Automatics
Freightliner's Summer Test Program hits the highways with a broad offering of automatic transmissions to tempt the marketplace.
Steve Sturgess
Senior Editor
Tracking the hidden problems in drivetrain spec'ing is one of the most important reasons truck manufacturers real-world test their products. To this end, Freightliner LLC goes on the road every summer with a two-week engineering Summer Test Program. This year, a 10-truck convoy hit the road with the emphasis fairly and squarely on the latest automatic and two-pedal automated heavy-duty transmissions - with Freightliner recognizing a trend of spec'ing user-friendly transmissions at the heavier end of the market.
Heavy Duty Trucking took a few days out to see a stretch of the on-highway mileage as well as the high-altitude testing over Colorado's Loveland Pass.
In all, Freightliner's Vehicle Performance Group had - with the marketing group - pulled together nine test trucks with widely different specs. The 10th in the convoy was a highly customized ex-prototype Coronado as the "tool truck."
The Portland, Ore., -based test group had prepared the trucks - most built specially for the grueling testing - and instrumented the vehicles with sensors and recorders. Some of the trucks were recording up to 100 channels of electronic data. Additionally, temperature strips that record underhood and component surface conditions were recorded daily. And available data was also collected from engine ECMs on an ongoing basis.
This data is analyzed and compiled into reports over a four- to six-week period when the group, under the watchful eye of Ramin Younessi, general manager and chief engineer of Freightliner's testing and prototype operations, returns to the group's base at the test and engineering center in Portland.
The Summer Test is an annual ritual designed to stress the trucks and components. It originates in Portland, heads southeast through Idaho to Rock Springs, Wyo., where a small group of journalists caught up with convoy. From there the route heads up into the mountains of Colorado to overnight beside the Eisenhower Tunnel on I-70. Several days of testing on the long grades follow, here and up over the 13,000-foot Loveland Pass, which is a tough pull for a loaded truck and even tougher downgrade of up to 8% grades.
From there the convoy - without us, unfortunately - heads to Laughlin, Nev., for a series of hot weather tests in and around Death Valley before heading home to Portland.
On hand, we motor-noters (four in all including Jim Park, who's editor of our Canadian sister publication HighwayStar and myself as drivers) had a terrific assortment of powertrains to evaluate. Under the Sterling brand there was an Acterra 2-axle with Mercedes-Benz 900 series power and an M-B AGS2 auto trans; an Acterra with a Cummins ISC and an Allison auto; and a Sterling L-Line daycab tandem with Mercedes-Benz MBE 4000 power and a Meritor FreedomLine automated transmission. The Freightliner brand was represented by a Business Class M2 112 (just launched) with MBE 4000 and a prototype Allison XD auto, an M2 with 900 MBE power and a prototype Allison MD. Moving up to the big trucks, a Columbia with a Detroit Series 60 and next generation Eaton Ultrashift and a Century ST with bigger power Series 60 and an Ultrashift. Manual transmissions featured in the two Western Stars: One was the cool LowMax EX with a Series 60 and an Eaton Lightning transmission, the other was a King of the Hill; a 4900 FA with a Cat 625 and an Eaton Fuller 18-speed.
On The Road
The full summer test exercise extends over a two-week period with Freightliner engineers from various disciplines joined by vendor engineers keen to see how their products fare in the testing. The journalists had only a couple of days' snapshot, but there was still time to get in as many trucks as we desired. Day One was a relatively easy-driving 450 miles from the Little America on I-80 at Rock Springs to Frisco, which is just to the west of the Eisenhower Memorial Tunnel. We had five stops, allowing drivers to evaluate six different vehicles. Day Two saw us with a relatively high-altitude start up in Frisco, and a climb up to the Eisenhower again to a staging area just to the west of the tunnel entrance where the old highway - Route 6 - starts up and over the Loveland Pass.
The rest of the day was given over to driving trucks up to the 13,000-foot-plus summit and leaning into the engine retarders all the way down the 8% grade into Dillon, only to get back on I-70 and grind all the way back up the hill and through the tunnel to the staging area. That day I drove three trucks over this testing route which, ironically, is where all the dangerous hazmat trucks must go because they aren't allowed through the tunnel.
