Oops:
http://www.railpictures.ca/?attachment_id=30865
Greetings from Alberta
-an Articulate Malcontent
Counterpart to some of those scalloped rail pictures?
I don't see why the snark in the picture caption? It's not that the wheels "didn't" roll ... it's that for a while, perhaps a considerable while, they rolled a little too well.
Now ... someone refresh my memory? was it Sprinters or ACS64s or F125s that had two examples 'totalled' when someone forgot to release their electric parking brakes during delivery? Pictures of those wheels would likely be an example of wheels that would not roll again...
What would cause that wheelset to rotate slower than what would match track speed?
EuclidWhat would cause that wheelset to rotate slower than what would match track speed?
Dragging brakes, something bad in the traction motor or gearing if it's a motored axle, compromised bearings*.
This looks far more like the opposite issue: motored around and around and around while heat and metal transfer progressively shell out the tread...
*Note that BaltACD specifically mentioned retainers left on. Yes, I can see that being a cause.
Why does the photo seem to show a wheel with flanges on both edges?
Thanks to Chris / CopCarSS for my avatar.
Overmod This looks far more like the opposite issue: motored around and around and around while heat and metal transfer progressively shell out the tread...
Oh yes, that would produce the the result shown. I was thinking that the wheel was partially braked enought to slow its rotation but not lock it up. That seems unlikely. But this would be a case of a prolonged wheel slip under power, either with the train stopped or moving slower than what matched the spin rate. So, if this is what happened, this wheelset is from a locomotive rather than rolling stock.
Murphy Siding Why does the photo seem to show a wheel with flanges on both edges?
EuclidSo, if this is what happened, this wheelset is from a locomotive rather than rolling stock.
The more I look at the picture, the less I am sure.
I see no trace of bull gears, no matter how carefully I look -- doesn't mean they aren't there, and it does look to me as if spots have been machined from the inside edge of one of those sets, indicating dynamic balance, but this might have been done on passive sets too...
If you look at the damage to the set in the foreground, the 'depth of cut' appears to be progressively, and somewhat alarmingly, deepening from the right (where it seems comparatively shallow) to the left. I see gouge marks in the edges of the shelled-out "trench" walls, too, and what looks like at least some flange-bearing damage (which, to be honest, looks like the sort of thing a spinning wheelset 'digging in' would start to produce as it dug far enough down into the railhead).
The wheelset in the background has some visible flatting in its trench, and what looks like different amounts of heat damage on those flats.
It is possible that you're looking at the effects of something like running partially-applied brakes without release, the progressive flatting damage getting worse and worse as the sliding and hammering get worse, cutting what amounts to an oval excuse for a running profile into the tread. Perhaps some of the damage occurred after the brakeshoes no longer had a clean surface to 'bind' against...
OvermodThis looks far more like the opposite issue: motored around and around and around while heat and metal transfer progressively shell out the tread...
I remember reading years ago about a railroad that somehow discovered that one axle on a locomotive wasn't playing well with the others, and was spinning along at about 100 MPH while the rest were running at track speed (well under 100). This looks like it would be a possible result of such a phenomenon.
But - this doesn't look like a powered axle - I don't see a bull gear.
I'd go with bad bearings, but I'd think the odds of two adjacent axles both having bad bearing would be pretty low.
OTOH, one might wonder how the brakes would continue dragging with that much wear.
Curious.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Does the bull gear split to mount or remove from the axle, or is it pressed onto the axle?
Looks like the wheels may be the result of a car - back in a train - having the retainer set to one of the on positions - and no one noticing for many, many miles.
Never too old to have a happy childhood!
EuclidDoes the bull gear split to mount or remove from the axle, or is it pressed onto the axle?
It is forged and ground in one piece, and is pressed onto its seat on the axle, perhaps with a different combination of heat and cold than used for the wheels on their respective seats (which may be changed over the life of a particular axle). At some points in history the gear would also be mechanically keyed on the shaft, but as this introduces stress raisers both in the gear and in the axle I don't think this is common current practice.
