Weight on towbar

Read this


http://www.goseeaustralia.com.au/article/371/


and this



towing guide

Simple answer traction!!! if a sway picks up in either direction of the trailer you wan't the Tug to have more control than the trailer.


Cheers.

Wait till the December Caravan Mags come out Collyn Rivers apparently has a big article about towing and weights etc.

It has been debated in extensive thread over several forums and noone has come up with an unarguable answer.

Phil,
What you are really trying to do by adding weight to the towbar is to ensure you have more weight in front of the caravan wheels than behind because the latter can result in the caravan swaying to the extent that you can lose control. The 10% rule is all about that theory. How much weight you have at your towball should be a percentage of the caravans weight. 1500kg caravan=150kg towball weight.

WBS

The physics of towing are a little like black magic to my non-mathematical brain but, like me, you might get some benefit from reading How Stuff Works - Towing.

Hi Phil

Not being a physicist i have a list of easy to read article links on Safe Towing Links. Links to Collyn River's website will be added here when he has finished the current updates. I have links to his older artciles on the safety section on towing weights and definitions.

We use the Hayman Reece WDH to distribute weight to the front car wheels.Image Could Not Be Found

Motherhen

I think you need to look at the whole picture.

The weight of caravan loaded
total weight of tow vehicle, loaded
maximum allowable tow ball weight
GCM

Using a weigh bridge to share the weight over all the axles including the steer.

The same rules apply to heavy transport. Each axle configuration has a maximum allowable weight it is allowed to carry

Once you have the load even, i think you will find this is where the 10% rule comes in, and only then.

Cheers Col

Not going to read this whole thread but 100-200Lb's on the towbar is the guide. I recently imported a pontoon boat from the USA, it had accidentally shifted aft during transit. When I picked it up and started towing from the docks it was a high wind alert on the bridges in Melbourne, very very scary. Reckon the pontoon which weighs around 1 x tonne shifted 3-4 feet back, got it now around 100KG on the bar which is heavy but overall stability and towing comfort has changed dramatically. I tow with a current model Hilux and there is no sag at the rear, the vehicle is steady, to me a lot to do with towing is the vehicle itself. Remember the old days towing a ski boat behind a VL wagon, my things have changed.. LOL

Phil

I have often wondered about that 10% theory as well.

My first introduction to towing dates back to the time I commenced working as a 15 year old apprentice mechanic in 1961. I would occasionally hear the boss discussing tow ball weights with customers. The figure that came up all the time was around 70 lbs. That would be about 32 kgs for a 1000 kg van or boat trailer. That seems very light but I can't remember a customer ever having a towing accident.

When I was old enough to get a driver's licence, my mates and I went straight into towing old 1930s cars on rented four wheel trailers. We would push the old car forward on the trailer until the rear of the tow car went down "a little bit" then tie it on and away we would go. We never had a problem.

I tried the same practice when my wife and travelled for a year with a small van after we married in '74 and once again there were no problems.

I have not towed anything for many years but if I did I would be asking a lot of questions about caravan suspensions. I can't help but think they may be contributing to swaying problems. To me they look so primitive. You still see plenty of solid axles with springs heavy enough to hold up a train but with no shocks. Look up what Colyn Rivers thinks of that idea. At least the wheels stay upright on corners with that system though.

The independents usually have a heavy A arm pivoting off four bushes mounted on a straight chassis crossmember. With this design the wheels can only go straight up and down so as the van leans the tyres also lean reducing tread contact with the road. Car manufactures often use a similar design but they don't place the pivot points in a straight line across the chassis. The inner points are usually positioned a little further to the rear than the outer ones. This means the wheel changes camber as it moves just like the front wheels do. The idea is to keep the wheel on the outside of a corner as vertical as possible to maintain full tread contact.

The old VW used this type of trailing axle design on their cross torsion bar front suspension. It was never noted for its good handling qualities although I did read somewhere once that there was some degree of bending designed into the trailer arms for camber compensation. I doubt if that idea has been built into current vans.

The other issue with van suspensions is the lack of sway bars. If vans can sway then why don't their manufacturers use car style sway bars to transfer weight from the outside wheels in a corner over to the other side in order to keep the van more level? Is there a technical reason for not doing this or is it just economics or in the research and development too hard basket?

To date I have not looked at any imported European vans. Their recommended tow ball weights seem to be a lot lower that locally manufactured vans. I have also read about them being towed at well above 200 kph behind Porsches and the like. That might be only on roads like the autobahns but what happens if it runs into a sudden strong cross wind? One would expect the suspensions to be designed to cope with that so are they different to local vans?