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Auto vs. manual transmission: Data-driven tech better than complete control?

| July 22, 2013

Manufactures say automatic transmissions make drivers safer and more productive. Older drivers say they’re a crutch. Who’s right?

Adapting automatic transmissions for use in trucking has proven to be difficult. One reason was the inability of mechanical engines and transmissions to “talk” to one another and ensure optimal vehicle performance across a broad array of applications and road conditions.


Will drivers come around on automatic transmissions?

Manufacturers say enhanced data sharing between engines and transmissions is boosting the efficiency of automatic transmissions over manual. Will they ever gain acceptance among drivers?

Early transmissions had a hard time figuring out what drivers wanted. Complaints concerning both frequent and uneven shifts were common, as were problems with “searching” – when transmissions would struggle in hilly terrain to find and stick with an optimal gear. Other problems along those lines emerged at low speeds – in traffic and while docking.

Manufactures say automatic transmissions make drivers safer and more productive. Older drivers say they're a crutch. Who's right?

Manufactures say automatic transmissions make drivers safer and more productive. Older drivers say they’re a crutch. Who’s right?

Even so, AMTs continued to make inroads in trucking. Now, engines and transmissions are sharing more data, so performance issues are getting smoothed out. AMTs now are being spec’d on a significant share of new trucks for reasons including fuel economy and easier driver training – and the trend is likely to continue.

Two types of automatic transmissions are available for heavy-duty trucks: Automated manual transmissions and automatic transmissions. Both are two-pedal designs, and most drivers probably would be hard-pressed to tell much of a difference between them in real-world driving situations.

True automatic transmissions feature fluid drive and a torque convertor. Adherents argue they provide 100 percent power and double rim pull, making them ideal for vocational applications.

True automatic transmissions feature fluid drive and a torque convertor. Adherents argue they provide 100 percent power and double rim pull, making them ideal for vocational applications.

The basic difference is that automated manuals are manual gearboxes, with all the clutch actuation and gearshifts handled by electronically controlled systems. True automatic transmissions feature planetary gearing with disc packs for clutches and torque converters.

“In this context, an automatic for a Class 8 truck is usually fully automatic, like a typical car transmission, with planetary gearing with several multidisc packs for clutches,” says Ed Saxman, product marketing manager with Volvo Trucks North America. These transmissions have a torque converter to enable powershifts of the planetary epicyclic gearing units that provide the various gear ratios.

An automated manual transmission uses the gearbox of a manual transmission and shifts it by computer, using a computer-operated single large-diameter disc clutch, otherwise similar to a manual clutch.

Mack Trucks says the take rate for its mDrive AMT is currently in the neighborhood of 38 percent, which aligns with other OEMs that report figures ranging from 35 percent to the low 40-percent range.

Mack Trucks says the take rate for its mDrive AMT is currently in the neighborhood of 38 percent, which aligns with other OEMs that report figures ranging from 35 percent to the low 40-percent range.

Allison Transmission’s automatic is designed with the company’s Continuous Power Technology, meaning it never interrupts torque and power to the wheels, says Steve Spurlin, executive director of international application engineering and vehicle integration. “It also uses a torque converter as the starting device,” he says.

An automated manual has incorporated electronic controls with basic manual transmission architecture to facilitate automated shifting of the gears and the input clutch-starting device. Both the automated manual and the basic manual interrupt power and torque every time a shift is made, whether automated or manually, Spurlin says.

According to Steve Rutherford, powertrain marketing manager for Caterpillar OEM Solutions Group, the advantages of a pure automatic design are a perfect fit for the company’s vocational truck line – although he points out that both types of transmissions work well in specific applications.

“Both types of transmissions have two pedals and a shift pad instead of a gearshift lever,” Rutherford says. “It took a lot of work to perfect automated manuals to engage a dry clutch and generate well-synchronized shifts. What they’ve done with those products is amazing.”

But many drivers – primarily older ones – feel that automatic transmissions somehow detract from a skill set they’ve honed over decades. “I’m a truck driver, not a steering wheel holder,” says Carl Ciprian, a driver with Fayette, Ala.-based N&N Transport. Ciprian never has driven an AMT and says he never will, preferring to stick with an Eaton-Fuller 18-speed manual gearbox.

Several OEMS have developed integrated powertrains that share proprietary information between the engine and transmission to deliver optimal fuel economy consistently.

