1. Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!
  2. ALL NEW MEMBERS READ THIS FIRST!! Thank you for joining Heavy Equipment Forums! If you are new to forums we communicate with "Threads", please search our threads to see if your topic may have already been answered and if not then click "Post New Thread" in the appropriate forum. This will allow all of our members to see your question and give you the best chance to be answered. After you've made a number of posts you will graduate to Full Member status where you'll see a few more privileges. Following these guidelines will help make this the best resource for heavy equipment on the net. Thanks for joining us and I hope you enjoy your stay!!

Cat 312 final drive issue

Discussion in 'Excavators' started by Beegs, Sep 16, 2020.

  1. Beegs

    Beegs Member

    Joined:
    Oct 23, 2010
    Messages:
    20
    Location:
    NH
    1995 Cat 312 SN: 6BL00906

    When I track forward or reverse the machine could push a mountain over. Plenty of speed etc... The problem is if I try to turn or try to move one track at a time, it basically falls on it's face. It doesn't stall the engine, it almost seems like fluid is bypassing.

    Any thoughts on where I should start to look? Initially I thought maybe it could be the rotary manifold that needed to be resealed. A mechanic friend said if the seals where bad that it would also bypass when using both tracks simultaneously.

    Thanks for any leads.
     
  2. John C.

    John C. Senior Member

    Joined:
    Jun 11, 2007
    Messages:
    11,523
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    That depends on how the passageways are stacked. Does this machine have a stick control for steering on one pedal for forward and the other for reverse?
     
  3. heymccall

    heymccall Senior Member

    Joined:
    Feb 19, 2007
    Messages:
    3,797
    Location:
    White Oak, Pa
    It has a conventional side by side travel pilot valve.
     
    Beegs likes this.
  4. Beegs

    Beegs Member

    Joined:
    Oct 23, 2010
    Messages:
    20
    Location:
    NH
    Ok... I can see how depending on the way they are stacked, it could cause my issue. This has one lever/foot pedal for each track.
     
  5. Nige

    Nige Senior Member

    Joined:
    Jun 22, 2011
    Messages:
    21,168
    Location:
    G..G..G..Granville.........!! Fetch your cloth.
    Centre swivel seals bypassing.?
     
    Beegs likes this.
  6. uffex

    uffex Senior Member

    Joined:
    Jan 23, 2012
    Messages:
    2,885
    Occupation:
    Admin
    Location:
    Lincoln UK
    Good day
    This may not be the case but worth a check.
    Kind regards
    Uffex
     

    Attached Files:

    Beegs likes this.
  7. Per Eriksson

    Per Eriksson Senior Member

    Joined:
    Oct 24, 2007
    Messages:
    643
    Location:
    Sweden
    I have the same advice as the others, pull the swivel and reseal it.
     
    Beegs likes this.
  8. Nige

    Nige Senior Member

    Joined:
    Jun 22, 2011
    Messages:
    21,168
    Location:
    G..G..G..Granville.........!! Fetch your cloth.
    Nice to see you around Per. I was thinking about you only the other day.
     
  9. Beegs

    Beegs Member

    Joined:
    Oct 23, 2010
    Messages:
    20
    Location:
    NH
    Thanks for the replies! I hope to have time in two weeks to reseal the swivel. For some reason, I've always referred to it as the rotary manifold.

    I will report back with the results. Cheers!
     
  10. John C.

    John C. Senior Member

    Joined:
    Jun 11, 2007
    Messages:
    11,523
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    Swivel, rotary manifold? It just depends on where you grew up.
     
    Beegs likes this.
  11. Nige

    Nige Senior Member

    Joined:
    Jun 22, 2011
    Messages:
    21,168
    Location:
    G..G..G..Granville.........!! Fetch your cloth.
    Also depends how It’s referred to in the OEM’s Parts Manual......
     

    Attached Files:

  12. uffex

    uffex Senior Member

    Joined:
    Jan 23, 2012
    Messages:
    2,885
    Occupation:
    Admin
    Location:
    Lincoln UK
    Good day
    Removing the central passage – rotary joint/ manifold – swivel coupling is not always easy being sure it is at fault costs less time and money and you know if it needs new seals.
    May be a little drawn out but diagnostics is better that guess work. Please see attached.
    Kind regards
    Uffex
     

    Attached Files:

    Beegs, Mark250 and Nige like this.
  13. Nige

    Nige Senior Member

    Joined:
    Jun 22, 2011
    Messages:
    21,168
    Location:
    G..G..G..Granville.........!! Fetch your cloth.
    I agree, but on a 25 year-old machine I'd bet my bottom dollar that the seals in the swivel are like rock and are bypassing as a result. A complete set of seals for that joint comes to about $70.
     
    Beegs and uffex like this.
  14. Jam

    Jam Well-Known Member

    Joined:
    Nov 11, 2009
    Messages:
    209
    Occupation:
    Building contractor
    Location:
    Cork, Ireland
    Seals are cheap. If are gone hard it’s probably pressuring your case drain as well (which is tee’d into the swing motor) buggering your swing motor. I have the t-shirt!
     
    uffex likes this.
  15. John C.

    John C. Senior Member

    Joined:
    Jun 11, 2007
    Messages:
    11,523
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    Swivel seals don't fail by getting hard as rock. They disintegrate in pieces that usually end up in the return filters. While the seals for the case drain can fail it is usually the middle seals that fail and come out. That then lets the pressure side of one bypass into the return side of another circuit. That is why it matters as to how the circuits are stacked in the swivel. Case drain lines are usually only a #4 or #6 size so not a lot of oil can get through at once. On small to mid sized excavators it usually is easier to just pull the swivel and reseal than it is to cap and plug a lot of lines looking for the leak.
     
    Beegs and Jam like this.
  16. Tones

    Tones Senior Member

    Joined:
    Mar 15, 2009
    Messages:
    2,339
    Occupation:
    Ex land clearing contractor, part-time retired
    Location:
    Ubique
    Or centre joint.:)
     
    Beegs likes this.
  17. Per Eriksson

    Per Eriksson Senior Member

    Joined:
    Oct 24, 2007
    Messages:
    643
    Location:
    Sweden
    No time to spend online with 2 small kids it seems, only get to put in an hour here or there nowadays.
     
    Beegs likes this.
  18. Per Eriksson

    Per Eriksson Senior Member

    Joined:
    Oct 24, 2007
    Messages:
    643
    Location:
    Sweden
    Most swivels I have pulled has shown no signs of seals whatsoever, somehow they evaporate with out a trace and leaves only the top and bottom oring, crazy considering the clearances.

    And yes, when having even the slightest doubt that the swivel might be the cause of problems, just pull and reseal, it's so quick cheap and easy to do.
     
    anuradha, Beegs, Jam and 3 others like this.
  19. uffex

    uffex Senior Member

    Joined:
    Jan 23, 2012
    Messages:
    2,885
    Occupation:
    Admin
    Location:
    Lincoln UK
    Good day
    This may be of interest a center passage devoid of seals, was used througout Akerman production I have no knowledge of failure or replacement must have been good telorance.
    Kind regards
    Uffex

    upload_2020-9-19_8-57-25.png
     
    Beegs likes this.
  20. Beegs

    Beegs Member

    Joined:
    Oct 23, 2010
    Messages:
    20
    Location:
    NH