The gorgeous Kenworth W900L I’d been driving all day was great, and there was no snarling traffic to deal with on the lesser highways of north-central Michigan. But at the end of the day I was uncomfortable.
It was the transmission. The darned thing was just so good that I thought I hadn’t worked hard enough to make it burp or blush or otherwise lose its perfect composure.
I’m talking about the new ZF Meritor FreedomLine, North America’s first heavy-duty transmission to lose its clutch pedal without losing its clutch – and without adding a torque converter. It actually does have an ordinary clutch but it’s
operated automatically by way of pneumatic and of course electronic controls.
And there really is no clutch pedal. Unlike competing automated mechanical
gearboxes, and ZF Meritor’s own SureShift, both starting and stopping are accomplished with the throttle and brake pedals alone.
Developed by ZF Friedrichshafen, Europe’s largest transmission maker, and the ZF Meritor joint venture, the FreedomLine is that partnership’s first product. In Europe it’s dubbed the ASTronic, but its first generation has been available exclusively in Iveco trucks for a couple of years as the EuroTronic – also clutchless, but the driver initiates shifts by moving the lever backwards or
forwards. With the addition of full automation and helical-cut gears, the
FreedomLine will be available here late this year, likely in Freightliner, Kenworth
and Peterbilt trucks first.
The FreedomLine is a familiar twin-countershaft design with splitter/range-change box, integrated with the clutch housing which has an air cylinder at the bottom to actuate the release fork. Unlike other European transmissions, this is a constant-mesh, non-synchronized gearbox, though there are synchronizers on
the range-change and splitter.
It was designed from the start for automation, not based on an existing manual
with electronic controls overlaid. It was also created for both North American and
European duty cycles.
Features unique to North America include the input and output shafts and the 12-volt power of the electronic control unit, connected to the engine via an SAE J-1939 link. The electronic interface is also ours alone, which allows for J-1587
diagnostics and flexibility in the driver interface. In standard trim it will use the
existing ZF Meritor SureShift joystick mounted to the seat, though other mountings are possible like Freightliner’s SmartShift.
The FreedomLine is available in 12- and 16-speed versions, direct or overdrive in each case, with torque capacities from 1450 to 1850 lb ft. The 12-speed’s overdrive ratio is 0.78:1, while the 16-speed’s is a rather mild 0.83. Steps
between gears in the 16-speed are between 18% and 21%. In the 12-speed they’re mostly 29%. The 12-speed weighs in at 550 lb, 594 for the 16, quite a bit less than its rivals.
The dry clutch is a mechanical single-plate type with an organic facing, which
explains the very ‘soft’ startoffs I experienced. It’s a 430mm or 17-in. clutch, and
you have no choice here, which may bother some folks and probably shouldn’t.
Other automated mechanical transmissions also demand certain clutches, though
the real issue here may be the single-plate matter. Will it hold up?
ZF Meritor director of sales and marketing Charlie Allen says ‘no sweat,’ pointing
to European experience. Along with lots of testing, zillions of real miles have been run in Iveco trucks with the EuroTronic, and they’ve found clutch life has actually been extended by two or three times compared with manual gearboxes.
“We don’t think it’s an issue,” says Allen, who rode shotgun on my test drive.
The FreedomLine doesn’t float-shift through the gears the way an experienced driver can do. It uses the clutch on each shift. It commands the engine to reach synchronous but doesn’t use the engine brake to help out; rather it retards the spinning of the transmission itself using an inertia brake on the driver-side countershaft. A different approach from what we’re used to. But does it work?
You bet. This transmission takes automation technology to a new level with
consummate skill. It actually seems to know what you’re thinking.
The FreedomLine reacted so quickly and accurately to changing road and throttle
conditions that it seemed to have a mind of its own. Its response never seemed to be the same, as it skipped gears in one set of circumstances but not in another, even though they were more or less similar. Obviously, it had detected even minor differences in engine loading. Engineering types call this ‘adaptive’ technology, meaning exactly what it says – something that adapts to new situations on the fly.
On the Road
That adaptive skill was obvious right from the start of my test in Troy, Mi., where Meritor is headquartered. Yes, Michigan, and no great hulking hills. But lots of traffic at the start and then lots of shifting as I tried to stay off the interstates as much as possible. Charlie and I drove north looking for a grade or two.
