DOT??

I don't want to side track the post below about towing 11 tons, so I'll start my own.

I like to haul things the right way, so I've asked hard questions in the past. That gives some the opinion I don't care and I'm an accident ready happen.

Here is a copy of the DOT regulation I found interesting.

FMCSA requires that cargo securement systems be capable of withstanding the forces associated with following three deceleration/accelerations, applied separately:
1.0.8 g deceleration in the forward direction;
2.0.5 g acceleration in the rearward direction; and
3.0.5 g acceleration in a lateral direction.

These values were chosen based on researchers' analysis of studies concerning commercial motor vehicle performance. The analysis indicated that the highest deceleration likely for an empty or lightly loaded vehicle with an antilock brake system, all brakes properly adjusted, and warmed to provide optimal braking performance, is in the range of 0.8-0.85 g.

If I'm reading the regulations right, the two chains and D rings preventing load form moving forward have to be able to withstand 0.8g's. What that means the chains must be strong enough to withstand 80% the weight of the tractor. That's going to be a big chain and some strong D ring isn't it?

A 10,000# tractor would need 8000# chain and rings.

A 20,000# tractor would need a 16,000# chain and rings.

My question is do they make chains and D rings that strong? IF so what are they called?

Keep in mind DOT came up 0.8g's based on braking only. All bets are off if you are in an accident, the g value is many times the value of gravity. I can see if you were hit a tree with truck, come to a sudden stop, it won't take long before the tractor you are towing is going to hit you in the back of the head.

So, are we all using strong enough chains?

I use 3/8 G70 chains on my tractors which are between 3-4000#. D rings on my sur-track trailer look like 1/2 inch. Are they strong enough for DOT? I don't think too many things are strong enough if I come to a sudden stop, so I'm going off roading instead of having a head on.

Footnote: I've asked in the past, why aren't the cops stopping landscapers who pull 3 Dixie choppers, no straps, advertisement on truck, no DOT's.

This answer may not be accurate, it came from a retired trucker who has a son who is a DOT inspector and the other is a State cop. I was told only cops with an Indiana DOT certificate can stop you and inspect your load. Any cop can be certified, but their department will need to send you to school to get one. Our city and county boys are not certified, only some state boys are. In the past Indiana had DOT and State cops. DOT boys didn't carry guns. New DOT boys are also state cops, can write tickets and pack heat.

Retired trucker told me if any cop stops me, just politely ask to see his DOT certificate. This is just hear say, may not be accurate. Best answer I've gotten when I ask why aren't my cops doing their job. When in reality it isn't their job unless they are certified.

So what's the answer to chain strength???

geo
dot

I have driven big trucks for over 30yrs and one thing I can tell you It's a crap shoot on what type of Dot officer you will get. As far as chains go is it american grade 70 or from the land of almost right? I have hauled 9540 kubota's with loaders and cab in a 53'box trailer with one 10000 strap on the front of each tractor and one on the hitch of the last. I did not think that was safe but that is what was required in a box.

I know nothing, but don't you need to tie each corner seperate, so you have 2 chains holding, can cut your requirements in half?

If you need more, add more chains?

From what I hear, dot is just a luck of the draw, every officer has a different personality and reads the many, complicated, regulations a bit differently.....

Was a thread couple years ago on this forum or more likely on NAT where a fella that hauled frequently from north Iowa to west central MN had to stop half way and re chain his equipment, as two districts he passed through saw the rules very differently and got tot the point it was easier to take 15 minutes to re gain than to deal with the questions and different requirements, he was getting targeted because he was always 'wrong' passing through.

Paul

OK, I think after reading that clear a mud set of rules that the chainS with an s at the end have to total 80%.

Not positive though.

Rick

Your 3/8 g70 chain should be rated at 6600 lbs.
With 2 chains on the back (required) you would be good to 13200 lbs.
If your tractor weighs over 13200 you just get a bigger chain or use more.

