First off I need to be up front about not having much experience with dozers even after working on heavy equipment for over 40 years. 90% of the equipment I have worked on has been either front end loaders and haul truck in the 30 to 65 ton range. In all these years I think I replaced a track adjuster on one Cat dozer. So now with just over a month till I retire seems like I have been working on dozers at least half the time! To get to the question/problem that came up just before quitting time today. D6D LGP 6X00408 right track very loose, operator attempter to adjust it and it only held till he moved dozer. Walked it down off hill and to wash bay. Then we removed the guards off the track frame. So much wet clay under covers it looked like the covers were still on! Another shot at the wash bay and from what he said most of the gobs of grease were inside the spring area. I was hoping the leak was going to be something simple like the grease fitting had come loose. As it was end of shift and also end of work week for us have not had chance to pump grease in to confirm where it is leaking out. A quick look in SIS and it appears that if the adjusting cylinder is the problem we will have to drop the track off to get the front idler to move forward to have room to remove the cylinder. Just looking for advice if that is correct. I did see where the manual says to compress the spring by outting a pin in the sprocket and then run the nut on some to hold the spring compressed. As nasty as this thing looks I'll be surprised if that nut will ever turn, any safe options to go to in that case? I recall a detailed project someone on this forum worked on last year but so far have not found that thread, anyone able to point me in that direction? I will be getting back to this project Monday morning so I was hoping to have some good ideas of what way to go so I look as smart as some people think I am
I think the spring will not need to be removed. You either have a blown lip seal on the piston or the cylinder is damaged internally or cracked. Park the machine inside so the spring can be removed if needed, split the track and move the idler forward. Force the adjuster forward out of the front recoil pilot. Inspect for cyl bore damage and cracks. They can have damage in one area and adjust up but not hold long. Be careful around the spring. Later Bob
You are correct, the track has to be split ant the idler rolled forward. I've only done it on my D6c, but I think it's pretty much the same. On my 6c I compressed the spring just enough to put a couple of 1/2" steel blocks between the spring and the stops to gain a little clearance for the cylinder to come out. Not sure if it was necessary, but wanted to be sure it had room. I also ran the nut up on the back as a safety but my nut & bolt had been replaced recently so they were in good condition. (If you have a new cylinder on hand you can do some measuring to see if it will come out without compressing the spring) I'm always nervous working around recoil springs.....There is 25,000 pounds preload on the spring. I wouldn't trust the nut alone to hold the spring because you can't tell what condition it's in. If your nut is bad or won't move you're relying completely on the stops to hold it. The stops can be worn or damaged too. If it were to jump off the stops it would come out with lethal force. Don't take chances! You don't want to make a mistake with only a month to go! Someone else here has probably had a lot more experience that I have....hopefully more will reply.
Just what I was thinking. And I'm well aware of the stored energy in springs. Back in the day we often would rebuild MaxiCans and other brake chambers. Compared to the springs in the Dozers those were like the spring in a ball point pen! Also have had fun replacing springs in non-air ride suspension seats in older Cat trucks and loaders.
Just thinking about this project again. If as I expect I do have to remove the adjuster cylinder and the nut will not turn would it be possible to compress the spring with the pin in sprocket and then make a "U" shaped washer to slip between the nut and spring retainer? Just took a look at some spec's. Installed force on spring is 13.9 tons and it is compressed 4.75 inches from free length. Bet 13.9 tons will move 4.75 inches pretty fast Better do a couple extra cups of coffee so I can out run it, NOT!
JUst did a complete bottom on my 6C same as a D. You don't need to mess with the spring unless the cup is cracked or the bolt is broke. Drop the track and slide the idler to the very edge. You will have more than enough room to pull the sleeve and piston.
Part of the problem with the nut/bolt is that the threads might not be good enough to hold with a spacer. I think DoyleX is correct...you probably don't need to compress the spring to have room. That way you're not relying on the nut at all and not disturbing the spring. If it's like mine the cylinder was pitted badly so needed to be replaced. Aftermarket cylinders weren't very expensive, but check that the valve will screw in and seal correctly before you install it. On the one I got the threaded holes for the valves weren't tapped quite deep enough for the valve to seal on the taper.
You know, as I said I think I only replaced one of these adjusters several years ago. Well I do recall that on that one we bought an aftermarket part and the hole for one of the valves had the threaded section off set from the tapered seat and we had to do that job twice!
are you sure the bolt is not broken? how rusty are the threads(if not broken)? if it is broken the spring will have to be cut to get the thing apart. at least I couldn't think of a good, and safe, way to get it all out of there when mine needed rebuilt. check to see how many bolts are holding the bracket to the roller frame, two out of four were completely broken off on mine. that was a challenging day.. I had cat r&r the cylinder and press it all back together with a new spring/bolt.
I was thinking about a few zip ties on the spring would hold it while I pry it out! Think my soon to be widow could collect on my pension?
Well got to work on this D6D this morning. Hooked up the grease gun to adjust the track to see where grease was leaking. Seemed to push front idle just fine. Then noticed a bit of grease weeping from the vent hole for the grease fitting, the on down on the back side about 1 inch down. Put a wrench on the large hex of the grease valve and a stiff breeze could have turned the wrench! Not sure why it did not leak till last Thursday as we have had this machine here since the middle of last year. But it was not used much until they started using it a couple weeks ago doing the stripping. Guess in a way it was lucky it did back off when it did. While operator was washing machine after guards were off he just happened to park the machine in the right position so he could see one of the bolts was missing out of one of the rear sprocket tooth segments. A quick look and found the next one in line was barely held on with nuts half way off the bolts! We removed each loose segment and smoothed off the burs where the bolts had worked loose. Reinstalled them with new hardware and then removed the other bolts one at a time so all are now new bolts and nuts. None others were real tight but not loose either. We then tightened all the bolts on the left sprocket, a few turned about 1/2 a hex. Guess the two that came loose were put on just before lunch and someone forgot to tighten them! Got four hours out of it with no new problems! Fingers crossed for Tuesday!
good job! I am really glad it turned out to be such an easy fix! the 6D's were a fine tractor.
They used it for 10 hours today and no one came running screaming bad words at me so maybe it is going to hang in there a bit longer!:woohoo
so I guess no news is good news!