We tightened the tracks on the 953C and somehow now the end of the yoke is against the front roller. I do not understand why or how this happened. Any advice on what to do would be great.
that would mean that the rails and pin's/bushings are worn out if you look the yoke mounts on a cam type instead of the main axle of the idler. the piston is more than likely almost extended all the way out. you may be able to put new sprockets segments on the rear and take up some slack and get a couple hundred more HR'S out of the rails but it's a crap shoot if that will work iv'e done that on a 963 yr's ago it worked for a little while but you better be looking for a new set of tracks soon ether way you go
Can't see your problem but check all the pins in the linkage plus the idler shaft bearings. Later Bob
You will be amazed as to how far the pins/bushings have eroded from OE spec, as little as a 1/8" (.125) can be too much wear exaggerated by the number of pairs to the rail. Measure from the face edge left or right, from one pin across four full links to the same face edge of the fifth pin away from that one, that encompasses four full links, divide that number by four and you get the average link measurement. You either have 6.906 rail or 7.50, the latter is SALT but yours does not appear to be.
If I had to bet money I'd say that something in the linkage for the idler/tensioner bushings are badly worn. Also that track looks awful tight to me, have you tried easing off the track tension a hair and if so what happened..?
Thanks for the replies to all. The machine has 5900 hours and these are the original undercarriage components, so I am sure it needs a undercarriage but I would like to get all the wear possible. I can't seem to get in my head how that yoke is touching the roller because there is no adjustment on that part and it is solid steel parts that should keep it away a safe distance, but I must be missing something there, just not sure what. I am going to loosen the track and see what that does.
Thanks Nige, I am unsure what the idler / tension bearings are and where they are located. You are correct the track is way to tight and we had just tightened them a few minutes before this happened, we are loosening them to see what happens.
This is what the mechanism looks like on a machine of BBX-prefix S/N 2619-Up. Not necessarily your S/N range but it was the best exploded drawing I could find that shows what the tensioner mechanism looks like. First, see how many pins & bushes it has and how a bit of wear in any/all of them could combine to cause your problem. Second, what about wear in the bushes ref. #4 supporting the front idler..? Note that I am not discounting wear in track pins/bushes resulting in over-extension of the tensioner as being the root cause of your problem either.
You can see in the pic the rod is detached from the yolk, they should be in alignment, check to see if bearings in idler are bad. Measure from idler edge to axle center at the front and back, should be the same. Check the bottom guards. (Mounts). There are two sets of holes for mounting to adjust for track wear.
Correction, there might be a pivot at the rod and yolk connection, under the dirt on track frame there should be a plug to grease the adjuster rod and bushings, guards look to be in the rear position. Moving them forward will take up play in track and allow adjuster rod to be pushed back in.
slide item#27 to the forward set of holes if it hasn't been done already. you would be amazed how much it gives you in taking up slack.
Thanks for the replies to all. Nige, I will check the bushing wear on the #4 , I did try to move the idler side to side before I tightened the tracks and could not get any movement by hand however. Overworked you are correct the yoke does have a pivot and is hooked together with appox a 1" pin. I am going to move the guards to the forward position . Mljohn, I also see the holes you are referring too, I think they are different than the guard holes overworked is talking about, but I will try that also. I keep thinking that moving forward would make the situation worse and increase slack but this is a first for me in this type of problem area.
The idler mount in the guides that Nige's picture refers to as 27-26-6. They bolt to the lower front portion of the track frame on the inside and outside. My 953 20Z has either 5 or 6 bolts up into the track frame. Those will unbolt and move forward so I'm told....... I'm starting this process Friday morning after I broke a track tensioner rod on my machine. I'm hoping I can hook a chain around the back side of the idler and up to a bucket tooth to scoot my idler mounts forward once they are unbolted. Keep us posted how it goes I'm not looking forward to this weekend just because of this. John
Let the grease out of the adjuster and the bearings will move easier. Later Bob
Not sure on 953, I have only worked on 963 & 973, the bushings in the track frame where the adjuster rod comes out gets grease from a fitting under a plug in the track frame, should be under the dirt in the first picture inline with the equalizer bar. JD8875, if your repairing the track adjuster you will have to unbolt the guards to move the idler out of the way, then just put in forward position when you reassemble.