Quick noseweight question

[Ian_374360734]

I understand the need to have the caravan on level ground to check the noseweight, however my driveway is slightly inclined and I currently check the noseweight by putting a couple of bricks underneath the noseweight gauge in order to keep the caravan roughly level when measuring.

I know level ground is best but given my location it would be impossible to check noseweight on level ground before hitching up.

Am I correct in assuming that this will give an accurate noseweight figure ?

 

[WatsonJohnG]

My drive slopes down a lot so I put the noseweight gauge onto the small trolley jack and jack up the front so that the van is as level as it is on the car

I have always thought as you do that this should give an accurate enough reading

 

[paulktnichols]

If you have a single axle van then what you do should be OK. If, however, you hav a twin axle then it is important to have the wheels on level ground as altering the angle of the van can make significant difference in nose weight.

 

[ProfJohnL]

Hello Ian,

I can understand you predicament, But for accuracy you need to ensure that the caravan assumes the same attitude to the true horizontal, as when it is coupled to the car and loaded for towing on level ground. It is very unlikely that given those conditions the caravan floor or chassis will actually be level.

For reasons explained quite fully elsewhere on this forum, the nose load of a caravan (and this may not be true for all types of trailers) will increase if the hitch height is reduced, and decrease if the hitch level is raised. Sadly there is no simple calculation that tells us by how much the nose load changes for different heights, but most importantly it means that the load will be greatest at its lowest height.

Fortunately, the EU have set limits for the height of a tow hitch, so if the height is set as low as it is allowed (350mm to the centre of the ball from level ground) then if we adopt this as a standard test height, then for all legal combinations of car and caravan the nose load can be measured without the car being present, and the resultant nose load will always be within the permissible range.

Your problem is you don't have level ground. The caravan will have either the jockey wheel or the main wheels higher than the other. The question is how much? Here is a suggestion. You need a spirit level, string and a ruler.

Put a mark on the ground vertically below the caravan hitch socket.

Trap one end of piece of string on the mark you have made and unravel the string to one of the main wheels (I am assuming the caravan is level from side to side). Trap the free end under the wheel

Pull it tight and raise the lowest end until the string is level.

Mark or measure how high you have had to raise the sting to make it level.

This measurement is you height offset for your load gauge. If the hitch is pointing down the hill, then you need to add the offset to the 350mm, conversely if the hitch is pointing up hill you need to subtract the offset from the 350mm

You can now set you gauge length and check you nose weight. Provided you always park in the same place and the same way round then the same length of gauge will give a good reading.

Pauls point about twin axles is very important, and this process will not be reliable with twins.

If this all seems too much, then find some level ground.

 

[trucker]

John L every piece of litriture you read about nose weight says that the van must be level. I understand what you are saying and Ive tried it and the difference in nose weight is great from level to van towing hight. Why do the clubs and the PC mag still say the van must be level.

When the load on the tow ball increases and decreases dramaticly whilst driving surly if the nose weight is done whilst the van is level its good enough.

Kevin H

 

[ProfJohnL]

Hello Trucker,

If every caravan and outfit were level it would be great, but it is a utopian goal, and the reason is that nose weights are variable depending on how you load a caravan, and the degree of compression of the cars suspension will vary according to the nose weight and how you load your car.

So it is very unlikely that every caravan outfit will be level. Although we berate many of the EU's directives, the one about towball heights is actually a sensible and practical approach to the issues of nose weight and suspension rates, The regulations imply that when a loaded trailer is attached to the loaded car, the tow ball height must be between 350 and 420 mm from level ground to the centre of the tow ball. That is a maximum variation of 70mm or in old English about 2.8"

All caravan manufactures will be designing their products with the tow ball height regulations in mind. It is impossible to have a caravan that will be perfectly level at all possible tow ball heights. So their product must be able to cope with some degree of nose height variation. This might include nose as well as nose down attitudes. It must be pointed out here that the degree of tilt is not going to be very much for all allowable ball heights, but it will make a difference to the applied nose force.

There is no mechanical reason for a caravan to be towed absolutely level. It just looks good.

BUT, there can be a problem if you aim to set it your caravan level rather than follow the nose loading regulations. The maximum allowable nose force is determined by the lowest value f the either car caravan or tow hitch manufactures specifications. For most caravan the limit sis 100Kg, but most saloon cars&tow balls are limited to 75Kg. (Always check your manufactures specification for your particular models)

For the sake of this example I will assume your car has a limit of 75Kg. Let us suppose you set a caravan nose load gauge so that the caravan is level. The height of the hitch is found to be 375mm. You the load the caravan so it produces a nose force of 75Kg which is the maximum for your car.

When you connect the caravan to the car the hitch assumes a height of 350mm which is still within the allowable range, however as you have noted yourself, as the height of the hitch varies so the nose load force also changes. Because of the inherent design of caravans, the nose load will always increase as the nose is lowered. So now your caravan nose lower so the applied load will have increased to more than 75Kg. This means that the nose load is now in excess of the cars limit, and as a result the outfit is not legal.

You can of course now change the caravans loading to reduce the nose load and bring it level, but most cars have their fuel tanks near the rear, so whilst driving a long distance the reduction in the fuel load will change the tow ball height. So if you set up your caravan to be absolutely level, by the time you reach your destination it will have assumed a slight nose up attitude.

So it really is not a practical exercise to try to arrange for a perfectly level caravan whilst towing, because for so many other factors it wont stay that way.

My suggestion of always setting nose force with the hitch at its lowest allowable height ensures that provide the car maintain the correct range of hitch heights the nose load will remain legal.

 

[trucker]

Thanks for that John, I do note however that in the pc mag this month it states that the caravan be level when checking nose weight. I know you are right as i have had experience of the difference but for these publications to state incorrect info is at best wrong but at worst disaterous.

Can PC through any light onto this matter

Kevin H