Effects of where the weight is on a trailer
Found this on my Facebook stream and thought it showed pretty well the effects of moving the weight around a trailer:
https://www.facebook.com/permalink.php?story_fbid=1116974931722813
(Link doesn't work, sorry - Google Science Scoop and search for Weight Distribution Dynamics, if you can be bothered, which you should do as it is interesting).
Comments
-
Also rather shows the difficulty some of us have trying to put a damn video on a forum! Shame, it is an interesting video where the madel car and trailer is on a rolling road and the trailer is weighted biased to the front, he pushes the trailer and it self-corrects. Moves the weight further back, pushes it, and the car and trailer go into a severe snake. Any new tow-ers here may have found in informative.
0 -
This one, assuming it works?
https://www.youtube.com/watch?feature=player_embedded&v=4jk9H5AB4lM
0 -
Sorry, tried to make the link live but it doesn't want to play ball.
0 -
-
thanks, jeff. Makes interesting watching.
0 -
I thought tha tit would be that one. Thing is however that in moving the weight drom front of trailer to rear had the effect of moving the centre of gravity behind the axle. Obviously a no no as possibly too little noseweight.
It reminded me of something that I did over 30 years ago. As I had experience working on cars a friend who was doing a total engine rebuild on a tasty car asked for help in doing the rebuild. I said I would come down in the caravan and stay on his ;and over
a couple of nights and do it for him. Stupidlt I put my toolbox that probably weighed 40kg and additional stuff in the toilet compartment at the rear of the 'van. Fortunately before I hit derestricted roads I had a habit of sawing the wheel and ensuring that
the 'van settled out. At less than 30mph it didn't. I moved my tool box, hoist etc to middle of the 'van and no problem. Seems rather like the simplistic demo IMO0 -
That's the one, thanks. Simplistic, yes, but gets the point over clearly.
0 -
Even in the second scenario the noseweight could be correct. Snake (there) is caused by excess weight at rear, as used by some to reduce noseweight.
0 -
Probably with my “word-smithing” abilities it is best I don't try, other than to say the video being discussed earlier, somewhat confuses things in that two fundamental changes were being made simultaneously. They changed, the moment of inertia of the system
and the noseweight.Better we just watch a video that I note Practical Caravan's web site has unearthed on this issue:
https://www.youtube.com/watch?feature=player_embedded&v=PFzrWHTG5e8
And the one from the late master at simplifying the technical essence of all things caravanning the late much missed John Wickersham:https://www.youtube.com/watch?feature=player_embedded&v=9P0ajgaZgDg
As will be seen it is not just the mass that is being carried, it is very much where that mass is carried. The latter has a powerful effect on the frequency at which the unit goes unstable. Carried to an extreme it means we can't tow at tolerable speeds,
but that becomes self evident so unless one is silly is not going to be an issue, you know things are wrong and do something about it.IMO far more dangerous is the case where normally towing you think everything is okay as the natural frequency is higher than speed and the normal disturbances set things off going wrong.
However, that margin is too little to protect you from the abnormal, the van snapping into ruts, passing bow waves, danger avoidance steering movements; all these occurring when you are travelling up at the speed limit anyway. Here, that speed alone means there
is a lot of potential for things to very quickly go unstable; simply there is masses of kinetic energy there to throw the unit about.0 -
the video doesnt tell you the ratio between the gree weights and the red weight.
it certainly looks like the red weight was significantly larger than the two green weights, supposedly to amplify the demonstation.
not being a caravanner.....however, with many caravans having payloads of two hundred kilos or (much) less, its fairly obvious that (with just a couple of extras (mover etc) and your clothes and food) there isnt any payload spare to be putting (say) an extra
50kg in the rear washroom (though why would you) the van would almost certainly already be illegal (overweight) and the noseweight would be far too light...wouldnt it?....0 -
As a new caravanner myself. I've found that my van has 150Kg of cargo capacity. Which would bring the total weight up to 1300Kg on it's single axel.
The noseweight can vary considerably between 50Kg and 90Kg, just by moving a 10Kg awning from over the axel back a couple of feet.
For me, the video shows clearly what shifting the weight around in the van can do, and how it can effect the stability. Correct loading is important.
The thing that I took from that Video, is that most of the things they talk about are not things that I have control over day to day - position of the kitchen, bed, gas bottle, heaters are fixed.
That said, I can control some of the things - lower the weight of the gas bottle. Placement of the awning, aqua roll, wastemaster and other things Can effect the stability of the caravan and effect the towing.
As I've not towed any significant distance with a loaded van, I like the idea of waggling the stearing wheel and trying to induce a low speed snake before I get up on high speed roads. Think I'll try that when I tow at the weekend.
0 -
I'm on a restricted data wifi currently do can't see the video.
We have the Eldis xplore 586
When travelling we put the awning across thd axle. we've clothes in the wardrobe, towards back, spare bedding in the underseat cupboard at front. With some lightweight art items at back. His fishing bag along side awning over axle Thus the heaviest weight is across axle which is where the dealership told us.
Water bottles always emptied before travel
Being a lightweight single axle we do have a lot of snaking at the top speeds espec if hit with crosswinds or are being passed by hgv's.
The first one we had, bedding was at back and some heavier craft/stock boxes st back with the awning still over axle. A box of craft went between lounfe seatscat front and the art items were under loungd seating. we seemed to have less snaking then or at least for the three weeks we had her noticed it less.
I've been trying to undersrand the posrs above but it webt way over ny head. Am I right you are saying heavy items should be over axle with some weight at back better to help redyced snaking?
Sorry if my questions seem stupid
0
