Share Your Real World Tongue Weights & Trailer Weights

[rostam]

Originally Posted by cwf

9120# with 50 gallons fresh water aboard, two batteries and Bout 50 pounds of LP..(one 40# tank partially used) , all food, clothes, assorted wines... For 4 days. ( fridge was almost full). Had clothes for Sunday, too.

My wife remarked...(oh, so I can put more in the AS!!!????).. Uh, no, sweetie!!!

Thanks cwf!

I had heard that the 34 ft Airstreams have tongue weight less than 10% of the trailer weight (in your case its just below 9%), yet they are very stable.

[cwf]

Originally Posted by rostam

Thanks cwf!

I had heard that the 34 ft Airstreams have tongue weight less than 10% of the trailer weight (in your case its just below 9%), yet they are very stable.

Yes, that much mass along with good and well set hitch, plus, the right horse to lead the way and it works!

Now, because of length, if careless, I could imbalance things. For instance, if I were to have full waste tanks, store 200k rounds of 50cal ammo and weapons against the stern wall, I could get a lot of weight off the "front/bow". That would put more weight on rear AND increase load on rear axle.

On " level " ground, the "bow"/nose is about 3/8" higher than the rear/"stern".

We run with very consistent loading on TV and AS and have no surprises. The AS once had EzyLift WD and "sway damping". It did "move" when big trucks passed and other wind conditions occurred. Now, there is no "sway" at all.

Now, my first transportation after my feet and bicycle was a boat. Then aircraft. I am keen on "weight and balance" having experienced / survived "improper" loading.

So, take time to PLAN then execute well. Hardware will only get you so far.

[Adiredneck]

Originally Posted by Adiredneck

I ordered and received the Sherline shortly after my prior post, but my A/S was down in Gulfport for some warranty work (cracked FW tank), so I didn't get to try it out. Results of today's weigh in showed 900# tongue weight, with the TT dead level front to back (per the stick-on bubble levels, anyway). All tanks are empty, one propane tank full, the other at 1/2. The manufacture weight sticker says it weighed 6509 at the factory, and the literature for a 2014 27FB Classic Limited says the base weight (w/ LP, w/o water or cargo) should be 6672 and "hitch weight" (also w/ LP and w/o water or cargo) should be 792.

At 900# "dry weight" I guess I need to watch what/where we pack. We don't bring all that much, as a two-week vacation is the extent of all trips, and I don't see us exceeding the 2491 lbs of allowable cargo/fluids per weight sticker (9000#GVW).

We're heading out for a trip next month, and I will weigh her again when she is loaded with clothes, food, gear and around 25% filled FW tank. I also want to hit some CAT scales on our trip to get some axle weights for both TV and TT. Anything else I should be watching or aware of?

PS - dumb newbie off-subject question: I'd like to check the torque on A/S lug nuts, but they have aluminum snap caps over them. Is there a trick to popping them off so I can put a socket on them without breaking/bending them?
__________________________________________________ _____

2014 Classic Limited 27FB, Equilizer hitch with 1000# bars
2001 Dodge 2500HD Reg Cab/8' box with 24v Cummins TD/5pd stck

Sorry for doing this in fits and starts, but that's pretty much the way things go around here.

First, I need to make a clarification on the above post due to a later discovery. When I weighed the tongue with the Sherline and got 900# I was assuming that was on a pretty much "dry weight" basis, as we had not started to load anything for the trip, and I thought all water tanks were empty. Come to find out, the shop had loaded the fresh water tank to full after they had replaced it, so it was carrying the full 54 gallons.

I did manage to stop by a CAT scale on my way back to Mississippi from New York State last week, and here are my readings:

With TV/TT hitched and WD (Equil-i-zer) connected, 25% in FW tank, 1 full 40 gal LP tank, one empty; maybe 5 gals each in BW and GW, driver, full diesel fuel tank and gear/cargo on board for a 2 week vacation:

Front Axle: 3980

Rear Axle: 4240

Trailer axle: 6620

Gross Weight: 14480

I know that to get a full and accurate picture, I needed to unhitch the truck and trailer and weigh each individually and without weight distribution, but we were already pushing for a 600 mile day, so that didn't happen. The factory weight (with propane, without water or cargo) of the trailer was 6509; also, per the old window sticker, the dry weight of the truck should be 6140 (GVWR - stated payload). So, if I'm doing the math correctly - which is highly doubtable - my combined curb weight for both should be 12649, meaning I had 1831# of fuel and cargo? Does that sound right?