Grade 70 chain ratings.
1/4 3150 lbs
5/16 4700
3/8 6600
7/16 8750
1/2 11300
5/8 15800

George,

Remember that your cargo probably isn't sitting on ball bearings. Most items you're going to carry will withstand a certain G force without any straps or chains. So the tiedown doesn't have to withstand the full force of acceleration, just whatever force is needed in addition to the static friction of the load on the trailer.

Note also that as the tiedowns are secured, their tension increases the downward force of the load against the trailer, which increases the friction between load and trailer. If, for example, the tiedown is under 200 lbs of tension and is at 45 degree angle from verticle, it's going to add 141 pounds of downward force to the load.

That said, I don't think you can tie a load down too well. I remember seeing a car on the side of a Detroit freeway with everything smashed ahead of the firewall. Apparently the car was following a semi with an enclosed trailer, the driver probably unaware that the trailer was loaded will coils of sheet metal. One of those coils broke free and came right through the trailer doors, demolishing the car. The driver appeared to be very shaken but unhurt.

And in North Caroling I saw a brand-new 23' Mako center console sportfisherman loaded into the bed of a brand-new Ford pickup. Apparently the new boat owner didn't bother to buy a 30 dollar tiedown strap to keep his 20 thousand dollar boat from launching out of its trailer and into the back of his 20 thousand dollar pickup truck. One hard stop was all it took.

Interesting how you seem to think that DOT doesn't apply to you in other posts, yet also seem to think they would need a DOT certification to inspect you..... Seriously though you are commercial like it or not, and it's not hard at all to find chains that will stand those forces. 4400lbs for a grade 43 chain will easily handle holding back a 10,000 lb machine since they would be 8800lbs with one at each corner as you should do

3/8 inch Gr 70 chain has a working load limit of 6600 lbs so per the regulations one at each corner of your 3000-4000 lbs tractor provides a large overkill in strength. Even a 1/4 Gr 70 chain (3150 lbs WWL) at each corner would be in compliance for securing a tractor this size.

As you state, the regulations are based on braking, accelerating, and lateral loads since those are the only ones that are realistic and predictable. There's simply no way to predict the forces that could be applied in a collision scenario so there's no point in mandating to some completely arbitrary number. A Gr 70 chain's breaking strength is 4 times the working load limit so you already have a large safety factor working for you to cover unforeseen circumstances.

I haul a lot of equipment on my 24,000 capacity goose-neck trailer and once in a while I get to visit with the DOT inspectors but it seems that if you trying to follow the rules they will give you a break. I always put more chains on my load than is necessary just because it gives me peace of mind when I am traveling. I am careful to keep my vehicle inspections current [my trailer to} and I keep a sharp eye on the trailer lights and brakes. Knowing you have done everything that a reasonable trucker should do will give you confidence that you are in compliance and that shows when you say "good day to you sir" when the inspector approaches your cab.

how did you determine that .8G is 80% of the weight of the tractor? Doesn't force= mass times acceleration?

> how did you determine that .8G is 80% of the weight of the tractor? Doesn't force= mass times acceleration?

George is right; it takes a force equal to .8 times the vehicle's mass to generate a .8 G acceleration.

Newton laws of motion, F=ma. Ask any Physics major if you don't believe me.

I still have reservations if DOT regs apply to non commercial. Someday I'll ask someone who is DOT certification. Are you certified?


I do know a little Physics and the last things I want is for anything in my truck or trailer to smack me in the head.

No one has addressed D ring strength. Can they really stand up when things get ugly?

I did find the answer why aren't city, county ,and some state boys stopping trucks who look commercial, 3 Dixie choppers, no straps, NO DOT numbers. It's not their job unless they are certified.

1/2 d rings are rated around 4000 most brands, that's work load, and I see 1" is rated 15,600 in a couple websites so well within reason. And geo yes you are commercial maintaining your rental properties.

Followed a semi yesterday that was hauling a Deere 4 wheeler , duals hanging way off the sides. Escort vehicle front and rear. He went 60 mph on a 55 asphalt county road, curves and all. Dust would fly when meeting a vehicle as he had to get on the shoulder. I stayed a long ways behind. When I came upon him at a stop sign I was thinking I would pass him while he was gaining speed. Well, he had plenty of horses under that hood as he accelerated at a good rate of speed so I just stayed back. Apparently he had it tied good.

