Hello everyone. This looks like another great forum. I spent about 2 hours just looking at pics of old equipment and restorations. Just saw the dozer that was found buried. Crazy! While adjusting the driver's side tracks on our D7H, this cable broke off inside the cylinder. Not really sure of what it is or does (as I never noticed it before) so I'm afraid to run it 'till I find out. I still had about 2" of slack left to adjust when it broke off. I always helped PM this thing, but I'm not a heavy euipment mechanic so any help with identification or tips would be greatly appreciated. I was kind of told "You're the new dozer guy" at work, so I grabbed the manual and got to it on my own. Never even sat in one before, so it was pretty scary. I have a video of my first pants soiling so to speak Thanks for reading this.
Well by the looks of it, the cable its there to hold the barrel in the trackframe when you pull the track off, if the cable was tight when you began adjustment, either the tracks are severely worn to service limits, the recoil spring is broke, or both. A recoil spring is pretty much a dealer job, or at least a job for someone with the proper experience and presses. Recoil springs are like a loaded cannon.
I'd agree. Either the tracks are so worn that the tensioner has over-extended, or the recoil spring has broken. Easy way to check for internal track link wear. Drop the blade and push forward lightly, stop the tractor and set the brakes. Make sure the top run of the tracks is tight. Take a tape measure and check the centre-to-centre measurement of 4 links (so measure between the centres of the 1st & 5th pins). Your tracks are 8.5" pitch so you should measure 34" if everything is OK. If you measure anything more than 34.75" (which corresponds to 120% internal wear) you have major internal wear on your tracks. Internal pin/bush wear on the track links would be a contributor to the track tensioner being over-extended.
On D6H if the track pins get dry and wore out you can't over tighter like old D6.There is a slot in the track tighter that lets the grease pump into the track frame.If recoil spring tube is broke then usually the track is tighter then a drum.Had it happen on the older D6H's. Becarefull if the tube is broke.The track tighter, tube, and recoil come fly out when you break the tracks. Had to have it put in a jig at Cat and rewelded.Both side different time,caught the last one with a crack before it completely broke.They did a good job on welding, it has been years since it was done and hasn't been a problem since. Usually you can tell when the tracks are getting to be shot by just looking at the chrone tube by the idler.If 6" plus of chrome showing on a D6H or R is maxed out!Width of your big hand.Good luck
yupthedump, the cable is to retain the track adjuster in the spring housing during the removal/installation procedure. so what caused the eye bolt to brake? Is the track chain wore out and the front idler extended to far? Are the guides or grooves wore out in the track adjuster tube allowing it to rotate side to side? Is the spring tube broke allowing all sorts of crazy things to be out of place? Are the guide studs on the end of the greaser broke allowing greaser to rotate? There is no problem with the eye bolt being broken if it wasn't caused by something else..........TIO
Nige, You ever hear of SALT tracks? Stands for sealed and lubricated tracks. That means the pins and bushings have oil in them to prevent wear.Cats been using them for about 40 yesrs. There are no wear charts for salt track pin and bushings. Bob
Sealed and lubricated are not permanent. My 2007 track guide has all of the salt specs.
I think you'd best look at an undercarriage guide. There certainley are wear limits and specifications for salt tracks. Just because they're lubricated (for a little while anyways) doesn't mean they last forever.
Sealed and lubricated means when the seals goes ,so does the lub the you have dry pins and soon are wore out.!
Hay Nige, I guess Bluox taught you and me both a lesson, I thought SALT tracks were ones used in the salt mines, guess your never to old to start learnin.:notworthy
Look at your guidefor s< tracks ,there are no charts for pin and bushing wear. You can look for the same thing Bob
lmao, thats funny **** right there. I guess i have never heard of a wear resistant SALT track...... what machines are they availible on and how much do they cost ? there would be NO PRICE i wouldnt pay to never replace U/C again..... what will they think of next, I bet before long they are going to start putting hydraulics on machines instead of cables....boy that'd be the day pj
They do say this . Wear and Structural Problems on Sealed and Lubricated Track Pins Once dry, the wear pattern and rate on Sealed and Lubricated Track pins and bushings should be approximately equal to the wear on Sealed Track. For a discussion of those wear patterns, see the section entitled “SEALED TRACK PINS & BUSHINGS.” So I think you can use the sealed track wear chart if you're running them to destruction. I've seen this cable broken before and kept on running the machine, as long as you don't overextend the tensioner piston you're ok. You could just replace the cable and eye.
If we can get away from arguing for a moment .............. and back to the OP. The guy described the symptoms on a 20+ year-old tractor, stated he was not a mechanic, and asked for guidance. I think everyone agreed (initially anyway) that the root cause of the problem was either inside the tensioner/recoil spring assembly mechanism itself or excessive wear in the track links. IMHO the simplest way would be to eliminate the possibilty of external wear that would cause the tensioner mechanism to over-extend itself. You can do that by either measuring track pitch or, as someone else pointed out, measure the extension of the chrome cylinder of the idler "cannon". If external causes are eliminated the only possibility is something inside the tensioner/recoil mechanism itself, possibly even a broken recoil spring. No-one has been told what type of tracks this tractor had on it, given its age but no idea of hours they might even be the originals, if they are aftermarket who's to say if they are lubricated of not..?
Powerjoke, have you heard the rumors of.... what is it they call them? Oh yes! infernal or is that internal combustion engines? I think some guy called Rudolf is working on some such thing.:cool2
I'm guessing that the connection cable is there so that when you remove the assembly from the track frame the piston assembly stays in the barrel and all comes out in one piece. Like Nige said for there to be enough slack taken out of the cable the front idler has to be adjusted out to the end which means the internal wear in the track chains are worn out. The most likely scenario in my mind as to how that broke is that something pushed the idler back against the spring and then let go suddenly which let the recoil over extend the cylinder and barrel and snapping the cable. As far as measuring SALT track goes there are no specifications given for internal wear of the pin and bushings. For SALT track you have all master pins with some kind of synthetic seal material installed to hold the oil in the joint. When you get dry links the tracks stretch out real quick and you are constantly adjusting the idler out. On standard SALT applications the adjustment you have to do is because of the wear on the outside diameter of the bushings, the outside wear on the idlers, the wear on the link rails and the bottom wear between the sprocket teeth. With oil in the joints there is no wear. On standard sealed track the bushings actually engage with both sets of links providing more wear area and greater support over the life of the chains. You can't use the sealed track specifications to estimate wear in SALT track.
The point Nige made was not to check internal wear against a spec for rebuilding. It was to check for internal wear on a track that should have none. A very good indication the chain needs some attention as I am sure the chain in question does. Also when the telescope is out check it closely for cracks, external forced have great leverage when it`s fully extended. Later Bob
Looked in some of our D7H and D7H series 2 O&MM books. The D7H seems to have a 4.9 inch spec on the track tubular section when service is needed on the track group. The D7H series 2 shows 5.9 inches. Most likely this spec is by s/n also and with or without a top roller? Looking into the series 2 book it shows the eyebolt with a length adjustment spec also. We only run waste handler packages on the 7 and 8's and I am thinking we have different rails and larger pin and bushing along with different sprockets on them. It would help to have some pics and more info from the poster just to see.