Fifth wheel jaws locking on their own?

Discussion in 'Questions From New Drivers' started by Canadianhauler21, Nov 1, 2021.

  1. Canadianhauler21

    Canadianhauler21 Heavy Load Member

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    Two times in two weeks when I have gone to hook to a trailer I realized that my jaws were already locked. I can't figure out why my jaws would be locked if I am bobtail? I tried searching all over the internet to figure out a cause but haven't been able to find anything.

    Anything to be concerned about?
     
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  3. lilillill

    lilillill Sarcasm... it's not just for breakfast

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    How old is the 5th wheel? If it's doing that, I wouldn't trust it to stay locked with a trailer on it. I've never seen one do that before.
     
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  4. Gliding ProStar

    Gliding ProStar Medium Load Member

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    I would have the 5th wheel assembly inspected by a mechanic and properly adjusted. Then, if it happens again I would replace the top plate of the 5th wheel with a new one. I have purchased some good used ones in the past but in a situation like this I would only buy a new one.

    For an example, I recently purchased a new top plate from Fleet Pride for $799.99
     
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  5. wis bang

    wis bang Road Train Member

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    Depending on the brand it may be possible for a high pin to close the jaw.

    How far did you bobtail?

    How smoothe were the roads?

    Mechanical things wear out it might be worn enough that a good bit of rough bobtail might bounce it closed.

    Looks like a re-build/replacement should be done now.
     
  6. Mototom

    Mototom Road Train Member

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    Out of adjustment most likely. Had one that would do that when I was a newbie the shop fixed it. Didn't bother to pay attention to how because new guy.
     
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  7. Long FLD

    Long FLD Road Train Member

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    How far are you bobtailing? I’ve had mine be closed after bobtailing about 90 miles round trip to the shop on fairly rough roads.
     
  8. LoboSolo

    LoboSolo Heavy Load Member

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    Mine does that sometimes, after running over rough ground.

    Sometimes happens when I'm about to pull out from under a trailer, drop the air, and it will pop shut enough to snag the kingpin. My cure is a bungie from the handle hooked on the fender to keep it released until I get out from under.
     
  9. slim shady

    slim shady Road Train Member

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    I'm driving a 2021 and that's a usual accourance for me, I bobtail home often so I know before hooking I need to pull it open
     
  10. Canadianhauler21

    Canadianhauler21 Heavy Load Member

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    I only bobtail within 60 miles, the roads are smooth with occasional potholes. But nothing too bad. Truck is 3 years old with 250k miles on it. Not sure which brand of fifth wheel.

    Thanks to everyone who replied.
     
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  11. WesternPlains

    WesternPlains Road Train Member

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    I hate those fifth wheels with jaws.
    I have one with a triangle shaped bar that goes across to lock the kingpin in. They are for heavier hauling in general. A better fifth wheel.
     
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