Mass, weight, moment, axle load

[Eenansue]

Hi all,
Having noticed that all of the above are quite important, I've taxed my previous knowledge and experience, plus a bit of excel magic, and come up with a spreadsheet to ensure that I don't fall foul of the relevant rules and regumalations. It provides me with the AUW (all up weight) and individual axle loads based upon weighbridge results and the weight added along with the distance from the rear axle (moment). It works, but still requires a bit of manual maffs ('riffmatic to the more chronologically challenged amongst us - myself included) involving division of the mass added by the wheelbase. My question is, "Is there a recognised app/spreadsheet/software/thang that does the same thing?".
Eenansue

 

[Jo662]

There is this but you have to be a paid up member to be able to download it!

https://www.motorhomefun.co.uk/forum/resources/motorhome-weight-calculator.226/

Or try this

http://www.svtech.co.uk/wp-content/uploads/2015/11/6x2-Conversion-form-Motorhome.pdf

Another one!

http://www.watling-towbars.co.uk/motorhome_axle_loads.html

Another!

https://www.caravanguard.co.uk/news/how-to-calculate-your-motorhome’s-safe-weight-limits-4104/

 

[Eenansue]

Thanks for that Jo662, I've seen all of those, except the download from this forum (not a subscriber yet) and whilst they contain usefull information they aren' t really what I was looking for in that they aren't variable enough. They are aimed more at initial calculations as opposed to being able to add and remove items over and above the basic configuration, which is obtained from a visit to a weighbridge. My spreadsheet is aimed at things added and subtracted from the basic weight whilst on the road. For example, if I buy a bbq in Spain and store it in the garage, how does it effect my AUW, front and rear axle loads. A minor change perhaps, that could possibly be ignored but could, potentially, put my rear axle over the limit if I have a moped in there already, and decrease my front axle load to the point that it is potentially hazardous. Likewise if I scrap my bbq it could increase the front axle load so that it is over the limit, having been stored aft of the rear axle.

 

[Minxy]

Hi and welcome to the fun house!

IMV you are 'over thinking' it ... if your axle loads are so close to max that you need to take into account such types of changes then you'll drive yourself silly ... eg if you have a full tank of fresh water (at the rear) and use some of it (eg washing up with the waste tank towards the front) do you then calculate the amount you've 'moved' from the rear and add it to the weight being placed on the front axle? I can understand you wanting to know for heavier items but other than that you'll drive yourself nuts.

 

[two]

Worry less. There is a tolerance anyway. It's good to be aware of your payload but not to be worrying over it.
A formula will require not just the weight you are adding or removing, but also the position of it's centre of gravity along the chassis = far too much of a fiddle. Even then you'd need to think about the distribution across the vehicle, which many people miss. How often do you check your personal weight?
Do an annual weight check (things accumulate) then relax and enjoy it. In general, most of any added weight is added to the back axle. The effect is small on the front axle unless adding something heavy right at the back.

^{_{Subscribers  do not see these advertisements}}

 

[autorouter]

For example, if I buy a bbq in Spain and store it in the garage, how does it effect my AUW, front and rear axle loads.

The motorhome Weight Calculator spreadsheet resource from this forum will do exactly what you ask. You can add or subtract items. You can move an item to a known position, either in front of or behind the rear axle, and see its effect on the axle loads.

I have not checked every aspect of the spreadsheet formulae, but those I have checked seem to be absolutely spot on.

A formula will require not just the weight you are adding or removing, but also the position of it's centre of gravity along the chassis = far too much of a fiddle.

Yes, it does that too.
It may be useful for deciding whether you can carry a particular heavy item like a scooter, or where to put that extra bank of leisure batteries, but for small items you soon get the idea it doesn't make a great difference.

 

[suavecarve]

If concerned that much buy a portable weighing machine. They cost about 150 quid and weigh about 2kgs so just add that to the axle weights after your daily weigh. It will save you a fortune keep going back to the weighbridge