Day One
First off I wanted to refamiliarize myself with the Meritor FreedomLine transmission. This is a 12-speed automated transmission based on the ZF AS Tronic from Germany. In its summer test version, it was running the latest level of software that has a lot of decision-making capability. This software should be in current FreedomLines as you read this.
I remembered from a much earlier drive that I was impressed by the transmission's response to throttle, upshifting early at light throttle much as any practiced, fuel-saving driver would. The transmission can also skip shift if it deems conditions allow, and will downshift early to provide optimal retarding power on a downgrade. There's also a manual override, but why would you with such an intelligent box? The latest FreedomLine in the Acterra was at least as good as that early drive, matching up well to the Mercedes-Benz six-cylinder, 12-liter engine. Of course, it didn't have a lot to do, shifting up through the gears as we pulled away from Little America, then downshifting again some 80 miles later, but the shifts were fast, smooth and the truck was easy to handle.
That gave me a baseline for the Eaton Ultrashift. I have not been particularly enamored of the early AutoShift, three-pedal Eaton automatics because they tended to be a little slow to shift and would drive the rpms up much higher than ever I would before shifting. But with the latest Ultrashift 10-speed, you can forget all about that. The unit in the Freightliner Columbia - described as a next-generation transmission - was a marvel, shifting nice and early, and very responsive to the throttle pedal when a kick-down was needed. It also picked up engine speed for the Jake brake and did everything as well as the Meritor transmission. And the Detroit Diesel with 455 hp and 1,650 lbs.-ft. torque from the 12.7 liter engine hauled the loaded truck very well.
After these automated transmissions, it was time to jam some gears with the Eaton Fuller Roadranger 18-speed and get my first drive of the 625-hp, 2,050 lbs.-ft. C15 Cat. As anticipated, this was pure joy. With so much torque, there's no need to run through the lower splits, but the pleasure of the combination of big Cat and multispeed transmission is to use the short splits in the upper range, just using marginal rpms when accelerating up through each split, rolling off only a couple hundred revs between gears. As you might expect, with so much torque on hand, this Western Star didn't need any gearshifting on the grades on I-80 as we headed toward Cheyenne, Wyo.
At the next driver change it was time to renew acquaintances with the Lightening transmission, up behind a 515-hp, 14-liter Series 60 in the Western Star LowMax. This is the latest twin countershaft 10-speed Eaton transmission that has a five gear lever position and lo/hi splitter to get the 10 speeds, with an automated shift on the top two. It also has a measure of intelligence so that, if a driver hesitates a little, the transmission will talk to the engine to bring the gears to synchronous speed to ease the shift through.
The Lightning is a sweet transmission to drive, though there's no question it takes a little learning. On Day One it all went well enough. With the bigger Series 60 running an experimental high-torque 1,850 lbs.-ft. rating, it was easy to get the truck rolling at idle, then tickle the throttle, back out and split up to second. Next is a lever shift, so the splitter was back down and a lever shift forward and to the center of the gate picked up third gear. The Lightning is progressive, with an automated range-change as the lever passes through the third to the fourth position. Once in the fifth lever position at around 35 mph, there's no more shifting, with the automated top two taking over. It is actually pretty slick, though I was to learn the next day when driving this truck in the mountains that I was not as clever as I thought.
For the moment, though, I parked the LowMax and the lunch break just outside of Cheyenne. When next we saddled up, we were heading south. This time I had selected a true automatic, the Allison XD prototype in the recently introduced 112-in BBC Business Class M2, This neat little unit was set up as a construction chassis with the 46,000-pound TuffTrac tandem suspension and a 20,000-pound front end. Under the hood was an MBE 4000.
This little unit is the tough little red dump truck sort of chassis, and the Allison is a great match for the sort of municipal and construction applications this chassis would find itself. Based on recent drives, the Allison gives great throttle control off-highway and is really useful when hauling out of a quarry, when the powershift transmission can pick up gears without breaking torque. And on the highway, as shown in this Summer Test, the torque converter and the fast, positive shifts make for spirited performance. This little M2 112 was often the chase truck when the convoy started to get out of shape because it would get up and go so well.
