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Old 08-13-2012, 11:22 PM   #6 (permalink)
slowmover
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Location: Fort Worth, Texas
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2004 CTD - '04 DODGE RAM 2500 SLT
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This trans is, as noted, more about a clean sheet approach to being an automated manual transmission with more sophisticated shift algorithms than with big truck automatics of the recent past. There are variants of what is a big truck "automatic transmission".

Suffice it to say that fleet owners are the ones interested. A "real" truck driver, with five or more years of experience already has the ability to chose the right gear at the right time despite the vagaries of road, load, weather and traffic. (Each of these is worthy of study in depth. The combinations of these puts the lie to the classification of truck driving as "unskilled" labor by the US Dept. of Labor).

Years back one had two transmissions and sometimes a two speed rear axle. Three sticks to control. Multiple times. In more recent decades the usual fleet transmission has been either a 9 or 10 speed (effectively, an 8 or 9 speed plus a granny low).

The 2012 367 Peterbilt I drive at present has an EATON 10-speed. I often wish for a 13-speed, but they take more attention, and more finesse. An automated 12 is an obvious way of cutting some tenths for most fleet trucks. I often spend a great deal of time moving between the top two gears as they cover such a wide range of travel speeds. A 13 would give me more control over engine rpm (shorter rpm range between shifts, say a 250-rpm rise).

Being able to split the "high range" of the gearbox would really be great. But the sheer number of choices when descending a curving piece of shiny, wet asphalt loaded to 74k into an intersection can be too much when one is new. How many gears to drop, and how long to pause between gears [as well as steer, brake and visually command the scene) is something only experience can do for a driver.

An automated manual is the obvious future for what is needed for reliable predictable big truck fleet fuel consumption. And not compromise safety or the load.
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