The Physics of Towed-Vehicle Braking

[wa8yxm]

Another poster in another thread got me to looking at the Michigan Vehicle Code.. (I have heard the same "It is a car, not a trailer" argument) and like George in California I found the law is quite clear.

A car in tow, IS a trailer

Any vheicle, WITH OR WITHOUT MOTIVE POWER (emphasis mine)
Designed so the weight of the vehicle does not rest on the tow vehicle.

Actually this applies more to a car towed 4-down (no weight at all on the tow vehicle) than to a 5er (Some weight on the tow vehicle)

But the bottom line, is if it is towed, it' is a trailer

(NOTE: I did paraphrase. and leave out stuff) Ask if you want a direct quote or visit SOM - State of Michigan and download for yourself)

IN a reference to Lou and Peter Barrymore.. (They have a song the title of which I'm about to invoke)

you can often make that www. (Your State's Name Here) . com (The very funny, and accurate, song is titled "Your State's Name Here")

[melvonnar]

Definitions of 'trailer'
(trā́lər)

Dictionary.com · The American Heritage® Dictionary - (5 definitions)


(noun)

1. A large transport vehicle designed to be hauled by a truck or tractor.
2. A furnished vehicle drawn by a truck or automobile and used when parked as a dwelling or office.
3. • A short filmed advertisement for a movie; a preview.
   • A short, blank strip of film at the end of a reel.

[melvonnar]

Definitions of 'trailer'
- 4 definitions - WordNet

trailer(n.)someone who takes more time than necessary : someone who lags behindtrailer(n.)an advertisement consisting of short scenes from a motion picture that will appear in the near futuretrailer(n.)a large transport conveyance designed to be pulled by a truck or tractor

[melvonnar]

you pays your money and takes your choise.

[RustyJC]

Dictionary definitions don't count in courts of law - legal definitions do. From the Texas Transportation Code, Title 7, Subtitle C, Chapter 541, Subchapter C, Section 541.201:

(20) "Trailer" means a vehicle, other than a pole trailer, with or without motive power:

(A) designed to be drawn by a motor vehicle and to transport persons or property; and

(B) constructed so that no part of the vehicle's weight and load rests on the motor vehicle.

Rusty

[melvonnar]

I've been traveling all my life; been to every state (lower 48) many times;never been stopped; have always pulled (call it what you like) a toad; been through nearly every city; I have never been stopped because i'm pulling a (trailer ??). question? why worry about something that in all likely hood will never happen. I'm presently working on the next 500,000 miles. I say enjoy what you can and quite worring about something that in all probibility will never happen.
they have laws for just about everything; I say go with the flow and don't worry about the small stuff.
I put those definations up there to only show that there are many definations about just about every word.
legal, smigal

[TXiceman]

The bottom line is, legal or dictionary definitions, the laws of physics still rule. The motorhome has no way to sense if you are pulling 4000# 4-down, a dinghy on a dolly of a utility trailer loaded with 4000# of rocks, the motorhome now has an additional 4000# to stop. The mass is moving and has energy which has to be absorbed or dissipated to stop the additional load. The brakes on the motorhome can only stop so much weight. The more weight, the more braking force is required to stop it.

So, the dinghy with brakes will assist by taking part of the braking load. With the dinghy brakes, you should stop a bit faster and a shorter distance. This may be the distance that is required to prevent an accident. Stopping 3 feet shorted may mean that are are not 2 feet into the vehicle in front of you.

Yes, I am an engineer and I have been know to wear a belt and suspenders.

Ken

[melvonnar]

Originally Posted by TXiceman

The bottom line is, legal or dictionary definitions, the laws of physics still rule. The motorhome has no way to sense if you are pulling 4000# 4-down, a dinghy on a dolly of a utility trailer loaded with 4000# of rocks, the motorhome now has an additional 4000# to stop. The mass is moving and has energy which has to be absorbed or dissipated to stop the additional load. The brakes on the motorhome can only stop so much weight. The more weight, the more braking force is required to stop it.

So, the dinghy with brakes will assist by taking part of the braking load. With the dinghy brakes, you should stop a bit faster and a shorter distance. This may be the distance that is required to prevent an accident. Stopping 3 feet shorted may mean that are are not 2 feet into the vehicle in front of you.

Yes, I am an engineer and I have been know to wear a belt and suspenders.

Ken

I'm a chew chew driver to; whoo whoo goes the train. pun intended

[Ken-55]

Originally Posted by SMI Manufacturing, Inc.

Managing momentum does get hairy with one of these beasts. The coach, in effect, becomes a giant lever with far more mechanical advantage than that of a regular automobile, and when you reach the turning moment, hang on! If this change of motion takes 50% of the tires available traction, then there is only 50% left for braking, resulting in a longer stopping distance. So in short, if you are not going to clear the accident, you are better off to put 100% of available traction to stopping rather than frivolously using it for lateral movement; and the amount of available braking traction greatly increases with the "towed's rubber" in the braking picture.

Brent Schuck
Research and Development
Graphic Design

Wow! . . . I never thought of it that way.

This is valuable info even when not towing.

Thanks!

[RustyJC]

Originally Posted by Ken-55

Wow! . . . I never thought of it that way.

This is valuable info even when not towing.

Thanks!

If you Google the term "friction circle", you'll find a lot more reading on this concept. "Friction circle" is a mathematical/graphical representation used in the racing community that illustrates how a tire's available traction is being used - i.e., what percentage is used for turning, for deceleration or for acceleration.

HERE is one article on the subject.

An illustration, as a racer "trail brakes" into a turn, as he turns the steering wheel into the turn, he will lighten up on the braking, thereby using more traction for turning and less for deceleration.

Rusty

[wa8yxm]

Originally Posted by robert h

Definitions of 'trailer'
- 4 definitions - WordNet

trailer(n.)someone who takes more time than necessary : someone who lags behindtrailer(n.)an advertisement consisting of short scenes from a motion picture that will appear in the near futuretrailer(n.)a large transport conveyance designed to be pulled by a truck or tractor

That is very good Robert but has nothing to do with anything.. The dictionary you used is a very good one but it is NOT the law.

The one I used, which says clearly that a car, towed 4-down IS a trailer.. IS the law, at least in the state of Michigan.

If you look in a good biology dictionary you will see that a Tomato is a fruit

But by law Congress has declared it a vegetable.

The dictionary you cited is correct.. But it is NOT the law.

I will add that in some cases (The trailer) I happen to agree with Congress.. In others.. Well.. I'll let you decide.

[desertdust]

Thanks for all the info. I just bought a Jeep Wrangler to tow behind my gasser Winnebago. A local hitch installer said people tow all the time with no supplemental braking. I told him I won't be one of them. Happy RVING

[TXiceman]

Originally Posted by desertdust

Thanks for all the info. I just bought a Jeep Wrangler to tow behind my gasser Winnebago. A local hitch installer said people tow all the time with no supplemental braking. I told him I won't be one of them. Happy RVING

Ken

[tbfirm]

My installer told me for every 20 hitch setups he installs on toads he does 1 brake setup. I say there are alot of foolish RVers out there if this is the case.