Re: [SilverStreak] size of propane tanks

[<waymark1@xxxxxxxx>]

Minimum 15% sounds more like a 5th wheel/gooseneck trailer. They are commonly up 
to 25% of the total trailer weight for towing by pickup trucks or flatbeds. (Freight 
semitrailers are typically 50%-50% 5th wheel-trailer axles.)
The recommendations (such as SS owner's manual) for weight on the trailer tongue (at 
the coupler socket where it goes on the hitch ball) BEFORE tensioning the spring bars 
is usually 10%-15%. One says 7%-12% but that's the only one I've seen.

TYPE OF TRAILER               PERCENT OF WT. ON TONGUE
Single Axle                   10% minimum/15% maximum
Tandem Axle                   9% to 15%
Travel Trailer                11% to 12%
5th Wheel                     15% to 25%
Reference: www.sherline.com/lmbook.htm#refrn9

Conventional travel semitrailers are tricycles. The single "virtual" front wheel of the 
trailer is at the center of the rear axle of the tow vehicle. A hitch ball provides no 
roll resistance to the trailer. All roll stability is provided by the trailer axles. A 
weight carrying setup (no WD) becomes less and less resistant to trailer roll as the 
proportion of the trailer weight is shifted to the hitch. A WD hitch shifts part of the 
tongue/hitch load to the trailer axles - "weight transfer" - increasing trailer roll 
stability toward its maximum, which is if there was no load on the hitch and all trailer 
weight was on its axles. Such would likely sway like mad at the slightest provocation, but 
it wouldn't roll. WD hitches are never supposed to be set up that tightly.
5th wheel hitches that rock freely from side to side for several degrees give no roll 
stability from the tow vehicle until the 5th wheel rocks to its limit. Some have hydraulic 
dampers to provide some roll stability to the trailer from the tow vehicle.
Gooseneck/stinger (farm/utility trailer) hitches (ball in the truck bed) give no roll 
stability other than the friction of the coupler socket on the ball, which if greased 
should be very slight. They depend entirely on the trailer axles for roll stability. The 
lower the center of gravity, the less roll tendency.
Illustration of roll: www.sherline.com/lmbook.htm#refrn9 under 
"Driving In Windy Conditions"
Illustration of sway (tailwagging of either or both trailer and tow vehicle): 
www.sherline.com/lmbook.htm#refrn9 under "More Towing Tips"

"NOTE ABOUT LOAD EQUALIZING HITCHES...
"A load equalizing [weight distributing] hitch is selected base[d] on the trailer's actual 
tongue weight rather than on gross weight. This type of hitch has some real advantages, 
but government studies have shown they can actually work too well, lightening the load on 
the rear wheels of the tow vehicle sufficient to reduce traction. This kind of hitch should 
be selected carefully, installed by professionals and its operation understood by the user." 
www.sherline.com/lmbook.htm#refrn9 scroll between 1/2 and 2/3 down the web page

The spring bars should be rated such that the loaded trailer weight is between the spring bar 
spec limits. Too light for the trailer weight and the spring bars can't be tightened enough 
to do a good job. Too strong and the spring bars may do nothing (go loose) on road crests and 
practically lift the tow vehicle rear axle off the road in dips. The load on the tow vehicle 
rear axle should never be less than the tow vehicle rear axle load without the trailer.

