Komat'su PC60-7 --Just Purchased Used--Some Questions

[heymccall]

If you don't want to cut the track, and can't walk the track off otherwise, unbolt the sprocket, and use a drift from inboard, while repositioning the track, and drive off the sprocket. The sprocket is a snug slip fit. Then remove the track and slide out the whole assembly.
#15 is apparently stuck in #1. Once free of the machine, some rotating in the bore, along will pulling and creativity, you should be able to separate #15.

 

[John C.]

At this point, not likely.

 

[Mark A Weiss]

If you don't want to cut the track, and can't walk the track off otherwise, unbolt the sprocket, and use a drift from inboard, while repositioning the track, and drive off the sprocket. The sprocket is a snug slip fit. Then remove the track and slide out the whole assembly.
#15 is apparently stuck in #1. Once free of the machine, some rotating in the bore, along will pulling and creativity, you should be able to separate #15.
View attachment 242663

I suppose if I can't pull free the idler with the track on (and loose with lots of slack), there's little point in removing the track, since the block and piston would be frozen and requiring resources that I don't have to unstick it.

I need to find a 3" diameter solid iron bar to put through the idler wheel hole that I can chain the bucket to for pulling. my 1-1/4" dia bar just bends when I do this. If I were able to unstuck it with the loose track in place, then I can remove the track and know the adjuster will move.

 

[John C.]

The track will take itself off when it's ready. The assembly will be easy to remove at that point.

Worry about getting the work you have planned for the machine done, then work on the machine. .

 

[Mark A Weiss]

The track will take itself off when it's ready. The assembly will be easy to remove at that point.

Worry about getting the work you have planned for the machine done, then work on the machine. .

I was fiddling with it again today. This after flooding it two days ago with WD-40 via a pump bottle sprayer from Agway. Lifted the machine again, put the iron bar through the hole in the idler wheel, chained it to the bucket and pulled. Again, only the recoil spring stretched a bit. Then it occurred to me, what's keeping the whole assembly from sliding out even just until the track is pulled tight? That big nut is said to hold the spring in place under tension. But there must be a bolt somewhere that holds that whole assembly to the frame, because it's solidly affixed and won't budge in the slightest. Isn't that entire adjuster, piston, yoke and idler supposed to slide out of the track frame? Why doesn't it slide forward a bit when I pull on the idler with a very loose track? Only the spring expands. Nothing else moves!

I have my neighbor's pressure washer on loan. Tomorrow, I wash down the machine.

 

[John C.]

That assembly fits into a bulk head in front of the adjuster fitting. The track is the only thing that holds the whole assembly in the track frame.
The track frame is likely packed tight with dirt is all. You might be able to pick up that side and spray out enough stuff to see the bottom of the spring.

 

[Mark A Weiss]

That assembly fits into a bulk head in front of the adjuster fitting. The track is the only thing that holds the whole assembly in the track frame.
The track frame is likely packed tight with dirt is all. You might be able to pick up that side and spray out enough stuff to see the bottom of the spring.

I will try pressure washing again that track assembly. It seems pretty clean now. If only I could use WD40 instead of water in a pressure washer! If I had 50 gallons of WD40 in a large tub, could submerge the whole thing for a few weeks and let the WD40 work its way in.
If the rain isn't too hard, I'll try pressure washing from the underside of the track frame as well as from the opening near the idler. When it dries, I'll load up a gallon of WD40 in the pressurized sprayer and flood the whole thing again with WD40. It's GOT to find it's way in eventually!

 

[Mark A Weiss]

After pressure washing again, I gave a closer look at the whole assembly.
I circled what I suspect to be causing the jam. Notice there's a small dent, about 2mm deep in the frame. If this is preventing the assembly from being slid out, it is also preventing the adjuster from moving.
Now the question is how to pull out this dent. The metal is at least 6mm thick.

 

[skyking1]

It is highly doubtful a 2mm dent is the cause. If you do figure out through further investigation that it is actually pinching the widest part of the yoke, you can weld a stud on it, use some big washers for spacers on each side and put a heavy bar across with a hole in it over the stud. Then heat up the area in question, tighten up the nut and pull the dent out.