Several OEMS have developed integrated powertrains that share proprietary information between the engine and transmission to deliver optimal fuel economy consistently.

“I can understand why fleets like AMTs,” he says. “It’s all about fuel economy. You know – ‘Instead of teaching new drivers how to drive, just give them all an automatic transmission, and turn them loose on the highway.’ ”

Ciprian, however, sees truck driving as a skill – one in which a truck driver needs to be engaged to do it properly. “Changing gears, and having the additional control over the vehicle that a manual transmission gives you, is an integral part of that,” he says.

But fleets are gravitating toward automatic transmissions – and in surprisingly high numbers. David McKenna, director of powertrain sales for Mack Truck, says the mDrive’s take rate in Pinnacle tractors is currently in the neighborhood of 38 percent, which aligns with other OEMs that report figures ranging from 35 percent to the low 40-percent range.

In some medium-duty applications, AMTs now are spec’d in more than half of new trucks sold. Saxman says that more than 50 percent of all new Volvos sold this year have been spec’d with the company’s I-Shift AMT.

There are several reasons for this significant shift, experts say. Shane Groner, Eaton’s manager of NAFTA product development, says his company’s UltraShift Plus AMT now is enjoying a 25 percent take rate in heavy-duty trucking applications, with on-highway applications logging in at about 15 percent.

“There are still a lot of highly experienced drivers out there who can get the most out of a manual transmission,” Groner says. “Those gearboxes are essentially bulletproof. If you’re a fleet and you’re blessed with an abundance of experienced drivers, and upfront costs are still your primary expense driver, then it’s hard to argue with manual transmissions.”

On the other hand, Groner says, driver skill sets in the industry are changing rapidly. “Many young drivers have never driven even a car with a manual transmission, so they lack even basic familiarity with them,” he says. “The driver demographic is changing. Older drivers are retiring, and they are not being replaced.”

For fleets, though, the appeal of automatics goes far beyond driver preferences, with safety and fuel economy topping the list. “We’ve found that automatics help with driver recruitment and retention,” Spurlin adds. “Automatics allow less-skilled drivers to be very productive. They are also a large help with safety because the drivers can stay focused on the road or the task at hand instead of shifting gears.” Also, drivers do not get as fatigued with an automatic since they do not have to shift gears constantly, he says.

“We have encountered many ‘converts’ – veteran drivers who were once skeptical but now prefer our I-Shift automated manual transmission,” Saxman adds. “Manual transmissions are difficult to ‘skip,’ and most drivers use all 10 gears.”

In contrast, Saxman says, AMTs like the Volvo I-Shift can reach top gear by using just six of 12 available forward ratios. “Fewer interruptions mean faster acceleration,” he says. “As far as fuel efficiency, it is often said that an automated transmission can make the worst driver deliver the same fuel mileage as the best driver, because it’s in the right gear at the right time – all of the time.”

Brad Williamson, powertrain marketing manager for Daimler Trucks North America, says the way fleets spec a drivetrain is changing and that automatic transmissions are a key part of that formula. “The industry at large is now spec’ing lower gear ratios, with direct-drive powertrains becoming more common,” he says.

The concept of “downspeeding” – operating a diesel at lower rpms while at cruise speeds – is being driven by the push for better fuel economy, Williamson says.

“Information is key,” he says. “If you designed both the engine and the transmission, then they can ‘talk’ to one another and share critical information, like what the driver wants, the fuel map, the load, the grade and what the engine is trying to do. The transmission can manage all this information and deliver the best performance possible given all those criteria. A driver just can’t do that consistently. Even if they had all that information, they couldn’t process it and manage the shifts to deliver the same level of performance an automatic transmission can.”

Williamson’s point addresses the latest development in the evolution of automatics in heavy-duty trucking: complete powertrain integration. To date, Volvo, Mack, Daimler and Eaton – via a just-announced partnership with Cummins – all have developed highly integrated powertrains that share unprecedented levels of proprietary information between the engine and transmission to deliver consistently optimal fuel economy at all times.

“It all boils down to the electronics,” McKenna says. “When you have Vendor A supplying an engine and Vendor B supplying a transmission, rarely do those two components share 100 percent of their information 100 percent of the time. Typically, the transmission in those instances ends up making decisions with about 75 percent of the data it needs to make an optimal shift.”

Part 2 of the automatic vs. manual transmission piece will run Tuesday and will cover drivers’ takes on automatic transmissions.

