tpitt
Well-Known Member
Thank you. I can't believe how good of shape it's in.
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Section for komatsu d20,21 and similar grey market dozers
- Thread starter rangerfreak
- Start date
Thank you. I can't believe how good of shape it's in.
Thanks everyone for all the help,It was the adjustment on the brakes.Everything is working fine now.This has been a great winter project because of everyone here THANKS AGAIN.By the way my serial number is 67811 what year would that be?
JRGCUMMINS
New Member
darinray - Thanks for the reply, I finally got it. I let penetrating soak in the threads for a couple of hours then got after it with a cheater bar, broke a ratchet, got a bigger wrench and a longer cheater bar and it finally broke free. I was able to adjust the brake and it is working fine now. I couldn't believe how seized up that thing was!
It looks like he didn't dodge that bullet after all. I dropped the pan yesterday and inspected the bearings, #4 rod bearings are toast, hammered flat. Crank's not looking too good either. I'm amazed it still had any oil pressure at all, and even more so that it was as good as it is. I moved on to working on pulling the engine so the crank can come out and I can have it turned.
RRRancher
Well-Known Member
Bummer. Oh well, an expensive lesson learned. Good luck with the overhaul.
RRRancher
Well-Known Member
This just popped up on CraigsList here in east Texas. For that price, joystick control, and just over 2000 hours, it looks like a pretty good deal to me, although closer inspection may prove differently.
http://easttexas.craigslist.org/grd/4387472921.html
http://easttexas.craigslist.org/grd/4387472921.html
tpitt
Well-Known Member
Does anyone know where to get rippers for a Komatsu 21a? Or has anyone built a set? I would like to put some behind mine. If not feasible, I think I might build a root rake.
DwayneC
Member
tpitt
Well-Known Member
Thanks DwayneC: I'm in contact with them. They are supposed to get back to me.
DwayneC
Member
No Problem, let me know what kinda prices there asking...
crawlake
Member
Hi there,
I just finished installing new steering clutches in my D21-P6. The clutches on the right hand side were pretty rough looking, all rusted up and pitted. The machine steers really good either way now, and when i'm pushing snow, or where I don't have really good traction both tracks will spin. But when I push up against a big tree on dry ground, the right side track doesn't spin? There is no grinding, or strange noises, just won't spin. What could it be other than the clutches?
I just finished installing new steering clutches in my D21-P6. The clutches on the right hand side were pretty rough looking, all rusted up and pitted. The machine steers really good either way now, and when i'm pushing snow, or where I don't have really good traction both tracks will spin. But when I push up against a big tree on dry ground, the right side track doesn't spin? There is no grinding, or strange noises, just won't spin. What could it be other than the clutches?
John25mm
Active Member
Thanks for the replies the other day RRRancher and mitch504 about attaching a winch to the back of my D20. To clear up what I was saying this is the type of ROPS system I have. I was planning to attach it from the bottom of the rear ROPS point by bolting on a plate to it. Again any ideas are greatly appriciated.
I also am looking with great lust at the ripper attachment above. I don't really need one but I WANT one.
I also am looking with great lust at the ripper attachment above. I don't really need one but I WANT one.crawlake
Member
I have read through all 121 pages, and steering clutch replacement has fixed pretty much all issues in regards to track not spinning. Everything in the bevel case seems to be fine, I'm assuming if the problem was gear related I would hear some sort of noises, or grinding? Not sure what could be going on that I loose power to the one side when I get really good traction?
Be sure your clutch adjustment fork is at 121mm to the center of bevel gear?And the transmission screen is clean?Is the brake adjustment right?Those brakes can be trickey to put back togather. Hope this helps its just a few thoughts.
RRRancher
Well-Known Member
I have given this some thought, crawlake, and I surely don't know the exact answer to your problem, but this is what I'm thinking. As far as I can tell from reading the service manual, I don't see any actual adjustments for the steering clutches themselves. The clutch is normally engaged by the springs inside of it pushing the plates and discs together. It is disengaged by actuating the release yoke. The release yoke is actuated by the steering booster cylinder, which is supplied oil under pressure from the steering control valve when the steering lever is pulled back, pushing the plunger in on the steering control valve assembly.
So what I'm wondering is, is it possible that your steering lever linkage is partially pushing in that plunger, even when it is fully forward? I really don't think that is what is happening, but it could, I suppose. If it is not that, I'm wondering if there is something wrong in your steering control valve assembly that is causing it to always be supplying a little oil pressure to the steering booster cylinder, which is almost disengaging the clutch. Not enough to disengage it during normal operation, but enough to disengage it when you are driving against an immovable object.