Yes 1/2 inch D rings are usually in the 4000 lb range.
Depends on what the are mounted to.

So George you just wasted money buying 3/8 g70 chain.
You could have gotten 5/16 G70 chain and held down just as much tractor.
Remember that the limit of a tie down is calculated by the weakest link.

Per Federal regulations, ANY VEHICLE with a GVR of more than 10,001 pounds, that is used in interstate commerce (of any type) is considered commercial.

Further, if you have a vehicle pulling a trailer with a GVW of more than 10,001 pounds you are required to have a class A CDL (with restrictions limiting you to the smaller class of towing vehicle) in order to drive the 'vehicle combination'.

That being the case, you need just about everything a semi does to be legal, in most cases.

Good luck proving I'm commercial. Truck is in my name, not a business name. Trailer is in my name too, not a business name. Tractors are mine. Absolutely no advertisement on truck like landscapers have. SO HOW IS ANYONE GOING TO KNOW I HAVE HOUSES FOR RENT??

You are saying just because I have more than one property I'm commercial carrier of freight. That's NUTS. If I'm stopped never tell the cops anything.

The irony of you starting a post about how to comply with DOT regs and then saying it's ok to ignor those regs as long as you lie about it and don't get caught is not lost on me.

It all boils down the the attitude of the officer,,if he is having a bad day ,,he is going to share it with you...and if you ask 5 different officers about what is right..you will get 5 different answers...Keep your lights working,, chain them good and try to keep your outfit looking good and hope for the best..

John in La,
Interesting point, weakest link.

My implement trailer is rated at 14k which means it could haul 11k tractor. I never will, but if someone is correct stating my D rings are rated at 4k, then someone could have a problem stopping a 11k load, right? geo.

Mark,
It's hard to believe someone on YT thinks I'm right. What's the world coming to?
geo.

Here is the irony, how many people think they are in compliance and are not?

Just because I said DOT regulations may not apply to non commercial vehicles towing private loads, not for hire and not going across state lines, doesn't mean I don't believe the LAWS OF PHYSICS have been appealed by the supreme court either. They apply to everyone.

I think there is a loop hole in the law excluding non commercial vehicles. Perhaps that should be fixed.

My loads are more than in compliance with DOT regulations, not to mention I use angle strapping to prevent tractor from falling off trailer in the event trailer wants to tip over. 2 chains pulling backwards are the two most important ones and I have way more strength than needed but not enough strength in the event of an accident. I doubt if anyone had enough either just because they are DOT compliant.

Someday I have a chat with someone who is DOT certified and post back. Is anyone on YT certified???

Are there any chains and D rings strong enough for a 11 ton load?
geo.

I always thought that mass is weight divided by gravity, which is usually 32.2 here on earth, and isn't force measured in Newtons??

The real irony of the matter is you think that because you are not commercial; or can lie and make the DOT believe you are not commercial; that you do not have to follow safety laws such as tie downs just because the laws are listed in the commercial truck book.

Isn't that like saying my wife's car is not commercial so she does not need tail of headlights.

> I always thought that mass is weight divided by gravity, which is usually 32.2 here on earth, and isn't force measured in Newtons??

Well, for starters you're mixing English and metric units. The acceleration of gravity is indeed 32.2 ft/s². But newtons are the metric unit of force, so you would use the metric value for the acceleration of gravity, which is 9.8 m/s².

But George isn't working in metric units; the French hadn't invented the metric system back when he took physics, so he's working entirely in English units. Here's the deal with the English system: there are actually two kinds of pounds: pounds-force (lbf) and pounds-mass (lbm). So if George's tractor weighs 2000 pounds, it has a MASS of 2000 pounds-mass, and an it exerts a force of 2000 pounds-force on the earth. If we shoot it up to the moon, it will still have a mass of 2000 lbm, but it will only push into the moondust with a force of about 300 lbf. On earth or the moon, it takes 2000 lbf to accelerate the beast laterally at one earth G.

