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Centre of gravity

Posted: December 8th, 2015, 1:25 pm
by Big Jim
Hello All
I have bought a caravan chassis to move the camper around , it has a motor mover on the jockey. The camper measures about 7' wide with all the bits sticking out . I have to get it through a gateway 8' wide with tall brick pillars . It sounds easy enough , but I had a right game . The ground is fairly even but even a Little rocking on the suspension eats up the gap .
Anyway where do you think I should drop the camper on the trailer , do you think looks about right ?
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Re: Centre of gravity

Posted: December 8th, 2015, 5:37 pm
by Toshbins
Will your Reich scales measure the weight of each camper leg? Then you could get the centre of gravity just in front of the caravan wheels.

Re: Centre of gravity

Posted: December 8th, 2015, 7:29 pm
by zildjian
Not allowed them Till Christmas morning (early) :D

In terms of finding C/G its trial and error, I've been moving the camper slightly using an hydraulic lift table

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and I had to drop that and shuffle it along a few times to get it right

Re: Centre of gravity

Posted: December 8th, 2015, 9:05 pm
by sabconsulting
The way you have drawn that I would expect it to have too much nose weight. You probably only want around 100kg or less on the nose wheel. Though of course you don't want the nose weight to be too low and to risk it pivoting backwards.

One option - you could probably measure the nose weight with a set of cheap bathroom scales. E.g. you could use the jacks to gently lower the camper on the chassis at different points.

Steve.

Re: Centre of gravity

Posted: December 8th, 2015, 9:06 pm
by derestrictor
Only a pity makers don't stamp c of G on the side somewhere really

Re: Centre of gravity

Posted: December 8th, 2015, 10:14 pm
by sabconsulting
derestrictor wrote:Only a pity makers don't stamp c of G on the side somewhere really
Some do:

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Steve.

Re: Centre of gravity

Posted: December 8th, 2015, 11:38 pm
by Toshbins
sabconsulting wrote:The way you have drawn that I would expect it to have too much nose weight. You probably only want around 100kg or less on the nose wheel. Though of course you don't want the nose weight to be too low and to risk it pivoting backwards.

One option - you could probably measure the nose weight with a set of cheap bathroom scales. E.g. you could use the jacks to gently lower the camper on the chassis at different points.
OK. Hitch the caravan chassis to the car. Stand on the A frame and adjust the jockey wheel so it just touches the ground. That's how much weight you want on it. Get the camper loaded on so that you get the jockey wheel just touching the ground the same.

Re: Centre of gravity

Posted: December 9th, 2015, 8:10 am
by rubberrat
I move my camper on a four wheel platform trolley with a drawbar that I hook onto my towball.
The sidewards rocking is an issue.. I take things really slow and have all the legs down and just 10mm off the floor so if things go wrong its not going to go far. Slow enough to stop dead if a leg touches down.

In my opinion I'd want the weight biased on the jockey so it doesnt tip back.. its not like you are driving it down the street.

Re: Centre of gravity

Posted: December 9th, 2015, 11:01 am
by rubberrat
I just had a thought. As a 20mm movement at ground level may translate to 200mm at the camper top (I can't bring myself o get paper and pen to do the math/trig)
How about laying two builders planks in the area through the pillars to ensure a smooth level transit. Then the risk of clouting the pillars with the side of the camper should be minimised.

Re: Centre of gravity

Posted: December 10th, 2015, 8:16 am
by zildjian
So what happened Jim, did you try this yet?

In moving ours about on the slightly sloped drive here I keep the camper as low I can & the feet only just above the ground