Noseweight advice

Posted on 08/11/2017 14:59 by Metheven

Oh I'm still in there I think its now a play on words and interpretation, but interesting nonetheless.

Posted on 08/11/2017 19:40 by Cornersteady

but all you are doing is supporting the van, did you notice a difference btw as you lower and raise through the horizontal as you predict it would ? or did it feel the same? Simple Newtonian physics says it must be the same. Is this some war against Newton? I know you Germans think that Leibniz invented Calculus but this is taking things too far

the van when pointing upward is not trying to raise you as it would when connected to a towball is it? Think about it if it's nose up the hitch must take tow ball with it and take some weight off the car's tyres? QED again

Posted on 08/11/2017 20:48 by Lutz

Within reasonable limits, the difference in noseweight between noseup and nosedown on a longish caravan is typically not large and only just noticeable by hand, but in the case of my short tarpaulin trailer, if I raise the hitch high enough, the noseweight actually reduces to such an extent that it turns negative as the CoM moves from ahead of the axle to just behind. The trailer will then remain nose up until physically pulled down again when the noseweight returns to its normal value.

Posted on 08/11/2017 19:40 by Cornersteady

but all you are doing is supporting the van, did you notice a difference btw as you lower and raise through the horizontal as you predict it would ? or did it feel the same? Simple Newtonian physics says it must be the same. Is this some war against Newton? I know you Germans think that Leibniz invented Calculus but this is taking things too far

the van when pointing upward is not trying to raise you as it would when connected to a towball is it? Think about it if it's nose up the hitch must take tow ball with it and take some weight off the car's tyres? QED again

Posted on 08/11/2017 21:34 by Cornersteady

well the nose weight cannot, cannot disappear, the hitch exists , it has a mass, and therefore it is affected by gravity, now what you are saying is that the effect of the nose weight on the tow ball might be zero but it will still be there supported somewhere else.  In the same way that tension in a tow bar might be zero overall (with a +T in the direction of travel and -T the opposite) when travelling at a constant speed but taking the tension on the car and trailer separately the tensions still exist.

But if you have found a way of making a mass become weightless get in touch with NASA

I think we look at things in different ways, you look at the end result, I look at individual forces.

Posted on 08/11/2017 21:47 by Lutz

Of course the noseweight can't disappear. The total weight of the trailer remains constant. It is the sum of the noseweight and the axle load. Therefore, if the hitch is raised so high that the trailer remains nose up due to the CoM being at or behind the axle, all the load is transmitted through the axle and none through the hitch.

Posted on 08/11/2017 21:56 by Cornersteady

So you retract your previous statement?

the noseweight actually reduces to such an extent that it turns negative

(To turn from positive to negative it has to go through zero)

Posted on 08/11/2017 22:07 by Lutz

No, i'm not retracting any statement. I need to hold the hitch down (negative noseweight) in order to stop the back of the trailer touching the ground. Once the back is actually touching the ground I can obviously release the hitch and then the noseweight is zero.

To put it another way, when hitched to the car, the total weight of the trailer is the axle load plus the noseweight acting on the towball. When the unhitched and the nose raised so high that it stays there, the total weight of the trailer is the axle load plus whatever the back of the trailer exerts on touching the ground (and no noseweight). Just before the back of the trailer is touching the ground the noseweight is negative because it is acting upwards.

Posted on 09/11/2017 10:31 by Cornersteady

once again you cannot change the laws physics, laws of physics....

you know how the song goes?

Here is an idea of what you are saying in a different format. A heavy chap (possibly me) sits on a see saw. A very light baby sits at the other end (please no H&S comments) what happens? The baby is held up in the air just like your caravan. Now the weight of the man and see saw is taken on the pivot and the man touching the floor. According to you the baby has now zero weight? The weight of the baby is zero? really?