From what I read, when the steering lever is pulled back partially, there is a modulating action taking place within the steering control assembly, which partially releases the clutch. When pulled back all the way, the modulation ceases and there is complete release of the clutch. If there is a problem in your steering control valve assembly, perhaps it is always in a modulating mode and the clutch is never fully engaged. If you have the service manual, pages 21-63 and 21-64 explain this in detail. I have not been inside my steering control valve assembly, and I have no idea how hard it would be to open it and inspect the inside for something like a bad o-ring, broken spring, or stuck spool, etc. I think that would be the last thing I would do, and only if I couldn't find anything else.
All of what I'm thinking here is assuming the steering clutches are assembled properly and function as they should when the release yoke is not engaged. You said you replaced the clutches, so you should have a pretty good feeling about that part. If they are working properly, I just tend to think that the release yoke has to be partially engaged enough to partially release the clutch plates when pushing against an immovable object, but not enough to release them under normal loading. I may very well be totally wrong about this, and I will defer to any expert who knows more about this. Hopefully this may help you troubleshoot and find the problem. Best of luck with it.
So what I'm wondering is, is it possible that your steering lever linkage is partially pushing in that plunger, even when it is fully forward? I really don't think that is what is happening, but it could, I suppose. If it is not that, I'm wondering if there is something wrong in your steering control valve assembly that is causing it to always be supplying a little oil pressure to the steering booster cylinder, which is almost disengaging the clutch. Not enough to disengage it during normal operation, but enough to disengage it when you are driving against an immovable object.
From what I read, when the steering lever is pulled back partially, there is a modulating action taking place within the steering control assembly, which partially releases the clutch. When pulled back all the way, the modulation ceases and there is complete release of the clutch. If there is a problem in your steering control valve assembly, perhaps it is always in a modulating mode and the clutch is never fully engaged. If you have the service manual, pages 21-63 and 21-64 explain this in detail. I have not been inside my steering control valve assembly, and I have no idea how hard it would be to open it and inspect the inside for something like a bad o-ring, broken spring, or stuck spool, etc. I think that would be the last thing I would do, and only if I couldn't find anything else.
All of what I'm thinking here is assuming the steering clutches are assembled properly and function as they should when the release yoke is not engaged. You said you replaced the clutches, so you should have a pretty good feeling about that part. If they are working properly, I just tend to think that the release yoke has to be partially engaged enough to partially release the clutch plates when pushing against an immovable object, but not enough to release them under normal loading. I may very well be totally wrong about this, and I will defer to any expert who knows more about this. Hopefully this may help you troubleshoot and find the problem. Best of luck with it.
crawlake
Member
Thanks for the ideas guys. I actually talked to Darin about the 121mm adjustment, so I'm pretty confident I got that set properly. I did a full service at the same time, fresh oil in bevel case and final drives, cleaned trans screen and replaced oil, replaced hydraulic fluid and filter. I went up a hill and slowly pulled both steering levers, the machine stopped when both levers were halfway and began rolling backward, when I pulled the levers a bit further the machine stopped, I believe I have the brake adjustment right? As for putting the brake bands back together, and getting the linkages hooked up, I did have some problems with that. I already had the clutch case covers on and siliconed down, so I got the brake band linkages hooked up through the plunger hole and adjustment hole with hay wire, long screwdrivers and an extendable magnet. ( Not a mistake I will make again ).
RRRancher. Do you think if I got the machine positioned in front of a tree, then took the hydraulic line off of the right hand side plunger and plugged it off. Would I then be able to start the machine and run it up against the tree to see if both tracks would spin? I'm just trying to think of an easy way to test your idea without tearing the clutch covers back off. I'm not sure if unhooking that line and plugging it off would affect the rest of the hydraulic system, just thinking it might rule out any pressure being put on the adjustment fork? Thanks again for the help.
RRRancher. Do you think if I got the machine positioned in front of a tree, then took the hydraulic line off of the right hand side plunger and plugged it off. Would I then be able to start the machine and run it up against the tree to see if both tracks would spin? I'm just trying to think of an easy way to test your idea without tearing the clutch covers back off. I'm not sure if unhooking that line and plugging it off would affect the rest of the hydraulic system, just thinking it might rule out any pressure being put on the adjustment fork? Thanks again for the help.
