Axle-Forward Cat CT681 Vocational Truck in Full Production
Caterpillar has begun serving more vocational segments with its CT681, a Class 8 set-forward-axle model with “industrial” styling based on customer preferences, representatives said Thursday at a press briefing at Cat’s demonstration facility west of Peoria, Ill.

Cat's CT681, right, features more “industrial” styling than the current CT660. Photo by Tom Berg

Caterpillar has begun serving more vocational segments with its CT681, a Class 8 set-forward-axle model with “industrial” styling based on customer preferences, representatives said Thursday at a press briefing at Cat’s demonstration facility west of Peoria, Ill.
The new model is aimed at dumper, mixer and snow-plow applications whose operators usually dispense with cosmetic frills and are more concerned with reliability and durability, said Dave Schmitz, product manager in Cat’s Global Truck Sales division. Its nose therefore lacks the brushed-aluminum grille trim of the CT660, the setback-axle version introduced in 2011 as the first model in the series.
The new model’s set-forward steer axle makes it suitable for bridge-formula states, many in the West, that favor wide axle spacing to spread out weight. The steer axle’s center is 28 inches behind the bumper, which is flat to reduce the chances of faulty measuring by enforcement personnel, he said.
Some operators believe a set-forward axle delivers a superior ride because it’s farther away from the driver. Parabolic leaf springs at the CT681’s steer axle, now also used on the CT660, allow for a smooth ride.
The CT681 has a 114-inch bumper-to-back-of-cab measurement and comes only as a truck, whereas the CT660 is available as a truck and tractor. A third model, a long-nose CT680 with a 124-inch BBC and set-forward steer axle, is due out next year and also will come as a truck and tractor.
Unveiled early this year, the CT681 is now in full production at Navistar’s plant in Escobedo, Mexico, Schmitz said. Navistar builds Cat Trucks based on the International PayStar but with enhancements specified by Cat.
Among those is a nicely outfitted cab that includes deluxe trim, attractive and useful gauges, and wide rocker switches that can be operated with gloved hands. The cab also has round ducting pipes for efficient movement of air, which is filtered to keep out dust and other impurities.
“My father and uncle were in the ready mix business in Milwaukee,” Schmitz said. “I remember it was always dusty – dust all over the place -- and noisy. So we took that into account in designing our cab” with the air filtration system and noice-reduction insulation.
Mixer drivers must maneuver their trucks at job sites and need good visibility, so the cab has a large windshield and windows, he added.
The CT681 is available with a front frame extension using long frame rails, along with a front engine power take-off, making it easy to mount snow plows, hose reels, winches and hydraulic pumps. Mixer installation is also simplified with vertical tie-in plates mounted to the frame rails behind the cab. Frame rails are 12 inches high for durability throughout an anticipated 10- to 12-year life, he said.
The standard and only engine is the CT13, a Navistar N13 with selective catalytic reduction, that Cat has tuned for vocational duties. It has five ratings from 365 to 430 hp and 1,250 to 1,550 lb-ft.
Cat’s CX31 6-speed torque-converter automatic transmission has been a popular option on the CT660, with more than half of all customers taking it, Schmitz said, and it’s expected to also sell well with the CT681. The CX31 includes a provision for a rear power take-off in addition to side mounts.
Also available are vocational-type manual and UltraShift Plus automated mechanical transmissions from Eaton. UltraShifts are Vocational Service types with eight to 18 forward ratios.
Like the axle-back CT660, the first model in the Cat vocational truck line, the new CT681 is backed by bumper-to-bumper service at more than 400 Cat dealer locations with over 2,300 service bays in North America.
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