Bold styling on tractors with ‘L’ trim includes stainless steel grille bezels and chrome bumper. ‘LG’ styling is simpler.

Bold styling on tractors with ‘L’ trim includes stainless steel grille bezels and chrome bumper. ‘LG’ styling is simpler. 

Caterpillar is moving faster in expanding its line of Navistar-built Cat Trucks following the 2011 introduction of its original CT660 with a setback steer axle. Last fall brought the CT681, with a forward-set steer axle, and now we have the CT680, also with a forward-mounted front axle but a longer hood.

All are powered by diesels with “vocational-specific” ratings and drivetrain options. The new 680 is available as a truck and tractor in two exterior trim levels. Like the others, the 680 aims at vocational work, though its compelling appearance might cause a few guys to think about outfitting it for on-highway. 

Cat executives announced the new truck model in mid-May at their Tinaja Hills Demonstration Center southwest of Tucson, Ariz. The low-key presentation let the truck do most of the talking, and it proved eloquent.

However, they began answering a question many people have been asking since the original model’s intro: Will there be a larger 15-liter engine? Yes, they said; look for an announcement later this year. They added that it will use the same Cummins-made emissions aftertreatment system as the current Cat-branded diesels. So the bigger engine could come from one of several directions, and we’ll have to wait and see.

Looks are subjective, but I think this is one of the most handsome Class 8 trucks out there – big, bold and masculine, with a tall, upright hood and grille. Cat gave it styling accents to set it apart from the previous two models, though if you study photos of the others you’ll see similar lines in the hood and fenders.

The CT680 comes in two versions: L, with a three-piece Metton composite-plastic hood, composite halogen headlights and polished stainless steel grille bezel and chromed bumper; and LG, with a one-piece fiberglass hood, sealed-beam halogens, painted grille-surround and black bumper for those who want a simpler appearance. From the front, both hoods appear wider at the top than the bottom, a “broad shouldered” feature first used on Volvo’s VHD model.

A pair of L-type tractors were available to drive, one with a loaded dump trailer and the other bobtail. From behind the wheel I saw the long hood sticking out ahead, yet I had no sense that it blocked my view forward or to either side.

A note on tilting the hood for pre-tripping or maintenance: You don’t pull it open from the top-front, and indeed there’s no handhold up there. You lift it from the bottom-rear of either fender, each of which has a fluted grasping point. The hood’s stiff enough that it doesn’t wobble, and lifting is amazingly easy because it’s well balanced and cushioned by a pair of gas struts. It tilts forward and settles into place, well out of the way for access to the engine and its accessories. To lower it, you push it back over center and it falls gently into place. Two straps secure it.

The CT680’s forward-set steer axle stretches wheelbases and adds legal payload in bridge-formula states. I drove the gray bobtail tractor on gravel and dirt, and it rode and handled nicely. It had an Eaton Fuller 18-speed manual that was a joy to manipulate. Even with barely 3,000 miles on the odometer there was no stiffness. The lever moved easily through the H pattern and into and out of gear positions, and the splitter changed ratios in each of nine forward speeds, including Low. It’ll also split Reverse, quickening progress if there’s a long path to where a load must be dumped or placed.  

The red four-axle tractor was my mount for the on-highway portion. It pulled a Trail King 48-foot steel side-dump trailer whose rear end rode on three axles. The round-bottom tub carried some big boulders — BFRs, some people call them — which gave us some serious weight. The crew said the rig scaled at nearly 92,000 pounds, but with six axles down we left the tractor’s pusher-type lift axle hanging in the air.

Riding shotgun was Brad Zingre, a Cat industrial sales representative who works out of Indianapolis. He also rode along to answer questions as I test-drove the previous two models, starting with the CT660 in Ohio several years ago.

Last fall we took out a CT681 dump truck in Illinois, and we recalled the bouncing we experienced as we moved over bowed and broken concrete on a state highway. We agreed that this 680 tractor rode better, partly because pavement in Arizona is smoother and this time Zingre had an air-ride passenger seat, whereas he sat on a solid-mount seat in the 681. Also, the 681 dumper had an 18,000-pound steer axle while this 680 tractor had a 13,200-pound steer axle whose springs weren’t as stiff.

