Third Time’s the Charm

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Perfection is a relative thing. I’m sure someone out there will discover a glitch in this transmission, or find it lacking some subtle performance attribute, but as product evolution goes, this third iteration of Eaton’s automated manual transmission line comes as close to perfect as one would dare to hope.

Bear in mind, these automated manual transmissions are essentially the same boxes full of gears and shafts as their manual counterparts.

They are differentiated only by electric actuators, electronic controllers — and a set of shift algorithms bestowed upon them by engineers who really did their homework. At the end of the day, the marvel isn’t so much the machine, but the thinking that went into it.

The engineering mandate was to build a range of transmissions suitable for any application with no compromises. A product for the most demanding environments emerged from the design studios first — vocational boxes with low-low gearing. The high-performance construction and highway applications came next, with the docile linehaul version bringing up the rear — equally robust and no less sophisticated, just simpler to program.

Not accidentally — given the UltraShift’s balky and unpredictable centrifugal clutch — work on the UltraShift PLUS began with the clutch. This one is a two-plate ceramic type that opens and closes on almost every shift. It sports two pedals, but functions like a three-pedal set up. The ‘third pedal’ is located inside the bell housing.

The electronic clutch actuator (ECA) can feather the clutch like a driver while backing under or docking a trailer, and on launch depending on the load and grade. It also features an inertia brake (which Eaton describes as a clutch brake on steroids), which can complete difficult shifts in a half to a quarter of the time.

In the lower gears, bias is toward opening the clutch, but it may float-shift the upper gears, depending on its read of driver demand.

Nuts and bolts aside, the only differentiating features across the three series of transmissions is software. Each has specific shift algorithms tailored to the application. A certain standard profile will please 80 to 90 percent of the intended market, but if you have some unique desire to make a linehaul unit shift like a dump truck, you could change its disposition in about two minutes by flashing the ECM. 

Gone from the LAS is the grabby centrifugal clutch.
The new two-plate design feathers engagement
like a driver would use a clutch pedal.

The other significant performance enhancing addition to the UltraShift PLUS is a grade sensor. In addition to sensing vehicle weight and therefore power demand plus driver demand vis-a-vis throttle position and application pressure, it can sense the grade it’s on and plan shifts accordingly.

It will, for example, make slow lingering skip shifts on a downhill grade or fire the inertia brake on an uphill grade for lightning fast upshifts, as required.

The electronic control of the shifting sequence is much more refined than in previous models, and there’s more processing power in the transmission’s ECM, giving it the ability to make shifting decisions that previously only the driver could gauge. The difference is, the transmission is fast enough to actually carry them out.

One other brilliant new feature is the hill-start aid, intended to prevent roll back when starting on a grade — up or down. It uses the vehicle’s ABS system to hold and then release the brakes, based again on throttle position.

The brakes are applied normally with the foot valve, but the ABS system takes a cue from the transmission ECM and holds the brake on between the time the brake pedal is released and the throttle is applied.

Electronically controlled clutch engagement ensures a smooth launch, while the gradual release of the ABS-controlled brakes prevents roll-back. The brakes will remain applied for no more than three seconds after release, discouraging drivers from using this feature as a parking brake.


You could measure how well these transmissions serve their purpose in two ways. First, by comparing them to the alternatives, and by how well they do what the best drivers could do under the same conditions. In either case, I’d argue that the UltraShift PLUS leaves the competition in the dust.

I doubt many drivers would have the guts to try launching 126,000 lb on a 15-percent grade. I suggested that stunt while driving the heavy-haul test truck, a Western Star powered by a 600-hp Cat C15 with an 18-speed VXP.

Jon Steeby, one of the chief engineers on the UltraShift project, was in the passenger seat. He shrugged his shoulders and said "Go for it," noting that what I was proposing was "beyond the performance envelope of the transmission."

I pulled the truck and centipede trailer fully onto the measured 15-percent grade at Eaton’s proving grounds in Marshall, Mich., stopped, made a stiff brake application to set the hill-start aid, and then put my foot into it. The UltraShift PLUS VXP not only launched smoothly but without so much as a grunt grabbed four more gears as it climbed to the crest of the hill.

Earlier in the day, the VMS vocational low-low transmission walked me up a 25-percent grade on soft earth. I set the diff locks and power divider on the International 5500i mixer loaded to 48,600 lb and let it creep up the hill, as if pouring a curb as it went.

