One should really go to a workshop for trucks or in this case for busses to see a dismanteled automatic gearbox. Repairers of passenger cars only generally take care of such gearboxes, as long as it has to do with the sensor systems or the actuators of modern gear boxes. They hardly ever concern themselves with the mechanics. There's a good reason for this. One notices it in the metal slivers in the gear oil or if the oil smells slightly burnt. In most cases odd noises point to this as the source of the error. In this case the repair would mean the exchange of numerous parts. How should one get out the slivers of a completely sealed passenger car converter with a very high degree of certainty? Or remove them to 100-percent from an engine oil cooler? The repair would certainly be more expensive and less reliable than a replacement part.
Let's dwell for a moment on the big brother of the passenger car automatic gearbox. As pointed out in figure 3, the converter can be dismantled. However, a large number of parts, stored of course in suitably marked containers, (figure 5) are necessary. If one can make use of a reasonably good assembly stand, as seen in figure 1, the necessary knowledge, attained through appropriate courses, the job should pose no problem. However, before the installation, the testing of almost all the functions is necessary. In this case the gearbox is driven by an electric motor and the electric transfer valves (figure 5) are worked individually. In figure 1 parts of the oil-flow check can be seen. 09/08