Fast 12-speed Manual Transmission Gearbox 12JSDX220T-B

The reasons for air leakage in the double H valve of Faserte transmission

In the early days, due to the scarcity of Faserte transmissions, when such problems occurred, many double H valves were replaced, but the problem couldn't be solved. Now that this type of transmission has become very common, we all know that most of the problems are related to the shift cylinder. After replacing the repair kit, the problem can be solved, but sometimes it still can't be resolved.

Causes of leakage in the double H valve: I have encountered this problem before. After spending half a day troubleshooting, we still couldn't pinpoint the cause. Eventually, we measured the air pressure of the high and low gear air pipes in the shifting cylinder using an air pressure gauge. It turned out that the air pressure reached 0.78 Mpa. It was discovered that the working air pressure of the shifting cylinder was too high. After adjusting the air pressure adjustment screws of the air filter and pressure regulating valve, it still couldn't bring the air pressure to the standard value. As a result, a new one was replaced, and the problem was resolved. Therefore, when you encounter this problem, you must take the air filter and pressure regulating valve into consideration. When it has a problem, it usually causes leakage in both the high and low gears of the double H valve!! Finally, I would like to inform you that the normal working pressure of the shifting cylinder is generally 0.41 Mpa - 0.44 Mpa (for the double intermediate shaft series transmission); 0.57 Mpa - 0.60 Mpa (for the double intermediate shaft full synchronizer transmission).

The gear shifting failure of Faist transmission can be divided into main box failure and auxiliary box failure. If it is found that the gear shifting occurs in the low gear range or high gear range, that is, more than one gear is shifted out, then it must be the problem of the auxiliary box. If it is shifted out in the low gear range, then it is caused by the wear of the clutch slip sleeve engagement teeth and the reduction teeth, with taper or non-full-length engagement; if it is shifted out in the high gear range, then it is caused by the wear of the clutch slip sleeve engagement teeth and the driving teeth, with taper or non-full-length engagement. These are common problems (no matter which situation occurs, everyone should replace the clutch and the two gears together, because if one part fails, the others will fail soon as well). Also, if the gear shifting occurs in both high and low gears, then it may be caused by insufficient air pressure in the circuit, which is usually a problem with the air filter and pressure regulating valve of the transmission, or it may be a problem with the four-way protection valve. Because the four-way protection valve has an outlet that charges the auxiliary circuit of the entire vehicle, you can judge. If it is this problem, then at the same time, the clutch will also not work properly. If this is the case, then it must be that the four-way protection valve is damaged and it should be replaced! In addition, improper installation of the transmission shaft can also cause gear shifting failure. However, the driver will usually have a reaction in advance!