Towing - Weight Distribution

Whenever a vehicle towing a trailer travels along the road with the back down and front up, a problem of weight transfer exists. This means that there is less weight on the front wheels but more on the rear than without the trailer in tow.

For maximum safety, stability and vehicle control, both the caravan and towing vehicle should be level. The reasons that one or both may not be level could be due to:

  • Incorrect towball height compared to the trailer coupling height.
  • Uneven loading of the caravan.
  • Lack of proper towing equipment.

To determine the correct ball height, measure the distance from the ground to the bottom of the coupling on the front of the A-frame. Then compare this with the distance from the ground to the base of the towball on the rear of the vehicle.

These measurements should be nearly the same. If this is not the case, the ball mount or tongue may need to be adjusted or altered.

Even loading of the caravan can be checked by weighing the caravan on and off the vehicle. The difference between the two is the ball or nose weight. This should be about 10% of the total weight of the loaded caravan. Some of the heavier items normally carried in the caravan may need to be moved around to achieve this.

For a four to five metre touring caravan the vertical ball load could be between 100kg and 150kg. Although this may be only 10% of the overall weight, it is certainly enough to push down the back of most vehicles. If due to stiff springs the back goes down very little, some weight will still be transferred from the vehicle’s front wheels onto the back wheels. With a ball weight of 100kg the rear wheels may actually be carrying an additional 130kg-l40kg. The extra weight has been removed from the front wheels due to a simple leverage factor. Whenever the weight on the front wheels of a vehicle is reduced the steering and braking are affected. To prevent this occurring weight has to be moved from the back to the front wheels. This can only be achieved by using a weight distribution hitch (sometimes these are called stabilisers, torsion, anti-sway bars or level-rides).

The effect of the weight distributing bars can be compared to handles on a wheelbarrow. The higher the handles are lifted the more weight is moved onto the wheel and the easier it becomes to hold it up. Similarly, the more tension that is placed on the weight distribution bars, the more weight is transferred forward onto the front wheels of the vehicle.

These weight distributing bars are necessary on all but the lightest camper trailers. When correctly fitted the bars will ensure that some of the ball weight is carried by the front wheels. As a result the complete outfit will be level but slightly lower.

It is unwise to set off on a trip if the caravan and tow vehicle are not level. If you are in doubt as to the best way to cope with the weight of the trailer, consult someone specialising in towing equipment. People who boast that they do not need or use weight distributing bars are either not aware of the implications or do not have safety as their utmost concern.

And after all, the safety of your family as well as that of the car and caravan are paramount.

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