Leaving the demo center, we turned east on Duval Mine Road, following it down to Interstate 19. There we turned north toward Tucson. With help from strong winds blowing from the southwest, I quickly got us up to cruising speed of 65 or so mph, set the cruise control there, and enjoyed the ride.

A roomy engine compartment houses the CT13 diesel, but there’s space for a larger 15-liter model. Cat says an announcement on that will come later this year.

A roomy engine compartment houses the CT13 diesel, but there’s space for a larger 15-liter model. Cat says an announcement on that will come later this year.

Power under the 680’s hood came from a Navistar-built CT13 diesel, the larger of two engines currently available in the Cat Truck series. This one had the strongest rating of 475 hp and 1,750 lb-ft. The CX31 torque-converter automatic sent all that twist to the drive wheels smoothly and positively, and, with power steering and strong air brakes, made the rig amazingly easy to operate. We followed eastbound Duval Mine Road as it meandered. The steering was precise, visibility in all directions was excellent, and too soon we had to turn around to head back to our starting point.

Backtracking west on the mine road was more taxing, because now we moved slightly upgrade for much of the way. Also, we fought against those winds. So I got on the accelerator harder and the engine pulled well, growling just enough to be pleasurable. I’ve all but bought into the idea espoused by Cat, Navistar and others that 12-13 liters of displacement is just fine for most applications, especially when an engine develops the power and torque they now do. And historically, this is the engine size found in most dump trucks. However, the upcoming 15-liter diesel will help with extra-heavy hauling, and proponents of larger engines say they last longer.

The aluminum cab certainly showed its premium status on this leg of the trip. There was some faint whistling as the air moved around the big mirrors, but that’s all, indicating the doors and windows were effectively sealed. Quietness in the cab allowed Zingre and me to converse in near-normal voice tones. The CT680’s interior is refined and comfortable, and almost coddles a driver. The basic cab structure is from the International PayStar and 9900i — also premium vehicles — but there doesn’t seem to be much sharing of interior components. The CT681’s fabrics and plastics in the seat covers and wall, door and dash panels have a rich look and feel.

I’ve come to like the single big gauge that houses both the speedometer and tachometer, whose needles swing around individual arcs on the instrument’s face. It takes up less space than a separate speedo and tach, leaving room for eight good-size gauges nearby for air brake, engine condition and transmission oil temp values, and fuel and diesel-exhaust fluid levels. More gauges were on the panel to the right, along with rocker switches for lights, engine brake, cruise control, tandem diff locks and other functions.

Before parking the rig near the demo center’s offices I went out onto the gravel roads to check its off-pavement behavior. The big Cat hardly seemed to notice what was under its tires, even if the “viper red” paint got a little dusty. This was such a nice rig to drive that I suggested we take it out to Ohio so I could avoid an impending late-night airplane ride back home. “I’ll just drop you in Indy,” I told Zingre, and he almost agreed.



2016 Caterpillar CT680L, conventional daycab, set-forward axle 6x4, BBC 124 in., GVW 65,850 lbs. (w/ lift axle), GCW 93,000 lbs.


Cat CT13 (Navistar N13), 12.4 liters (758 cu. in), 475 hp @ 1,700 rpm, 1,750 lb-ft @ 1,000 rpm, w/ engine brake


Cat CX31, torque converter 6-speed automatic

Steer axle

13,200-lb. Meritor MFS-13-143A on 14,000-lb. parabolic taperleaf springs, w/ Sheppard M100 hydraulic power gear

Lift axle

13,500-lb. Watson & Chalin SL1190, steerable

Rear axles:

40,000-lb Meritor MT-40-14X-5DCR-P, ½-in.-thick carrier walls, w/ locking differentials and 4.63 ratio, on 40,000-lb. Hendrickson HAS-402-55 air-ride


244 inches


 Meritor S-cam drums

Tires & wheels

11R22.5 Continental HSR2 front, HDR2 rear, on polished aluminum discs

Fifth wheel

Fontaine SL7LWB825024 air-slide

Fuel tank

120-gal., 24-in. dia. polished aluminum

DEF tank

9.5-gal. plastic


Trail King 60SSD tri-axle 48-ft. steel side-dump

About the author
Tom Berg

Tom Berg

Former Senior Contributing Editor

Journalist since 1965, truck writer and editor since 1978.

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