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I heard rumors of companies switching to automatic transmissions. Is this true?
weed4@ds2.virtualscape.com


Yes indeed, many carriers are switching gears, so to speak, but the transmission of the future isn’t an automatic --it’s an automated manual transmission.

Say What...? An automated manual transmission? Exactly. The gearbox itself is a regular 10- or 18-speed transmission but the gearshifting is done automatically using a pair of servo motors to move the shift levers the way your right hand presently does.

The concept is fairly simple, but the electronics involved are pretty complex. The engine and the transmission each have an electronic control module, and they both communicate to make the shift happen. One brand of automated manual transmission is preset to make the shifts without prompting by the driver, and another brand relies on the driver to initiate the shift by pressing a shift button in the cab. Because the shift timing can be so precisely controlled, it isn’t necessary to use the clutch. Here’s how it works:

Once the decision has been made to make an up-shift, the engine control module (ECM) throttles back, and sends a signal to the transmission control module (TCM) shift the transmission into neutral. The ECM monitors the falling engine rpm, then sends a signal to the TCM at the precise moment when the next gear will mesh properly, then it throttles back up again when the shift is complete.

To make a downshift, the ECM will rev the engine until the correct engine speed is reach to allow the gears to mesh. When up-shifting on an uphill grade, the ECM may engage the engine brake to slow the revs down more quickly so as to avoid any loss of road speed. When making a up-shift on a downhill grade, the ECM may instruct the TCM to skip a gear if there’s sufficient roadspeed to maintain the proper engine speed range following the shift.

To the driver, it may all seem automatic, but this kind of transmission retains all the advantages of a manual gear box.

And as for the clutch? There’s a new automated transmission on the market called the Freedom Line from ZF Meritor: it does the clutching for you as well. As for the others, the driver uses the clutch only on start-up and when coming to a stop. The rest of the time, the shifting is so precise, the clutch isn’t needed. Just like a veteran driver who has learned to shift without the clutch.



Jim Park