Detrimental Sprocket Damage Caused by Misuse and poor maintenance
In this article, Ben Jobson a 15+ year veteran of the all things Rubber Tracks and Mini Excavators talks about his assessment of an excavator sprocket a customer brought in for replacement.
The sprocket pictured is severely worn and damaged. To let a sprocket get to this stage of disrepair is quite frightening, not to mention the added cost of further component repairs leading from this one issue.
Let’s start from the beginning:
1.The first issue I see that has developed with this sprocket is that it has worn to one side as if it’s been heavily side loaded all of its life:
Suggested cause and effect: Sprocket bolts have not remained tight, thus not enabling an even clamping force all of the way around the sprocket. Causing it to warp under load, Imagine a car wheel with only one wheel nut securing it. Impossible for it to run true, causing premature wear on track rails, dismounting of the tracks, unnecessary load on the drive motor and other undercarriage components. Solution: Regularly check the tension of drive motor bolts. Retighten when servicing drive motor oil at your designated service interval.
2. Second, we can see the severe rounding off of the sprocket teeth.
Suggested cause and effect: The teeth of the sprocket have been in effect ground away, causing ratcheting or slipping of the track sprocket within the track guide. This issue can develop from more than one cause. The first cause could be track tension, the track may be too loose causing the sprocket to not grip the drive pins in the track, secondly the track you have been supplied may not be the correct pitch for your machine, causing the sprocket to jump over the drive pins and grind the teeth away. Thirdly, there could be a problem with the recoil or spring system in the undercarriage, for example, if the recoil spring is broken the track may compress too easily causing a release in tension which may cause the sprocket to spin over the drive pins. Also you may have purchased an inferior sprocket. By buying quality parts you ensure the best materials have been used. Solution: If your sprocket is grinding and skipping in your track, there is a reason. Solve the cause of the problem, eliminate possibilities of above failures by ensuring correct fit of products supplied by buying genuine HXRT products. These issues only compound the longer they are left.
3. The sprocket is no longer round, it is out of shape.
Suggested cause and effect: Out of round sprocket. This is probably one of the worse condition sprockets I have seen in 15+ years of dealing wholly and solely with machinery undercarriage. The causes of issue 2. Above are the same as this issue with a few exceptions. In this case and knowing how this specific machine was being operated, I suggest there has been lots of foreign material in the track rail causing extensive wear in specific parts. This issue would have happened later in this sprockets life after it was already worn past being serviceable. Perhaps the machine may have been stuck in a rocky/muddy environment and with the sprocket already worn may have been slipping in one spot, as if the machine was stuck and the operator was going back and forth in one small area to try and free machine. The issue is compounded with the teeth being down to the level of the base forging, not at the tips which are obviously a lot harder and heat treated. Solution: As above, these issues happen for a reason. Correct maintenance and inspection of all undercarriage components is a must.
In closing, a brief summary of why it pays to deal and buy from the people who know. In this case, here is a basic list of costs this customer has incurred from this issue.
Final drive repair/rebuild $2800
New HXRT Rubber Track $1700
New HXRT Sprocket $200
Total: $4700 plus gst
All caused by a $200 sprocket and poor maintenance……….
Deal with the people who know. Money can’t buy experience.
HXRT Rubber Tracks