Thread: Weight Question

[QUOTE=dirvine;2935726]

Originally Posted by Tombie

What are you actually trying to find out?

It has been quoted to me that when you put 350Kg on a tow ball, because of the see saw effect you are really putting nearly 500 kgs extra on the rear axle. As such you cannot load the car up to 350kg below GVM as the rear axle load has been exceeded. It was said that the New RAM cannot tow 3.5T because of that and neither can a D4. If we want to tow 3.5T then we need to use a DOG trailer. As I cannot find what the rear axle load weight is before a trailer is hooked on, I am just wondering what weight can we put on the ball before the axle load is exceeded. Whilst i read what LR says, that 100Kg seems to be a very "loose" type of figure. How do you remove 100Kg if you have nothing in the back? How much can i put in and still not be over? Then i can fire back with some authority. Physics was never my strong point at school

thats easy...

you have 2 figures in play.

1. how much you can put in the back
2. how much you can put on the ball.

theres 3 sets of limitations in play.

1. the structural capability of the bodywork/mounts to chassis
2. the structural capability of the tow hitch to the chassis/ the chassis it self
3. the load limit of the suspension.

Landrovers are built to carry the full payload and then have an additional amount of downforce applied to the towball and the vehicle will still be inside its GVM/GCM. in your case that number is 250KG.
the towbar is designed to carry 350KG of downforce

SO (and im making up numbers now for the purpose of an easy demo)

if you have a 1000Kg payload capability you can then drop on 250KG of downforce for free, dont worry about a thing.

BUT...

if you have a 350KG downforce you need to free up the 100KG from the payload.

so you can have 900Kg of payload and then the 350Kg on the ball.

What gets right up the toyosan drivers noses and why they cant wrap their heads around this is simple.

Their vehicles generally make no allowance for towball load, every KG on the ball comes out of the payload.
Same as their allowance for included weight on some models doesnt include an allowance for a driver, fuel, spare tyre.....

Originally Posted by yobarr

The experts then advise that a WDH be used,but all that does is add even more weight to your cars rear axle,as well as increasing your TBO (towball overhang, or distance from rear axle to hitch point). This means that even more weight is transferred from the front axle to the rear.

And I give up... thats not how the physics of them works..
short version.. they create a seperate path of force that levers against the hitch the van and the chassis to create a lifting effect. this takes weight off of the back axle by pushing it onto the front axle of the vehicle and the trailer.

Originally Posted by yobarr

The much-adored McHitch multiplies that weight transfer even further! When the WDH is tensioned in an effort to put some weight back onto the front axle of the car,some weight is indeed taken off the rear axle of the car,and put back onto the front,but there also is weight transferred to the vans axle group,putting you over your ATM

and thats why I give up, hes just contradicted himself in less than 2 lines of text. his example here is also marginally wrong which is seemingly a trifling but it means that his example trailer was already illegal to hook up in the first place.

so lets look at

Originally Posted by yobarr

The 1500 has a rear axle limit of a miserable 1770kg,

Originally Posted by yobarr

The Dodge Ram 1500 has over 1000kg rear axle weight at tare.A towball weight of 350kg transfers around 500kg (+/-) to the rear axle of the car, Add another 100kg for fuel,and already we are up to 1600kg.

nope..
https://www.ramtrucks.com.au/include...ons_V009_2.pdf

Originally Posted by the manufacturers blurb as above

Kerb weight includes the vehicle with a full tank of fuel and all standard equipment

I'll just ignore the fact that if you're towing a van the luggage should be in the van and assume that it is so if Ive got 1500kg used of 1770 I have 270 KG to play with.... so unless you're an American couple, a Family of Americans, Samoans, or of other fluffy producing heritage stock 270KG isnt that big a deal. Myself and my partner + the gear we need to go for a week (I'll take out the tent and the food and the water, its in the van in this case) weighs in at ~160KG. take out the weight of the packs and the gear (cause they're in the van) and thats down to 140Kg.

and a quicky from one of the older dodge ram adds "So if you want to tow OR carry a big load then dodge is the truck for you" (its american, its not really a truck, just a big ute, the GVM is way to low to be a truck, a landrover 6x6 is actually a truck)

Originally Posted by yobarr

All my comments are based on the generally accepted 10% towball weight.I sort-of know how the towing ability of a vehicle is calculated,but you may wish to access RV books by Collyn Rivers,a recognised expert in weights wnd dynamics,with over 60 years experience.All will become clear!

From the authors bio....
Author/engineer, Collyn Rivers practices what he publishes. Originally trained (by the UK’s Royal Air Force) as a ground radar engineer, he later worked as a research engineer at Vauxhall/Bedford Motors, then (in Australia) founded and ran Electronics Today International. It was published in seven countries and within seven years became the world’s most successful popular electronics publication. Collyn later started up his own technical publishing company specialising in the RV and solar areas.

Originally Posted by yobarr

the weight on the wheels of the car should be at least 10% more than the weight on the vans wheels (GTM),only a fool would tow a 3150kg GTM van behind a car with GVM of only 3090kg.

I know some farmers and truck drivers that this guy is going to need to have some big long discussions with and tell them how to do their job safely. We've got road trains out here massing over 100T all up and at best maybe 16 of that is the prime mover, lets be really generous and say that the prime mover and the front trailer weigh about 1/3 of the total mass, the next 2 to 7 trailers (I'm including mine specials on closed roads) still hughely out weigh the mover and trailer.

12T tractor hauling 35+T worth of machinery trailer or a string of product bins, every other day.


The only credit I can give him is this...

if you look at his exact arguments and accept all of the situations he presents as being factual and the only examples available he is more or less close enough to correct. However we dont operate in his exceptionally limited range of exposure.