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03-22-2019, 02:03 PM
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#1
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Rivet Master
2019 28' Flying Cloud
2014 22' FB Sport
Davie
, FL
Join Date: Feb 2019
Posts: 904
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Weight distribution and sway control hitch not allowed
I saw this on the U-Hail website:
Weight distributing or sway control devices ARE NOT USED for towing U-Haul trailers. Towing a properly loaded U-Haul trailer does not require these devices. These devices may have a negative effect on vehicle handling and braking and may restrict the operation of the trailer coupling mechanism.
Any thoughts?
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03-22-2019, 02:29 PM
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#2
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 19,977
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No...
...Not really, they only use surge brakes on their larger trailers and don't care that your headlights are stargazing.
Bob
🇺🇸
__________________
"You don't know where you've been until you leave, enjoy life" RLC
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03-22-2019, 02:31 PM
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#3
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Site Team
2017 30' International
Broomfield
, Colorado
Join Date: Apr 2009
Posts: 3,555
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I those trailers (at least the ones I've rented) typically deploy surge braking mechanisms, which are not (generally speaking) compatible with WD and anti-sway hitches as they can restrict the movement of the braking mechanism.
They typically also have low GVWR, which reduces risk further from sway / heavy tongue that requires WD.
My wife drove our 2500 from Denver to Las Vegas tugging a U-haul trailer which probably weighed about 1,500lbs loaded. I had no concerns whatsoever for her safety.
That is my guess anyways... there are lots of knowledgeable folks on the forum who I'm sure weigh in.
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03-22-2019, 03:44 PM
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#4
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4 Rivet Member
Currently Looking...
Baltimore
, Maryland
Join Date: Nov 2017
Posts: 377
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03-22-2019, 03:49 PM
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#5
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Rivet Master
2007 27' International CCD FB
San Diego
, California
Join Date: Sep 2014
Posts: 2,115
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What wulfraat said about surge brakes being incompatible with WD equipment.
That said, U-Haul equipment is exceeding robust for the expected abuse they go though. They won't let you tow if the tow vehicle to trailer combination is not safe based on their database.
They also have some design elements that help protect from sway. Namely longer draw bars. This helps to minimize actual tongue weight on the vehicle, yet ensures that the center of gravity (what it's really about) that we like to reference as having enough tongue weight, is sufficiently ahead of the trailer axle to ensure stability and sway resistance.
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03-22-2019, 04:10 PM
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#6
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 19,977
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Yep...they sure are smart. 🤓
A toy car on a treadmill.😂
Bob
🇺🇸
__________________
"You don't know where you've been until you leave, enjoy life" RLC
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03-23-2019, 04:52 AM
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#7
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4 Rivet Member
Currently Looking...
Baltimore
, Maryland
Join Date: Nov 2017
Posts: 377
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They have to dumb it down so people on forums can understand it
Jim Fait is also chairman of the SAE Trailer Committee, he understands towing dynamics better than anyone on this forum for sure.
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03-23-2019, 05:02 AM
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#8
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Rivet Master
2014 20' Flying Cloud
Sag Harbor
, New York
Join Date: Jun 2015
Posts: 17,523
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03-23-2019, 06:40 AM
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#9
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 19,977
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Quote:
Originally Posted by Profxd
They have to dumb it down so people on forums can understand it
Jim Fait is also chairman of the SAE Trailer Committee, he understands towing dynamics better than anyone on this forum for sure.
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We be dumb all right...but happy.😁
I have never seen an AS designed like the trailer on the treadmill, single axle located dead center, and it sways...da.
I'm sorry but I feel that was just a cover your butt demonstration.
Setting up an AS properly is not SAE difficult. 🤓
Common sense, CAT tickets and/or a tape measure, all us dumb people can do it.👍
Bob
🇺🇸
__________________
"You don't know where you've been until you leave, enjoy life" RLC
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03-23-2019, 09:25 AM
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#10
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Moderator
2004 30' Classic Slideout
Fenton
, Missouri
Join Date: Mar 2002
Posts: 10,401
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Watched a single axle U Hall box trailer in a nose down position go into a yaw while being pulled by a Chevy Monte Carlo. I was behind him on the highway and we were both doing about 60. I noticed the sway and dropped back behind him. As the arc of the sway increased I knew he was going to lose control. I saw him throw on the brakes and the trailer back end of the car lost traction and the car skidded perpendicular to the highway. The trailer at that point was at a 45 degree angle fro the car. They all stayed upright and skidded off the shoulder. Very scary. I remember those trailers used to have decals that said max speed 45 mph on them.
