Oops....

Discussion in 'Heavy Haul Trucking Forum' started by Cat sdp, Oct 25, 2017.

  1. nikmirbre

    nikmirbre Road Train Member

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    It looks as if the rear wasn't turning.......
     
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  3. not4hire

    not4hire Road Train Member

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    I was thinking the same. It looks like both sets of axles on the rear are crabbing to the right (towards the camera), but then the forward set should turn in the direction of the truck, but don't. You can see the fender on the rear set bear down on the tires as the load slowly twists to the right
     
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  4. cnsper

    cnsper Road Train Member

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    You all missed the biggest thing. No the front set does not need to follow the truck. As a matter of fact you steer opposite the turn. Crabbing in certain situations is what you need to do. If you watch closely you can see the only steering being done was the rear set of axles.

    If he had been crabbing with both axles he might have been ok but no guarantees.

    Here is what he did wrong

    1. He was moving too fast for steering response on the dolly.

    2. When you corner like t hat you drop the front neck of the dolly to reduce the lateral force from the turn.

    I have run that exact setup several times. We always drop the neck when making turns like that. You will see that the neck on the dolly is dropped because when you turn it swings out from under the beam.
    IMG_20151012_101204788.jpg

    Here is a video my pilot took one day. It is a 3 axle but the process is the same. The three axle does not have a neck like the 6 axle dollies do.
     
  5. m16ty

    m16ty Road Train Member

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    The main principle behind pre-stressed concrete is concrete is very strong in compression, very weak in tension. The tensioned cables are there to always keep the concrete in compression.

    Beams like this are also engineered by the shape of the beam and the cables, to be very strong on one position (usually force applied straight down from the top) but can't take much load from the side or twisting. This beam could probably hold 100s of 1,000s of pounds from the top but can't even support it's own weight from the side.
     
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  6. hammer1022

    hammer1022 Bobtail Member

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    Just out of curiosity, was that a self steering trailer or a remote control steer?
     
  7. Jumbo

    Jumbo Road Train Member

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    Remote more than likely
     
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  8. cnsper

    cnsper Road Train Member

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    Wireless remote. Eked some concentration to steer the truck and trailer at the same time
     
  9. hammer1022

    hammer1022 Bobtail Member

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    Didn't mean the driver was steering, there are new model trailers that "self steer" that adjust the rear based off the position of the trailer to the fifth wheel plate.
     
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