Aiming to Please

There’s something satisfying about a truck that’s just plain built to work. No pretence, just ability. And so it was with the Kenworth T300 I spent a day driving last month. I was aiming to check out refinements made to the Spicer AMT-7 transmission which I first drove at its launch two years back. But somehow I’d never tried the T300 on the road, so I was pleased that Transmission Technologies Corp. (TTC) had chosen one as its demo truck.

Neither the Kenworth nor the AMT-7 are entirely new to the market. The very solid class-7 Kenworth was introduced way back in 1994, the transmission in 1998. TTC, for those who’ve forgotten, is the Mexican company that bought Dana’s Spicer transmission business a few years ago. Dana has part ownership of the firm, which had been making transmissions and/or components for Spicer for many years. Ironically, it also makes components for some competing transmission manufacturers. Its other claim to fame is that it makes many light-duty gearboxes, including the Tremec six-speeds found in the Dodge Viper sports car. Its sales and engineering offices remain in Michigan and Ohio; the main factories-ISO-registered-are located in Mexico.

THE TRUCK

The T300 is quite obviously based on the aluminum-and-fibreglass cab of its big brother, the T600, which means it’s roomy and tall, though not hard to climb into. Reasonably light, it uses huck-bolt construction instead of rivets.

The T300 is available as a straight truck with GVWs in the 30,000-35,000-pound range and as a tractor (70,000-pound GCWR) with single or tandem rears, so it’s often seen hauling expedited freight or doing local P&D work. Wheelbase options range from 150 to 280 inches, allowing bodies up to 28 feet. Cummins ISB and ISC engines, along with Caterpillar’s 3126, are available with ratings from 190 to 300 horsepower. Allison automatic transmissions are optional. So is the AMT-7, though not yet as a databook option, and at this point only if you were to order 50 trucks or so.

The test truck, sitting on a 189-inch wheelbase, had a 250-horse Cummins ISB (660 pound feet of torque at 1600 rpm), Eaton 23,000-pound single axle with 5.29:1 ratio, Hendrickson air suspension, Eaton ES brakes, and Michelin 22.5-inch rubber.

My first impression was that this is a big “small” truck, a real truck, though its 50-degree wheel cut up front gives it commendable manoeuvrability. That’s further helped by excellent forward sight lines across the sharply sloped hood. Vision to the right side is aided by the standard “Daylite” lower door window.

All of those features contributed to a comfortable feeling of security in downtown Toronto and on the expressways leading to it. With a light load, the T300’s ride wasn’t the best I’ve experienced, nor was it especially quiet, but it did handle in a way that inspired confidence. On the highway, it tracked well. Overall, it seemed very tough, very capable.

THE TRANSMISSION

Using the familiar Spicer mechanical seven-speed box as the base for the AMT-7, TTC added electronic controls to manage shifting, and then went one better-they took the clutch away, or at least the clutch pedal. It’s the only mid-range mechanical transmission with clutchless automated starts and stops, so it’s ideal for applications in which the person at the wheel is not a seasoned driver. You just select “Drive” and off you go.

The AMT-7’s microprocessor-driven control system continually gathers and evaluates operational inputs such as engine rpm, driveshaft speed, gear position, and brakes, communicating via a J1939 data link. If it figures a gear change is needed, the computer tells the AMT-7’s hydraulic system to engage the clutch, shift to the proper gear, and disengage the clutch. In practice, it does all this smoothly, including downshifts. If the truck has an engine brake, it will be used to help dethrottle the motor prior to a shift, but it’s not required.

As you slow the truck down, it will drop gears one at a time, though in a panic stop it may skip-shift. TTC marketing manager Jim Averill says it will find the right gear within 1.5 seconds if you jam on the binders in a hurry and then want to go again, and that matches my experience.

Programming shift points is a simple process that only requires a TTC-supplied CD that can be used with any computer running Windows 95 or later. You might want more aggressive shifting for off-road applications, for example. This could come in handy at re-sale time.

One of the key refinements to the transmission has to do with starting and stopping. In its earliest versions, the AMT-7 would stand still until the driver touched the throttle. After observations from drivers that it would sometimes start off jerkily, which made backing into a loading dock difficult, TTC engineers changed things so that the truck would be launched with the release of the brake.

This has indeed made for smoother starts, though it takes a little practice to get it right consistently.

Among the transmission’s features is something called Launch Assist, which prevents the vehicle from rolling once it’s reached a stop. It also has a “Hold” selector which will leave you in a particular gear until you want otherwise.

The Kenworth had a very ordinary car-like shifter on the floor, but there’s no mechanical link so the shift control can be just about anywhere-pushbuttons on the dash, Freightliner’s steering-column-mounted SmartShift, or whatever. TTC is leaving that decision to the truck makers.

Compared to an Allison automatic, TTC’s Averill expects the AMT-7 to be 15% to 20% less expensive, and it should bring some fuel economy benefits as well. “We have seen as much as a 20% improvement in some applications,” he says. On the maintenance front, fleets already using the Spicer manual seven-speed will be familiar with its workings and may well be able to do repairs in-house. The clutch (a 14-inch Solo ceramic in the test rig) is self-adjusting, and since it’s fully automated, you won’t have to worry about drivers burning it up. The rest of the driveline should have an easier life as well.

You can get an AMT-7 in two models: the AS056-7B rated at 560 pound feet and the AS066-7B at 660. So far, TTC’s development work has been with Caterpillar and Cummins only, but the transmission is not yet broadly available in OEM terms. It’s currently available as a special-order option from GM and Ford, with full release from those two plus Kenworth, Freightliner, and Sterling expected in the first quarter of 2001.

Keep your eye on TTC. Averill says the company is busy working on the next generation of automation that will be applied to everything from medium-duty five-speeds all the way up to a heavy-duty 18 speed.

And one of those technologies, maybe a little further out, will bring us a transmission with no gears at all. More on that one later.