How do truck drivers carrying a liquid load combat the force of the liquid moving around in the back of the truck when turning or braking?
In: Engineering
An article on the nuances of driving hazardous liquids …
[A Fleet of One: Eighty Thousand Pounds of Dangerous Goods](https://archive.ph/5GIIg)
>*Just as the body of a fish tells you how that fish makes a living, the body of a tanker can tell you what it contains. In Ainsworth’s words, “The architecture of the tank says what is in it.” If a tank has gasoline inside, it has a full-length permanent manway on top, and, seen from the rear, is a recumbent oval. If a truck is a water wagon, the tank—rear view—is rectangular. A perfect circle ambiguously suggests asphalt, milk, or other food. If the vessel is all aluminum and shaped in tiers like nesting cups, it is a food-grade pneumatic hopper full of flour, granulated sugar, and things like that. If stiffeners are exposed—a series of structural rings circling and reinforcing the tank—the vessel is uninsulated, generally operates in a warm climate, and often hauls flammables and combustibles. Ainsworth said, “That is what mine looks like without the designer dress” (the stainless mirror sheath). The double conical side view speaks of chemical hazmats. Since September 11, 2001, all these shapes have scattered more than fish.*
>*Backing blindsided at the Peterbilt dealer’s in Missouri, he said, “Sometimes you do this by Zen.” He had never been to driver school. “I’m a farm boy,” he explained. “I know how to shift. There are two things you need to know: how to shift, and how to align yourself and maintain lane control—exactly how much space is on each side. In city traffic it’s critical.” In the open country of western Kentucky, he said, “Out here, you look way ahead. It’s the same as steering a ship. There’s a silver car about a mile ahead that I’m looking at now. When you steer a ship, you don’t look at the bow, you look at the horizon. When I’m in a four-wheeler, I stay away from trucks, because if a tire blows or an entire wheel set comes off I’m going to Beulah Land.”*
>*From Harrisburg, North Carolina, to Sumner, Washington, the load in the tank behind us kicked us like a mule whenever it had a chance. The jolt—which he called slosh, or slop—came mainly on surface streets and on-ramps when gears were shifting at low speeds. On the open road, it happened occasionally when we were gearing down, mashing on the accelerator, stepping on the brakes, going downhill, or going uphill. Ainsworth minimized the slosh with skills analogous to fly casting. “You coördinate shifting with the shifting of the load,” he said. “You wait for the slop or you can pretzel your drive line.” The more ullage the more slop. The density of the monoethanolamine had allowed us to take only six thousand gallons in the seven-thousand-gallon tank. The ullage was the difference was the mule.*
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