Komatsu PC60-7 lost a track, so loosened the adjuster nut and let grease come out as I pulled the idler sprocket. Got the track back on but now I can't get grease into the adjuster. The zirk fitting is free. My hand grease gun should generate enough pressure, correct? Are there any tricks for forcing the adjuster to tighten? I can use my bucket to pull the idler back out and the track will get tight but still can't get grease in there, even with the idler extended.
I know nothing about those adjusters but I was wondering if there was a valve of some kind that has to be opened to let grease from zerk to flow to the adjuster? Or is the zerk in a fitting with a check valve in it. Seems like trusting the little ball in a zerk to hold all the pressure would be asking a lot of the little thing.
I'm no expert either but I'm pretty sure that zirk fittings have a one-way valve...there's a little ball in the end to prevent grease from coming back out. I mean, they use them everywhere to push grease into tight places. But there's a lot more to this issue than the zirk...if you look at a parts breakdown of these adjusters it's more complicated and I can't picture what's stuck inside there.
Track adjusters generally don't work that way. There is usually a screwed valve below the zerk that has to be opened before grease can be added, there is often a second screwed valve that is used to remove grease from the assembly. IMO the ball in the end of the zerk alone would not be adequate to withstand the load of impacts on the idler/recoil mechanism over an extended period of time without failing. Also if the system relies on nothing more than the ball in the zerk as a non-return valve for the grease how are you expected to release the pressure in the track adjuster in a controlled fashion.? Not by removing the zerk surely.? Sounds like you have the parts breakdown. Can you post it up.?
Nige is right. I once had a united rentals mechanic install the check valve backwards on a ditch witch and he had the same problem as you.
The zerk is screwed into what looks like a bolt head. Loosen the bolt ( 1 turn max) then try to adjust the track. Retighten the bolt when you have the correct tension on the track. To loosen the track unscrew that bolt until grease starts coming out . Do not remove it with tension on the track, it could hurt you.
Every one of these I have seen the grease fitting is part of the release valve and the ball holds the grease in. A lot of the adjusters also have a separate release valve to allow grease out of the cylinder. I mean what could the surface area of that ball be 0.0002 sq.inches? Bob
Surface area of a sphere is 4pi r^2 so you're off by a couple decimal points. Figure maybe 1/2 the ball is getting grease contact so its ~0.025sqin for a 1/8 ball Edit correct typo
But that's pretty big for a grease zerk isn't it. A 1mm ball would be 10x less surface area
The fitting does not have to be loosened in order to add grease to adjust the idler out. There is a check ball and spring inside the track adjuster fitting that takes the load. The front of the fitting is a cone that seals the grease in the cylinder. Turning the whole adjuster fitting backs off the cone which allows grease to pass through a relief hole. The common problem with these is dirt getting forced around the track adjuster cylinder and hardening in the bushing inside the cylinder. It happens because the chains are stretched out and the idler can bounce around in the track frame which creates a space around the track adjuster cylinder rod and cylinder head for dirt to get shoved in. You should have pulled the adjuster cylinder apart before you put the track back on. You would have found that you couldn't get it to move at all and will likely have to scrap it and get another one. I have actually chained each end of an adjuster to two D6 sized dozers and all they did was spin their tracks.
Appreciate the info. Question I have now is what exactly does the track adjuster consist of? Is it the entire (expensive) assembly including the spring or is it a smaller cylinder in the back that accepts the grease? Is there no way to take it apart and clean it rather than buying a new one?
Now you are taxing my memory. I would suggest that if you don't have a parts book to get a Komatsu dealer parts guy to email you a copy of the page in the book. A couple of machines I did have to replace the whole set up, spring and all. I just can't remember which ones. To take it apart, the cylinder rod just pulls out the end of the barrel as I recall. The problem is you are able to pump 10,000 PSI with a normal grease gun. If the piston is one inch in diameter, you are able to put about 15,700 PSI of force pushing the piston out of the barrel. That's a conservative estimate of what it will take to get the adjuster apart.
Thanks for confirming that John. I couldn't see how a track adjuster would depend simply on the ball in a grease zerk to hold the pressure.
