Well, we are gearheads, aren’t we? The type of guys or gals you see in the truckstop at 3 am calculating gear splits for the latest trannies over coffee and greasy stuff that vaguely resembles food. Thus it’s this blog’s gearhead duty to join the truckstop debate on the wisdom of Volvo dropping a single countershaft automatic tranny into the placid waters of the Eaton twin countershaft dominated american truck tranny market.

Techie background: Transmissions, great and small, are just boxfuls of gears that change the speed and torque output, devices to shift varying combinations or such gears in and out of the flow of power, and a bunch of bearings to keep them from quickly wearing out. In the simplest trannies, the gears are on two shafts and the gears on those two shafts are slid around by the selector mechanism linked to the gearshift lever you’ve been stirring to pick different “gears”. To get more gears, tranny makers will combine transmissions to multiply the available ratios… For example the currently en vogue 6 and 8 speed automatics are 3 or 4 speeds coupled to a 2 speed “splitter” to produce 8 forward gears, and an Eaton or Mack 18 speed tranny is a 5 speed multiplied by a 2 speed range tranny split by a 2 speed splitter tranny, with a couple duplicative ratios they don’t count. Most trannies have just 2 shafts, a main and a single countershaft, though a lot of automotive manual trannies have 3 shafts and no direct gear, in which the drive goes straight through with no gearing change. True automatics like the Allisons use epicyclic gearing, with an outer gear and three or so inner gears doing the reduction and a torque converter to provide more low speed reduction and keep the engine from dying when the vehicle is stopped.

American truckers not so happily used these basic manual transmission types until about a half century ago, enduring rebuilds every few hundred thousand miles. Why? Because except when the truck was in direct drive, the massive torque required to move truckloads pushed the gears on the mainshaft and countershaft apart and played hell with the bearings. Then Fuller which later became part of Eaton changed the world with a twin countershaft design that split the torque loads between twin countershafts which balanced and greatly reduced the loads on the bearings. Suddenly transmissions were lasting twice as long, and Eaton got to supply most of those truck transmissions. Within a couple years Spicer offered a twin countershaft tranny with a splitter rather than range  configuration that many old timers preferred, and Mack one upped Eaton with a triple countershaft tranny that was all but unbreakable.

For damn near a half century since, Eaton has damn near owned the market for heavy truck transmissions with it’s twin countershaft line. Spicer gave up, Meritor built a clone and gave up, and even though it had a superior triple countershaft tranny, Mack made Eaton’s tranny standard equipment and reserved their own tranny as a premium extra cost option. In the meantime, the big truckload fleets, ever hoping to employ the vast unwashed (for lack of truckstop showers) hordes of drivers who had never learned to drive a manual transmission, started sampling automatics. Ever willing to undercut the competition on price, Eaton turned loose version 1.0 automated variants of their trannies  at bargain prices. The truckload carriers sucked them up, and the premature clutch replacements began… Eaton’s budget automatic didn’t take well to slow creeping like happens when backing into loading docks and such.

Meanwhile, the four surviving big truck makers in america, eager to force buyers to accept their engines, trannies, and such instead of speccing their trucks ala carte with Cummins engines and Eaton trannies, counterattacked. Volvo was first into the fight for automatic tranny market share, with an old skool back to the bad old days single countershaft 12 speed manual automated by some very proficient computer software. In fact, in the Euro versions they’re even putting the grade profiles of major highways into it  and they’re linking it to the onboard GPS so it can anticipate the next hill!

Like Eaton, Volvo is pushing this automated tranny hard, foresaking their own Mack triple countershaft manual, despite it being reputedly the world’s highest capacity truck tranny. This marketplace battle of the trannies had caused much consternation amongst the gearheads and sparked heated debate over at forums like http://www.bigmacktrucks.com . Mack fans have berated both Volvo’s “one countershaft short” tranny as well as Eaton’s creep challenged offering. Before the jury of the used truck market, the Eaton is such an albatros that Eaton has had to offer an extended warranty to move them, and Volvo’s automated tranny is too new to have really tested that used truck marketplace.

Which after Eaton’s missteps with automated manuals and half century of success with twin countershafts, makes one wonder why a smart company like Volvo would stake it’s future in america on a transmission with the worst features of both?

Bear with me, their may be a method to Volvo’s madness. Note how Volvo is promoting their automated trannies with a high torque low RPM engine that can lug down to the vicinity of 1000 RPM before downshifting. Note also how Volvo is promoting this powertrain combo for flat to rolling interstate highway use with engines in the 400+ HP range at 80,000 pounds weight or less? With 400+ horsepower at the average dry van trailer combination weight of 60,000 pounds, Volvo’s big rig will climb a 3% grade at 50 MPH or so. Grades of over 3% are rare on the interstate system, anything steeper requires a truck lane. And 50 MPH, even with the long gearing Volvo is promoting in their powertrain package, is still just above the point where Volvo’s automated tranny will make it’s first downshift out of direct drive top gear.

Now remember my treatise about the advantages of two or more countershafts a few paragraphs back? Well, doesn’t apply in direct drive when the torque goes straight through the tranny and all those bearings and such are just along for the ride. Even if a downshift is required, the first downshift will be in the two speed splitter in Volvo’s 3 speed main ‘box times 2 speed range ‘box times 2 speed splitter ‘box tranny. And those hardest working splitter gears and bearings can be oversized to handle the extra work they might see.

Thus the Mack or Volvo truck with Volvo’s automated manual sold to a trucking company that will seldom fully load it and pretty much just cruise the interstate will probably give Volvo little grief within Volvo’s 750,000 mile warranty. But let UPS assign that now million mile truck ten years from now to battling through city traffic that rarely allows the use of top gear, and all bets are off. And how about the second owner of that freeway cruising Volvo with the big sleeper, running it from field or gravel pit to elevator or construction site on roads and through towns that are narrow, crooked, hilly, and often not even paved… Wonder how much it costs to rebuild an automated Volvo tranny?

To be honest, I don’t know- From what I hear there are no parts available, only new complete trannies, no doubt at heart attack inspiring prices. Right now darn near half of Volvo and Mack’s on highway trucks are being sold with Volvo’s automated tranny… Volvo, you might expect a big drop in sales in about 5 years!

 

 

 

 

 

 

 

 

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