Track Shoe Design

[Tsiolkovsky]

I'm currently investigating a dozer/rock-clearer used in the mines to clear blast ore. The problem is that the slope condition in the working area is not only downhill but tilting downwards to the side as-well. Even if the dozer can resist sliding forward it may still have a dangerous tendency to "yaw" or "slip" to the side. After sliding, the machine sustains heavy knocks and with no damping systems whatsoever, this results in part failures. Even worse, the sliding machine can take out a mine ceiling supporting column or "stick". It may also harm nearby miners.

Anyhow, this problem must be solved by increasing traction. One thing that I noticed particularly were the current track shoes. They have triple grouser bars. Now the theory behind grousers is that they deform the ground into the grouser profile and the tracks compressive strength on the flanks of the grousers is transferred into internal shear stress within the soil itself (see Attachment 1). So now the traction derives from the soils ability to withstand its own shearing. This principle only works if the ground is deformed around the grouser bar. The problem arises in the surface condition in the mines. Its basically hard substrate rock with a thin covering of fine, dry and low shear strength mine "silt". So the hard underlying rock does not deform. And even if its thin covering of silt does deform (in other words the grousers manages to "bite in" the silt), its such a thin layer with poor shear resistance and with a poor shear resisting shear silt/hard rock interface (see Attachment 2).

An actual picture of the tracks and the hard substrate with the fine silt covering is seen in Attachment 3 and Attachment 4 (Notice the grousers inability to bite in the surface)..

Ultimately my conclusion is that the grouser principle counts for nothing on this surface condition and a new track shoe design must be utilized.

I ultimately need your opinions on:

1) Is my ultimate conclusion correct? (That the grousers are ineffective on this surface condition)
2) If my conclusion is correct, to what degree can a new track shoe design offer better traction?
3) Is this problem worth investigating further with a solution needed? (My boss wasn't too concerned about this problem mainly because solution finding was not heavily stressed in my job description, but I'm increasingly obsessed with a solution even willing to experiment and test from my own pocket to a viable new track shoe design)

Also note that the environment contains residual Chrome particles which abrade everything and anything in their path (in-case you're wondering about using rubber shoe attachments).

Any further comments or ingenious solutions are welcome!

 

[ae137]

look at the tracks of landfill dozers, if anything, garbage shear much more easily. Their tracks are spiked and staggered typically.

 

[IRstuff]

True, but most of the time landfills are not yet compacted to the degree that spikes wouldn't work.

TTFN

FAQ731-376

 

[EdDanzer]

This link (3.8 mb PDF) is for carbide teeth used for road leveling, these type of teeth are also used in trenching but that is a 80+ mb PDF:

http://www.kennametal.com/images/repositories/PDFs/EMCS/B07-24_Road_Planing.pdf

Weld one of these every few feet in the middle of the pad sticking our 1/2” to 3/4” beyond the grouser bar.


Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[rmw]

One other thing to be remembered about tracked vehicles is that the tracks are designed to spread the load and reduce the ground loading at any given point so that they don't sink down through the surface-hardly a worry for your situation. Hard to get a good bite when the original design was to minimize biting into the substrate.

Some of the suggestions above bring the loads back more closely to a point loads. That is what I would go for, concentrating the loads at hardened points that have to bite in due to the tractor's weight.

rmw

 

[okeng]

I vote for EdDanzer's idea--your company probably already has 20 types of mining bits from Kennametal and Sandvik, and already has welders that are accustomed to welding the holders onto cutter heads. I can vouch for the traction you can get, based on an attempt to run a cutter head the wrong direction, on too light of a machine. It had more traction than the rubber-tired loader it was on, and was just about impossible to operate.

No idea how you would apply any theory to determine how much traction you would have, but if you think about it, those mining bits are about the only thing you'll find that are actually DESIGNED to dig into rock.

I can see some potential there. If your company isn't interested in doing it, make sure you do it on your own time, buy the bits and grousers with your own money (and keep the receipts), build a set, and have SOMEONE ELSE come in and sell them to the company.

Remember, "a prophet is not without honor except in his own home country."

 

[chicopee]

One important aspect of operating such vehicles on steep slopes that I have not seen mentioned is that properly trained operators(operating engineers) will work their machines up and down the slopes without turning around and sliding sideways. This is a fundamental safety practice excercise with properly trained operators. Sure there will be "hot shot" operating engineers that will attempt to turn sideways on steep slopes and they often get into trouble.