Well, here's my contribution - more raw data if not enlightenment!

[boondockdad]

Originally Posted by Ron Gratz

Ross, your scales data indicate a tongue weight of 1316# with 136# transferred to the TT's axles giving a net load addition of 1580# on the TV. The numbers also indicate a FALR of about 42%.
However, since the TT was nose down by about 4-5", both the tongue weight and the load transferred to the TT probably are larger than the indicated values.

Have you considered switching to a High Rise Ball?
If you lift the coupler by 2", relative to the hitch head, you should get a significant increase in load transfer.

Ron

I know this sounds pretty anti-intuitive but, tongue low will register lighter tongue weight, while tongue high will register higher weight. Only perfectly level trailer will register accurate tongue weight

[dznf0g]

Originally Posted by boondockdad

I know this sounds pretty anti-intuitive but, tongue low will register lighter tongue weight, while tongue high will register higher weight. Only perfectly level trailer will register accurate tongue weight

Tongue low moves the CG forward and increases TW.....on a single axle trailer or trailers with spring suspension and an equalizing link.

On a multi axle trailer with independent torsion axles, the change in CG is offset by more weight on front axle when tongue is low. What that offset is, I don't know, but it is different when center of combined axles' load moves forward relative to the midpoint between axles.

So....IMO, you're both thinking right with certain setups.

[Ron Gratz]

Originally Posted by dznf0g

On a multi axle trailer with independent torsion axles, the change in CG is offset by more weight on front axle when tongue is low. What that offset is, I don't know, but it is different when center of combined axles' load moves forward relative to the midpoint between axles.

When a trailer with independent torsion axles is in a nose-down stance, the front axle arm pivot point moves downward relative to its axle and the rear axle pivot point moves upward.
The load on the front axle increases and the load on the rear axle decreases.

If the TT's ball coupler is down 4" relative to a "level" stance, and the distance from ball to axles' mid-point is 20', the slope of the TT would be about 1 degree.
Assuming the center-to-center axle spacing is 3', the front torsion tube axis would drop about 0.32" and the rear tube axis would rise about 0.32".
Assuming an axle pivot arm length of 6", the arm would rotate about 3 degrees.

A typical torsion axle will swing 22.5 degrees when the load changes from unloaded to rated load.
An torsion axle rated for 5000# would have a spring coefficient of 5000/22.5 = 222 #/degree.
An axle-arm angle change of 3 degrees would correspond to a tire load change of 666#.

With a center-to-center axle spacing of 3', an increased load of 666# on the front axle and a decreased load of 666# on the rear axle would generate a torque of 666*3 = about 2000 lb-ft.

For this example, the torque combined with the ball-to-axles distance of 20' would result in a decreased tongue load of about 100#.

Ron

[dznf0g]

Ron, Unless I am missing something, I don't see where you have accounted for the change in CG of the sprung load as the AS tilts forward.

[Ron Gratz]

Originally Posted by dznf0g

Ron, Unless I am missing something, I don't see where you have accounted for the change in CG of the sprung load as the AS tilts forward.

It depends on how far above the axles the CG is located.

If we assume the CG is 2' above the axles, a 1 degree nose-down slope would cause the CG to move forward about 0.4".
Assuming 8000# of unsprung weight, this forward movement would result in a torque of about 8000*0.4/12 = 267 lb-ft.

With a ball-to-axles distance of 20', the forward movement of the CG would cause the ball load to increase by about 267/20 = 13#.

Ron

[dznf0g]

right, And I am being a bit picky though...and this exercise illustrates muti-axle torsion axles only, but even an empty AS will have some CG forward movement and as the body and all the furnishings are above the axle centerline. Too many variables for individual loading to be really accurate here. Storing all your ceramic dishes, canned goods, pots and pans in overhead locker would have a greater effect than all of them in drawers at floor level and bread and cereal in the overheads......etc. Partially full holding tanks will have some effect as well.

Theoretically, it is possible, with enough forward tilt that you could pass the point of CG equilibrium and increase tongue weight on a torsion axle....but not practically. I imagine the tongue would have to be below street level to reach equilibrium.

[Lance M]

I heard a new term on another forum that describes the last few posts here-
"Engineer induced mental masturbation"

[dznf0g]

Originally Posted by Top

I heard a new term on another forum that describes the last few posts here-
"Engineer induced mental masturbation"

NICE!!!! Thank goodness I am not an engineer.....I just get to play/discuss/argue with them for the last 30 years.

