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Trailer towing safety



 
 
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  #1  
Old August 11th 03, 05:34 AM
CH
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Default Trailer towing safety

"Tom Seim" wrote in message
There has been several threads in the past concerning towing Cobra
trailers with motorhomes, resulting in fatigue cracking of the
tongues.....
..................
I use a DrawTite load leveling hitch normally seen on travel trailers.
It uses two spring bars to apply an opposing torque to level the
trailer and tow vehicle. I started using it when the 600 lb tongue
weight (yes, 600lb=270kg!) sank my minivan to its knees...............
.................................................. ...... I have since

reduced my tongue
weight down to about 300 lbs (for a 2500 lb trailer). This is within
the 10-15% recommended range. I did try 125 lbs and found the
lowered stability objectionable.


Hi Tom,
I cannot help, but to shake my head mate.
No wonder some guys kill the tongue tube if applying 270kg load
onto it when 50kg=110lb are recommended and give you good
stability with an appropriate towing vehicle (I do not mean a big one,
one with stable suspension and short overhang will do).
Big overhang vehicles like motorhomes lead to high accelerations
at the tongue when driving over bumpy roads. More than once I have
seen trailers towed by motorhomes touch the ground when leaving
petrol stations. The standard Cobra tubes have been tested and pro-
vide a 25 safety factor for normal use. If you really want to experiment
with high tongue loading, then get the heavy duty square tube an re-
place the round one.

Chris Hostettler



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  #2  
Old August 11th 03, 07:07 AM
tango4
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Default

My setup.
Tow vehicle - 2.3 litre petrol engined MPV ( Ford Galaxy ) - I was stunned
at how well this vehicle tows a load.
Load in vehicle - 3 adults plus 2 weeks gear, flying kit and 6 cases of
assorted Bordeaux wines.
Trailer - Bog standard Komet II - about 350 kg and running on cross-ply high
load utility vehicle tyres
Load in trailer - Ventus Bt ( 325 kg ) tow out and tie down, gear, stands,
engine spares - the usual garbage.
Tongue load - 55 - 60 kg

This lot on a French motorway can do a very stable, but very illegal ,
100mph on the flats, I have a GPS track to prove it.
It will cruise all day at 70 - 75. It does not add significantly to the
driver workload, I can manage a semi-continuous drive ( 2 or 3 hour long
nap-stops ) from Tunbridge Wells England to Jaca in Spain - about 800 miles.

Possibly the biggest difference was made when I fitted 2 spoiler strips to
the leading edge of the vertical fin of the trailer. Following that mod
passing an articulated truck with less than 30mph speed differential, which
used to cause a 'dip' of the trailer due to the fin passing through the
trucks 'bow wave', has all but been eliminated. Try it!

If you need a 4, 5 or 6 litre travelling suburb, 220 kg tongue loads, fancy
air suspension or expensive sway dampers you simply are not doing it right!

Ian

"CH" wrote in message
...
"Tom Seim" wrote in message
There has been several threads in the past concerning towing Cobra
trailers with motorhomes, resulting in fatigue cracking of the
tongues.....
..................
I use a DrawTite load leveling hitch normally seen on travel trailers.
It uses two spring bars to apply an opposing torque to level the
trailer and tow vehicle. I started using it when the 600 lb tongue
weight (yes, 600lb=270kg!) sank my minivan to its knees...............
.................................................. ...... I have since

reduced my tongue
weight down to about 300 lbs (for a 2500 lb trailer). This is within
the 10-15% recommended range. I did try 125 lbs and found the
lowered stability objectionable.


Hi Tom,
I cannot help, but to shake my head mate.
No wonder some guys kill the tongue tube if applying 270kg load
onto it when 50kg=110lb are recommended and give you good
stability with an appropriate towing vehicle (I do not mean a big one,
one with stable suspension and short overhang will do).
Big overhang vehicles like motorhomes lead to high accelerations
at the tongue when driving over bumpy roads. More than once I have
seen trailers towed by motorhomes touch the ground when leaving
petrol stations. The standard Cobra tubes have been tested and pro-
vide a 25 safety factor for normal use. If you really want to experiment
with high tongue loading, then get the heavy duty square tube an re-
place the round one.

Chris Hostettler





  #3  
Old August 11th 03, 09:44 AM
Bruce Greeff
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Default

I must be missing something, but that tongue weight is crazy to me.

If I put my Cirrus in its trailer, and can't lift the hitch onto the
ball with one hand I know I have packed it wrong. OK - it is a light
combination with a total of 840Kg (around 1900lb) but not that different
from the one you tow. Stability is fine up to 65Mph behind my Renault
Scenic (2l mini-mpv) with a tongue weight of 40-50Kg. More will simply
load the suspension of the tow car unnecessarily and induce a pitching
motion. (tested the theory) My tow vehicle only weighs 50% more than the
trailer , but it tows effortlessly with a well balanced trailer.

A good stable tow car, with decent suspension and short rear axle to tow
hitch distance is the key. Introducing huge forces and then adding a big
"breakout" force in the form of a spring coupling merely makes the
combination harder to turn when you want it to turn, and makes the
transition to out of control sudden and unrecoverable.

