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What jack?


  • Andries Doman
    Andries Doman on

    <p style=”text-align: left;”>Hello, I need to lift my caravan to fit parking wheels. What jack – bottle, trolley or scissor do you recommend?</p>


    Abee Hills
    Abee Hills on

    Hi Andries, why not use the caravan’s own “jacks” – corner steadies.


    Simon Tasman
    Simon Tasman on

    Corner steadies are nowhere near capable of supporting the full weight of a caravan.

    There’s a power-levelling kit available that uses modified electric jacks. These jacks each have a capacity of 2000Kg and together can easily lift any caravan, but they lack the lateral stability to stop the trailer toppling sideways once the wheels leave the ground.

    Corner steadies don’t have the strength to lift the van and are even more prone to having the top of the leg slipping off the narrow slider surface and doing serious damage.

    Steadies are intended to rotate the chassis around the axle while the wheels carry the most of the weight.

    Any 2000kg jack placed under one end of the axle will lift one wheel safely while the other wheel stays firmly on the ground.


    Fyko van der Molen
    Fyko van der Molen on

    The side arms that attach to the leg about halfway up are made from mild steel flatbar. They have 2 bends, one at the leg to conform to that component’s surface, and the other at the ends of the T-bar of the mounting frame. These arms come under compression when the leadscrew pulls the leg erect, and one or the other will buckle under the increasing compression load

    This will spell disaster.  Don’t try it.


    Fyko van der Molen
    Fyko van der Molen on

    I see that a reference is made to our using electric jacks with our powdered leveling system. This needs a bit of explanation

    We initially motorised the corner steadies with 12VDC gearmotors, but these are ridiculously expensive and total overkill for machines that will be used only a few times per year.

    We have a few clients in Australia who sourced their motors directly from China and mated them to Italian gearboxes.  That cost about R1500 per unit in Oz, but neither of these components can be imported here at a similar cost. We are asked to pay over R4000 per pair, R16.000 for all 4 corners.

    However there’s a whole lot of Chinese scissors jacks sold here by Adendorff and others for around R1600 per unit. The quality is far short of the gearmotors but still quite adequate for the low frequency duty of leveling a caravan. Another advantage is that they take very little modification to do the job successfully.

    The problem, as has been pointed above, is that they don’t have the lateral stability to safely lift the entire trailer when strong lateral forces are applied, say like high winds or being bumped from the side.

    To stop the jack lifting the caravan clear off the ground we limit the current electronically.  There’s enough power in the motors to level the chassis, but not lift the wheels off the ground. Though under full power any one of them could lift the gross weight of the entire trailer.

     


    Athol Hughes
    Athol Hughes on

    My solution to the jack question is this:

    All 4 of my levelling jacks are securely mounted in quick-release brackets that need only one 13mm bolt be removed to allow them to slide out.

    Also they all have Anderson plugs that connect to the controller, so it takes less than a minute to remove any jack from its mounting and redeploy it under the axle for changing a wheel, adjusting the brakes or servicing the wheel bearings.

    I have an Anderson outlet at the towbar that just needs a couple of metres of cable to power the jack directly using the original switch panel that it came with.

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