Kobelco adjuster fittings are bad for not taking grease if a spec of dirt gets behind the initial check valve on the zerk-replaced lots. Take the fitting right off and see if grease flows freely-if not the cylinder is dicked. Sometimes you can disassemble by welding an on the end and yanking it out-put a new rod in cause it'll be damaged-clean all the corrosion in the tube and reseal. When I see it this bad, I like to replace the entire assembly and be done with it
I have had the zerk fitting off, and I loosened the big nut the fitting screws into. No grease came out of the zerk hole but some did come from around the big nut, when I pulled the idler backwards. So the idler is back pretty far now. Doesn't this imply that there is movement in the cylinder? Why else would grease come out? Then I pulled the idler forward far enough to tighten the track, thinking it would then be easy to get grease in, but that didn't work. As soon as I release the forward pressure from the idler it returns to where it was and the track is slack again. SO....if I try pulling the cylinder out as you say, how do I get at it? Could I screw in an eye bolt in place of the zerk fitting and yank on that? I'm thinking run a cable through the eye and use the bucket to pull rearward. (I also assume that the large nut would have to be unscrewed first.) Or is this all done only with the entire assembly removed from the machine?
Pull the big nut fitting out and see if you can pump grease thu it with the grease fitting back in it. Bob
Before doing much more I would want to have at the very least a good parts breakdown or preferably an actually factory service manual. Just guessing at how something works or comes apart can be costly or even deadly!
Sounds like you're creating a vacuum when pulling out the idler like no air can get in the cylinder while you're pulling. Some kinda blockage going on not that that wasn't already clear just saying
ing Here's a parts breakdown from the repair manual. "Creating a vacuum" is an interesting thought. I will remove the zerk fitting before I pull the idler out and see what happens.
That disassembly & assembly procedure is for the recoil spring assembly, not the tensioner. The tensioner sits behind what's shown in the illustration above.
That’s the kind that will require taking the assembly to someone with a big press to remove the spring if you can’t get the piston out.
Item 11 is the piston. Item 9 is the cylinder and retaining rod for the spring.
I'm gona bet 1 2 ,3 are the track tensioner grease fittings and group 5 is the adjuster rod and seals. Looks like a grease fitting between 2 &3 with 3 being the release valve that has to be open to release the adjuster. Bob
I was thinking assembly #5 is the tensioner which slides into the recoil assy (#4). The grease fitting is # 1,2 and 3. The way I read it, pushing grease into #3 forces the piston through the cylinder and moves the yoke. Unfortunately as I examine it, my assembly doesn't look exactly like this. I have a double nut where it shows the single #6 and the zerk screws into the outside one. So I guess my hesitation is, can I safely remove that big nut? On this diagram that's the one that holds the spring assembly together.
Take heed of what John C posted 4 posts above regarding disassembly. He’s well clued up on Komatsu. Those big springs are not known as Death Springs for no reason.
Exactly my thought...but as I say above, this isn't quite what mine looks like. This diagram comes from the PC60 repair manual. I guess there may have been some changes made. I'll try calling the Komatsu service guy on Monday before I start removing things.
You can slide the whole assembly out the end of the track frame and look it over. Some units have a lock nut on top of the retaining nut.
Good idea, Does yours have the #3 part on it? Bob
I do not have part #3....the zerk screws directly into what looks like a "double headed nut" piece with a thin "retainer" between the heads. Unscrewing the outermost nut unscrews the inside one as well, but the "retainer" between them prevents that whole piece from coming all the way out. It seems like the intention there is to allow backing it out a short distance but not completely out. There is a small bolt holding the "retainer" piece in. So maybe that's the way to release the grease pressure from the cylinder while ensuring the nut piece can't come out (which may be what is holding the spring assembly together, and which is what you guys have been warning me about). In fact I did back off that nut and grease did come out when I pulled backward on the idler. Assuming this is the case, perhaps the reason A. Williamson suggested - I created a vacuum when I forcefully tightened the idler - is why I can't push grease in it now. That would mean I don't have to take anything more apart, but simply remove the zerk allowing air to get out, reinsert it and then try to put grease in there. Sounds too simple, but worth a try. One more question though....if that double nut does hold the spring assembly together, shouldn't it be really difficult to turn when there is all that spring pressure on it? This loosened fairly easily and was almost finger-tight after a few cranks with the big wrench. All the input is much appreciated. I'm very glad to have found this forum. Joined years ago but forgot completely about it.
Is the retainer held on with a couple of screws? What size is this nut? What you are describing sounds like a #3 piece which is a release valve /check valve. With the nut loosened try pumping grease thru the fitting. Could you post a few pictures of this? Bob
Just to be clear I thought you were pulling the piston out of the cylinder and seeing it pull back to its resting position when you let go. In that case the grease inside the cylinder would have "stretched" and vacuum formed but no air would have gotten in - otherwise there would be no vacuum. I may have misunderstood the situation.