Things like steam-locomotive eccentrics can be split and pressed because they don't involve heavy torque or stress. Note the tradition of going to forged inside cranks rather than built-up pressed-on webs -- let alone keyed or clamped connections for 'ease of demounting'. It is difficult to conceive of the effects of the various loading on a locomotive drive axle, particularly at speed. We had someone from, if I recall, the Cotton Belt shops (he was the guy who provided me the insight about the all-too-brief commercial promotion of centrifugally-cast steam-locomotive axles) who pointed out that all locomotive axles bend in service (or at least 'try to') ... and not just a few thou. While many of the couples involved are much greater for steam than diesel-electric, it should be noted that just as the lateral forces are more extreme for nose-suspended-motor wheelsets than for high-drivered ones, some of the resultants of those forces, especially transient shocks, with the stresses in the gear fit and seat under heavy torque may be unsuspectedly severe.
BaltACD Looks like the wheels may be the result of a car - back in a train - having the retainer set to one of the on positions - and no one noticing for many, many miles.
Didn't think of that. Good possibility.
Thank You.
This suggests a combination of friction effects:
1) The wheel rotating with an applied brake shoe.
2) The wheel locked by an applied brake shoe, and sliding on the rail.
For producing what the photo shows, it would require a combination of items #1 and #2.
It if were only item #1, the rotating wheel would have burned up the brake shoe and not left all of that spalling and piling of cut material in multiple locations along the circumference of the wheel tread.
If it were only item #2, the wheel tread would have not been damaged anywhere other than flattening at the wheel tread contact with the rail head.
So it had to have been a combination of items #1 and #2. That would suggest enough brake application to reduce the wheel rotation speed to a lower speed than would would correspond to the train travel speed. However, not only does that seem to be too delicate of a balance of forces to maintain, but it also fails to explain all of the gouging and irregualrity to the removal of wheel tread material
After the brake shoes wore away the steel brake shoe mounting heads on the brake beam would continue to cut into the wheel.
mvlandsw After the brake shoes wore away the steel brake shoe mounting heads on the brake beam would continue to cut into the wheel.
I can see how that would happen. But the wheel damage appears to be a combination of alternating brake shoe/brake beam cutting on the rotating wheel; and of locked wheel-slide on the rail. Achieving that combination of alternating causes seems rather unusual to me.
I also conclude that this wheelset is not from a locomotive. So the cutting around the wheel tread was not caused by a wheel spinning under power.
EuclidAchieving that combination of alternating causes seems rather unusual to me.
When handbrakes are left on, it is perfectly common for wheels to go from sliding, to rotating, to sliding, depending on speed, load/empty, etc.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
zugmann Euclid Achieving that combination of alternating causes seems rather unusual to me. When handbrakes are left on, it is perfectly common for wheels to go from sliding, to rotating, to sliding, depending on speed, load/empty, etc.
Euclid Achieving that combination of alternating causes seems rather unusual to me.
I was called to check an engine that the crewset out because some wheels were smoking. It was the trailing engine in a consist of four. Myself and a co-worker arrived about 20 minutes later and found the wheels on the rear (non handbrake) truck were radiating heat. My co-worker suggested that the brake shoes were recently changed and that the slack adjusters were too tight so that even with the brake cylinder all the way in, the shoes were still tight against the wheels.
Using his theory that would mean that number five and number six axle should be hot. Number six was quite hot, even from a distance. I proceeded to place my bare hand on the number five wheel and proved his theory beyond a doubt.
RSS
" My co-worker suggested that the brake shoes were recently changed and that the slack adjusters were too tight so that even with the brake cylinder all the way in, the shoes were still tight against the wheels."
I had that problem with an engine fresh out of the Cumberland, Md. shop. By the time I got to Hyndman the unit was trailing a smoke cloud. Not wanting to wait for the shop to send someone out to look at it, I adjusted the brakes myself and continued on.
I had watched the machinists at Glenwood do that several times so I knew what to do.
Adjusting locomotive brakes isn't hard. And everything you need is normally in the toolbox on the locomotive.
I've done it a few times, usually while working an outpost assignment that would use the same engine every day. Once we got a good one, we would try to keep it for as long as possible, and avoid booking 'little things'.
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