Towing Setup

[Ricey]

Hi, I'm fairly new to caravanning and towing and would appreciate some comment from experiences tow-ers. I've been away once so far and set the caravan up on the tow ball (of an Isuzu Trooper) so that the caravan sat as level as I could get it.

However, having read a bit more about noseweights and stability I wonder if the caravan should be perhaps sitting slightly nose down (but only very slightly) onto the towball? However, it's been suggested to me that setting up the caravan to sit nose down would cause the brakes to bind as the forward pressure would cause them to rub. Having only towed with the Trooper I also wonder if towing with a car, which i presume has a lower towball height, would allow me to have the caravan sitting level if that is the best set up.

Thanks in anticipation of your responses.

 

[Lutz]

The standard height of a tow ball on the car when it is fully laden is between 350 and 420mm, measured to centre of ball. The standard height of the coupling of the also fully laden caravan when it is standing level is between 385 and 455mm. These figures result in a nominally slightly nose down setup, but tolerances could permit a marginally nose up attitude, too, especially when the car is not fully laden when towing.

 

[Glenn_5132962]

William,

You dont set up a caravan so that it looks "right" when connected to the car. What you do is load the van up & then measure the noseweight by using either a proprietary gauge or (like I do) an axle stand & bathroom scales. The noseweight should ideally be about 7% of the max caravan weight but if your towball limit on the car is lower than this then adjust the loading of the caravan until its just below the towball limit. If you do this you will have a balanced outfit & it doesnt matter if it sits nose up or down when connected to the car.

 

[KeithJ]

William

There is nothing you can do to adjust the height of the towball on the car except, in extreme cases, fitting a drop plate, which will lower it a couple of inches. In all my years of towing I have never found the need for a drop plate and the van usually sits fairly level. As Glen has said, it is the weight that is important.

Keith

 

[Lutz]

William

There is nothing you can do to adjust the height of the towball on the car except, in extreme cases, fitting a drop plate, which will lower it a couple of inches. In all my years of towing I have never found the need for a drop plate and the van usually sits fairly level. As Glen has said, it is the weight that is important.

Keith

If at all, drop plates should only be necessary with true off-road vehicles as these are exempt from the standard towball height requirement.

 

[ProfJohnL]

Hello William,

The governing factor here is the nose load. Both the car and the caravan will each have a stated maximum allowed, and you should use the lower of the two figures as your absolute maximum nose load.

The regulations require a minimum nose load of 25Kg, or 4% of the trailer weight. The 7% figure is purely a guideline, and in many cases cannot be achieved within the manufacturers limits.

The nose load must be measured with the caravan hitch at the same height as when it is coupled to the car. In general trailers tow better with bigger nose loads.

As Lutz states the actual height of the towball when the car (not off roaders) and caravan are loaded, should sit between 350 and 420mm from the ground to the centre of the towball. If the tow ball is outside of this height range, then either the loading is wrong or something has broken.

All height and weight measurements must be done on horizontal ground

 

[Steve L]

Theres good advice here, but to keep it basically simple for a relatively new tower, here's a few simple guidelines.

First of all William, set your adjustable tow bar on your trooper to between 350 & 420mm as quoted by John and Lutz. This needs to be done with the vehicle unladen.

Now knowing that a fair few troopers have gone green towing horse trailers etc across fields, you should ensure the springs are all sound and not cracked/broken as this does affect your vehicles handling and safety.

Second following the very good advice available in Practical Cravan mag or here on tinternet, load the van to ahcieve a nose weight of around 75 Kgs. Undoubtably your trooper can handle more and the van probably can, but this figure seems to be a good weight to aim for and over the last 27 years has not caused me concern. do by all means check both the car and caravan data for the tow hitch load for both and the lower figure of the two is the max that you can operate with.

As for weighing methods I would use bathroom scales with a thick piece of plywood on the foot pad, and then re-set to zero. Put down the front steadies of the van, wind up the jockey wheel and place the scales under the wheel. Also ensure the brake is on for the van, or the wheels are chocked. Now wind down the jocky wheel and raise the steadies. Adjust the hitch height to that of the car and then take your reading.

As mentioned by John, you should be doing this on relatively flat and level ground.

Once you have formulated a typical loading plan (awning here, box of groceries there, manadtory pack of beer's etc), use that as a guide, but always measure your hitch weight prior to setting off. I use the scales at homw and a yellow guage that fits in the caravan hitch and onto the towball while away. I have compared the two guages and they give the same readings.

You can get these yellow guages from any caravan shop or camping supplier.

As for the look of the van while towing, I would aim for slightly nose down as this creates a wedge type shape look to the caravan and when it is on the move, wind passage over it would naturally create a small down force thus improoving handling.

Final tip which 80% of people overlook is to, check tyre pressures on all tyres car & van to ensure correct pressure for towing with the car fully loaded.

Most of all relax and make this small task part of the fun of caravanning rather than a technical tussel.

Atb Steve L.

 

[Glenn_5132962]

Well Steve's advice was looking good until he said put the scales under the jockey wheel. This is wrong - the scales need to go under the hitch head. The reading at the hitch will be a lot lower than that measured under the jockey wheel.

(Think about it - the further back you go the more of the caravan weight you measure until you get directly under it's centre of gravity - at that point you would have the total weight - if it were possible to measure at that point obviously).

 

[ProfJohnL]

Also Steve,

The hight of the tow ball should be between 350 and 420, when loaded, not unladen.

 

[Philspadders]

Load x distance =

The distance from hitch to jockey wheel is negligable when measuring nose weight, at 400mm or so behind the hitch the difference in reading will be negligable

Taking moments along the theoretical beam that exists between the jockey wheel and hitch would give load difference of aprox 3kg.

 

[ProfJohnL]

Load x distance =

The distance from hitch to jockey wheel is negligable when measuring nose weight, at 400mm or so behind the hitch the difference in reading will be negligable

Taking moments along the theoretical beam that exists between the jockey wheel and hitch would give load difference of aprox 3kg.

Hello Phil,

Reg posted some interesting diagrams that helped to show the variation in down force in relation to distance from the main axle, and the figures See thread at:

http://www.practicalcaravan.com/newforums/fm_messages.asp?FO=1&FM=501348
The difference is more than you suggest, and as the max nose load has a legal implication the value has an increased significance as does the direction of the jockey wheel.

 

[Ricey]

Load x distance =

The distance from hitch to jockey wheel is negligable when measuring nose weight, at 400mm or so behind the hitch the difference in reading will be negligable

Taking moments along the theoretical beam that exists between the jockey wheel and hitch would give load difference of aprox 3kg.

Hi all,

thanks for the advice, very comprehensive and much appreciated. I have the adjustable tow bar set-up on the Trooper and can ensure that the ball sits between the 350-420mm limit. Noseweight gauge to be purchased before the next trip to ensure safe and appropriate nose-weight and loading.

Thanks again.