1. Failure to correctly judge and analyze the fault, and the phenomenon of blindly dismantling and disassembling is commonplace.
Because some maintenance personnel are not clear about the mechanical structure and principle, they do not carefully analyze the cause of the failure, and cannot accurately determine the fault location. Maintenance skills and craftsmanship are poor, and new problems arise. For example, in a certain station, the 120KW diesel generator had insufficient power and the machinery could not work. The maintenance personnel disassembled and disassembled the PT fuel injection pump and fuel injector, but did not find the cause of the failure. They replaced one fuel injection pump and tested, and the fault remained the same. The final inspection failure is caused by excessive impurities and moisture inside the diesel used. However, this dismantling resulted in a significant decrease in the performance of the PT fuel injection pump and insufficient diesel generator power.
Therefore, when a mechanical failure occurs, it must be detected by testing equipment; if there is no testing equipment, traditional fault judgment methods and means such as "ask, see, check, and test" can be used, combined with the structure and working principle of the equipment, to determine the most possible malfunctioning parts.
When judging equipment failures, the "exclusion method" and the "comparison method" are generally used, in the order from simple to complex, first appearance, then interior, first assembly and then components. Do not "disassemble and dismantle blindly" .
2. There are many phenomena that do not pay attention to detecting the fitting clearance of parts.
For example, in the maintenance of common diesel generator sets, the clearance with the cylinder liner, the "three clearances" of the piston ring, the piston head clearance, the valve clearance, the plunger clearance, the brake shoe clearance, the driving and driven gear meshing clearance, the bearing shaft All types of models have strict requirements on radial and radial clearances, the clearance between valves and valve guides, etc., which must be measured during maintenance, and parts that do not meet the requirements must be adjusted or replaced.
In the actual maintenance work, there are many phenomena of blindly assembling parts without measuring the fitting clearance, resulting in early wear or ablation of bearings, burning oil in diesel generators, difficulty in starting or deflagration, broken piston rings, collision of parts, and oil leakage. , air leakage and other faults. Sometimes even due to improper fitting clearance of parts, serious mechanical damage accidents occur.
3. The phenomenon of blindly replacing parts and blindly replacing parts and repairing exists to varying degrees.
It is relatively difficult to judge and eliminate equipment failures. Some maintenance personnel have always adopted the method of replacement test. Regardless of large or small parts, as long as the parts that may cause the failure are considered, they will replace the test one by one. As a result, not only the fault was not eliminated, but also the parts that should not be replaced were replaced at will, which increased the maintenance cost.
Some faulty parts can be repaired to restore their technical performance, such as generators, air compressors, blowers, burners, gear oil pumps, etc., which can be repaired without complicated repair processes. During maintenance, the cause and location of the fault should be carefully analyzed and judged according to the fault phenomenon, and the repairable parts should be repaired to restore the technical performance, and the practice of blindly replacing parts should be avoided.
4. The situation of the parts being assembled and dispatched during assembly occurs from time to time.
When repairing equipment, some parts are assembled with strict direction requirements; only correct installation can ensure the normal operation of parts. The tail features of some parts are not obvious, and the front and back can be installed in reverse. In actual work, the reverse installation often occurs, resulting in early damage to parts, machinery not working properly, and equipment damage accidents. Such as engine cylinder liners, unequal distance valve springs, engine pistons, piston rings, fan blades, gear oil pump side plates, skeleton oil seals, thrust washers, thrust bearings, thrust washers, oil retaining rings, fuel injection pump plungers , Clutch friction disc hub, drive shaft universal joint and other components are most likely to be installed backwards if they do not understand the structure and installation precautions. Resulting in abnormal work after assembly, resulting in equipment failure.
Therefore, when assembling parts, maintenance personnel must master the structure and installation direction requirements of parts, and cannot blindly install them for granted.
5. The maintenance method is not formal, and it is still the habit of some maintenance units to "solve the symptoms but not the root cause".
When repairing equipment, some maintenance personnel do not take correct maintenance methods, thinking that emergency measures are omnipotent, and replace "maintenance" with "emergency", and there are still many phenomena of "solving the symptoms but not the root cause". Such as the often encountered "repair by welding", is an example. Some parts can be repaired, but some maintenance personnel often use the method of "welding to death" in order to save trouble; in order to make the diesel generator "powerful", artificially increase the fuel supply of the fuel injection pump and increase the fuel injection of the injector. pressure.
These irregular maintenance methods can only be used in an emergency, but cannot be used for a long time. It is necessary to fundamentally find out the cause of the failure, and adopt a formal maintenance method to eliminate the fault, which should attract the attention of the maintenance personnel.