After reading your post a little closer you are talking about the #3 fitting. You can remove the keeper and unscrew the double nut fitting, it don't hold the spring on. I'm guessing you big wrench is about 19mm. put the grease fitting back in and see if grease will go thru it. If not you may be able to clean it. Good luck Bob
Does it look like this.? If so do like Bob says, remove the two small bolts, the keeper plate and the block. That will allow you to remove the "double nut" as an assembly which likely has a check valve inside it. Try installing the zerk into the assembly with it off the machine and see if you can pump grease through it. If it won't take grease then the check valve would appear to be stuck. You might be able to free it with penetrating oil or paraffin or something similar.
Most adjuster have the zirk as part of the adjuster. I would guess that adjuster has been modified and that ninety degree angle fitting has been installed. The picture is worth a thousand words.
Just to point out John that the photo is not from the OP’s machine.
I figured that but all the factory adjuster fittings I've had to put my hands on had the nipple in line with the fitting and actually being a part of the fitting. There were no threads to install an angle fitting. Of the units that had angle fittings installed, the nipple would interfere with loosening the adjuster with a socket.
Agreed. And certainly on Cat equipment the fitting is generally a button-head type rather than a zerk. Because there is only one valve on that tensioner setup I suspect that to relieve the grease pressure in the tensioner the valve would need to be unscrewed maybe a couple of turns. It looks like the idea of the lock plate is to prevent the valve being completely removed while pressure is still behind it and doing double duty as a retainer to prevent the big nut on the recoil spring assembly from unscrewing.
I've never seen any piece of Cat tracked equipment that has a button head on the track adjuster. The plate is only to keep someone from unscrewing the adjuster fitting more than a couple of turns. The issue is someone having their hands in there when an operator suddenly throws the machine in reverse to try and pull the idler back. The added plate is only window dressing for the big nut. The spring on that machine is compressed to half the weight of the machine. PC60 is around 13,000 pounds so the nut is holding between six and seven thousand pounds of pressure.
Well I've never seen a Cat machine with a grease zerk on it! Bob
Maybe I missed something. All the track adjusters I have seen have nipples to plug a grease gun into. The button grease fittings look like below and I've never seen one on a track adjuster.
That is a button head fitting can't tell which size I have never seen one on a Cat adjuster. I meant I have never seen a zerk fitting anywhere on a Cat machine. Bob
No you did understand...that's exactly what I did. But now after reading more responses I'm thinking there is also a check valve in there someplace that is causing issues, so removing the zirk isn't going to buy me anything at his point.
No mine is a bit different...I'll submit a picture when I go back out in the woods and mess with it some more. I'm not totally convinced that I can safely remove the big double-nut unit. That retainer has to have a purpose.
I'm pretty sure my unit has different parts than are shown here. I'll take a picture or maybe get the Komatsu guy to send me an accurate breakdown. If I pumped grease with the nut loosened I'm pretty sure I'd have grease coming right back out past the nut......it came from there when I pulled backwards on the track. I think the nut is 11/16".
I lost track what are you trying to do? 11/16 is not big and it's not a nut it is a check valve. The retainer is to keep the valve from getting lost, once you open the valve you have relieved the grease pressure. If you can pump grease threw that valve no reason to take it out. I give Good luck Bob
I asked initially if anyone knew a trick for getting grease in there. So it IS a check valve then? And no I can't get grease through it, so I'm hoping that it is just that valve, which should be a fairly inexpensive fix. (If it's still available. Or even cleanable.) But check valve or not, is it safe to remove it? Is it under pressure from the grease or the spring?
THe guys here have posted earlier that you can pull the retainer clip and unscrew the valve all the way, reinstall the zirk (or grease fitting of other variety) on your test bench and check if grease flows through when it is uninstalled. If not, try cleaning it out with a solvent bath of some kind and trying again.
If you follow the procedure below to release the pressure before removing the valve, then it should not be. However you always should use caution when removing parts that potentially could have pressure behind them. Note the part highlighted in red, especially the comment regarding not loosening the valve initially by more than 1 turn when releasing the grease pressure. When the pressure is released then you can remove the 2 bolts and the lock plate which will allow the valve to come all the way out. Once you get it out, try cleaning it internally as suggested in the post above. Someone mentioned earlier that it is easy for the check ball to get jammed if a piece of something such as grit gets in it.
There is no way to clean the adjuster valve. Remove it and then pump some grease through it. If you get grease through the end, there is nothing wrong with it. The failure mode for this part is to leak because of a groove worn on the cone at the bottom.
OK first of all where did you get this diagram? That looks exactly like my setup (see attached picture). These instructions sound good to me too, and I will try that. And John C I will try what you said and will keep you posted as to the results. Thanks again....
Removed the adjuster valve today and pushed grease through it just fine. Put it all back together and I suppose now I'll work the machine until it throws the track again, and then pull the whole assembly out for repair. Rats....