Jack
__________________
Jack Canavera
STL Mo.
AIR #56 S/OS#15
'04 Classic 30' S.O.,'03 GMC Savana 2500
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03-23-2019, 09:40 AM
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#11
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Rivet Master
2007 27' International CCD FB
San Diego
, California
Join Date: Sep 2014
Posts: 2,115
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Boy are we a dysfunctional group. Toys are so beneath them as to provide no value?
For the uninformed, this is called a model based design. It is as legit as diagrams on a paper for which some might call a "drawing". Every discipline that has ever done design or engineering work, or heck just laying out a yard, utilizes drawings and if warranted, models to help understand and iterate.
It helps set the context, describe, and visualize the problem. In this case, to help layman better understand the dynamics of what's happening when putting too much load behind the rear axle. The proportions may be different, and it doesn't look like a 3/4 ton truck and AS, but the fundamental dynamics are absolutely the same.
For those interested in more than just "load behind rear axle". It's really about the center of gravity. When the center of gravity of the trailer is ahead of the rear axle, it is stable. Once the center of gravity moves rear, and ultimately past the rear axle, it get unstable to the degree that the center of mass goes further to the rear.
WD, PPP, HD trucks will help control and dampen the motions. But ultimately, get the tongue weight and center of gravity wrong, and with enough speed and force at play, it will bite you.
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03-23-2019, 09:51 AM
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#12
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 19,977
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Jack,
It's now 55mph to avoid... "Combination Disturbances" 🤔
"REDUCE SPEED to 55 mph or LESS.
Combination disturbances happen most often at higher speeds."
Toys do provide value...as playthings, like Airstreams.
Bob
🇺🇸
__________________
"You don't know where you've been until you leave, enjoy life" RLC
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03-23-2019, 10:39 AM
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#13
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Rivet Master
2019 28' Flying Cloud
2014 22' FB Sport
Davie
, FL
Join Date: Feb 2019
Posts: 904
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U-Haul has to make their trailers idiot proof so that weekend warriors who have never towed before can tow them without wrecking them. They seem to have settled on two basic conditions for safe towing, namely, loading the trailer with at least 60% of the load in front of the trailer axle, and having a tow vehicle with a curb weight of at least 80% of the trailer gross weight. They also tell you not to go over 55 mph even though they know most people won't adhere to that but hopefully will not exceed highway speed limits.
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03-23-2019, 11:00 AM
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#14
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Rivet Master
2007 22' International CCD
Corona
, California
Join Date: Jul 2013
Posts: 9,180
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Weight distribution and sway control hitch not allowed
Probably have the speed limit in their contract and on warning placards on their equipment to limit their liability. If you tow a Uhaul faster than what it’s marked for, liability will land on you, if push comes to shove, for violating the agreed speed limit. I can’t blame them. I’ve seen folks towing Uhaul hardware doing way over the speed limit. And in California, any vehicle towing a trailer is limited by law to no more than 55 miles per hour. Most of them are not even close to going the posted speed limit, trailer or not.
I usually set cruise control to no more than two or three MPH over, and I constantly get passed like I’m parked...and it’s particularly disturbing when it’s a dinky pickup pulling a 30 foot SOB toy hauler trailer with three feet of air under it. Their headlights are usually lighting up the trees as well.
I just let them go by, and hope I can stop before I get to their debris field down the road...
And we won’t talk about how they drive in the rain and fog. Lately it’s been rather wet and windy out here.
__________________
Rich, KE4GNK/AE, Overkill Engineering Dept.
'The Silver HamShack' ('07 International 22FB CCD 75th Anniversary)
Multiple Yaesu Ham Radios inside and many antennae sprouting from roof, ProPride hitch, Prodigy P2 controller.
2012 shortbed CrewMax 4x4 Toyota Tacoma TV with more antennae on it.
