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
There are baffles in the tanks to break up the liquid into smaller volumes so the sloshing around is dampened.
We drive slower and more carefully. My truck is a single tube, I don’t speed and I don’t turn sharply.
Braking can happen as far as 500 metres ahead.
1. Don’t make sudden moves while loaded.
2. The tanks are either divided or they have baffles to absorb and dampen the effect of the liquid sloshing around.
Count the number of hose connections on the tank trailer to determine how many separate tanks are inside. Baffles are used in large ranks but transporting liquids in multiple separate tanks is quite common.
Just send it. I work with truckers that ship fish, they drive the same as if they were hauling something solid. And people saying milk trucks don’t have baffles don’t know what they are talking about, we’ve had to cut those baffles out of them to repurpose as fish trailers.
I used to drive tanker.
One day I had a load in a smoothbore tank. If I would let off the throttle, I would get a “push” from the surge. As I accelerated, I could feel a “tug.”
Because I’m a child, and just for funzies I had to at least once see what would happen if I could intensify that effect.
So every time I got the push, I’d accelerate, and every time I got the tug, I’d let off.
Push, go, tug, slow.
After a few cycles, we’ll say 5-7, on the last “push,” the liquid slammed so hard it felt like I got rear-ended by a freight train, and I could hear a loud BAM. I decided I’d pushed my luck enough. To this day I have to wonder if I could have created enough force to detach the trailer.
Another time, I was pulling a load out of Missouri, in the hills and the hollars south of St. Louis. I had a stop with a left hand turn that went uphill, and I was driving a manual transmission. Every time I would clutch to grab the next gear, the surge would practically stop the truck. So I had to crawl about half a mile up the hill in 2nd gear because I couldn’t make the shift.
Also, last one, fun fact. If I was on a scale, the sloshing would throw off the weight and I would have to wait for it to settle. I found the quickest fix was to release the brake and let the truck roll free. The scale was completely level. The free movement countered the surge and after a few waves everything would stabilize.
Good times.
I pull a 7000 smooth bore tanker, no baffles. Typical load is 45,000lbs oil/petroleum products are 7 lbs per gal, and will get the tanker pretty full, water is 8, it’s common for some to weigh 11- 15 lbs per gallon, wheel it’s not full, the surge will feel like another truck slammed into you. With a manual shift, you can time the shifting with the surge, not so easy with an automatic.
I’m a concrete mixer driver, but this is kinda sorta related. In my case, I just be sure to slow down to 10mph or less during turns, and for braking, that’s only a problem if I have an exceptionally wet load (8 inch slump or higher, if you know what that means), in which case I will have the drum in full charge, meaning it’s rotating as quickly as possible, which constantly pushed the concrete towards the front of the drum, rather than towards the rear (where the opening is). Slamming on the brakes will still result in concrete shooting out the opening of the drum, so I just have to be careful.
Why wouldn’t they just inflate an air bladder to take up the extra space?
I drove trucks for 25 years, the last 13 years I drive chemical tankers with no baffles. You just have to be smooth with your driving, no sudden stops or starts and take the turns slowly. Sometimes the liquid would remind you it’s there, the surge can knock you out of your seat!
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