Twin Axle Nose weight

[chris_5090619]

Hi

We believe that it is difficult to alter the nose weight of a twin axle van, We need to hit 75kgs max can anyone advise whether this would be possible. Caravan would be a Lunar Quasar 615, with a Volvo S80.

Thanks

 

[Lutz]

There is no basic difference between trimming the noseweight of a twin axle compared to a single axle caravan. It is always achieved by moving payload forward or rearward of the axle(s) to suit.

 

[mcghee]

Hi Chris. In my experience twin axles are no harder to adjust than singles, but with a twin axle the load on the towball is less consistent than with a single axle, and for this reason I like to keep it as heavy as possible. I think the Lunar has a miro of about 1200kgs? and I think you'll struggle to get the noseweight below 85-90kgs with the van safely loaded.

 

[ProfJohnL]

Hello Chris

I fully agree with Lutz on this one, but Craig also alludes to an important variation.

When a twin axle caravan is towed any bump in the road will be mounted first by the leading axle and then by the trailing one. As each of the axles has a different distance to the tow hitch, the upward force on the caravan created by the road bump will affect the caravan rather like a see-saw. This will affect the nose load, firstly by reducing it then by increasing it. The ammount it changes will depend on the car/caravan combination and the way the caravan is loaded.

It is concivable that the nose load may momentarily become negative (i.e actually lifting) during this process. but it may also become substantially greater than the static load nose load.

For these reasons it is essential that proper care is taken when loading, to aim to achieve a static nose load of no greater than the manufactures maximum limits. Always compare the car manufactures tow ball limit and the caravan(or trailers) hitch limits and use the lower of the two. You are illegal if you excede the lowest limit.

The manufacturers should have taken the dynamic loading effects of the trailers into account, so the nose load changes that occure during towing should be within the design specification for the car and trailer.

 

[Lutz]

Good comments, John, but they apply equally, although maybe to a slightly lesser extent, to any single axle caravan, too. Because of the noseweight, the centre of gravity of the caravan is slightly ahead of the axle so any bumps in the road acting on the axle will apply a torque about the centre of gravity causing a tendancy for the caravan to pitch. This effect, though less with a single axle because it only happens once, is nevertheless present there as well and momentary dynamic negative noseweight will be experienced with a single axle arrangement, too.

 

[ProfJohnL]

Good comments, John, but they apply equally, although maybe to a slightly lesser extent, to any single axle caravan, too. Because of the noseweight, the centre of gravity of the caravan is slightly ahead of the axle so any bumps in the road acting on the axle will apply a torque about the centre of gravity causing a tendancy for the caravan to pitch. This effect, though less with a single axle because it only happens once, is nevertheless present there as well and momentary dynamic negative noseweight will be experienced with a single axle arrangement, too.

Morning Lutz,

You are an early riser!

Yes I agree that a similar but less marked effect will occur with single axle trailers.