Dale, I will try to give a brief a brief explanation to a somewhat complex story (not easy for me
).
The Eaton AutoShift was developed for the heavy truck market in the late 90's. It took the typical truck transmission and automated the shifting process. The driver had to use the clutch to start and stop, but after that, he just had to sit back and steer. A very large number of trucks use that type transmission today, because of the available work force who are not able to master the art of shifting.
What Eaton did was to replace the shifting tower with one that had two servos. Those servos are controlled by two computers which, in turn, talk to the engine computer (via J1939 protocol). Between the two they decide when to make a shift (up or down). It is all very smooth and the driver does not have to worry about being in the correct gear. The driver can manually select a gear with shift buttons if the shift is within the acceptable RPM range.
If the AutoShift does not see an engine computer (mechanical engine for example) it becomes an AutoSelect and the driver makes the shifts by backing off the throttle to break the torque, pushing the button to select the gear desired and then, with the help of a gauge, changes the engine speed up or down. When the engine speed is correct, the transmission will slide into gear.
Both of these options are based on what many truck drivers do with normal truck transmission. They let the clutch out and then row through the gears by changing the rpm with the foot feed without the clutch.
For bus folks, this kind of transmission allows the owner to have a true mechanical transmission with great gear options for any condition, without having to deal with sloppy mechanical linkage running from front to back. It also gives them a good overdrive ratio without having to buy an Allison World transmission -- especially important when making a engine conversion from two to four stroke.
Jim
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