Absolutely amazing.

You don’t see many 25-percent grades in the civilized world, but on job sites — coming up out of a pit, or on a logging road — they’re not uncommon. 

The UltraShift PLUS grabs gears like nobody’s
business on the short steep off-road pulls.

Later in the day, I backed down a short 10-percent grade in what was the most eye-opening product comparison ever, in my opinion.

Eaton had prepared two nearly identical four-axle Kenworth T800 dumps loaded to 82,200 lb. Both had 475/1650 Cat power. One had an UltraShift PLUS 18-speed VXP, the other, an Allison 4500 RDS torque-converted six-speed automatic.

We made two passes of the course — a twisting, turning trail through a patch of woods on the proving grounds, with soft earth, and steep grades — in each truck.

The Allison has this urge to pull forward even at idle, and requires a stiff brake application to keep it still. That was exacerbated when descending a grade.

The VMX, on the other hand, simply downshifted and applied the Cat’s engine brake. I needed to make no brake application at all. At low speed, frequent brake applications were required with the automatic. Merely taking my foot off the throttle worked most of the time with the VMX.

We also crept backwards down a 10-percent grade at 1 mph to test the hill-holding capability of the transmissions. Accepted practice with the automatic, I’ve been told, is to place it in the opposite gear for the descent to get the maximum retarding power — in this case, I had the transmission in drive while idling backwards down the grade. The engine stalled, leaving me without the benefit of power steering and needing to make a 50-psi brake application just to hold the thing in a controlled descent. The VMX stayed in low reverse, idling down the hill as if it was walking in the park.

In fairness to Allison, while its retarding ability cuts out at about 10 mph in 2nd gear, where the torque convertor unlocks, if it’s manually placed into 1st gear, the retarder will function down to about
3 mph — faster than we were travelling.

The off-road performance of the VMX is an impressive comeback for a transmission that had previously won very few converts in this tough-to-please sector.

Next, I hopped into a Volvo VN780 to check out the linehaul transmission. Fresh off my off-road adventures, the oval test track was downright anti-climactic. Still, the UltraShift PLUS LAS proved to be an exponential improvement over Eaton’s previous automated manuals.

The two-plate ECA-controlled clutch puts out to pasture the rorty-torty and unpredictable centrifugal clutch used in earlier versions. That one tends to grab, rather than engage smoothly, launching you back under a trailer or smashing you into a dock. With this one, the ECA takes its engagement cue from the throttle pedal position. So, a light feathering of the throttle, as a driver would previously do with the clutch pedal, modulates the engagement and smoothly urges the truck into motion. This was aptly proven during a routine hook-and-drop maneuver. The gentle ‘clink’ of the jaws locking shut was the final satisfying stroke.

The hill start was equally effective in this case, executing a very smooth start on the five- and eight-percent test grades. The Volvo D13 485 even managed two upshifts before the truck made level ground. In creep mode, the driver can idle through heavy traffic at slow speed using gear selection rather than throttle to maintain road speed.

To test the LAS’s gear-selection savvy, I placed it in drive while bobtailing and mashed on the throttle. It launched me from fourth gear, sensing I was bobtailing, then upshifted to seventh and a moment later to 10th. Each shift revved to about 1,700 rpm. In a subsequent run, going much easier on the throttle, I launched again in fourth, but skipped only a single gear each time, and at a much lower 1,200-to-1,300 rpm.

It responded much the same way under load, shifting at lower rpm with a lighter, less urgent throttle application, and at higher revs when my right foot demanded quicker acceleration.

In case it’s not abundantly clear, the UltraShift PLUS has winner written all over it. It does everything a very skilled driver could do — and then some — and it manages tasks that might distract any driver under demanding circumstances.

I’ll be the first to confess — being a dinosaur of sorts who likes to shift gears because getting it right feels good — that automated transmissions leave me a little cold, but I really like what Eaton has done here.

This one is a quantum leap in function and functionality from Eaton’s previous versions, and the competition’s too. It’s the other guys’ turn to play catch up now. 

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Jim Park was a CDL driver and owner-operator from 1978 until 1998, when he began his second career as a trucking journalist. During that career transition, he hosted an overnight radio show on a Hamilton, Ontario radio station and later went on to anchor the trucking news in SiriusXM's Road Dog Trucking channel. Jim is a regular contributor to Today's Trucking and, and produces Focus On and On the Spot test drive videos.

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