Revisited - Track off of a D7-17A fixed

Thanks for all of the ideas about getting my track back on. Finished it up Sunday afternoon. Here is what I ended up doing. I thought the tightener was pretty much all of the way back already so I didn't bother to take the plug out to dump the grease. I jacked the side up and blocked the back under the drawbar then jacked towards the front to finish lifting the side rail. I didn't lift it too far, just enough for the track to pass under the rock guards and rollers. Then I pony motored the left rear sprocket inorder to get some more slack to work with up front. Using a pry bar I lifted little by little the track up onto the top two rollers. It was still on the rollers but no where in the right grooves. Then with the pry bar I did the same with the front idler. First onto the edge, then up onto the raised portion. Nothing moves very fast, but I knew I was making headway when I had it on a good portion of the top of the idler. Then maybe a couple of jerks with a tractor and chain pulling the track forward to get more slack. Then a couple of jerks pulling the track somewhat forward but now also sideways pulling the track across the idler. Nothing hard, just jerks. This stuff is heavy and it seemed like cable pullers had limited benefit. Then I backed the tractor up to the side of the dozer and chained to the track and pulled it outward in three places. The front "popped" into place on one of these pulls. Lowered the dozer and everything fell into place. Got the grease gun and pushed the idler outward tightening the track. Toughest part of doing this was jacking. Started with a 20 ton bottle jack. The ground wanted to swallow the jacks. Took a 4 foot long by 1 foot wide piece of oak to support the jack. Fortunately a neighbor had a jack powered off of a tractor hydraulic system. Made jacking much easier. Learned that the problem can be solved, but honestly I don't want to do it again!!!

Glad you got it back on. Don't put it too tight though or you'll wear the undercarriage out real fast.

Nope, it isn't too tight. I think between the top rollers it is sagging 1 - 2 inches which is where it is subpose to be. Someday I need to take the covers off and check that the spring is still expanded and working. Someone told me today that the springs sometimes give way and allow the tension cylinder to move backward. Then when you pump the tension cylinder outward to tighten the track you really don't have the give and take of the big spring to provide some shock resistance to the track and idler.

Glad to hear it went back on relatively easy a a thrown track is usually a real PITA.....not to mention they usually happen in the absolute worst place you can imagine to work on one.

That said, a tip for future refference. You can usually eleminate the need for a jack on the older machines with enough hardwood blocks. What you do is put the blocks under the rear of the machine, first making a good base, and then stacking them as high as possible. If you can get them to touch the bottom of the machine that's great. The placement will depend on the way the machine is balanced, the lay of the land, etc, but typically you want to stack as close to the side your wanting in the air as possible. Once you get it blocked then put the blade on the ground and apply enough down pressure to lift the machine. What will happen is the machine will pivot on the blocks and lift the whole side, drive sprocket included, off the ground. In a case like your talking about, with soft ground, a good foundation is a must, but it it will still usually take a time or two of lifting and reblocking to get the foundation blocks imbedded in the ground as far as they want to go, and for the stack to become solid. Once you get the back up you can either block the front to keep it up, even if the blade drifts, or simply keep the machine running and keep adjusting as it drifts. Either way you can maintain the complete side of the machine, and therefore the whole length of the track off the ground without using any tools other than a few hardwood blocks. Working on equipment for a living I've done it many, may times over the years and have only had a small handfull of machines where it did work, and most of those were the newer ones. Good luck next time.

You have the later type adjuster, could not recall, but 17A's must be where those started in '55 or so. Sounds like a typical track toss event & solution. I believe you are correct on track tension, should be about that when pried up from the carrier roller 1 1/2"-2" Probably also glad you did not split the track, once you get some relief on the track frame, by jacking or raising like Wayne said, then its a matter of being able to manipulate the track with what you have, certainly nice to have a tractor with a loader or backhoe, we had none of those and still got it back on after a few attempts. Like you said, I hope to not have to deal with that again either !

Think that might be a little hard to do as mine is a cable machine!

Your right, I obviously should have been, but wasn't, thinking about that when I saw the 17A prefix. The cable machines present their own share of problems when it comes to having the machine do the work for you in many cases just like this. Next time just do like I do when I need to change a tire on my service truck. Simply hook up the crane mounted to it (in your case the winch) and pick it up.....LOL Seriously I had a guy asked me once if I could do that. I kept him going for a little while before it got to hard to hold back the laughter....

LOL, thats funny, but the line speed is too fast on those CCU's if I recall, you can't use em like a winch, interesing enough though, I have seen photos of D7's in WWII using LeTourneau PCU's as a winch, must have been hard on the driving and driven cones and or friction part on either, if you used them like that without somehow gearing it down, multi part line or what, hard to visualize being able to do that with cable control from one of these.