I assume that grease came out when you released the adjuster.? When you put it back in could you actually get grease into it up to a certain point where it wouldn’t take any more.? If that’s the case maybe the adjuster is extended as far as it will go (there is a limit) and the problem is wear in the track.
Kind of like those adjusting screws on the swing arm of a motorcycle rear wheel? Can only pull that axle so far back before you get to the end of the slot in the swingarm!
Yes some grease did come out but not much. I could not get one shot of grease in there after reinstalling the valve. I just don't get it. How can it move backward but not forward? I have moved it both directions with the bucket and a chain. Thanks anyway guys.....
Have you tried a different grease gun?
The whole assembly can move forward and not move the piston. The only thing holding that assembly in the machine is the track.
Well that's the answer then....the piston is jammed somehow. And yes Mr. Williamson I actually went out and bought a new grease gun when, after it seemed like my old one was actually working - I could get the handle (pushing really hard with both hands) all the way down so it seemed it was reluctantly pushing grease - but after pumping for maybe 45 minutes with nothing happening I concluded that my gun was simply failing me. Don't ever want to do that again, kneeling on rocky ground, pumping and sweating with ticks crawling up my legs. (Worst year yet for ticks.)
Update and finish.....I took the assembly to Komatsu dealer and they repaired it in one day. They had to use very high pressure to get the piston to move. They cleaned up the piston, honed the cylinder and installed new seals. Just under $500 for parts and labor. I was able to get the assembly back in by myself but it took a lot of finagling using the bucket with chains, ropes and a come-along. But it works great and I'm back in action. My piston did have rust spots which they cleaned up but he said it shouldn't be a problem. The service manager said that there are new assemblies available from after-market...around $800 without the idler. (Which means I'd have to remove my old idler and reinstall it on the new assembly - or pay them to do it.) Thanks again for the advice.
How did you get the assembly to come out of the track frame? Did you have to remove a bolt? I'm in an identical situation, same machine, track adjuster stuck, but can't pull the assembly out of the track frame, even chained to the bucket, the hydraulics aren't strong enough, so I suspect there's a bolt that needs to come out first, but where...
Hi Mark, The assembly is not bolted in. It slides out once you get the track out of the way. I put a chain through a hole in the idler wheel and attached it to the bucket. It's heavy so can't pull it by hand. Only reason I can think of is that it's rusted in place. Might take a solid whack with a sledge hammer? There is a stop built in to the frame at the rear end of the assembly which keeps it from sliding rearward, so any hammering has to be done toward the front. Good luck, Bill
I've been working on trying to free mine for nearly 3 weeks now. The only movement is the recoil spring stretching, which made me wonder if the giant nut near the Zerk is holding the whole thing in place. I've whacked it, I've yanked on it with a chain. I've flooded it with nearly 2 gallons of WD40 purchased in bulk and sprayed in with an Agway pressure sprayer. The only thing I haven't done is gotten two CAT D9 bulldozers to pull from opposing ends of the track. It's really solidly in, like it's welded in place.
So it sounds like your track is still in place? If so there's no way you're going to pull the assembly out of there. That "giant nut" is only about 1 1/16". That's the valve unit, and it's held in place with a piece of 90 degree angle steel, which is held on to the assembly with a couple of smaller bolts. That is only there to prevent removing the valve, allowing a slight release of grease. All of that will come out with the assembly. I'm curious as to how you know the spring is stretching. It's hidden inside the frame.
I realize that the adjuster cannot be removed with the track in place, but it should move a little until the track slack is taken up. Mine does not move at all. If it moved even slightly, the big nut and Zerk should have moved but they did not. The big nut I'm referring to looks to be over 3" in diameter. Some are saying that holds the spring in place and not to touch it. I've already removed the keeper plate and the smaller nut with the Zerk in it last week. Tested the Zerk (it passes grease) and put it back together after still being unable to move the piston. How do I know the spring is moving? Because when I pull on the idler, it moves forward 1/2" and then returns to it's former position when I remove the pulling force. It's certainly acting like the spring is pulling back. Same thing when I was pushing in to loosen the track. It would move in a few fractions of an inch and then spring back to former position. I contacted AMS for a new assembly and asked about how to remove mine and this was there reply: "Mark, You’re very welcome! There should be a bolt to loosen adjuster so you can pull it out. Keep me in the loop, it’s not too difficult to remove and once you get it out, I’ll be happy to help you move forward. Thank you, An Industry Leading Supplier Stefan Pendergrass Account Executive"
"Account Executive" means know nothing sales person.
