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Truck Topics

Shifting Gears

By Jeff Jensen, Editor
Posted May 8th 2006 6:02AM

shifting-gears.jpgYou know, a great deal of the "mystique" of being a truck driver is in the gearjamming - that mysterious quality that only the best drivers have somehow mastered, the physical activity of sliding that shift lever into the right gear at the right time, combined with the trained ear that tells the savvy "hand" behind the wheel when to shift.  It's a skill, alright, intuitive in some, but for most, learned only after many miles and missed shifts.

The question is, with the technology we have had available to us in recent years, is shifting still a necessary skill?  Especially, when according to the experts, that technology can do the job of changing gears more efficiently and with (possibly) greater economy?

We're speaking of course of automated or fully automatic transmissions in today's Class 7 and Class 8 trucks.  They have become increasingly popular with both the single truck owner-operators and the fleet owners of expediting.  

Why?  Actually, there are several reasons. 

The emergency freight business has traditionally been populated with second- and third-career individuals who do not come from a trucking background.  Most of them have spent their years of driving cars with automatic transmissions and they carry no emotional baggage about having to shift to be a real truck driver.  The same conditions can be applied to general trucking where a driver shortage has brought in many inexperienced operators.

Highway congestion has slowed interstate traffic to a crawl in many areas and increased clutching/shifting contributes mightily to driver fatigue.
 
Taking some of the driver fatigue out of shifting is an attractive prospect for the newbie, since learning to shift a constant mesh gearbox can be the hardest part of learning to drive.

Real world
Expedited fleet owner Joe Manley of DJ Trucking in Perrysburg, Ohio operates a total of 33 Class 7 and Class 8 trucks.  Of those, 12 of the trucks are equipped with the Eaton Fuller 10-speed Autoshift automated transmission (3 pedal) in his Class 8-based trucks and Allison 6-speed automatic transmission in his fleet's business class units.

Manley says that his company began experimenting with the auto transmissions a few years ago and says that automated (automatic) is the way to go.

"A lot of folks don't want to work with the non-synchronized manuals, so around three years ago, we began buying the Autoshifts.  We've since made a decision that we're only going to buy fully automatic transmissions from now on, whether it be the Allison or the new Eaton Fuller 10-speed Ultrashift's (2 pedal)".

"It gives us a broader market of drivers to work with.  Quite often, you have a situation where you have a driver who has been running big trucks in general trucking for the last twenty years.  The kids are out of the house and he wants to take his wife with him, but she has zero trucking experience.  She doesn't want something that's difficult to learn like pulling a 53' trailer and a non-synchro transmission."

"They can scale down to a straight truck with an automatic and a big sleeper and they're ready to go!"

He continues, "Now, if the truck has a 6-speed, most people can live with that, but everybody would rather have fully-automatic transmissions. Why work harder if you don't have to?"

"If you do it right, you can get better fuel economy with a manual trans, but the automatic will force the driver to run in a taller gear and not over rev the engine."

As author John Baxter says in his article, 'Easy Rider',"At a given cruise speed, a really good driver can do only one thing to improve fuel economy: Shift up. These days, lugging a diesel engine down too low is almost impossible. Going up a gear, or even just a split, can make a whopping difference in fuel use.
 
One problem is that even the best driver won’t bother to shift up if he knows a grade or a slowdown is just ahead.

An automated unit, in contrast, cares only about vehicle speed and load, so it shifts up as soon as you back out of the throttle.

Joe Manley says that the Allison is less expensive today (considering inflation) and the reliability has improved dramatically.

"The transmission shifts smoother than before and they don't have near the maintenance problems of before.  They're still expensive to fix, but they've improved the reliability."

Jon Mosier of Freightliner of Knoxville says that his dealership has been building Class 7 expediter trucks with the Allison 6-speed for a number of years; in fact, that transmission has replaced the manual trans in virtually all of its Business Class truck builds.

"For our Class 8-based expediters and trucks with higher-horsepower engines, we've been spec'ing them with the new Eaton Fuller 10-speed Ultrashifts and people have been raving about them."

"This is due to customer demand - especially with the husband/wife teams.  Even if the husband has a history of driving manual transmissions, after they've driven one of the automatics, they'll tell me, 'hey, this is pretty nice.'"  

He says, 'Expediting requires a variety of driving situations - in and out of the big cities all the time - and when you get caught up in the traffic, it doesn't take long before your leg is shaking trying to hold that clutch in."

Mosier adds that he expects the automatic/automated transmissions to offer the same level of reliability and longevity of the manual transmissions, with a service life of 750,000 miles and more.

"The automated/automatic transmissions offer fuel economy that's very close to a manual, better acceleration on hills, and great durability.  I'd say those are pretty good reasons to go to an automatic." 

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