Thanks---that clears up the confusion i had!!

Lol, no wonder I hated math in school! So at 60 mph in a head on crash into a wall how much force would that same 2,000lb tractor put on the tie downs? I'm curtious about this and not making fun, I would rwally love to know. The figure I've always used for tie downs is 150% of payload weight and I'm wondering how close that is.

MarkB_MI,
Do you have a masters in Physics? It's obvious you don't, calling mass pounds.

Here is how the physics works, F = ma, w = mg

CGS, mass is in grams, force is in dynes, a in cm/s2

MKS, mass is in KG and force in Newtons. a is in m/s2

In the old English system, which you don't know, mass is measured in slugs, acceleration is in Ft/s2

I'll bet no one knows has heard of a slug is or where it came from. It took me 30 years to find why the British call it a slug.

Mass = w/g

3200 pounds divided by gravity( 32 ft/s2 one gravity unit) is equal to 100 SLUGS OF MASS.

Newton's law, F = ma

To stop a 3200 pound tractor (a 100 slug mass) at 1 g (32 ft/s2) will require 3200 pounds, its weight.

To stop a 3200 pound tractor at .8 g's, the stopping force is .8(32) x 100 slugs = 2560 pounds 80% of the weight.

The stopping force to stop anything is take the value of g and multiply it by the weight. Any high school physics students know that.


geo.

You need the stopping distance for the correct answer.

I posted an example of a 160# person stopping in 1 ft traveling 30 mph. He is pulling 30g'. That means the seat belt is applying 30x his weight to stop him in 1 ft, 2.4 ton.

I would say the best answer for stopping distance would be to measure the distance the front bumper and motor is pushed back when it hits a solid object.

As a kid I read where a trucker carrying pipe was in a wreck. The pipe went through the cab and through the driver killing him.

Bottom line, there is no chain, D-ring, or DOT regulation that will withstand 30 g's.

It's a joke thinking DOT regulations of 0.8g's is going to keep you safe if you are in a serious accident.
link

Now I hope you realize they are talking about the sum of chains. Next time you are on the highway watch for a flatbed hauling steel coil. There will probably be 8 or so chains through the center of that coil. It is safe to assume a single coil is in the neighborhood of 22 tons. Now if you want to get really deep into it, you need to figure the vector forces. A load is never tied down where the chain is in a staight line to the movement force. Pulling on a chain at an angle against the trailer affects how much load there is on said chain.

Commercial or not, I still would want to think that basic safety and weight rules should be applied. Whether or not that is the law, I do not know. I would like to hope so.

I would say 1 inch d rings and 1/2 chain would be perfect for a load that size. And yes you can lie to the cop but I bet if you ever are in a serious wreck the lawyers will find out why you were moving your tractor and you will be commercial in the eyes of the law.

Just need to use more tie down points

In a serious accident you're screwed no matter what you do. Even if your chains stay intact it's a moot point since the entire trailer will probably be joining you in the cab anyway, either by shearing off the hitch and passing through the bed of the truck or upending and coming down on top of you. Nobody, including the DOT, is saying that you or others involved will walk away from accidents as long as your load is secured by the book. Following the regulations just means you're in compliance with the law, nothing more. And, obviously, if you're in compliance it will be much easier to defend yourself against accusations of negligence should someone get hurt by cargo that happens to break free in an accident.

Good morning George!

1 slug = 32.174 pounds (mass)
Acceleration of gravity on earth: 32.174 ft/s²

Coincidence? No. The mass unit of slug exists only so F=ma works out without using any conversion factors. Of course you just move the conversion out of the equation when you convert from pounds to slugs. In the real world nobody uses slugs. I don't buy a 644 slug sack of potatoes, I buy a 20 pound sack of potatoes. In the classroom, the slug is a useful unit of measure that clarifies the difference between weight and mass; in the real world it just gets in the way.