LOL Kinda like my boss! They call him a bean counter...LOL
Mmmmm I'm not sure I trust this answer. There IS a big nut holding the assembly together and if you look back over the earlier responses here you'll see warnings about the power in that spring when it's released. If yours is identical to mine I guarantee you there is nothing holding that assembly in place except for the track itself. I installed the thing myself and it just slid into place (well, it wasn't as easy as that, but...) and I pulled the track back over the idler. Then pump grease in to tighten. Ha ha I read again "help you move forward". Yes, if you're sitting in front of the idler when the nut lets go.....
It's like the back end of that spring were welded to the frame though. Every video I could find on replacing this part shows it sliding out without removing any bolts. I would think with a track as loose as mine is (stretched it out trying to loosen the adjuster with blocks of wood between the idler and track) would allow the whole assembly to pull back when the idler is yanked on with a chain tied to the bucket. But even with full hydraulic power applied to the limit, all I did was slightly stretch the spring, only to have it go back again when I release the pulling force. The back end of that spring is solidly stuck. I know not how any rust can be stronger than the hydraulics, but this one's stuck. It should move to the point where the track becomes taught, but it doesn't move at all. Oh yeah, I'm leery of that spring, believe me, I've been reading the threads.
And you're sure the track isn't holding you back? When you pull out on the idler doesn't the track stretch tight? Two things....first is get that track off by unbolting it. If you can't then while pulling on the idler keep the tension on it and whack the assembly wherever you can reach it....tough to do with the track on though. If you could reach in behind the assembly through the opening in the frame, stick a steel bar in there and bang on the end of it. It sure sounds like you will have to hit it hard while under pressure. That's how the shop did it when getting mine unstuck....they had the assembly under pressure and then banged it with a sledge. Just pulling on it won't be enough.
Oh believe me when I say this, that I've been all through it with iron bars and 16lb sledgehammer, and I've flooded the entire assembly with almost 2 gallons of WD40, care of a pesticide pressure sprayer, and I could not get it to move. If the track were truly holding it in place, then I should be able to pull the track taught when pulling on the idler (I put a thick iron bar through a hole in the idler and used a chain wrapped around each end of the bar to the bucket and pulled. Bent the bar into a U shape, but the spring stretched temporarily about 1/2").. even with all that pulling power, the track was still sloppy loose and hanging down. And as soon as I released the pull on the idler, it sprung back to original position. Two weeks ago, I removed the Zerk fitting and shot Marvel Mystery Oil into the space where the grease goes, then put the fitting back and pumped it full of grease and waited. I've let the grease out and pumped in new grease dozens of times over the past 3 weeks and not a single mm of movement. The spring stretches or compresses a little depending on whether I push or pull on the idler (pushed by inserting four 2x4s on the track and running it backwards. That's how I pushed back the adjuster on the other side of the machine.) It really seems like the spring seat at the Zerk end of the assembly is affixed to the frame right there, as if welded in place. Seems like this track is original from Japan too, as the part number is a Japanese number. The other side has an American part number like the ones we're familiar with. So this side on the right with the stuck adjuster may have the original factory track from who knows how many years ago and has never been changed.
No one in their right mind would weld that in there.....absolutely no reason. Seems like all you have left now is get out the acetylene outfit and heat the blazes out of it, yank it and bang it. Lay a steel plate on the track over it. Let the WD40 burn. Keep water handy. Another bright idea....run it back and forth over rocky places and give the assembly a good workout.
That is a gawdawful lot of mass to heat up. I have a Prest-o-lite acetyline torch, but I doubt that's going to be adequate to heat it enough. I suppose if I can get a good fire going in that assembly (and keep it from spreading) that the heat might reach a point where it might help unstick things. Heck, it might even unstick the piston/adjuster. I dunno. In a week or two, my neighbor's making another trip to his dad's in PA and can bring some sort of hydraulic device that can exert 30,000lbs of force. We can stick it in the opening near the Zerk fitting and try to push out that whole assembly. I've driven it all over the yard, over rocks and so on, but that adjuster remains as steadfast as if it were welded in place. I've never seen anything this stuck before.
Please don't light a fire anywhere in that area or anywhere on a machine ever. When you do have to remove the track it will be easier to see what going on in there. Don't waste any more time of money trying to diagnosis a problem that you can see with the track still on the machine. My bet on why the idler won't pull out is the spring has broken and maybe fallen down inside the frame. When the track is off the machine you can look up between the bottom rollers and you will be able to see what's holding it in
I guess if the spring has broken and fallen into the machine, then that would stop the adjuster from working too?
Snuck a smartphone selfie camera under the track and this is what is looks like. I don't see any broken spring though. What do you think?