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
My husband drives a tanker without baffling, he said that most food grade tanks won’t have it due to the cleaning issue. He says most of it is really just always allowing extra time for everything – drive like you’re in bad weather all the time, give yourself extra time to slow down, to turn, etc.
I drove a unbaffled 7000 gallon tanker for 4 years and the max fluid I hauled was around 5500 gallons. You just learn to drive slow and shift smooth and brake only has you have to. But what doesn’t help is when we are in traffic and we leave a gap to stop and cars keep jumping in front of up and making us slam on the brakes. And it isn’t bad unless we take off and slam on the brakes again. Then we get the bounce of the liquid sloshing around. But I have never been around a turn to fast for it to make my truck jerk sideways. But I always pictured me driving a 80s caddy taking grandma to church just taking my time.
Baffles in the tanks – lots of tanks however do not have baffles, called smooth bores, usually for food grade tanks as the baffles make it hard to clean.
Very careful driving with all tanks but especially smooth bores. Even with baffles when you come to even a moderately fast stop you can feel it push you.
The bonus though is that you can run overweight and the scale houses won’t be able to tell if you jam the brakes when you go to stop on it, they’re not going to wait a couple minutes for the surge to die down
Just anticipate it and ride it out. The closer to full, topped off, it is the less slosh. Some tanks have baffles some don’t. For instance most chemical tanks are smooth bore. It’s super important that they get a good clean out between loads of different product. Any extra edges ledges or corners make places the washout won’t reach. Different products handle differently. Depends on viscosity and density of the liquid. For instance, crude oil isn’t that bad. Water is terrible, so it is antifreeze. Sometimes it slams so hard after stopping you swear someone just ran into you.
While you always want a full tank your limited by how heavy the product is. A 200 bbl tank with a day cab can be topped off and still legal on weight. But if you load Water or brine in same tank your at 80k with a little over half a load.
Just fill the trucks with school lunch size cartons of milk?
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!
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.
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.
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