Tracks slipping when backing up

Billturner · Apr 29, 2017

I started using the 350D that I posted earlier about the winch problem, got it fixed and is 100%. I was working on my first old stump to be dug out and when I turned hard left in reverse, moving quite a bit of dirt with the track, the right track popped, sounded like it slipped a tooth on the sprocket. It only does that on that side and when pushing forward full throttle all the way to almost a stall no slip. It only does it when backing up and only to the left. It did it several times. I did check the track tension and the sag in the track from the sprocket to the top track roller is under 1". It looks like I could tighten the track a little more but not much. I did look at the sprocket teeth and that one does seem to be rounded rather then square on the end of the tooth. The thing that ran through my mind was finals, could there be a problem there? Seems like it would happen in forward also. This machine has an honest 3500 hours and has been taken care of well.

dpendzic · Apr 29, 2017

drain out the fluid in that final and look for metal fragments

Janicholson · Apr 29, 2017

Skipping a whole link is unlikely. It would require all teeth to disengage at the same moment. a single
track pin that has broken, or badly worn can cause that sound when it releases due to failed pitch
distance and forces on one or two teeth. Jim

2x4 · Apr 30, 2017

a worn track chain & sprocket will do that when the sprocket climbs out of its hole & drops in the next hole in the chain. Will happen when a machine has been used many times in a certain path, such as backing up & dumping into a truck.

AJ. · Apr 30, 2017

I agree with 2x4 the sprocket will slip when it and the bushings are worn esp when backing up because the slack is at the top,you could try tightening the track a bit,you can measure the track to give you an idea of the ware,stick something in the sprocket at the top and reverse back a bit to stretch the track,measure over four links,that's five pins center to center
New would be 23"
25% worn......23.1"
50% worn......23.25"
75% worn......23.38"
100% worn....23.57"
The track pitch is 5.75" The link height is 81mm Bushing O/S dia 44.45mm
AJ

Billturner · Apr 30, 2017

(quoted from post at 01:56:21 04/30/17) I agree with 2x4 the sprocket will slip when it and the bushings are worn esp when backing up because the slack is at the top,you could try tightening the track a bit,you can measure the track to give you an idea of the ware,stick something in the sprocket at the top and reverse back a bit to stretch the track,measure over four links,that's five pins center to center
New would be 23"
25% worn......23.1"
50% worn......23.25"
75% worn......23.38"
100% worn....23.57"
The track pitch is 5.75" The link height is 81mm Bushing O/S dia 44.45mm
AJ

I Will Measure ASAP. I can see how it might be a pin that gets hung up because of top slack then drops in under pressure. I'm guessing..... How common is this it seems like the other 350 B I had years ago did the same thing, Is it an issue that needs to be addressed immediately or is it something that makes you uneasy every time it happens.???? Thanks for the help

AJ. · Apr 30, 2017

Tracks are wearing parts and as they get worn they will stretch and become loose,when the sprocket teeth wear down and the bush in the track chain gets worn they can slip if they are loose.tighten the track up a bit,don't go too tight,just enough to stop them slip,when the track and sprocket are new the track bush sits into the well between the sprocket teeth snugly,this changes when the track and sprocket wears,all tracked machinery suffer the problem,you can download PDF file Undercarriage Basics from the link below,it is IH based but has some very good information about undercarriage.
AJ
www.external_link.com/PDFs/undrcarguide.pdf

jm. · May 1, 2017

I almost never disagree with Janicholson but in this case what is happening is when you back up all the slack is at the bottom and yes the sprocket will jump all the contacting teeth at one time. Backing up pulls the weak slack adjuster on that side and it is just jumping a tooth. Now continued operation like that and you will have cracked bushing in the track on that side. Firs of all adjust the track tension on that side, if it continues to slip under reverse load then replace the sprocket , Now when you put a new sprocket on the worn chain wear will be faster but you can get some use out of the thing. Sounds like you are about ready for undercarriage.

rustred · May 1, 2017

yes agree with that. tracks are designed for forward work.

caterpillar guy · May 6, 2017

If you are turning with the track over a dip in the ground the track can get off one of the rollers and will sound like that. Would do that both forward or backward. Just depends on if it happens to be over a dip. I try to turn on a hump in the ground. I suspect this since you are digging out stumps. you might be trying to turn over the ridge of dirt left on the side of the push before. The track can sag away from the bottom rollers as it climbs over the dirt, then pop back on as it gets to the middle of the roller frame. This would be an indication of worn rollers worn track and sprocket. Depending on how hard the sprocket is to get off and how worn you could weld it up. We have done that on our d-4 cat several times.
I really doubt the sprocket is slipping over the track pins. Especially if the track is as tight as you say it is. We got a set of tracks from a friend of dads that was a bit short pitched we run them a bit loose so they can fall back on to the sprockets and have never had the sprockets slip over the pins. Those are still on there and we put them on back in the 80's.

T in NE · May 14, 2017

Look at the track bushings. Worn bushings
and sprockets can easily jump on the
sprocket.

If they haven't been done before, the
bushings should be able to be turned and
get more life out of the track. P

Tracks slipping when backing up

Billturner

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dpendzic

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Janicholson

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2x4

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AJ.

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Billturner

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AJ.

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jm.

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rustred

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caterpillar guy

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T in NE

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