The importance of details in the maintenance of automatic transmission
  • Automotive

In the maintenance process of automatic transmission, the detail determines the quality of the whole maintenance. Because of the complex structure of the automatic transmission and the precise control principle, the requirements of the automatic transmission are very strict. A little carelessness will lead to the rework of the maintenance, and even cause serious maintenance quality problems. The following examples of failures encountered in several practical work illustrate the importance of paying attention to detail for the quality of automatic transmission maintenance. For example, one of the Shanghai Volkswagen Passat L 8T cars equipped with 01N automatic transmission always burns planet carrier and unidirectional clutch. When the automatic transmission is repaired, it has been dismantled by other repair plants. The one-way clutch has been severely burned and the planet rack has been damaged. At that time, the repair shop said that the automatic transmission had been repaired once because of the same problem. This is the second time that the fault has occurred, and it is less than 1 months away. Based on this phenomenon, we have carried out a thorough analysis of the whole fault and obtained two inferences: one is that there is a problem in one way clutch itself that causes one way clutch damage, and the two is the problem of the assembly of the maintenance personnel in the process of maintenance, that is to say, the bearing or gasket in the planetary frame is less installed, causing the planet frame and the big sun. The gap between the wheels becomes smaller, resulting in relative friction, which causes the high temperature to burn out the planet carrier. However, bearings and gaskets were found in the burned planet carrier, so the second possibility was ruled out. The possibility of first inferences was confirmed in the repairman's inquiry, which is that the unidirectional clutch itself has a problem, because the repairman said that there was only one old one because there was no new unidirectional clutch at the time, and it was not particularly good. In the process of maintenance, we replaced the new unidirectional clutch and the new planet rack, carefully checked the other components and assembled the assembly according to the assembly standards. There have been no failures for more than 3 months since the loading of the car. The 21 01N automatic transmission is repaired because of the shift impact into the factory. After the maintenance, the skid phenomenon is found. After repeated analysis without fruit, it is re examined. The result shows that the gap of the B2 brake is too large, and the gap of the B2 brake is adjusted to reload the car after reloading. For example, 31 Volvo XC90 cars equipped with 4T65 E automatic transmission, when the factory is servicing, the fault reported by the fault self diagnosis system is 4 gears transmission ratio is not correct. For 4T65 E automatic transmission, 4 gear transmission ratio is not a common fault, in general, it is the serious wear and tear of the 4 gear shaft and the damage of the solenoid valve. The disintegration of the automatic transmission found that the 4 gear shaft was worn seriously, and the 4 gear piston was checked, no problem was found, but the valve body was stagnant, because the new body was expensive, so the old valve body was changed to use. Replace the damaged parts and reassemble it. But after loading, it was found that although the original fault was ruled out, there were two new malfunctions, the shift impact and the 4 block skidding. After the fault detection of the vehicle, the fault code was not found. It was found that the valve and the solenoid valve may have problems. Then the automatic transmission was removed, the new solenoid valve and valve body were replaced, the road test was re loaded, and the shift impact phenomenon disappeared, but the 4 gear slipping fault still existed. At that time the entire repair fell into a state of paralysis, not knowing exactly where the problem was, and the inspection of the oil pressure was normal, and the assembly staff said the gap between the friction plates was also within the standard range. Almost all I could think of had been confirmed, and there was no trouble. Everyone was puzzled for a day. At the end of the day, a repairman said, "maybe I have a problem with the piston." Helplessness, the automatic transmission can only be removed to re check, the result found that the 4 gear piston has been damaged, there is pressure relief, the problem has been found, the transmission has been a strict assembly, after loading all normal, the failure completely eliminated. For example, 41 Audi A6 cars equipped with CVT (stepless automatic transmission) were moved into the factory for maintenance due to gear shifting. After inspection found that the valve body data is wrong, replaced a new body, loading after the car test everything normal, but the owner of the car after the car has not come home because it can not hang up the car dragged back. Lift the car and open the rear cover of the automatic transmission. It is found that the shift arm has fallen out. It was found that the rocker hole in the new valve body was large and the rocker arm on the old body was thin, and the problem was solved after changing the rocker arm of a coarse rod, but the maintenance station received an extra complaint. For example, the wide one accord with MAXA automatic transmission has been broken down for maintenance. After the maintenance, the skidding phenomenon disappeared, but the automatic transmission has a different noise, and the automatic transmission is re - disintegrated. It is found that a bearing gasket is installed on the shaft, and the gasket is reinstalled and the abnormal sound is disappearing. It is not difficult to find out how important the details are in the maintenance process of the automatic transmission through the above failure cases. For these problems, the loss of the economy and reputation is the final result. But let's turn around and think about whether these problems can be avoided. The answer is yes, it can be avoided. Some people are always asking why the automatic transmission is always bad? Why is the automatic transmission always reworking? There is only one answer, that is "not careful." If the failure is thoroughly analyzed during the maintenance process, but not by the experience of maintenance, will there be such a problem? If every part is carefully checked during the repair process, will there be such a problem? The answer is "no". There is a saying that "details determine success or failure". We quote it as "details determine the success rate of a maintenance". Yes, just the details determine everything. It can make one thing from complex to simple, and it can make one thing from simple to complex. In the maintenance of automatic transmission is also the same, success or failure in the details, then how to pay attention to these details? I want to have two factors: first is professional knowledge. Professional knowledge is the wing of practice, without professional knowledge, it will be very difficult in the actual operation. If the structure and working principle of the automatic transmission is not enough, it will cause a great obstacle to the fault diagnosis and assembly of the automatic transmission. Therefore, as an automatic transmission maintenance personnel, we must learn professional knowledge, professional knowledge and practice to improve the quality of automatic transmission maintenance. The second is the sense of responsibility. The sense of responsibility determines to a large extent the whole quality of maintenance. For the convenience of the customers and for the interests of the company, the only way to do the two is to pay attention to the details. Only in this way can we improve the success rate of the maintenance of the automatic transmission. If we know the importance of the details in the maintenance, then look back at the above failure cases, can we avoid? Of course, because all the problems are in detail and are careless. The first fault is that there is no new unidirectional clutch at the time to change an old one, but it does not take into account the impact of the poor working of the unidirectional clutch, which is sometimes invisible on the surface, until the failure occurs, and if these factors are taken into account, I think no one will do it. . The second fault is the assembly quality problem. If it is assembled according to the standard gap, there will be no such problem (the standard gap is 1.5 mm to 2 mm, but the actual clearance of the maintenance personnel is 4 mm). As a repairman, the standard clearance is sure to be known, but why is this problem appearing? It is the misfortune of experience. Some maintenance technicians think they are already familiar with them. They don't have to measure them again. But there are some people who can say that their eyes are a ruler. So the gap measurement must not be lazy and can avoid mistakes according to the regulations. Third failure cases are completely responsible. If the responsibility is not enough, the quality of the work is not enough. A piston, if it is assembled, is not likely to be damaged. If it is finished, it is impossible to find the problem. This is the negligence of the work and the reduction of the work. The process is caused by the process. Fourth and fifth fault cases also illustrate the same problem. In short, details are very important to us, which directly determines the quality of maintenance. So I hope your colleagues will be able to pay attention to these details, which is the basic quality as a repairman should have. Or that sentence, "the success or failure is only in the details".