The last drive of the day was in the diminutive Acterra two-axle truck with the Mercedes-Benz AGS 2 automated 6-speed. Like all the autos in this group, this was a two-pedal transmission with an easy take off. It, too, shifted nicely, would kick down when needed and also would maximize the retarding power of the engine brake in the Mercedes Benz 906 engine. Despite the relatively small size of the M-B engine, the little Acterra acquitted itself well, especially over this last section of the route, which was getting into the mountains on the climb to the overnight stop in Frisco.
The Acterra has been slower to get the M-B auto 6-speed because the transmission was designed to be used in a chassis with multiplexed wiring, which the Business Class M2 has, but the Acterra does not. So a number of modifications to the transmission were needed to get it to talk to the engine, which it now does to good effect. So the AGS 2 will shortly be offered in the Acterra as it is in the M2.
Day Two
An early morning briefing and a quick scoot around the trucks to check the instrumentation were set against a background of smoke and knock from high altitude engine starts. Then we moved to the staging area just off I-70 at the eastern end of the Eisenhower Tunnel. Taking the clockwise rotation on Route 6, we were faced with a short, sharp climb for two miles up from 10,000 to 13,000 feet. From the summit it was a longer and demanding downgrade for six miles through a number of switchbacks to finish up in Dillon and rejoin I-70 for the hard pull back up to and through the Eisenhower to the staging area again.
I had not driven the old Loveland Pass before and was promised a tough drive but, as it turned out, the Ortega Highway over the coastal mountains just down the road from where I live, is a whole lot tighter. Erring on the side of caution, I opted for an automated transmission so I could concentrate on the driving - emphasizing one of the big pluses of a two-pedal transmission setup. The first choice for me was the Century Class ST with its 515 hp Detroit and Eaton Ultrashift 10-speed. This proved very effective over the pass, making the climb a simple task of keeping the truck in lane around the switchbacks. On the downward grade, selecting the manual position on the clever SmartShift steering column control allowed for excellent control, relying on sixth gear and full Jake Brake to roll downhill without using the service brakes. As the grade settled out towards the lake and town of Dillon, moving back to auto mode made the driving a breeze.
The SmartShift control is Freightliner's standard interface with all the automated transmissions, whether they were the AGS on the lighter Acterra, the FreedomLine or the Ultrashift. Using this common control paddle made the driving of each automated box easier and, to an extent, hid the manufacturer from the driver. The control's functionality is completely intuitive and the transmission response to driver commands - when needed - were always immediate.
After finding the way up and down the mountain, I next took the Star with the six-and-a-quarter Cat and 18 speed to have a play with the gears. It was a lot of fun, especially blowing the doors off the other trucks on the grade up to the tunnel.
The final truck of the day was the LowMax with the Lightening. Starting out I was just fine, but then I got stuck on a grade and completely blew it. I was having a hard time picking up gears with the speed on the grade decaying faster between shifts than the speed of the 515 hp Series 60. Instead of thinking it through, I revved out to 2,000 before going for the next gear. That worked for the 1-2 split, but for the lever shift 2-3 the LowMax just rolled to a halt before I could get it done. Then, thinking it through, I used the absolute minimum rpms to get rolling and popped the shift through to pick up the next gear at just above idle speed.
This I eventually did - and got going quite satisfactorily - but not before a call on the radio asking what was the trouble. My riding companion said I had been "struck by Lightning."
There ended a memorable two days of driving a wide selection of powertrain combinations. The lasting impression was the driving ease, safety and comfort afforded by the two-pedal transmissions, whoever the supplier happened to be. Again, that SmartShift hid the component brand and to be honest, the functionality of the different transmissions meant it was virtually impossible to tell which transmission was doing the shifting for me.
As the engine/transmission communications control and software have become increasingly sophisticated, the automated - and torque-converter automatics where appropriate - will fast become the transmission of choice for fleets looking to recruit and retain a new generation of drivers. They will gain not only a much broader driver pool, but users of these transmissions will likely see less driveline repair, likely an improvement in fuel economy and a boost to safety with drivers getting on with the job of managing the truck instead of the transmission.
But that's not to say the 18-speed manual is dead. Not by a long shot. It's just too much fun to drive and too many good drivers will continue to prefer jammin' those gears to give up without a fight.