 

[Mark A Weiss]

It is highly doubtful a 2mm dent is the cause. If you do figure out through further investigation that it is actually pinching the widest part of the yoke, you can weld a stud on it, use some big washers for spacers on each side and put a heavy bar across with a hole in it over the stud. Then heat up the area in question, tighten up the nut and pull the dent out.

Excellent suggestion. I have a flux core welder, 125 amp. Think that might be adequate, or should I buy a better welder?
I've done up a quick 3D representation of what I think you are describing here. Is this the correct idea?
I have an air/acetylene torch to heat up the area of the dent. Would that be hot enough, or do I need oxyacetylene?

 

[skyking1]

Yes. Make sure that the washers don't affect the area you want to pull out, make sure your bridge is long enough, be sure to have a fire extinguisher on hand when you start heating things up. Most of all don't do any of this unless you're absolutely certain use a feeler gauge or some other thing to determine that it's actually bound up there otherwise you're just spinning your wheels.

 

[John C.]

I've seen plenty more and deeper dents than that. There is a lot of room around that spring. No way that that dimple is causing your problem.

 

[skyking1]

Yes there's no way that that would be holding the spring there would only be an outside chance it would be right lined up with the yoke. If you have to eliminate it for your own mental health, take a piece of welding wire and reach in there in the area of the dent and verify there's clearance. My suspicion is the wire will pass up and down in that area just fine.

 

[Welder Dave]

Is there maybe a way to put a bar in the hole on the side of the track frame to pound on the yoke or other solid part of the assembly? Thinking if you have pressure on it and the bucket also pulling, a couple good whacks might get it to move. There are no remnants of the rod still stuck in the yoke?

 

[Mark A Weiss]

It looks like there's no remnants of the rod left, because the space between the yoke and frame has decreased to contact. When the rod was stuck in that gap, there was at least 2mm gap between yoke and frame.

Yes, frankly, I'm not sure that the small dent is the problem either. But then, if the adjuster is not welded or bolted in there, it should come out with all the force I have been applying to it.

Just by tapping on it, I can tell the metal is much thicker toward the front of the dent and the spot where the dent is is hollow.

If the adjuster alone were seized up, at least the adjuster assembly should slide forward, but the fact that it does not even budge suggests something holding the entire assembly in place.

The track has original Japanese part number on it (I posted a picture of it earlier in this discussion) making me suspect that this track has never been changed since the manufacture of the machine. If the machine is 20 years old, then the adjuster hasn't been touched in all that time.

I'm studying the drawings on page 398 of the shop manual, but I don't see what could be holding the other end of the spring in place so tightly. The yoke can move when force is applied, but the back end of the spring is solidly in place, as if someone welded it to the frame.

Then there's the fact that I've flooded the entire assembly with WD40, over a gallon of the stuff was used in the past week with multiple applications via a pump sprayer.

 

[Bluox]

My WAG a broken spring.
Bob

 

[Mark A Weiss]

My WAG a broken spring.
Bob

I would think that if the spring were broken, the assembly would not be resisting like a spring was holding it back.

 

[John C.]

Since you pulled the spring forward, the socketed end that sits in the track frame bulkhead is now out of place and maybe a coil has dropped into a cross piece in the track frame.

Put the thing to work and don't worry about it.

 

[Mark A Weiss]

Since you pulled the spring forward, the socketed end that sits in the track frame bulkhead is now out of place and maybe a coil has dropped into a cross piece in the track frame.

Put the thing to work and don't worry about it.

Wouldn't the big nut and Zerk assembly have moved back if that were the case? They are right where they've always been.

The machine will work, I just have to be careful turning so as not to have the track come off. That's my plan for now. But I've got the extra track sitting here.

 

[Mark A Weiss]

I'm thinking of loosening the big giant nut a little, just to see if that will let the track tighten a bit. It's very loose and hanging down at present.