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PPM ATT400 - Electrical Swivel

Discussion in 'Cranes' started by Mic Bailey, Feb 15, 2019.

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  1. Mic Bailey

    Mic Bailey Member

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    Aug 16, 2018
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    Zambia
    Hi there,

    We have a PPM ATT400 crane (Serial No. 139626) that is having problems with electrical shorts within the wiring harness that passes through the swivel from the Turret to the main Carrier frame.
    We've dropped what I think is the "electrical swivel" from the bottom of the crane and everything looks tidy and dry (see photos). In our limited electrical experience we used a needle tester to check whether there was an earth between each of the wires coming out of the swivel and the swivel housing and found that quite a few were setting off the earth alarm. Unless some of them run to another earth somewhere else on the crane in which case they are probably ok.

    We are not sure what to do at this point, please can you help advise... If we were to replace the electrical swivel (been quoted one for $11,000!!! is this really what they cost!?) we are wondering how /where we would connect it as there doesn't seem to be any obvious "plugs" for the wires either side of the swivel?
    Is there any chance we can open and service the swivel?
    Many thanks for any advice /help!!
    regards, Mic
     

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  2. BillG

    BillG Senior Member

    Joined:
    Mar 26, 2009
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    Location:
    S. Wisconsin
    I am taking a guess that possibly the wires have chaffed internally or the slip rings maybe shorting. If it were mine I would try to isolate the wires on either side and using an ohm meter try to determine which ones are shorted if any before pulling it apart. You didn't say which functions were the problem. As far as taking it apart, I would inspect it very carefully first and mark everything. I suspect that this may be a dual purpose device, disconnect between the upper and lower (for mfg and service) and slip ring (swivel as you call it). Try and see if it has a disconnect point in the top end, the bottom end doesn't appear to. If it is grounded (earthed) you really don't have much choice, take it apart. But make sure the ground is actually at the swivel itself and not elsewhere.
     
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  3. ichudov

    ichudov Senior Member

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    Can you describe what is your exact problem with electrical shorts? It is very hard to create electrical shorts in a swivel. Does it happen as you swing the crane?
     
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  4. Mic Bailey

    Mic Bailey Member

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    Location:
    Zambia
    Thanks for your help and response. I have since had a call from Terex Uk to confirm that shorts in this device are quite common and especially in humid conditions (which we have where I am) which cause a kind of algae to form inside the swivel.. He explained how to remove the unit which is a 4hr job as it comes out with long lengths of harness on either end of the unit. We will then open it up and see whether it needs cleaning etc. I will let you know what happens!
     
  5. Mic Bailey

    Mic Bailey Member

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    Zambia
    The horn/hooter was coming on constantly and it started when we were slewing the crane clockwise, so we disconnected it at the blower under the front cabin dash. Also the outrigger retract function began to come on constantly.
     
  6. Mic Bailey

    Mic Bailey Member

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    Zambia
    We've done some further investigation and managed to open the swivel/ slip ring up (see attached photo's). Unfortunately it looks as though there was a big short somewhere that caused part of it to be burned out. We are not sure whether we can repair /clean this up back into working condition...(?)
    My concern is what may have caused this fault in the first place? If we buy and install a new one and the original fault is still there will it mean that we will destroy the new one!? Unless the fault was caused from wear and tear and perhaps the solder coming off from a connection?
     

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  7. BillG

    BillG Senior Member

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    S. Wisconsin
    I can't tell by the pictures but some of these units do not use every connection in the stack. Examine it closely and see if there are any spares, if so move the connections from the damaged area to the unused ones. Make sure to clean up the damaged area to prevent damage to neighboring connections. Also there is a special lube for slip rings that will help prevent future problems, I am trying to remember the name. I'll post it when I remember.
     
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  8. Mic Bailey

    Mic Bailey Member

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    Thanks for this BillG, that is a good idea! Any ideas how I can find out if there are any spares? Each wire goes into a 4 or 5m length of harness and then into a large plug either end , one plug into the turret and the other into the main drivers cabin. I guess i will need to start with a drawing of the swivel showing which pins are responsible for which functions?