Driving the Autocar concrete pump
Our subject truck has a Cummins ISX12, an older series product since superseded by the lighter (by about 600 pounds) X12, which will be in a Tri State chassis now on order. Older technology notwithstanding, the ISX12 hasn’t missed a beat. Bought with a 450-horsepower rating, it was locally up-rated to 500 horses with Cummins’ assistance. The extra power helps with propulsion in a truck that weighs 104,000 pounds just sitting still; it travels under permits issued by the states in which Tri State operates—mostly portions of Ohio, West Virginia, and Kentucky. The engine runs through a 6-speed Allison automatic. “With the labor market being what it is, this helps in hiring,” Windland says, because most young people have never driven a manual transmission of any kind, much less the non-synchronized multi-speed gearboxes now in many of Tri State’s trucks.
The Allison made the truck rather easy for me to drive in spite of its mass and bulk. It’s about 48 feet long, 13 feet, 2 inches high, and 102.3 inches wide, so at first it took a little concentration to keep it within the lanes of U.S. 50, which runs east and west through southern Ohio. Along for my demonstration ride was Steve Gilliland, Tri State’s shop foreman, who drove the hefty vehicle out to the highway where I took over. He directed me west about 10 miles to a small truck stop where I turned around and returned to the four-lane U.S. 50, which is a limited-access highway in places, and back toward the company’s headquarters and yard. On the open road, the truck’s ride was something like a motor coach’s, with gentle vertical movements over the twin-steer axles’ suspension and, thanks to air-ride over the tridem rears, virtually shock-free.
At 60 to 65 mph, the tach needle pointed to about 1,700 rpm, where the engine could produce the power and torque needed to climb moderate hills rather easily. The engine brake helped keep speed in check on downgrades. Although fine on the highway, the Autocar could use a deeper low gear to handle stiff hills in West Virginia, Gilliland said. A 7-speed Allison 4700 would probably solve this, but it’s not practical to retrofit this into an existing truck, said Adam Burck, Autocar’s marketing manager.