attn75 kingpin and plate?

Discussion in '<a href=' started by chip hayden, Apr 24, 2002.

  1. chip hayden

    chip hayden LawnSite Member
    Messages: 29

    have you ever replaced a kingpin and plate on a dump body? if so, could you give me any pertinent info. thanks, chip.
  2. 75

    75 LawnSite Senior Member
    Messages: 992

    Hi chip, at work we have done a couple of them on flatbed trailers but no dump trailers - however the basic operation is the same. Ideally the plate should end up flat when all the work is done, convex will rock on the fifth wheel and concave will concentrate the weight in a couple of spots, wearing it out fast.

    Arc-air is nice for taking the old plate out, biggest headache that can arise when welding the new one in is warpage - it can happen. When cutting the old plate out you'll have a good idea of how much weld you will be putting back on it, and adding some extra bracing on the top side helps control that warpage. No need to go into detail on welding in a pattern to help keep distortion to a minimum - I know you're already familiar with that.

    Lifting that plate up into place can be a "grunt", we have used the forklift or the boom truck, either one works well. If neither is available, it's also possible to chain-fall the plate into place, just hang it off a sturdy support above the trailer deck and drop it down through the hole.

    On the flatbeds it is possible to gain access to the top side by removing part of the deck, so welding the new kingpin in place is easy: just drop it in the hole and put a big flat weld all around. Also makes adding braces easy. It may be necessary to remove a section at the front of the dump trailer for similar access.

    Those wretched air lines can be another headache - plastic "synflex" lines work great but do not stand up to spark at all. Before closing everything up (if air and/or electrical lines run through where you are working - every trailer is different) check and make any needed repairs to those lines. (Been there - done that :( )

    Worst part of the job IMO? The overhead grinding after the old plate is cut off.
  3. chip hayden

    chip hayden LawnSite Member
    Messages: 29

    thanks a lot! hope to be able to return the favor sometime. best regards, chip.

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