Third Time's the Charm

Perfection is a relative thing, and I'm sure someone out there will discover a glitch in this new transmission.

But as product evolution goes, this third iteration of Eaton's automated manual transmission line comes as close to perfect as I'd dare to hope. Bear in mind, these automated gearboxes are essentially the same assembly of gears and shafts as their very well known manual counterparts, 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 came 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. This is the first time Eaton has produced an automated box for tough vocational use.

Not accidentally - given the previous UltraShift's balky and unpredictable centrifugal clutch - work on the UltraShift Plus began with the clutch. It's a two-plate ceramic affair that opens and closes on almost every shift. It sports two pedals, but functions like a three-pedal set up.

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 feature across the three series of transmissions is software. Each has specific shift algorithms tailored to the application. And 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.

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 by way of reading throttle position, it can also 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 rollback 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 rollback.

The brakes remain applied for no more than three seconds after release, discouraging drivers from using this feature as a parking brake.

On- and Off-road
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 wins. I doubt many drivers would have the guts to try launching 126,000 lb on a 15% 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 about to do was considered "beyond the performance envelope of the transmission."

I pulled the truck and centipede trailer fully onto the measured 15% grade at Eaton's proving grounds in Marshall, Mich., stopped, made a stiff brake application to set the hill-start aid, then put my foot into it. The VXP not only launched the truck smoothly but without so much as a grunt it 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% 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. Absolutely amazing.

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

Later in the day, I backed down a short 10% grade in each of 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, turningtrail through a patch of woods on the proving grounds, with soft earth, and steep grades - in each truck.

Like any torque-converter automatic, the Allison required a stiff brake application to keep it still, more so 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 made a creeping backwards trip down a 10% grade to test hill-holding capability. The
VMX stayed in low reverse, idling down the hill as if it was walking in the park.

Next, I hopped into a Volvo VN780 tocheck out the linehaul transmission. The oval test track was downright anti-climactic but 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 unpredictable centrifugal clutch used in earlier versions.

That one tends to grab, rather than engage smoothly, but with this new one, the ECA takes its engagement cue from the throttle-pedal position. So, a light feathering of the throttle, as a driver would 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 aid was equally effective in this case, executing a very smooth start on the 5 and 8% 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 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 light, then upshifted to seventh and a moment later to tenth. Each shift revved to about 1700 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 1200-1300 rpm. It responded much the same way under load.

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