Getting the big Kenworth rolling in the first place was no sweat with the 16-speed overdrive version of the FreedomLine. The truck had a prototype gear selector, similar to SureShift, mounted to the side of the seat – with a rotary switch offering a choice of R, N, or D and a joystick to shift up or down, with a ‘function button’ for
going to fully manual operation. To shift manually, you bump the stick forward to
upshift, back to downshift. You can also make it skip-shift. The clutch is held until you feed it some fuel, and then you get a smooth takeoff, whether your foot’s to the floor or not. No muss, no fuss, no jerky motions. Unlike a car, there’s no ‘creep’.
You just select ‘D’, apply some throttle, and go.
It runs a diagnostic test automatically on startup. Fault codes show on a small
dashboard display, which also tells you which gear you’re in. The test truck had the Cummins RoadRelay display, so we could keep track of engine load and other stuff as well.
We grossed just 73,000 lb, and the transmission knew it had a 600-horse Cummins ISX engine with 1850 lb ft of grunt, so it launched the KW in fourth gear pretty regularly. You can over-ride that choice if you want.
On the flat, left in automatic and with light throttle, it frequently shifted right to sixth, on to seventh, and then skipped all the way to 11th. Sometimes it went from fourth to fifth and then straight to eighth. Sometimes it would skip from 12th to 14th, sometimes not. It shifted more or less progressively, letting the engine run a little further into the tach if I ‘asked’ for more revs. Most shifts were done at around 1500 rpm.
Downshifts were similarly unpredictable, and were not done gear by gear by gear,
rather by appropriate skip-shifts. One of my driving habits, maybe a bad one, is
not to downshift through several gears as I approach a corner or an exit ramp.
Rather, I’ll drop a cog or two and then let the engine die in gear, hit the clutch as it starts to lug, and then find the next gear I need to accelerate out of the turn. I may have left 11th and then need 6th, for example, and that’s exactly what the
FreedomLine did – except rather more effectively than I sometimes do! As soon as I throttled up, it found the right gear instantly and off we went.
It obviously adapted to me just as much as to load and road, which should inspire
It’s also quiet, thanks to those helical-cut gears. In fact it’s generally very
unobtrusive. All shifts were made smoothly, even at full throttle (you don’t have to
lift your right foot). Starts were smooth too, as I’ve said, but you do have to
remember that there’s a clutch when you’re on a grade. The truck will roll back just like a standard transmission if you don’t use the foot brake or the spike.
Finally, A Hill
Michigan doesn’t have a lot of hills, so the bridge over the Zilwaukee River on I-75
was the best we could find, a fairly long grade in the 6% range. With approach
roads on either side, it was easy to make several runs trying different strategies –
sometimes from a dead stop on the grade, maybe just vaguely rolling with the engine lugging, sometimes manually, other times on auto pilot. On a few runs I put my foot right to the floor and left it there, on others I was more gentle.
Regardless, the transmission didn’t care, and in every case – thanks largely to the
big engine – it even managed to skip at least a couple of the lower gears. On one automatic run from a dead stop with the dash display reading fourth gear at the base of the hill – and the RoadRelay showing 100% engine load all the way – it shifted to fifth, skipped to 8th, and then went gear by gear all the way to 16th. All shifts were made at about 1700 rpm except for the last one, where the electronics let the engine run out to 1950 rpm. Responding, I guess, to the fact that my right foot was still planted. It was probably also trying to ensure that it really could hold 16th, to avoid ‘hunting’ for a gear. In fact, it never once went hunting through the
whole day, which is pretty impressive.
Also impressive is the gearing in reverse. The deep reduction of the lower reverse ratio (13.07:1 in the 16-speed overdrive) allows for excellent control in backing under a trailer or up to a dock. You can even shift into reverse high.
I wish I could find something about the FreedomLine to question, but I can’t. It’s
that good. And I’m no longer feeling that I didn’t try hard enough to make it hiccup, because one of the few other people to have given it a proper test came away with the same feeling. He’s an engineer and expert driver, not associated with
ZFMeritor, and he played hard with the FreedomLine on a 16% grade. On that devilish hill, he tells me, it once chose the wrong gear for a downshift – but corrected itself instantly and never did it again.
The transmission’s behavior shows just how much work went into its original design and subsequent development. It’ll cost more than a manual, but drivers will gain a lot – like the ability to concentrate on the road with a lot less stress. There
should be a small fuel-economy advantage as well, maybe as much as 5% in
It’ll be mighty interesting to see where this technology takes us next. In the
meantime, I’d guess that it will win converts from amongst those who say they
wouldn’t buy an automatic. Sooner or later, automation will not be a minority