Komatsu PC75 UU-2 I threw Track , Adjuster is stuck solid.

[mike69440]

Komatsu PC75 UU-2 I threw Track , Adjuster is stuck solid.
Tried to use the bucket to push back the adjuster. Then a 5 ton hydraulic jack against the blade.Very little grease came out where i removed the check valve Lubricator. Yoke is rusted.

I have not tried soaking in penetrating oil. As there is an O-ring at the front of cylinder, I'm not sure wrapping a soaked rag around the yoke will get me anywhere.

I do not dare loosen that big cylinder nut. Spring does not look like it can be compressed in the field.

I'm fairly sure if i try to pump out the yoke, the seal and yoke will be destroyed. if i can push it back in, the seal Might survive?

 

[uffex]

Good day Mike
With the unit removed and connected to a power greaser its a real surprise it does not shift, I suggest that the seal is a small cost to have it working, dare I ask have you removed the connector and observed that grease is passing through OK? even a rusted adjuster will normally shift given the grease force at the piston in fact we have seen the jacket expand and split in extreme situations.
See attached.
Kind regards
Uffex

 

[mike69440]

My tack adjuster is different than shown.
I have the parts manual.

The yoke is free, the Piston is stuck, especially as I beat the yoke in with a sledge hammer to get the track on.
I used a hydraulic jack and a 16# sledge hammer to drive it back. Track is back on but grease gun will not expand the adjuster. Other than the fitting the Cylinder is not leaking grease, Adjuster will not pump up & move forward.

What do you think the chances for success with a porta power at 10,000 Psi?

 

[uffex]

Good day Mike
The track adjuster illustrated may look a little different but they all work on the same principle, for me beating it with large hammers would not be a good solution, Getting it to work as intended must be the best idea. The grease gun makes extremely high pressure those good models pressure are equal to that of the ports power so I suggest there would be little advantage connecting it up. If you remove the adjuster nipple from the cylinder connect the grease gun does grease pass through the nipple ok? Can you post a photo of that nipple I have known these to prevent grease passing and lock up the grease gun is that your experience ? Even a rusted cylinder should move with the force of a greasing gun.
I will see if I can find specifics on the PC75 and post to you if I am lucky.
Kind regards
Uffex

 

[uffex]

Good day Mike
Please see the attached may be more relevant to your machine, I assume you have steel tracks fully extending the piston will give the possibility to clean and remove corrosion.

 

[uffex]

Mike something went past me earlier some of the track adjuster cylinders have a exposed part of the piston rod when the cylinder is fully retracted, it would be easy to misinterpret this to mean the cylinder was not fully retracted.
Removing the rod and measuring the jacket to the rod would explain if this is indeed the situation.
Kind regards
Uffex

 

[treemuncher]

As stated above, the first thing I would verify is that the grease nipple is allowing grease to pass through. A new nipple is fast and cheap peace of mind to ensure the basic problems are covered. While it is out, make sure that the grease remaining in the cylinder is not hardened up and is clean.

 

[Tones]

x 1 on that.

 

[Gordon1]

Had the same problem with my PC75UU-3, wouldn't adjust at all. i unscrewed the grease nipple, got a good 10,000 PSI grease gun screwed directly to the valve ) grease nipple clamping is useless for this pressure ), whacked a couple of cold chisels in between the Spring end plate and the T bar ( Piston end ) and a crow bar on the slot on the outside and behind the idler to pull it forward, and used a 1500kg ratchet tie down to push the idler forward, and heated the piston cylinder with a butane torch, But got it in the end, all working now! give it heaps!

 

[Gordon1]

PS: some grease guns are not very high pressure, use a good one, not the pieces if crap cheap ones. something strong. and don't bother with the the grease nipple, take it out, and screw the end of the hose directly into the valve, as you need maximum pressure to loosen the piston ( i bent the handle on a cheap one ). it worked! also I left the butane torch going for at least 10 minutes, it's a big piece if steel and takes a long time to heat up.that's my 2 cents!