RRRancher
Well-Known Member
You know, I actually thought about doing that last night when I was writing the last post, but then I remembered that it is not a line that screws into the valve control assembly. The steering boost cylinders have an opening where the line comes in from the block between it and the valve control assembly, and the line just has an o-ring that seats into the opening. There is nothing threaded to screw a plug into. I replaced both of these o-rings this last summer. I don't think there is a way to plug that line easily. I suppose you could remove the steering boost cylinder and then make a machined block that the oil line would plug into to just block it off for testing, but it would have to screw into the clutch compartment cover like the steering boost cylinder does so the pressure wouldn't just blow it off the end of the tube. I am including a parts diagram that shows the valve control assembly, the block with the rigid oil line, and the steering boost cylinder.
The valve control assembly is under the TSBO letters of KOMATSUPARTSBOOK.COM. The block and rigid oil line is part number 9, and receives oil under pressure from the valve control assembly via line 13, sealed by o-rings 14 and 15. The rigid oil line on part number 9 is sealed by o-ring part number 10, which is what I replaced on mine last summer. The steering boost cylinder is part number 1. There is no way to see if the steering boost cylinder is being driven by the oil as it is bolted to the top cover of the clutch compartment, which is in the bottom right corner of the diagram.
I understand your logic here, and that sounds like a great way to see if the clutch is just slipping on its own, or if the steering boost cylinder is actually partially releasing the clutch. I can't think of an easy way to test it without building a test block as I mentioned above. You can't remove the piston or it would blow oil into your clutch compartment. I suppose you could remove the piston (part number 2) and add a solid plate that would attach next to the gasket (part number 6) and would seal the oil in the steering boost cylinder from getting into the clutch compartment. That actually sounds quite doable, now that I think of it. A thin piece of sheet metal the same size as the gasket (part number 6) but without the large hole in the middle. Even if it leaked a little during testing, it would prove that the steering boost cylinder is or is not causing the clutch to partially release.
A little hint about the steering boost cylinders. Bolt them to the clutch compartment cover semi-tight, with the bolt (part number 11 ) loose enough to move block 9 around a bit. Line up the rigid line on block 9 to the steering boost cylinder so it will seal properly, then tighten everything up. There is a good bit of slop to play with.
As always, good luck with it, and make sure you let us know what you find.
The valve control assembly is under the TSBO letters of KOMATSUPARTSBOOK.COM. The block and rigid oil line is part number 9, and receives oil under pressure from the valve control assembly via line 13, sealed by o-rings 14 and 15. The rigid oil line on part number 9 is sealed by o-ring part number 10, which is what I replaced on mine last summer. The steering boost cylinder is part number 1. There is no way to see if the steering boost cylinder is being driven by the oil as it is bolted to the top cover of the clutch compartment, which is in the bottom right corner of the diagram.
I understand your logic here, and that sounds like a great way to see if the clutch is just slipping on its own, or if the steering boost cylinder is actually partially releasing the clutch. I can't think of an easy way to test it without building a test block as I mentioned above. You can't remove the piston or it would blow oil into your clutch compartment. I suppose you could remove the piston (part number 2) and add a solid plate that would attach next to the gasket (part number 6) and would seal the oil in the steering boost cylinder from getting into the clutch compartment. That actually sounds quite doable, now that I think of it. A thin piece of sheet metal the same size as the gasket (part number 6) but without the large hole in the middle. Even if it leaked a little during testing, it would prove that the steering boost cylinder is or is not causing the clutch to partially release.
A little hint about the steering boost cylinders. Bolt them to the clutch compartment cover semi-tight, with the bolt (part number 11 ) loose enough to move block 9 around a bit. Line up the rigid line on block 9 to the steering boost cylinder so it will seal properly, then tighten everything up. There is a good bit of slop to play with.
As always, good luck with it, and make sure you let us know what you find.
crawlake
Member
Hi Red Rock Rancher,
I'm away at work for a few more days, so haven't had time to look into my issue. I understand now what you are saying about the o-ring fit on the boost cylinder, that might be a bit tricky to fit up. Do you think it would work if I disconnected, and plugged off the 2 hydraulic hoses running into the main steering valve assembly? (Not sure if this is the correct name). It seems to me there is only the 2 lines that run into the entire assembly, just not sure if unhooking them would have any negative affect on any other part of the machine?
I'm away at work for a few more days, so haven't had time to look into my issue. I understand now what you are saying about the o-ring fit on the boost cylinder, that might be a bit tricky to fit up. Do you think it would work if I disconnected, and plugged off the 2 hydraulic hoses running into the main steering valve assembly? (Not sure if this is the correct name). It seems to me there is only the 2 lines that run into the entire assembly, just not sure if unhooking them would have any negative affect on any other part of the machine?