Keneth, the weight sticker on the door post or edge should give the maximum load for the axles 
individually. The tires are often the limiting factor. Neither rear (or any) tire should ever 
be loaded beyond its maximum load rating printed on the sidewall. If you have duals, note that 
the dual load rating is less per tire than for single loading.
The Dual Cam sway control is a separate device from the WD system. The spring bar cams used to 
be added on to the spring bars, and still can be obtained for adding to straight spring bars. 
Newer Cequent (Draw-Tite, Reese, Fulton, Wesbar, Bulldog, Crown Eclipse, Hidden Hitch, Bargman, 
ROLA and Tekonsha are the Cequent brands; not all are used on hitches) spring bars come with 
the spring bar cams formed into their rear ends so no separate spring bar cam is needed. The 
parts for each system, old and new models, are different but the function is the same.
The Dual Cam system functions by locking the tow vehicle and trailer in a straight line. This 
has enough "give" to allow rounding gentle curves without unlocking the cams. For sharp turns 
the cams release (with a "bonk" or "graunch" sound, which disconcerts new users!) and allow 
nearly free swiveling until the combination returns to a straight line, then the cams lock again.
The Dual Cam instructions prohibit greasing the cams. They should be kept clean; only a very 
light grease of the vaseline kind is permitted if the creaking sound of rounding gentle curves 
is too annoying.

You probably already know these things - some who read these posts may not.
Al

-- Keneth Wilson <ke5dfr@sbcglobal.net> wrote:

I also tow my SS with a WD sytems.  I use a Reese Dual Cam HP which is both sway control and 
weight distributing.  The truck can well handle the relative light load on the hitch.  My 
truck has an 11,500# GVWR and actual weight is about 8000#, so it can carry 3500# in the back.

The WD hitch is set to transfer some of the weight to the front axle which does improve the 
ride and the steering.

I am an engineer and like to make sure we have everything SAFE.  With a well balanced trailer, 
you can never say that it will never sway.  You never know when you will get hit by the sudden 
gust of wind from a passing vehicle, over a river or such.  The sway control is cheap insurance 
for that one time that you might need it.
 
Ken Wilson 
KE5DFR@sbcglobal.net 
Cypress, Texas

----- Original Message ----
From: Tom Patterson <pattersontj@sbcglobal.net>
To: sslist@tompatterson.com
Sent: Thursday, March 13, 2008 7:08:16 AM
Subject: Re: [SilverStreak] size of propane tanks

Al,

The recommendation by at least Sherline is not "maximum 15%", but rather "at 
least 15%".  Others will set the maximum lower, but I think that in many cases 
this is without a weight distribution hitch and spring bars.
The tricycle comparison is, I believe, not applicable as it ignores too many 
factors.  Fifth wheel trailers, also with a triangle setup have up to 25% of their 
weight on the tow vehicle.

The problem with too much weight is what it does to the tow vehicle.  Aside from 
the effect on the rear axle and suspension, both steering and braking deteriorate 
with all the weight on the rear.  The remedy is in the weight distribution  hitch 
and spring bars, which move some of that weight both to the tow vehicle front axle, 
and to the trailer wheels.

Again, in my case, I have neither a sway problem, nor a "wallowing" problem with 
approx. 800 lbs. and a 4,500 to 5,000 lb. trailer.  I do have a lot of truck, but 
I also use a weight distribution hitch with spring bars to move some of the 800 lbs 
forward and backward.  I have not weighed the setup after hitching up, but know that 
I have a lot less than 15% - perhaps 12% of the tongue weight on the hitch with the 
use of spring bars.

-Tom


----- Original Message ----- 
From: <waymark1@juno.com>
To: <sslist@tompatterson.com>
Sent: Thursday, March 13, 2008 6:05 AM
Subject: Re: [SilverStreak] size of propane tanks


> 15% of 4,500# is 675#; 15% of 5,000# is 750#. 800# is above the maximum 
15% recommendation for tongue weight.
> Too much weight on the tongue makes for "wallowing" by the trailer, which 
is supported on a triangle like a tricycle. If you recall your kids' trike, if 
you leaned forward it was easy to tip over. For coasting down hills you leaned 
back toward the rear wheels for stability. Of course there was little or no 
loading out behind the rear axle (5th wheel trailers are more like this), which 
is not the case with "teeter-totter" RV trailers. A second kid hanging out the 
back of the trike made the trike want to veer all over.
> If the center of gravity is high, it makes "wallowing" even more likely.
> A tow vehicle that is heavier than the trailer makes up for a lot of trailering 
sins. :-)