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Cat 312 final drive issue

B

Beegs

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Oct 23, 2010
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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.
 
John C.

John C.

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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?
 
B

Beegs

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John C. said:
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?
Click to expand...

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.
 
uffex

uffex

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Good day
This may not be the case but worth a check.
Kind regards
Uffex
 

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B

Beegs

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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!
 
John C.

John C.

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Swivel, rotary manifold? It just depends on where you grew up.
 
uffex

uffex

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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
 

Attachments

  • TestingCentralJoint.pdf
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  • Weak crawlers P1.pdf
    7.6 MB · Views: 13
J

Jam

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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!
 
John C.

John C.

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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.
 
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Per Eriksson

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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.
 
uffex

uffex

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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
 
B

Beegs

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John C. said:
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.[/
I am anxious to reseal it. I was pulling stumps yesterday and within a short period of time, the machine was not as responsive as it normally is. Particularly when swinging and raising the boom. I told my son, it’s almost as if some seals let go and have become lodged. After reading your comment, I feel confident that resealing will hopefully take care of what’s going on. Thanks!
Click to expand...
 
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