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Cat 302.5C tracking issue

The Learner

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Joined
Jul 22, 2012
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200
Location
SE Victoria Australia
Occupation
Hydraulic specialist
Hello all,

Been away a while but coming back for some advice
Have a 2.5t excavator at home
And it’s starting to have an intermittent hydraulic issue.

If anyone has experienced similar and can assist in my diagnosis I’d be wrapped.

Now you can operate it for hours on end and it’s fine
But increasingly it’s loosing most of the power in the tracks, but it’s a strange fault
You track forwards and it starts off moving normally then the engine starts to stall and the machine slows down until you stop tracking or the engine stalls.
It will fault in both travel directions BUT you can slew machine around 360 and the fault goes away sometimes for minutes sometimes for hours.

Would I be right to assume the swivel joint is causing this?

Qualified machinery mechanic here
But stumped to find the answer of this fault normally this would only happen in one drive so you can start swapping hoses to fault find but this time I don’t have that option

Cheers
 

John C.

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Jun 11, 2007
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12,870
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Northwest
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Machinery & Equipment Appraiser
The tracking issue is what I've seen typically with swivels in larger excavators. What is troublesome is the stalling of the engine. Does the machine travel straight when the stalling occurs?
 

The Learner

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Joined
Jul 22, 2012
Messages
200
Location
SE Victoria Australia
Occupation
Hydraulic specialist
Thanks John
Yes the machine still travels straight as it stalls

I believe the tracking and the stalling directly related as you can use all arm “top machine functions” with no issue

then you go to move on to next position and have tracking issues to stall engine
 

John C.

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Messages
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I'm thinking there is something going on in the electronics. I never learned how to get into the diagnostics on those machines. I don't recall the minis having a monitor panel with them.
 

The Learner

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Joined
Jul 22, 2012
Messages
200
Location
SE Victoria Australia
Occupation
Hydraulic specialist
That’s my thoughts also Per Ericksson just wanted more input or possibly some one who had same drama

John
There’s not too many electronics on this on full cable control from travel levers to spool’s
The swash on the pump is pilot operated however all other functions work to full capacity so I doubt it’s that
 

lantraxco

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Jan 1, 2009
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7,704
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Elsewhen
Excessive pypassing in the swivel may be causing a pressure drop that the computer and pumps are trying to make up for. If the pumps keep stroking up trying to build pressure, you run out of horsepower.

See this quite often on mechanical hydrostat machines with weak relief valves, operator keeps pushing the levers up because she ain't moving, eventually you run out of horsespower to push oil across the open reliefs.
 
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