Fifth wheel adjustment

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Dino soar, Oct 25, 2019.

  1. BoxCarKidd

    BoxCarKidd Road Train Member

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    I have a Holland on Blue to the left. It came off a 2005 Mack Serta mattress truck with 500,000 on it. When the handle is pulled out it has to be twisted all the way, counter clockwise I thank, and held while releasing.
    It catches every time. If not the handle goes right back it. That is a bit unusual but not the only one I have seen like that.
     
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  3. bowhunter67

    bowhunter67 Light Load Member

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    Just replaced my holland new plate,pins,bushings $850 @ allstate peterbilt st cloud mn.
     
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  4. Dino soar

    Dino soar Road Train Member

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    It turns out that the fifth wheel was unlocked and I did not realize it. The bar does not school out as far as I thought.

    So when I pull the lever I can see the Jaws unlock but they're not opened wide.

    When I take a bar and I pry against the jaws, they freely open and then when I let go the lever pops in and the jaws lock shut.

    Is this correct operation?
     
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  5. Working2party

    Working2party Medium Load Member

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    Can you get a pic of the bottom of the plate? Looking for all of the magic (levers and what not).

    Most plates pull the lever all the way out and you can move the jaws by hand (suggest using a bar instead of a finger!!) once there is pressure closing the jaws a lock will release that hold them in place.

    But a picture might help someone recognize the exact operation.
     
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  6. Dino soar

    Dino soar Road Train Member

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    It's probably going to be a couple of days before I get the fifth wheel separated from the frame so I have to get back to you on a photo.

    But I've been thinking about all of this and there's not that much to the operation in there. I'm going to look at the video again of how they rebuild them to understand it better, but it seems to me that when you pull that cam it allows the fork to come up and the Jaws can open.

    It seems to me that the cam plate however that works is not raising the fork far enough. It's far enough that I probably could pull out from a trailer but when I pull out it's going to lock itself.

    I have been watching the video now of how they rebuild them, and looking at the parts.

    When I get time I'll take some photos but I'm going to take a much closer look at the operation of that cam plate and see if I find anything else wrong in there.

    But what seems to be happening is it is locking too soon without having the full pull of the lever.
     
    Last edited: Oct 27, 2019
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