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03-23-2019, 11:58 AM
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#15
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Rivet Master
2017 28' Flying Cloud
2014 25' FB Flying Cloud
2008 25' Safari FB SE
Georgetown (winter)Thayne (summer)
, Texas & Wyoming
Join Date: Jan 2007
Posts: 6,602
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Quote:
Originally Posted by ROBERT CROSS
Jack,
It's now 55mph to avoid... "Combination Disturbances"
"REDUCE SPEED to 55 mph or LESS.
Combination disturbances happen most often at higher speeds."
Toys do provide value...as playthings, like Airstreams.
Bob
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Love that shirt!
__________________
Empty Nesters; Gypsies on the road! 2017 28' Twin Flying Cloud
2017 F250 King Ranch, 4X4, 6.7L, Blue-Ox WDH
Summer-Star Valley Ranch RV Resort (Thayne, WY); Winter-Sun City (Georgetown,TX)
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03-23-2019, 12:37 PM
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#16
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Liquid Cooled
2017 27' Flying Cloud
Currently Looking...
Currently Looking...
Currently Looking...
near Indy
, Indiana
Join Date: Mar 2006
Posts: 738
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Quote:
Originally Posted by ROBERT CROSS
Jack,
It's now 55mph to avoid... "Combination Disturbances" [emoji848]
"REDUCE SPEED to 55 mph or LESS.
Combination disturbances happen most often at higher speeds."
Toys do provide value...as playthings, like Airstreams.
Bob
[emoji631]
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I'll bite. What parts of the displayed physics become invalid when scaled up?
The Wright brothers used a wind tunnel; rocket scientists still do. Are they doing it wrong?
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03-23-2019, 01:23 PM
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#17
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 19,977
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...bite?
Are you saying we should not consider our Airstreams toys?
Bob
🇺🇸
__________________
"You don't know where you've been until you leave, enjoy life" RLC
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03-23-2019, 02:14 PM
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#18
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Registered User
2016 25' Flying Cloud
Fairfield
, California
Join Date: Sep 2016
Posts: 905
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Quote:
Originally Posted by ROBERT CROSS
...bite?
Are you saying we should not consider our Airstreams toys?
Bob
[emoji631]
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Wish I could afford to call it a toy [emoji56]
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03-23-2019, 04:18 PM
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#19
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4 Rivet Member
Currently Looking...
Baltimore
, Maryland
Join Date: Nov 2017
Posts: 377
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Quote:
Originally Posted by pteck
Boy are we a dysfunctional group. Toys are so beneath them as to provide no value?
For the uninformed, this is called a model based design. It is as legit as diagrams on a paper for which some might call a "drawing". Every discipline that has ever done design or engineering work, or heck just laying out a yard, utilizes drawings and if warranted, models to help understand and iterate.
It helps set the context, describe, and visualize the problem. In this case, to help layman better understand the dynamics of what's happening when putting too much load behind the rear axle. The proportions may be different, and it doesn't look like a 3/4 ton truck and AS, but the fundamental dynamics are absolutely the same.
For those interested in more than just "load behind rear axle". It's really about the center of gravity. When the center of gravity of the trailer is ahead of the rear axle, it is stable. Once the center of gravity moves rear, and ultimately past the rear axle, it get unstable to the degree that the center of mass goes further to the rear.
WD, PPP, HD trucks will help control and dampen the motions. But ultimately, get the tongue weight and center of gravity wrong, and with enough speed and force at play, it will bite you.
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Just as important as the COG is the position of the trailer axles. The further rearward the trailer axles are on the frame, the better the stability. This increases the distance of the coupler to the COG. So you can have a trailer that handles poorly even with the COG positioned just ahead of the trailer axles centerline.
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03-23-2019, 05:58 PM
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#20
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Rivet Master
2007 27' International CCD FB
San Diego
, California
Join Date: Sep 2014
Posts: 2,115
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Quote:
Originally Posted by Profxd
Just as important as the COG is the position of the trailer axles. The further rearward the trailer axles are on the frame, the better the stability. This increases the distance of the coupler to the COG. So you can have a trailer that handles poorly even with the COG positioned just ahead of the trailer axles centerline.
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Important. But we don't have much control to locate the axles. [emoji3]
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