No, I don't have an MS in physics. My college physics was taught using only [i:654c4848f0]Systeme International[/i:654c4848f0] (MKS) units, as were statics and dynamics. But the various thermodynamics courses I've taken used both SI and English units. Pounds-mass was always the unit of mass we used, NEVER slugs.

So, you ask, how do you get F=ma to work without using slugs as your unit of measure for mass? The engineer uses a conversion factor: one pound-force equals 32.174 pounds-mass feet/sec². So to calculate the force required to accelerate 2000 pounds at 1 G:

F = ma = 2000 lbm x (1 lbf / (32.174 lbm-ft/s²)) x 32.174 ft/s² = 2000 lbf

Notice that the pounds-mass units cancel out in this equation. As do the ft/s² units. That's very important for the engineer; engineers always check unit consistency to confirm their calculations.

150 percent of payload weight is nowhere near enough to withstand the acceleration forces of a head-on collision.

I looked up to see how strong passenger seat belts are required to be. Lap belts are required to handle 26,689 newtons before breaking. Which works out to 6000 pounds. Which we can double to 12,000 pounds since there are two attachment points. A 300 pound passenger would have to decelerate at 40 Gs to generate 12,000 pounds. Of course the passenger is going to sustain significant injuries at 40 Gs. But a 10 G crash is certainly survivable if you're restrained. And there's simply no practical way to tie down a heavy load so it can stand a 10 G crash.

Fortunately it would be a rare truck crash that generates 10 Gs. Unless you hit a stationary object or another truck, the truck's mass will be heavier than whatever it hits, so its momentum will continue to carry it forward through the crash, reducing the deceleration.

11000 lbe x .80 = 8800 lbs
8800 lbs / 2 tie downs = 4400 lbs each
So installing 1/2 inch D rings rated at 4000 lbs is pretty close especially when you are trying to cut cost and sell a trailer.
3/4 D rings would have been better but way over kill and would have made the trailer cost more.

You're education is a result of Jimmy Carter's voluntary metric conversion act requiring all text books to drop English units and go to MKS. Which later returned to English units.

I'm old school and slugs never got in my way. The slug is the proper English mass unit. Just get your units right in the English system and they will cancel out too. No need to convert to metric.

My point is the same. A 3200# tractor stopping at 1 g takes 3200# of stopping force. Stopping force at .8gs takes 80% the tractor's weight under normal braking.

The real issue what is the stopping force when you're in an accident and will the chains/D rings hole up? I really doubt it. It's not the fall that kills, it's the sudden stop that will. Same applies to a tractor on a trailer. Sudden stops will break DOT required chains and tractor will keep on going.

Below is a link to a Indy driver surviving 214g's. That would have to hurt. Hard to believe the seat belt held up to 214 times driver's weight and driver lived.

Don't think there is a chain strong enough to withstand 100g's

Where did the term slug come from? It was around before Newton laws of motion.

Hint: In was something in England, it's a round object and it weighed 32#. We even call a small lighter round object in the US A SLUG. Enough hints?
214gs

>You're [sic] education is a result of Jimmy Carter's voluntary metric conversion act requiring all text books to drop English units and go to MKS. Which later returned to English units.

Afraid not, George. I completed my college physics in 1976, before Born Again Jimmy took office. Our president was a guy who had played football in a leather helmet, and you could tell. Today he's remembered more for pardoning a suspected criminal before he'd even been charged with a crime, rather than for signing the Metric Conversion Act of 1975.

Out of curiosity, I pulled out some of my old textbooks to see if I could find any references to the slug.

My statics and dynamics textbooks, published in 1975, are 100 percent SI. No mention of pounds or slugs.

My physics textbook, copyright 1975 is also SI-only. But it does mention the slug in a brief footnote on one page.

The interesting one is my thermodynamics textbook, copyright 1973. It is mixed English and SI units. But there isn't a single mention of the shell-less mollusk that is supposed to be the English unit of mass. Instead, "pounds-mass" (lbm) is the unit used throughout the book.

