Accumulation of caoutchuc on tires and tire rail ways 1

[kopku7]

Hi members,

I work for a transportation company and we`ve been having a problem of caoutchuc accumulation through out the years. this year in particular, these piles of caoutchuc trippled compared to the number of last year.

This accumulation is happining on the guide concrete tracks. i understand the concept of accumilation of caotchuc on the wheels but the accumulation of this caoutchuc on the concrete tracks is weird, especially when this pile accumulates at the same place everytime.

i am a new member and i ahve no idea on how to attache pictures of these files.

any ideas ??

 

[TenPenny]

I would assume that it's just like race tracks, the tires wear and leave rubber 'pebbles' that collect. Obviously, in your case, the fact that they are in certain areas suggests that there is either some reason for extra wear in that area, or, just as likely, the wind or other environmental factors make the 'pebbles' accumulate in those areas, much like dust bunnies in a house.

If you're noticing a change, I would investigate if your tire formulation has changed somehow. That's the first place I'd look.

 

[kopku7]

Thank you for the comment.

We have tried everything, we changed the track where the accumulation happens and the piles were found 3 days after at the same exact place on that tracks.
I am not how to attache images on here, can you help6 this would give a clear idea of what i am talking about.

 

[kopku7]

Also to clear things out, i am talking about an underground train system.
We have measured the temperature of that place where the piles were found and its the same as the other places humidity is the same in the station. we even installed a camera on that place and u can clearly see how the caoutchouc is accumulating. but why at that exact place ?

 

[TenPenny]

Hmmm...rubber tires, underground, 'caoutchouc'....Montreal, perhaps?

I would look at whether or not there's some weird air currents causing them to collect in these spots, maybe from the vehicles themselves, or ventilation, or possibly ground vibrations.

 

[MikeHalloran]

The last time I rode the Montreal subway, which was decades ago, I was struck by its cleanliness. ... like orders of magnitude cleaner than the NYC system, and cleaner than most retail spaces. ... including around the tracks.

So I have to wonder if the piled wear products are only noticeable because of their surroundings. ... not to minimize the importance of the problem, just trying to get a handle on the size.


WRT step changes in things, I once ran a recording hygrothermometer inside an electronics factory in NY for more than a year. The RH changed each night as the A/C system was shut down to save energy, but it also changed in the fall about this time and again in the spring, as the seasons changed. At the time, I was investigating leak rates of small plunger pumps, and found a correlation to the RH. I wouldn't be terribly surprised to find a similar correlation to the tribology of rubber tires riding on concrete rails.

Can you find a historical record of RH within the subway environment? If not, consider starting to measure it now.


Mike Halloran
Pembroke Pines, FL, USA

 

[kopku7]

Thank you for the comments,

Its is in the motereal subway,

There is no ventilation ducts where they are accumulating, neither there is a problem with the vehicles. i measured the track temperatures a week ago and it was 32 C and the tire surfaces ranged from 45 to 48 degrees C. summer time i expect it to be higher. concerning the relative humidity, we have a historical record and the variation is not significant i even measured the RH during the last week and its the same.

Ground vibration is a great idea to check.
Also keep in mind that the place where they are being dumped is less than 2 feet long and its mainly when the train stops at the station. there is also many other stations that we found piles of rubber in this year .
We have been following this problem since 2008 and it started with 2 piles a year but this year its around 75 and increasing..

also one more thing to add i could clearly see the accumulation of rubber on the tires when i look at them but why are they deposing in specific places, that i do not understand.

Would grinding the tires be a good solution ?

 

[dhengr]

Kopku7:
Is there any correlation in the locations that this stuff accumulates and the start points and end points of tunnel sections, as they open up into the stations? I’ll bet this stuff is sucked along, in a semi- vacuum, by the train in the tunnel sections. And, when the train enters the station and the vacuum under and behind the train is broken or changes, the stuff just settles to the track surface.

 

[kopku7]

Also looking at the camera videos, the pile starts with a small piece of rubber and then the other tires deposes some more small pieces, but my theroy is that it takes one small piece to statrt gathering the rest because there is glue in the rubber and it will stick to the first small piece. the piles varies in size but i got some pretty big ones about a foot long and a foot in width.

also the pile sizes are dependant on the maintenance period or how long does it take to take it off.

 

[kopku7]

dhengr:

well how come it deposits only in one particular place?

 

[MikeHalloran]

http://en.wikipedia.org/wiki/Montreal_Metro

The locality of the deposit may have to do with the precision braking, claimed to bring each train to a stop at the exact same place, +/- 5cm.

At which time there may be a few shocks imparted to the wheels, e.g. associated with doors opening and closing, or taking up slack in the couplers on restart, or .. well, you can identify such things better than me.

I'm also wondering if there are gaps in the lateral guide rails, in which the lateral guide wheels might extend fully against their internal stops, or not extend fully and bump against the far side of the gap. Either scenario would dislodge some of the accumulated crud.

That's the sort of thing I'd be looking for, as I rode the train through the affected areas for at least a couple of days. It's tough work but someone has to do it...



Mike Halloran
Pembroke Pines, FL, USA

 

[kopku7]

The trains usually starts the breaking process a little far from the station, plus the breaks are not applied on the tire itself. I understand there might be a small grinding of the tires when breaks are applied, but its always the same place. I can view the accumulation of other tires in the train, but the rubber deposites are only on nearly the middle of the train on the right side of the train in the non motorized wagon.

concerning the gaps between the tracks, the gap does not exceed 5-10 mm but i will be checking for gaps between the tracks at a far distance as well, maybe the tires are hitting some place and they are depositing the rubber at this certain place.

Great comments.....

Thank you Mike.

 

[MikeHalloran]

>>>only on nearly the middle of the train on the right side of the train in the non motorized wagon. <<<

Odd, that.
Suggestive of maybe the lateral guide wheels being misaligned on that side? Axis not quite vertical anymore, thanks to unreported allisions or loose parts?

Okay, ride around with a recording accelerometer, _and_ record video of the right side bogies.

Another thought: Braking is done by pressing a wooden shoe against the tread of the steel wheel, which normally does not touch the steel safety rails beneath it.
That applies braking torque to an axle shared with the rubber drive wheels (or non-drive wheels on the middle wagon). How do the braking loads, i.e. the reaction from the rubber wheel dragging on the concrete rail, get back to the wagon? I.e. if the axle bearing carrier on one side is too loose in the bogie, the axle would yaw a few degrees on braking. Similarly the entire bogie might yaw on braking if a drag link/ thrust rod/ strut rod or something like that is missing or maladjusted, or if the noise control bushings are broken or gone.

Is there a procedure in place for visual inspection and prodding of all the moving bits on the bogie? Are there records? With photos? Have you done it, or watched it up close?



Mike Halloran
Pembroke Pines, FL, USA

 

[DerbyLoco]

Have your passenger loadings changed this year?

 

[MintJulep]

the non-motor wheels rotate without slip, while the powered wheels always have a small percent of creep. The creep keeps them clear.

So of course the rubber accumulates on the non-powered wheels. But it's coming from the powered wheels.

There's something wrong in the propulsion system.

 

[LittleInch]

A picture or two would be great. Just look at the bottom of the box you type your post in and click where it says "...or upload your file to ENGINEERING.com" When the box opens click "browse" then find your file on your computer, click open, then click the upload button and then finally confirm by clicking on the link.

Easy.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[ornerynorsk]

Static or grounding problem?

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[kopku7]

here you go,

That is a picture of a pile found recently, the size of the pile decreased a little due to the temperatures.

also keep in mind that the service was increased last year by a few hours.