No need for theory caravan shake

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windmill john
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No need for theory caravan shake

Postby windmill john » Mon Jul 09, 2018 3:17 pm

Well this explains it clear enough. No maths in sight, just a simple (even Windmill John understands!) demonstration:

https://www.youtube.com/watch?v=KyagKzvJwYw
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Schorsch - 1978-80 R65 - bit of a Shetland pony; frisky and naughty.
Max - 2009 F800GS- where’s the desert at!?
Too many bikes have come and gone, trying to be sensible now!

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Galactic Greyhound
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Re: No need for theory caravan shake

Postby Galactic Greyhound » Mon Jul 09, 2018 6:36 pm

John,

That is a great safety video and should be compulsory viewing for anyone towing!

Presumably, the instability is a function of the weight on the tow hitch.
Never having towed to any great extent, are there recommended tow hitch weights for caravans/trailers?
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

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windmill john
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Re: No need for theory caravan shake

Postby windmill john » Mon Jul 09, 2018 6:45 pm

Sorry Ced it is just an interesting video I found.

I would guess though the reason it works is that the first weights were in line with the wheels, whilst the later test would create swivelling round the wheel axis.

John
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Schorsch - 1978-80 R65 - bit of a Shetland pony; frisky and naughty.
Max - 2009 F800GS- where’s the desert at!?
Too many bikes have come and gone, trying to be sensible now!

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Galactic Greyhound
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Re: No need for theory caravan shake

Postby Galactic Greyhound » Mon Jul 09, 2018 7:10 pm

I was thinking of how many caravans with a scooter mounted on a rear rack I have seen snaking on the motorway!
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

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Re: No need for theory caravan shake

Postby Richard(Sande)Sanders » Mon Jul 09, 2018 8:30 pm

John,

That is a great safety video and should be compulsory viewing for anyone towing!

Presumably, the instability is a function of the weight on the tow hitch.
Never having towed to any great extent, are there recommended tow hitch weights for caravans/trailers?
There are weight limits for the towing hitch, the tow ball, & the towing vehicle, plus maximum weight of the trailer
& its load, the maximum weight of the towing vehicle & its load, axle weight limits, & the all important maximum
train weight of the towing vehicle.
Trailers should be loaded evenly but slightly nose heavy, 50 to 100 kgs is usually enough to prevent snaking. You
must not exceed ANY of the weights given for trailer or vehicle. The train weight of the towing vehicle is the
maximum weight that any particular vehicle & trailer combination, plus its load & passengers/driver, can weigh when
used on a public road. This means you can't always fill a trailer to its maximum.

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Re: No need for theory caravan shake

Postby Lolo » Mon Jul 09, 2018 10:11 pm

Great little video
Living the dream :sunny:

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Galactic Greyhound
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Re: No need for theory caravan shake

Postby Galactic Greyhound » Mon Jul 09, 2018 11:02 pm

..…………….. There are weight limits for the towing hitch, the tow ball, & the towing vehicle, plus maximum weight of the trailer
& its load, the maximum weight of the towing vehicle & its load, axle weight limits, & the all important maximum
train weight of the towing vehicle.
Trailers should be loaded evenly but slightly nose heavy, 50 to 100 kgs is usually enough to prevent snaking. You
must not exceed ANY of the weights given for trailer or vehicle. The train weight of the towing vehicle is the
maximum weight that any particular vehicle & trailer combination, plus its load & passengers/driver, can weigh when
used on a public road. This means you can't always fill a trailer to its maximum.

Thanks Richard! :smile:
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

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Re: No need for theory caravan shake

Postby DEEP DIVER » Tue Jul 10, 2018 10:49 am

Great find John. I used to tow a large box trailer behind a LWB Land Rover and it used to sit well on the road. It was only loaded with one thing, a hot air balloon basket with the burners and balloon.
A bit like this one.

https://www.bing.com/images/search?view ... ajaxhist=0
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Re: No need for theory caravan shake

Postby Nate » Wed Jul 11, 2018 10:19 am

Great video and some good information here - thanks.

I used to tow a 25' boat that sat on a combined launching trolley / breakback road trailer. The boat was about 2 tons and the trailer was a splendid thing - very nicely engineered. It was however a complete and utter b*stard and however I arranged the weight could and would break into heart-stopping weaves at anything over 50 mph. Later I had a 24' ex Navy rib on a cheapo twin axle trailer and the thing ran straight as an arrow and refused to be provoked whatever the speed.

You can buy gadgets that fit between the trailer and the towing vehicle that seek to damp down the oscillation that occurs in a weave, but I've always thought they were just symptomatic and were just masking the problem. The issue needs attention though - surprised the caravan industry aren't more bothered...

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Rob Frankhamr
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Re: No need for theory caravan shake

Postby Rob Frankhamr » Wed Jul 11, 2018 6:50 pm


You can buy gadgets that fit between the trailer and the towing vehicle that seek to damp down the oscillation that occurs in a weave, but I've always thought they were just symptomatic and were just masking the problem. The issue needs attention though - surprised the caravan industry aren't more bothered...

Most caravanners these days use some sort of friction stabiliser that seeks to control the build up of oscillation between the towing vehicle and the trailer. In most case, they are an integral part of the towing hitch. A simple solution that works well. As you say, it's treating symptoms not causes... but... that isn't a valid reason not to use one.

Like most youtube videos, this one, while making a valid point, is very simplistic. I towed caravans, vehicle trailers etc. for a number of years and many thousands of miles. The old rules to stop and control a 'snake' are still, I believe, valid:


  1. Don't exceed the gross trailer weight... it's amazing how difficult that can be sometimes when you're going on holiday with the wife and three teenagers.
  2. The trailer weight should not exceed 80% of the towing vehicle weight.
  3. The majority of distributable weight should be in the centre of the vehicle, over the axle(s) and should be equally distributed from side to side.
  4. If some items must be stowed at one end or the other of the trailer, put light items at the end and heavy items in the centre.
  5. All distributable weight should be securely secured in place.
  6. The noseweight (i.e. the down force on the towing hitch) should be around 80lbs max. There should never be a negative noseweight.
  7. The trailer should always be level or slightly nose down. It should never be tilted backwards.
  8. Trailer tyre pressures should be correct and most importantly the same on both sides.
  9. Tow vehicle rear tyre pressures should be higher than normal and most importantly the same on both sides.
  10. Tow vehicle front tyre pressures should be the same on both sides.
  11. When towing stay away from other large vehicles. The slipstream of an artic at 56mph can easily upset the balance of a car trailer combination.
  12. Do not slipstream.
  13. In high wind conditions, slow down.
  14. If a shake starts to develop DON'T TOUCH THE BRAKES. Which also means don't get yourself into a position where hard braking is likely to be essential.


Here endeth the lesson according to Rob [-o< :grin:

Rob
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windmill john
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Re: No need for theory caravan shake

Postby windmill john » Tue Jul 17, 2018 3:03 pm

http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Schorsch - 1978-80 R65 - bit of a Shetland pony; frisky and naughty.
Max - 2009 F800GS- where’s the desert at!?
Too many bikes have come and gone, trying to be sensible now!


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