  • Jimmy the Greek

    That well be as bad as when Harley put electric start on motorcycles , I still have two Sportsters XLCH with mag and kick , that is what statered the candyasses riding motorcycles And it well be the same with trucks Hell it is all ready apon us LOL I kind of wish they would go back to The old 3 on the spliterstick and five on the main box , that well weed out the bad ones lol, around the first day . LOL

  • Daryl Wirth

    If I have a choice I won’t go back to a manual trans

  • Jimmy the Greek

    Untill you have to pay the bill at a shop getting one fixed !

  • Daryl Wirth

    the money saved in fuel milage out was the repair bill

  • Allison all the way

    Jimmy the Greek you must know nothing about these transmissions. I have two Allison world transmissions, one just had it’s first service in 426,000 miles and the other pushes 7.0 miles per gallon pulling a 52 foot trailer. Your half as tired at the end of the day if you encounter any kind of traffic.

  • Allison

    Wrong Jimmy! 426,000 and my Allisoon just hads it’s first service.7.0 Miles per gallon. and if your against progress i.e. kick starters why not throw away your TV remote?

  • Jimmy the Greek

    You must buy new trucks ! the tractor i am driving i got when it was 4.5 years old , that was 10.5 years ago , I am looking to run it 4.5 more years , then sell it to the central americans , the last 1/4 IFTA report showed 6.7 avg MPG , 60 det. i never turn it off only in some of the winter mo. it’s a 1998 , I payed 25,000.00 at houston frightliner for it , i do not run caps not even on the trailer chang the oil every 10,000 miles and never added oil between oil changs , rear and tranny oils look like they just came out of the drum , I run only the southeast out of texas. last year i payed 18,000. to the tax man after all my write offs , i run on my own , not leased . run a dry van and do haz-mat 70% of the time the tractor could use a paint job it’s white with a green nose clip , lol however it has never been shut down on a DOT insp .

  • Jimmy the Greek

    When somthing bad goes wrong with it the bill well be 10,000. min i can have my trans rebult for under 5,000.

  • Anderson Dantas

    I am an instructor operations Mercedes-Benz, Brazil Here in the automated transmissions Volvo i-shift, Opticruise Scania, ZF Eurotronic and Mercedes-Benz PowerShift are on the rise. For severe applications still defend manual transmissions, especially when it comes to starting ramp truck loaded with the automated are not as good at it.

    For very severe applications are the ideal manual transmissions with torque converters coupled because this feature is easier to take the vehicle from a standstill.

    Particularly like an Eaton Fuller 18 speed, in my opinion, one of the best transmissions in the world.

  • Anderson Dantas

    Allison has developed a truly automatic transmission with 10 speeds, in my view, it is perhaps better than the automated because the gear changes with no loss of torque at the wheels, providing better performance and fuel economy.

    Although I recognize that the automated transmissions are growing, I prefer the manual or fully Automatic. As stated in the report still suffer greatly from automated exchanges unwanted, even though the driver is able to interfere with this procedure, but not everyone has this ahbilidade therefore even automated transmissions need for trained operators can deliver profitability to the fleet owner .

    Here in Brazil our line of Class 8 trucks (here called extra-heavy) Mercedes-Benz only come out with automated transmissions (Powershift 2). For severe applications I still defend the good old manual transmissions. Automatic transmissions are not common here in trucks, except for some specific applications, are more common in urban buses.

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  • Daryl Wirth

    Amazing how people only live in the past .a total waste of money changing oil at 10,000 miles. and only getting 6.7 mpg

  • Jimmy the Greek

    That is the reason my 1998 still runs as good as a new one , My next oil change well be at 780,000 miles , before you start harpping i only run 30 to 40 thousand miles a year , i have no payments and sometimes sit home a week , Untill someone needs something done fast and is willing to pay for the service , i do get calls at 11 pm on a saterday night at times .

  • Herlin

    Today semi and fully automatic gearboxes are increased. But still manual gearboxes are popular among car users.

