Nose weights

[Robert_374242026]

The other day on the Foram i said "what is the differance whether the caravan is on a slope to get correct noseweight"well there were some good remarks but i still had to find out myself, so this is the results.For what it is worth the caravan is a Coachman 460/2 not loaded and my drive is on a slight slope enough to make a ball move.Van faceing up slope 67 klg, Van faceing down slope 95 klg !!.Van on level ground faceing one way 84 Klg the other way 75 Klg even more !!!. So, you experts are right but how come differant figures on level ground

 

[MikeP]

If I wanted a "totally accurate" figure then I would weigh it on flat ground 5 times facing one direction, moving it a little each time, and then 5 times in the other direction. Make sure that the hitch is at towball height and the brakes are released (chock the wheels). Then take the average of the 10 weights.

But I wouldn't bother. I've said this before, and it works. If you can lift the front easily, the noseweight is too low. If you can lift it with a fair bit of effort and hold it off the ground for a couple of seconds, that's 50-70kg. If you slip a disc or rupture something, it's heavier.

 

[MikeP]

To answer the specific question about 84kg vs 75kg ...

Was the ground perfectly level?

Was the hitch at the same height each time?

Were the brakes released and the wheels chocked?

To be honest, many noseweight gauges are pretty crude and 9kg isn't a lot. Unless your noseweight limit is 75kg of course ...

 

[Lutz]

I agree with Mike. Few gauges are that accurate and 9kg one way or the other is not going to make or break anything. If the noseweight measured on the same slope one way is 67kg and 95kg the other way round, then by calculation, the figure on level ground will be (67+95)/2 = 81kg.

 

[Robert_374242026]

I agree with Mike. Few gauges are that accurate and 9kg one way or the other is not going to make or break anything. If the noseweight measured on the same slope one way is 67kg and 95kg the other way round, then by calculation, the figure on level ground will be (67+95)/2 = 81kg.

Thanks for replies,in answer whether the ground is flat i put a long spirit level on the awning rail and the caravan mover was on so it seemed level plus i did lift it to put it upon the bathroom scales with my "T" piece(upside down of coarse).And don't laugh at this but putting awning and all that clobber i ended up with twisted knee and had to use a walking stick to go back indoors!

 

[ProfJohnL]

Hello Robert.

Mike P I think has it about right. However If as you say you had a caravan mover engaged, then the nose weight will be affected depending the direction the mover was last used, and if there is any residual torque being applied to the main tyres after the last operation.

In just the same way as when you accelerate a car, the nose lifts as the torque applied to the driven wheels has to be counteracted by the weight of the car. And when you break the nose dips.

So for a more consistent reading as Mike P says, the wheels should be chocked and the brakes and in addition the motor mover released.

I am also slightly unsure of how you checked the ground was level, By checking the awning rail, you are only checking the caravan, not the road surface.

So I suspect there are experimental errors in your method, but despite the discrepancy on the 'level' the slope certainly displays the expected force differential due to the slope.

 

[ProfJohnL]

Hello Robert.

I have just seen you posting elsewhere where you describe your garage and drive. None of the spaces you describe are flat, and that is almost certainly what has caused or contributed to difference in your 'flat readings.

Just to clarify, the road surface must be flat, and the caravan hitch at the same height of the ground as when it is coupled to the car for towing.

If you had the caravan flat, but still on an inclined road, the hitch loading will still be different depending on which way round the caravan faced.

 

[Robert_374242026]

Hello Robert.

I have just seen you posting elsewhere where you describe your garage and drive. None of the spaces you describe are flat, and that is almost certainly what has caused or contributed to difference in your 'flat readings.

Just to clarify, the road surface must be flat, and the caravan hitch at the same height of the ground as when it is coupled to the car for towing.

If you had the caravan flat, but still on an inclined road, the hitch loading will still be different depending on which way round the caravan faced.

Many thanks again for all your comments on my noseweight trials.Today i put a spirit level on the " level surface" and it is level.Of coarse when you think about it having the caravan mover in the on position will have an effect,just did not give it enough thought at the time.I am sure all these comments will give some useful info to some caravaners .

 

[MAM]

This has got me thinking.

Let's say you have a max allowed nose weight of 75kg. You weigh the front of the van, accurately, and it's 75kg. Later...

...you are travelling down hill on a motorway at 60mph and are forced to brake hard.

Imagine the relative weight on the towbar under these conditions.

Is this taken into account when the 75kg limit is set?

 

[Lutz]

The 75kg is set primarily taking the structural durability of the vehicle underbody mounting points into account. But the 75kg is only a static force. Dynamically, due to braking or driving over poor road surfaces for example, the load on the the towbar can be many times this figure. The regulations state that a minimum durability of 2 million dynamic cycles, both under vertical and horizontal load, must be ensured.

 

[colin-yorkshire]

so what happens to the down force when a blade type stabliser is used which counteracts the nose weight by as much as 35kg

 

[ProfJohnL]

Hello Colin.

It may seem strange, but in fact the effective nose load of the caravan remains the same, all that happens is that the down force on the actual tow ball is reduced because it is now shared between the tow ball and the blade stabiliser, and as the stabiliser's bracket is usually fixed to the tow ball stem or sub frame, exactly the same load is applied to the tow vehicle.