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Measuring tow ball weight

  • Gabriela Valente
    Alda Matavele
    Alda Matavele on

    Can I please see a picture of how you place this weight sensor under the jockey wheel?

    Fyko van der Molen
    Fyko
    Fyko on

    You may need a block of wood to raise the sensor high enough that the wheel(s) don’t touch the ground.

    If your jockey wheel has a hollow jackscrew rest the edge of the jackscrew in the trough of the stirrup.

    If the bottom of the jackscrew is closed rest the bottom of it on either of both of the humps.

    If the bottom of the jackscrew cannot be reached, rest the axle in the trough of the stirrup.

    If there is only a single wheel then rest the wheel in the trough of the stirrup.

    Weighing the jockey wheel makes it easy to get the tow ball weight immediately before hooking on – so you get as accurate a reading as possible, and you can make final adjustments to the weight distribution right there.

    Don’t forget to set the correction factor in the phone to adjust for the jockey wheel position.

    For instance on my Classique:

    The tow ball is 4 metres from the axle,

    The jockey wheel is 470mm from the tow ball.

    Therefore the phone must correct 470/4000 = 12%

    The uncorrected reading from the load cell is 141 Kgs

    After I set the slider to 12% I get:

    141 Kgs – 12% = 124 Kgs.

    If I go to the considerable trouble of weighing the tow bar on a bathroom scale it indeed reads 124 Kgs.

    Considering that the tow ball weight should not be more than 7% of the caravan weight I find that it is actually 8,3% of gross weight – probably from the aircon compressor in the front compartment.

    I can now quickly enter the caravan and move some stuff behind the axle until my phone says 104 Kgs, which is 7%. Then I wind the jockey wheel down so the tow bar engages, snap my new magnetic plug into place, and I’m on my way!

     

    Josef Konrad
    Josef Konrad
    Josef Konrad on

    What should the tow ball weight be?

    Some say 5 – 7% of trailer weight.

    Some say 25 – 100 Kgs

    Aussies say 10% of trailer weight

    Germans say 5% of trailer weight.

     

    Fyko van der Molen
    Fyko
    Fyko on

    According to several articles published in the mothership magazine the law in SA says that the tow ball weight may not be less than 25 Kgs and not more than 100 Kgs. I don’t have chapter and verse in front of me but I’m willing to take their word for it.

    That’s why when we display the tow bar weight (calculated from the jockey wheel weight using user input) we put up a green background if the weight falls between 25 and 100 Kgs, and a red background if it does not.

    Fyko van der Molen
    Fyko
    Fyko on

    On top of this there are many opinions publicly expressed, by those that may or may not be knowledgeable, regarding the ideal proportion of the gross trailer weight that should be resting on the tow ball. These proportions vary from 5% to 7% for local experts, but can be as high as 10% from their Australian counterparts.

    We don’t have any opinion to contribute here but we do try to help the user by presenting the proportion of trailer weight being supported by the tow ball on the mobile phone’s screen. To do this we need the user to tell the app what the gross weight of the trailer is, which he does simply by moving a slide control until the correct weight is reflected. Once entered that value is saved until changed by the user.

    Josef Konrad
    Josef Konrad
    Josef Konrad on

    Thank you. That fits very nicely.

    With a Jurgens Exclusive at 1800 Kgs, 100 Kgs of tow ball weight is 5,5%, which fits inside to lower guideline.

    And a 70 Kg tow ball weight on a light caravan that weighs 1000 Kgs is 7% which is inside the upper guideline as well. And 70 Kgs on the tow ball I’m very comfortable with.

    Discussions about this matter with my friends leads me to believe that there are a great many caravans being towed with a tow ball weight in excess of 100 Kgs. I have found that with even modest loading of the front compartment it is likely you will break this law, unless your caravan is very small.

    I’m very happy to understand this now and I intend to make a habit of getting the tow ball weight as a last step before hooking on. Thank you.

    Simon Tasman
    Simon Tasman
    Simon Tasman on

    In the front compartment of my Exclusive the is a very clear instruction not to load more than 25 Kgs into this space, and to check that the tow ball weight does not exceed 100 Kgs before every hooking on.

    Which is not easy to do if you don’t have a reliable weighing device.

    I imagine this would be the first thing insurance claim adjusters will look at, since there must be many, many transgressions happening every single day. A good way for them to dodge any and every claim.

    Lao Juntasa
    Lao Juntasa
    Lao Juntasa on

    When towing, the weight of your tow ball is included in your Gross Car Mass, therefore keep this in mind to avoid overloading your vehicle. The tow ball weight should typically be 10% of the trailer’s loaded weight.

    Simon Tasman
    Simon Tasman
    Simon Tasman on

    The law allows no more than 100Kgs on the towbar.

    10% of 1500Kgs is 150Kg.

    Therefore 10% is not correct in this case.

    Tow ball weight should be measured before every hook-on.

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