loading the crankshaft, and then removing the bearing cover to check the bearing bush. After scraping the hard-point protruding part, measure the change of dimension, so as to ensure the reliability of use.

Improve the maintenance and assembly quality of bearings, strict control of the qualified rate of connecting rod on the car.Improve the quality of the bearing hinge, ensure the bearing back smooth without spots, positioning convex point intact;The self-elastic opening capacity is 0.5 ~ 1.5mm, which can ensure that the bearing bush fits closely with the bearing seat hole by virtue of its own elasticity after assembly.New and old connecting rods are required to measure their parallelism and distortion, and unqualified connecting rods are forbidden to get on the train.Each end of the upper and lower two bearing pads installed in the bearing seat should be 30 ~ 50mm higher than the bearing seat plane. The higher end can ensure that the bearing is closely matched with the bearing seat after the bearing cover bolts are tightened according to the specified torque. Sufficient frictional and self-locking force is generated.The working face of the bearing can not be used to scrape up to 75% ~ 85% contact mark as a standard, should not be scraped so that the bearing and journal clearance to meet the requirements.In addition, the assembly should pay attention to check the crankshaft journal and bearing processing quality, strict implementation of repair process specifications, to prevent improper installation method caused by improper installation and bearing bolts of uneven torque or not in accordance with the provisions, resulting in bending deformation and stress concentration, resulting in early bearing damage.

Spot check the purchased new bearing bush.The thickness difference of the bearing bush and the size of the free opening are measured, and the surface quality is measured by the appearance.After cleaning and testing the old bearing bush in good condition, the original body, the original crankshaft, the original bearing bush and the in-situ assembly shall be used.

Ensure the cleanliness of diesel assembly and oil.Improve the performance of cleaning equipment, strictly clean quality, improve the cleanliness of all parts of the diesel engine.At the same time, the environment of the assembly site is purified, and the dustproof cover of the cylinder liner is made, so that the assembly cleanliness of the diesel engine is improved obviously.

(3) reasonable selection and filling of lubricating oil.In the process of using the oil film surface tension should be selected small lubricating oil, so that the formation of bubble collapse when the impact of oil flow is reduced, can effectively prevent the bearing corrosion;The viscosity grade of the lubricating oil should not be increased at will, so as not to increase the coking tendency of the bearing;The lubricating oil level of the engine must be within the standard range, and the lubricating oil and filling tools must be clean 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 added shall be free from pollution and sandstorms to prevent the invasion of all pollutants.It is forbidden to mix lubricants with different qualities, viscosity levels and different usage types. The settling time before lubricating oil filling should generally not be less than 48h.

Proper use and maintenance of the engine.When installing the bearings, apply a specified brand of cleaning oil to the shaft and the moving surface of the bearings.After the engine bearing is reloaded, the fuel switch should be turned off before the initial start, and the engine should be idled for several times by the starter. When the engine oil pressure gauge is displayed, the fuel switch should be switched on and turned on, and the throttle should be placed in the medium-low speed position to start the engine for operation observation.Idle running time should not exceed 5min.Do a good job of running in the run-in period of the new machine and the engine after overhaul. During the run-in period, it is forbidden to work for a long time in the state of rapid increase and decrease of load and high speed.After a long period of full load work, the engine cannot stop immediately. The engine must be operated at a no-load medium or low speed for 15 minutes before it can stop. Otherwise, the internal heat cannot be dispersed.

Strictly control engine temperature and increase engine oil supply time.In winter, in addition to strictly controlling the engine temperature, the engine oil supply time should also be increased to ensure that the oil reaches the friction pairs of each part of the diesel engine, so as to reduce the mixing friction of each pair when the diesel engine starts.Replacement of oil filter.When the pressure difference between the front and rear of the oil filter reaches 0.8mpa, the oil filter is replaced. At the same time, in order to ensure the oil filtration effect, the oil filter is changed regularly to reduce the content of impurities in the oil.

Strengthen the cleaning and maintenance of the oil filter and crankcase ventilator, 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", it is strictly prohibited to drive without adding cooling water;Correct selection of fuel, accurate adjustment of valve phase and ignition timing, etc., to prevent abnormal engine combustion: timely check and adjust the crankshaft and bearing technical status.

Regular oil ferrogram analysis, reduce the occurrence of accidents, combined with oil ferrogram analysis, early detection of abnormal wear, according to the oil ferrogram analysis pattern, accurate determination of the composition of the abrasive particles and possible parts, prevention in advance, to avoid the occurrence of rolling burning shaft accident.

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