This is just one of many examples where scientists and engineers do things differently. Scientists are purists who can't stand the idea of two different units of measure sharing the same name. Engineers, on the other hand, are pragmatists who have jobs to get done. They don't see the value in converting everything to slugs when the pound-mass unit of measure works just fine.

Without looking it up, given the British fondness for naval warfare and artillery, I'm going to guess the slug is some sort of projectile. Let me know if I guessed wrong.

Yeah, it was a 6 or 7 inch cannon ball that weighed 32 pounds. Go to college physics websites. Google pounds to slugs, or mass unit in English. Slug is common mass unit , no conversions necessary. Guess I old school. Used slugs all the time.

> Guess I old school. Used slugs all the time.

Old school? Yes and no.

It seems the term "slug" wasn't coined until 1900, and was not in common use three decades later. So what did they do before then? It seems they used a conversion factor.
Slug history Wikipedia

Mark
Been retired 12 years. I always used slugs, KIS, divide weight by gravity, 32. Use what works for you.

Back to my original idea. Do you think the DOT chain requirements will really save your life when you stop faster than 0.8 g's?

I've never been in an ACCIDENT, knock on wood. Perhaps one of the reason is when I was 12 I got hurt on my motorcycle. Taught me pay attention and be a defensive driver. Avoid hitting anything, don't tailgate, always think ahead, plan on brakes not working.

People who have been in an accident say the seat belt leaves burses. So what's your best guess how many negative g's do they experience? Then apply the -g's to DOT chain requirement and D ring strength. Strong enough???

BYW, I've also researched DOT requirements in Indiana. What some post is not true in Indiana, there are commercial carriers and private carriers. No CDL's up to 26000. No DOT # private trucks. Only 10 weigh stations in Indiana, all on interstate, which I don't use when moving a tractor. ALL LOADS SHOULD BE SECURED FOLLOWING NEWTON'S LAWS OF MOTION. DOT CHAIN REQUIREMENTS ARE A JOKE IN AN ACCIDENT.
GEO

> Back to my original idea. Do you think the DOT chain requirements will really save your life when you stop faster than 0.8 g's?

> People who have been in an accident say the seat belt leaves burses. So what's your best guess how many negative g's do they experience? Then apply the -g's to DOT chain requirement and D ring strength. Strong enough???

Well George, no doubt the DOT requirements are intended to strike a balance between what is desired and what is practical. You're not going to tie down your machine using anchor chain off the Queen Mary, so at some point your chains will fail.

As I said in an earlier post, it seems that seat belts are designed to handle a 40 G crash. Most likely the assumption being that a 40 G crash is not survivable, even if your seat belts hold. But I'll bet most crashes are 10 Gs or less; enough to bruise you but not enough to sustain serious injury. And I'll bet very few truck crashes exceed 10 Gs. But that means there still must be a lot of truck crashes where the G forces on the load exceed the breaking strength of the restraints.

I suspect that the DOT wants to ensure that the tie-downs are not the weakest link. There are a lot of things that can fail in a 10 G crash: truck frame, trailer frame, trailer king pin, etc. If something else fails first, the full force of the impact will not be transmitted to the load tie-downs.

First off, there is a working load limit and a breaking strength for chains and D-rings. 6600lbs may be the working load limit for a G70 3/8" chain, but the breaking strength is 26,400lbs.

Second off, there is not likely to be a "sudden stop" because you will be bigger and heavier than what you hit. More high school physics here. You will "win" most collisions, unless your opponent is at least as large and heavy as you are. Your rig will plow through whatever you hit and you won't even come close to experiencing 30G.

Third off, okay, let's say you hit a bridge abutment at 60MPH and experience a 30G deceleration. You won't care because you'll be dead long before the tractor, whether or not it's still chained to the trailer, mashes the truck flat against the concrete.

You complain that the chains and D-rings aren't up to a 30G deceleration? Ad your truck and trailer to the list.

All this talk about G's and slugs and mass and force. All I can think of is......Gee, why would anyone force a slug to go to Mass??

My head hurts. :lol:

I agree, grab your ankles and kiss them goodbye.