COBRA Anti-Sway Coupler

My understanding is the ball in Europe is an integral part of the hitch,
and not bolted on like they are in the US; nonetheless, in the US it is
usually the trailer coming off the ball, not the ball coming off the hitch,

that causes a disconnect from the towing vehicle.

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me) "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorg.../download-the-
guide-1


Not sure about the rest of Europe but in UK tow balls can be of the bolt
on type. You do find more and more manufacturers of cars will provide
a detachable "swan neck" tow hitch

To get back to the original posters question the only thing I would say is
that really they are for make a good combination better not a bad
combination good. If it is not safe without an anti-sway hitch it probably
won't be safe with one, you will just be going a bit faster when it all
goes wrong.

To get back to the original posters question the only thing I would say is
that really they are for make a good combination better not a bad
combination good. If it is not safe without an anti-sway hitch it probably
won't be safe with one, you will just be going a bit faster when it all
goes wrong.

Similar Topic so figured I'd ask here rather than post a new thread.

Avoiding trailer sway by making sure there is enough weight at the front of the trailer is clearly stability enhancing as demonstrated in this video.

https://youtu.be/4jk9H5AB4lM

Does anyone know how much benefit might be obtained by increasing the weight at the back of the towing vehicle? If using a pickup truck, would adding a couple hundred pounds of weight at the very back of the pickup bed also add some stability, or is additional weight only helpful if it's behind the pivot point?

G

On Monday, September 7, 2020 at 11:30:06 AM UTC-6, Nick Hoare wrote:
To get back to the original posters question the only thing I would say is
that really they are for make a good combination better not a bad
combination good. If it is not safe without an anti-sway hitch it probably
won't be safe with one, you will just be going a bit faster when it all
goes wrong.

Nick is entirely correct. You can't fix an unstable trailer with an antisway device, but you can make up for a (slightly) unsatisfactory tow vehicle. Once again, MASS + longer wheelbase = better stability. And adding weight to the tow vehicle does NOTHING to increase the stability of the trailer, and the higher loading on the vehicle's rear wheels is likely to make a sway problem worse. (Think: Moment of Inertia.)

That being said, some weight on a lightly loaded rear axle will help with traction, but not stability.

On Thursday, September 3, 2020 at 4:40:00 PM UTC-7, wrote:
I've installed three or four of these on Cobra trailers. Very well made and nicely designed. I put them on both single place and two seat glider trailers. They are pretty effective at controlling sway, even though the customers all tow with full-size pickups or SUVs. It definitely helps when towing with a short wheelbase vehicle.

I can't say how effective they are with something like a VW Golf, (but I consider that to be too small to tow a glider anyway. Maybe the wagon, with the longer wheelbase will work better.) I know they tow with tiny vehicles in Europe, but the glider trailers all have an 80 kph limit over there. Here in the US, 75 mph freeway speeds, crosswinds and passing eighteen wheelers are going to make towing a pretty "sporty" adventure. Keep an eye on the rear view mirror. If the trailer changes lanes, try to stay in front of it ;-)

You do have to use an actual 50 mm ball. A two inch ball is too big for the clamping action and 1 7/8" is too small. Remember that it's unlikely that anyone else will be able to tow your trailer unless they also have a 50 mm ball. Order an un-plated (stainless steel) ball if possible. Chrome plating has a tendency to start flaking off under the clamping loads while turning. Lubrication is NOT permitted, as it negates the clamping friction that controls sway. Another issue is making sure the ball CANNOT turn and loosen the nut! No matter how much torque you put on the nut, it can still get loose. In Europe, the ball must be welded to the hitch plate. I usually machined a flat spot on the base of the ball just above the threaded shank and welded a piece of steel bar stock to the hitch plate.

Hope this helps.

I believe it may be important to get a "high profile" ball. These have more clearance between the bottom of the ball and the hitch plate. The anti-sway friction coupler itself is broader across than the typical non-friction coupler, so may hit the hitch plate when the trailer tilts to the side relative to the tow vehicle.

I believe it may be important to get a "high profile" ball. These have more clearance between the bottom of the ball and the hitch plate. The anti-sway friction coupler itself is broader across than the typical non-friction coupler, so may hit the hitch plate when the trailer tilts to the side relative to the tow vehicle.