[Jim Flower]

Originally Posted by dznf0g

NICE!!!! Thank goodness I am not an engineer.....I just get to play/discuss/argue with them for the last 30 years.

Same. But appreciate the proposed theory on why I enjoy the discussion so much. Jim


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[slowmover]

Originally Posted by dznf0g

Tongue low moves the CG forward and increases TW.....on a single axle trailer or trailers with spring suspension and an equalizing link.

.

Mine is a leaf sprung TT. TW was significant on that trip.



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[Larry C]

Originally Posted by Top

I heard a new term on another forum that describes the last few posts here-
"Engineer induced mental masturbation"

This comment precisely describes about 95% of these comments. Rving is supposed to be fun, but when it gets to be a "one upmanship" contest on knowledge, it begins to be boring.....not fun any more....

I've never seen so many people with so much knowledge, each one, just waiting to see if they can out do the one before.

For whatever it's worth.

Larry C

[slowmover]

You sure it's as you attempt to describe?

Recommend you go back ten years on this and other RV forums in re this type of discussion. Formulate the differences between then and now.

Otherwise it may be you've said more about your own motivations than of others when in this type of search.

The Net has made it both easier and more difficult. Easier in that these topics exist and not according to a few editors. Difficult in that there is far more to read through.

Your own tests are welcome and in the best spirit. Numbers, quantification, is neutral enough. How it may be interpreted appears to shed readers along the way. Knowledge is beset by lack of information and understanding seems too distant.

Have a long look. Good luck

.


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[SteveSueMac]

I don't agree, Larry C. There's all kinds of having fun camping. This will sound ridiculously geeky but for the 6 months I was waiting to take delivery, I read every piece of paper in that little briefcase they gave me - many of them several times. That was fun because it helped me prepare.

This is my first (and I trust last) rig ever. Part of being able to have fun for me included trying to absorb as much knowledge as I could from others who have both practical (i.e. camping) and technical (i.e. education) experience to share.

I don't consider myself an expert by a long shot so when someone like a Ron G is willing to share - not only in these forums but with a very generous offline series of conversations to help me understand my specific setup - I am deeply grateful. And for what it's worth - the spirit in which that advice is offered strikes me as generously willing to help a fellow camper - not boastful one upmanship in the least.

There are other experts too - you can agree, disagree, what have you. That's what makes the forums useful to me.

Now that I feel I have enough technical understanding on some issues a a layman - I'm much more comfortable with my rig, how to drive, how to set up, how to camp, etc. I have enough experience at the scales that I'm comfortable just going once at the start of the season to fine tune and then enjoy the heck out of it.

Some of us like that. You may be fine without it. To each his own - but I don't think the discussion here is usually one upmanship.

For whatever that's worth :-)

[cwf]

Sometimes we don't explain things in ways that make the info palatable. To each their own. I may be "biased" because of my experiences. For me THE truth is my truth. For Larry it may be a waste of bits-n-bytes, whatever THOSE are.

What are we trying to become as a "forum" is people who care. Chances are, most of you are... Jury still blinking at me personally.

If you are here to help, glad to have you... Let's figure out how to
Do that respectfully. Isn't that what yAll are saying?

[boondockdad]

Originally Posted by Top

I heard a new term on another forum that describes the last few posts here-
"Engineer induced mental masturbation"

That's pretty harsh

I appreciate factual information provided by members with real knowledge.. AOT the cow puck one usually finds in forums

[nickmeloy]

Originally Posted by Larry C

...
I've never seen so many people with so much knowledge, each one, just waiting to see if they can out do the one before.
...

On almost all of the forums that one may read, there are misleading and, sometimes, totally incorrect postings. Please don't rant, this is not a condemnation of any one person.

It is better to read many posts on a subject and learn to sift the correct information from the incorrect information. This is not easy, and it places a significant burden on the reader to learn enough to know what is correct ( or at least seek out an accepted expert in the field to determine what is the best thing to do).

We should be thankful that the people that post within their area of expertise are willing to do so,

[AirHeadsRus]

Originally Posted by Top

I heard a new term on another forum that describes the last few posts here-
"Engineer induced mental masturbation"

Dang Top, you may be on to something. Like in the good ole days when 2'Air kept them all honest and moderated the moderators.
Cheers!