  • gerald

    Maintenance issues: im a Trucking Company Owner of a small fleet: …running with a MBE 4000, Freightliner Columbia with the Eaton Fuller Auto Shift, MPG based from the last 5,500 gallons, (all miles & idle time) is 6.56 mpg. Freightliner Mechanics are having problems diagnosing maint. issues and giving out false positive solutions, the affect of the mech. false positive solution is the truck towed-in and the same issue is work thru 2 & 3 times. Two Examples: 1), eaton auto shift, goes into failure mode, truck towed to dealer, whom diagnose low current running thru the transmission wiring harness. Dealer replaces, tranny wire harness. truck works for 1.5 days. While greasing the trucks underside, I noticed one alternator wire running from was a 6 gauge cable and 75% of the 6 gauge. wire was broken off at a support hanger, with 25% of the wire intact. Periodically, tranny still going into failure mode. I went to another dealer, (not freightliner) ordered the cable’s replace. Second Issue: truck no starts on a fuel island, truck towed a the dealer, whom diagnose replacing the 4 month old, (new) starter. I instructed them, it was new, they returned with a linguistic game, …they have been known to go bad. After starter replaced, truck did start, a day or two later, truck no starts, called the shop mgr. recent repair, whom recommended jumping the starters solenoid…jump negative, then jump positive…truck started. Later, after complaining to another shop, they ran a computer diagnostic on the tranny, stated the issue was the input speed shaft sensor…$23.00. There are several more examples…

  • Billy Walker

    You are using them for O.T.R. use? Im a mechanic with many years experience in concrete and material hauling these trans are a perfect match but i haven’t talked to anyone who use them for O.T.R. Im pleased to hear this i think they are the best bar none.

  • Billy Walker

    A lot of opinions! I see it this way if you like auto run it if you like standard run it! i like both, both have there application and loyal customer base. its a healthy debate. good question!

  • Byron Emery Mayfield Sr

    If I was looking for another truck I would look for a 4×4 the only problem with 2 sticks is they are heavy. They are fun to drive.

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  • Guest ish

    You all are dinosaurs. Lets do the math. Say your automatic tranny gets 7.0 mpg, vs the 6.7 on the MT. You repair the Auto tranny for $10,000 at 500,000 miles. Total cost of fuel and Repair comes out to $81,429. Running the MT you have to shift gears (put down your coffee) Your total cost of fuel and repair after 500,000 Miles would be 79,626. Thats a savings of $1800 every 500,000 Miles for using a MT according to Jimmy’s Information. Jimmy might save a tiny bit of cash, however at least Allison doesnt have to get off the couch every time to change the channel. Technology is your friend Jimmy, its not the 1990’s anymore.

  • Jimmy the Greek

    The only thing i let in my truck is water , no food or other crap ! that’s is what restaurants are for !

  • Jimmy the Greek

    I own 5 with kick starters , all run points two are magneto no battery , I could get 7.0 if i wanted to i could follow a Swift Turn off the engine when i gt out of the cab ? i don’t have to , when i buy fuel it is real fuel ( no blended bi-o crap, ) I fuel at places that i know ,

  • David Allen

    The only reason they want these automatic transmission is so they can hire anyone that can hold a steering wheel and can’t back up or can’t drive a stick as the industry is short drivers and over half cant drive a stick shift

  • Partime Coach driver

    The next time your eaton auto goes into failure mode, shut engine off and wait 5 minutes before restarting ( computer reset). Trans should return to normal mode.

  • Trenton Riley

    saying tech is your friend. I have a 98 peterbilt with a 500hp big cam ntc Cummins..I put it in because I wanted all mechanical it is mated with an 18 speed Eaton and the transmission now has 2.7 million miles and that’s with me pulling 130000 also at 130000 I get 4.5 mpg and my friend with his AMT same haul gets 3.1

  • FoxStar

    Lol I wish more thought this way instead if acting like their masculinity and way of life was being threatened.

  • jr

    i had a spicer 20 .5in the main box and the rest on air shift. 4 reverse gears. loved it

  • Ray Tracy

    I have a bad knee and at times have a hart time pushing clutch. Will the auto hold up to hundred thousand pound loads and come out of bad places? I am old school hard to trust a auto in a big truck

  • SlenderSniper

    I realise that I am replying to an old comment, but my company just took me out of a 2012 T660 with a 10-speed manual transmission and put me into a brand new 2016 T680 with a 10-speed autoshift. I’m getting 5.5 average mpg with the 680, whereas with the 660 I was getting at least 6.6, up to 7 at some points. The only time I’ve hit 8.0 mpg was just after turning the truck on after having it off all night, and it quickly went back down to between 5 and 6. strives to maintain an open forum for reader opinions. Click here to read our comment policy.