HOW do you transport a 55-ton, 27-ft-diameter parabolic mirror — part of what will become the world's largest, most powerful telescope — on a 122-mile journey, the last 29 miles of which are on a rough road with multiple hairpin turns that lead to a 10,480-ft mountaintop?
To get the mirror to the Mount Graham International Observatory in Safford, Arizona, for the University of Arizona, heavy haul specialist Precision Heavy Haul Inc of Tolleson, Arizona, used a 12-axle Goldhofer trailer, a Kenworth T800, and a Caterpillar 980 wheel loader.
“This was the most complex move with the most challenges that we've ever had to overcome, but everything went exactly as planned,” Precision Heavy Haul president Michael Poppe says. “This was an extraordinary achievement between our team and our equipment.”
Cranes hoisted the mirror and casing onto the Goldhofer trailer, which had steel plates weighing 70,000 lb loaded onto the front deck to lower the overall center of gravity. The load was pulled by a Kenworth T800 powered by a Cummins 565-hp engine and driven through an Eaton Fuller Super 18-speed transmission. Poppe drove a Caterpillar 980 wheel loader that pushed the load at speeds never exceeding 4 mph over a two-day period.
“This job shows why we have an all-Kenworth fleet of trucks,” Poppe says. “Kenworth builds the best custom-engineered heavy-duty trucks on the market and has always been there for us to provide superior product support.
“The combination of the biggest engine we could get plus the 195-inch wheelbase delivered the traction and the tight turning radius we needed. This gave us great maneuverability for making those close to 180-degree turns climbing the mountain trail. Also, we needed a unit with a gear ratio low enough to go less than 1 mph without stalling.”
The $10 million mirror was hauled in a specially designed steel box outfitted with 280 pneumatic actuators that restrained and cushioned it. The mirror and box were 30' square and 9' thick and weighed a combined 55 tons. The 29'-diameter cell weighed 50 tons and was moved separately.
Precision Heavy Haul started spec'ing its Kenworth T800s for heavy hauls in 1991. Poppe says those early specs of big engine, small wheelbase, maximum weights on the steer and drive axles, and heavy-duty rear ends have been maintained, with a few modifications.
And the work is not done. The company will transport a second mirror and cell to the mountaintop later this year.