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Practice tells us that the characteristics of engine faults are various and the causes of faults are also complicated. A failure may be manifested as a variety of phenomena, and one phenomenon may reflect multiple failures, which brings complexity to failure analysis. Although the symptoms of the symptoms vary, they all have certain regularities. The following principles must be followed when conducting failure analysis and inspection: “discover the phenomenon and link the principle; distinguish the situation and conduct a thorough analysis; from simple to complex, from the table to the inside; the diagnosis is accurate and less dismantling is beneficial.†Diagnosing faults must be diligent in thinking, adopting diffuse thinking and methods of concentrating on thinking, paying attention to one tendency to cover up another tendency, and careful analysis after demolition. 2. It should be carried out step by step according to the function, principle, structure, characteristics of the parts and the relationship between them. 3. Accumulation of experience depends on production practices. It is only when practice is repeated in long-term production. Gradually realize, constantly summarize, and master the laws, can we be aware and accurate in deciding failures. The following is a brief description of the general method of fault analysis: 1. Analyze the fault phenomenon The fault symptoms of either the engine or the chassis are different due to their causes. According to the external symptoms of the locomotive, it can be determined whether the engine is faulty. To troubleshoot a problem successfully, you must first become familiar with its external symptoms. The rules can be roughly classified into the following categories: (1) Abrupt changes in operating conditions: If the engine suddenly shuts down, it is difficult to start even after the engine is suddenly shut off; even when the engine is running, the power is suddenly reduced, making the tractor unable to drive. 2 abnormal sound: Some faults often cause abnormal sound of the engine, such as the crank connecting rod mechanism has abnormal knocking sound, the exhaust pipe has a gunshot sound. 3 overheating phenomenon: Under normal circumstances, no matter how long locomotive work, engine, transmission, rear axle and other assemblies should be maintained within a certain operating temperature range, if the engine's cooling water and crankcase temperature is too high, are The locomotive may have a problem. 4 The phenomenon of leakage and the color of exhaust smoke are abnormal: If the exhaust pipe emits white smoke, black smoke, blue smoke, oil leakage, water leakage, leakage, etc. 5 has a special odor: If the string of burning oil, etc., the engine overheated oil burning will emit a special smell. When these failure phenomena occur, they should stop immediately and a detailed and comprehensive analysis of the failure phenomenon is required. For example, if the exhaust pipe of an engine emits black smoke, it is black smoke during idle operation or black smoke when working under load; it is intermittent black smoke or continuous black smoke. Only accurate understanding of the fault phenomenon can accurately analyze the fault. 2. Analyze the nature of the fault. After a comprehensive analysis of the fault phenomenon, the essential causes of the fault should be found through the phenomenon, and then determine the system, organization, location and use factors related to the fault. For example, the nature of black smoke in the engine is due to incomplete combustion of diesel in the combustion chamber, insufficient intake air, excessive fuel injection, or poor atomization quality, which may result in incomplete combustion. Therefore, failures mainly occur in air supply systems, compression systems, and fuel supply systems. Also related to the use of factors, such as the size of the load. 3. Possible Causes of Failure Analysis Since any failure is related to incorrect use factors, it is caused by a part or part that does not work properly. Therefore, the various possible causes of failure can only be generated on a part or part related to it. Therefore, starting from the failure phenomenon, according to the nature of the cause of the failure, contact with the principle of construction, you can find out the various possible causes related to the failure. 4. Determine the main cause or location of the failure to conduct a comprehensive analysis based on the various aspects of the situation. It should be searched from the most probable causes and then searched for the less likely causes. One by one negates the possibility of failure of certain systems, agencies or components, narrows the scope of failure analysis, and finally determines the main causes and locations of failures and eliminates them. Simple examination methods: 1 Partial stop method: Stop the work of a certain part or component for a short period of time, observe the changes in the phenomenon of failure, to determine the location of the failure. Such as the analysis of engine failure, commonly used "broken cylinder method" (applicable to multi-cylinder engine) and so on. 2Comparative method: Replace parts on the engine with parts with normal technical conditions, or replace the same parts on the engine with each other, and determine the technical status of the replaced part by comparing the changes in the phenomena before and after the replacement. . For example, in a multi-cylinder engine, a two-cylinder injector is sometimes swapped to see if the faulty phenomenon is transferred to determine the injector's technical state. 3 Test anti-evidence method: Try to change the working conditions or technical status of a certain part, observe the changes in the phenomenon of failure, to determine the location of the fault. For example, if the piston, piston ring, and cylinder wall are suspected to be heavily worn, a small amount of oil may be poured into the cylinder. If the compressibility becomes good, it is suspected to be true. 4 does not dismantle the inspection method: In order to accurately determine the fault, to avoid the inappropriate disassembly of some complex parts, you can use some special equipment, directly or indirectly check the technical status of the relevant parts, that is, do not disassemble inspection. For example, using a pressure gauge and connecting Accessories, you can check the cylinder pressure; check the oil pressure of the injection pump; check the oil pressure of the lubrication system, etc. Author: Mulan Agricultural Machinery Station, Heilongjiang Province