  #4  
Old August 11th 03, 08:19 PM
Tom Seim
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Default

If I put my Cirrus in its trailer, and can't lift the hitch onto the
ball with one hand I know I have packed it wrong. OK - it is a light
combination with a total of 840Kg (around 1900lb) but not that different
from the one you tow. Stability is fine up to 65Mph behind my Renault
Scenic (2l mini-mpv) with a tongue weight of 40-50Kg.


This works out to 4.7-6% tongue weight, clearly much less than the
recommended 10-15%. Don't take my word for it: there are plenty of RV
Trailer magazines and web sites that deal with this. I have tried a
lighter tongue weight and found the stability acceptable to only 60-65
mph.


Introducing huge forces and then adding a big
"breakout" force in the form of a spring coupling merely makes the
combination harder to turn when you want it to turn, and makes the
transition to out of control sudden and unrecoverable.



This is just simply wrong. These devices were developed specifically
for towing large travel trailers and they work. Period. They
distribute the tongue weight evenly between the front and rear tires
instead of taking the weight off of the front. They are not hard to
steer and they don't suddenly become uncontrollable.

I am towing a heavy trailer than most of you, so you may get by with
lighter tongue weights by lowering your speed and being very careful.
I like to drive faster and have the extra safety margin.

The Easy Rider will reduce shock and vibration to your trailer, which
your (expensive) glider will appreciate.
  #5  
Old August 12th 03, 01:55 AM
Duane Eisenbeiss
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Default

"Tom Seim" wrote in message
om...
If I put my Cirrus in its trailer, and can't lift the hitch onto the
ball with one hand I know I have packed it wrong. OK - it is a light
combination with a total of 840Kg (around 1900lb) but not that different
from the one you tow. Stability is fine up to 65Mph behind my Renault
Scenic (2l mini-mpv) with a tongue weight of 40-50Kg.


This works out to 4.7-6% tongue weight, clearly much less than the
recommended 10-15%. Don't take my word for it: there are plenty of RV
Trailer magazines and web sites that deal with this. I have tried a
lighter tongue weight and found the stability acceptable to only 60-65
mph.

The 10%-15% tongue weight is really for house trailers (and such) with large
weights and large side area. Our glider trailers just do not need that much
tongue weight. If you need more that 75 pounds on the tongue, you most
likely have some other problem. Go to a big contest and lift the tongue of
30 - 40 trailers.

Duane


  #6  
Old August 12th 03, 07:26 PM
Tom Seim
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Posts: n/a
Default

The Draw-Tite weight distribution hitch uses two pivoting spring bars
that get pre-loaded to oppose the torque imposed by the tongue weight.
This transfers weight from the rear wheels to the front, besides
leveling the hitch connection. If a side gust is encountered, causing
the trailer to yaw, spring tension will increase on the side of the
gust. The pivot points are offset from the ball, resulting in a
restoring (gust cancelling) force. A similar effect occurs when going
over dips or bumps in the road: pitching oscillations are also
reduced. More info is available at:

http://www.draw-tite.com/

Be advised that a full hitch can cost 500-600 USD, but I consider it
worth it. My wife won't drive the rig without it. You are also less
tired after a day of towing. Last week we had an 8 hour day of driving
and felt fine afterwards.

BTW: These hitches don't work for tubular tongues: they must be square
(AFAIK).
  #7  
Old August 12th 03, 10:58 PM
mm
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Posts: n/a
Default


"Tom Seim" wrote in message
om...
The Draw-Tite weight distribution hitch uses two pivoting spring bars
that get pre-loaded to oppose the torque imposed by the tongue weight.
This transfers weight from the rear wheels to the front, besides
leveling the hitch connection. If a side gust is encountered, causing
the trailer to yaw, spring tension will increase on the side of the
gust. The pivot points are offset from the ball, resulting in a
restoring (gust cancelling) force. A similar effect occurs when going
over dips or bumps in the road: pitching oscillations are also
reduced. More info is available at:

http://www.draw-tite.com/

Be advised that a full hitch can cost 500-600 USD, but I consider it
worth it. My wife won't drive the rig without it. You are also less
tired after a day of towing. Last week we had an 8 hour day of driving
and felt fine afterwards.

BTW: These hitches don't work for tubular tongues: they must be square
(AFAIK).


Does the trailer surge brake still function?


  #8  
Old August 13th 03, 02:32 AM
Tom Seim
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Default

Does the trailer surge brake still function?

Good question, I don't know. It probably will because there is
"flexibility" in the chain linkage. Trailers usually used with this
type of hitch has electrical brakes (they are required to have a brake
that functions if the trailer separates from the vehicle). I don't
have brakes on my trailer.
  #9  
Old August 13th 03, 06:03 AM
tango4
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Default

Electric brakes, wow! We have to make do with a 2 foot long piece of steel
cable! Gee, you yanks really do have this technology thing down to a T!

:-)

Ian

"Tom Seim" wrote in message
om...
Does the trailer surge brake still function?


Good question, I don't know. It probably will because there is
"flexibility" in the chain linkage. Trailers usually used with this
type of hitch has electrical brakes (they are required to have a brake
that functions if the trailer separates from the vehicle). I don't
have brakes on my trailer.



 




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