Valid point, but, so far I have not seen any interference issues. Of course, I have only used these on receiver hitches. The hitch plate is only slightly wider than the base of the ball. If it was on a flat, wide surface (like a bumper mount) you might have clearance issues if the vehicle tilts significantly relative to the trailer (or vice versa). I believe the AlKo documentation specifies permissible limits on the angles involved.

Also, many receiver hitches have a significant amount of play between the inserted hitch tube and the receiver. This "slop" can exacerbate sway. I recommend any of these to remove the play:

https://www.etrailer.com/s.aspx?qry=..._Anti%7eRattle

On Monday, September 7, 2020 at 5:55:57 AM UTC-7, Aldo Cernezzi wrote:
I've been towing an Arcus M in Cobra trailer for years, using a compact Ford C-max 1.6 TDCI. Speed limit in Italy is 80kph on highways. Occasionally (as in France where it's legal, let's say), I drove at 125 kph or higher with no problems at all. One must be experienced and use the steering wheel with extreme care. Overtaking semitrailer trucks (they actually drive not any faster than 85 kph GS) requires careful planning and... some cool blood.

Have you weighed your trailer (including all accessories and other cargo)? Your trailer may weigh as much, or more, than your car. The heavier the trailer the more unstable the combination becomes.


please not that European towing bars (except maybe in UK) are very expensive at about 1800 USD with installation, they come to the market only after certification, are installed by few authorised stations, and require a technical inspection by the national authorities before you can hitch anything to it. I've never seen a tow ball coming off a vehicle, not even after 30 years in service.
Never under-estimate the ability of bureaucrats to make anything cost 4-5 times what it is worth.

wrote on 9/7/2020 2:51 PM:
On Monday, September 7, 2020 at 11:30:06 AM UTC-6, Nick Hoare wrote:
To get back to the original posters question the only thing I would say is
that really they are for make a good combination better not a bad
combination good. If it is not safe without an anti-sway hitch it probably
won't be safe with one, you will just be going a bit faster when it all
goes wrong.

Nick is entirely correct. You can't fix an unstable trailer with an antisway device, but you can make up for a (slightly) unsatisfactory tow vehicle. Once again, MASS + longer wheelbase = better stability. And adding weight to the tow vehicle does NOTHING to increase the stability of the trailer, and the higher loading on the vehicle's rear wheels is likely to make a sway problem worse. (Think: Moment of Inertia.)

That being said, some weight on a lightly loaded rear axle will help with traction, but not stability.

Generally, it's the characteristics of the tow vehicle and trailer that determines
the stability of the combination. We all know a trailer might tow better with one
vehicle but not the other one. My motorhome and mini-van illustrate this principle
well: the motorhome can tow the trailer much faster for the same wiggle than the
van can.

So, by adding weight to the tow vehicle (usually between the axles but favoring
the rear axle), then raising the tire pressures to match the new weight, can yield
a more stable combination. Using a friction damping device like the Cobra clamp
coupler can also increase the stability of the combination. There are other
devices to increase the damping that are frequently used on travel trailers, but
the Cobra unit is easy to use.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

wrote on 9/7/2020 3:31 PM:

I believe it may be important to get a "high profile" ball. These have more clearance between the bottom of the ball and the hitch plate. The anti-sway friction coupler itself is broader across than the typical non-friction coupler, so may hit the hitch plate when the trailer tilts to the side relative to the tow vehicle.

Valid point, but, so far I have not seen any interference issues. Of course, I have only used these on receiver hitches. The hitch plate is only slightly wider than the base of the ball. If it was on a flat, wide surface (like a bumper mount) you might have clearance issues if the vehicle tilts significantly relative to the trailer (or vice versa). I believe the AlKo documentation specifies permissible limits on the angles involved.

Also, many receiver hitches have a significant amount of play between the inserted hitch tube and the receiver. This "slop" can exacerbate sway. I recommend any of these to remove the play:

https://www.etrailer.com/s.aspx?qry=..._Anti%7eRattle

I use the style with the U-bolt for the ball mount on my van, which raised the
"safe" speed about 5 mph. I was surprised it was so effective, but I do have a
particularly tall and wobbly ball mount.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1