Lightweight is the holy grail of most bulk haulers, who can often convert a pound cut from vehicle weight directly to payload, be it grain, gravel, chemicals and food-grade liquids, or building materials. Kenworth recently showed off a T680 sleeper-cab tractor that scaled at 14,200 pounds (not counting fuel), according to hosts at a ride-and-drive event staged at the KW plant in Chillicothe, Ohio. 

As with any lightweight specification, saving weight comes from the careful choice of components. Kenworth’s list, and estimated weight savings, include:

• Standard aluminum cab, about 400 pounds less than a comparable steel cabin.

• A 52-inch mid-rise aluminum sleeper compartment, 500 pounds less than a longer and taller unit. The lower height is a better match for the tank and flatbed trailers often operated by weight-conscious fleets. Extra length adds pounds, not only in the sleeper structure but also in the longer main-frame rails, but this modest length makes for very livable accommodations.

• Paccar’s MX-11 diesel, about 400 pounds under an MX-13 or Cummins ISX12. Thanks to advanced electronic controls and combustion technology, the smaller MX can make more power and torque than size alone would suggest. This one had the top rating of 430 hp and 1,550 lb-ft.

• Eaton Advantage 10-speed manual transmission, 70 pounds less than an automated version.

• Meritor FueLite 6x2 tandem, saving about 300 pounds vs. a twin-screw and can save up to 3% in fuel. The partially liftable dead axle can transfer weight to the drive axle, making traction more than adequate under most circumstances.

• Wide-base single tires on aluminum wheels, saving 350 to 400 pounds over dual wheels.

• A 100-gallon aluminum fuel tank instead of higher capacity; diesel weighs about 7.5 pounds per gallon. A hundred gallons is still enough for a day’s running by one driver.

It doesn’t appear that the lightweight parts will result in any loss of reliability. This Kenworth has a strong feel and it, and the chosen components, have a history — or at least the potential — of being rugged. The Eaton manual transmission, for example, has almost nothing to go wrong – no electronics or servos or any other form of automation to fail. I did have occasional difficulty with a sticky shift lever during up- or downshifting, just as I’ve had with previous new-generation KWs. Is it me, as company reps have suggested? (Maybe, but at least one other editor, a former owner-operator, had similar problems.) Or was it the gearboxes’ modern, tightly contoured teeth and utter newness — that is, simply not being broken in?

Otherwise this tractor presented a pleasurable driving experience. It rode and handled well, and aside from exhibiting an overall sense of quality and tightness, the cab was roomy with great visibility in all directions. It was almost uncannily quiet while underway, an attribute of other T680s and T880s I’ve driven since their introduction several years ago. That this one was a lightweight adds to its utility and value.