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Post by edwardsutorik on Jun 10, 2022 11:40:03 GMT -8
On the subject of metal fatigue developing in die-cast zinc or Zamac components. e.g loco frames, etc. This phenomena is not due, as commonly stated, to a bad mix of the metals used in the alloy. Contamination in the mix might cause a bad casting, but not fatigue. The cause of the fatigue which sometimes develops in die-castings is due to incorrect settings or parameters during the molding process. i.e. the temperature of the melt, the mold temperature and the injection pressure. When the mold/melt temperatures are correct the melt will flow easily into the mold at a relatively low pressure, and a stable casting will result. When the temperatures are too low the melt flows badly and a much higher injection pressure has to be used to force the sluggish melt into the mold. This causes stresses in the casting and these stresses will eventually work their way to release and thereby to deform or destroy the casting. The same can be true of injection molded thermoplastic parts. But since thermoplastic is a more malleable material, the finished part will warp and maybe develop cracks, but only very seldom will a thermoplastic item disintegrate or crumble. Interesting theory. It doesn't explain how a zinc alloy casting can be stable and tight for years, and then suddenly decide to twist and warp and start cracking and expanding. I don't know where you get the idea that it takes years for stresses to work their way to the surface. I will also add that other metals and alloys can have the very same problems during casting that you describe, and never have a problem that fits the description of zinc pest. You are just plain wrong. I am having trouble finding anything in what you say that makes sense. I suggest you read up on this problem. Here is an excellent paper to start with: web.archive.org/web/20110716065232/http://www.nlr.nl/id~4210/lang~en.pdfEd
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Post by Deleted on Jun 10, 2022 19:11:15 GMT -8
Our model trains are mostly made in China, with a few from Japan and Korea.
Zinc pest is capable of happening to anybody's zamac product, even today. The amount of lead necessary to cause it is less than 1% lead in the alloy, and there's lots of ways for that less than 1% amount to get there. Many manufacturers have experienced the occasional but rare issue with zinc pest. Don't ask me to start listing names. It has factually happened to many if you dig far enough online to research it. It is not my place to call them out.
As I've said before, there is absolutely no way that you are going to convince anybody half a world away to inspect each and every zinc or zamac bar and to certify that it is 100% pure. It is not going to happen at any price. They (our friends in SE Asia) really don't even give a crap about carbon emissions or lead paint (still allegedly being used on brass model trains), let alone a little bit of lead impurity in a pot of zamac.
I'm not saying zinc pest is common, far from it, but it cannot be guaranteed NOT to happen.
The Pennsylvania Railroad had a practice of buying some diesel locos from just about everybody--they figured out that even if you have one manufacturer you love, you still need to encourage competition. The best way of guaranteeing that your model trains will last till you are of retirement age is to buy something from everybody. That way, in the rare instance of zinc pest, you will always have some models that survive just fine as long as you will ever need them. I've spent 49 years playing with lots of HO trains, and zinc pest is extremely rare, but can still happen.
Respectfully submitted--
John
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Post by drolsen on Jun 10, 2022 22:28:39 GMT -8
What are some of the brands suffering from this issue? I know several manufacturers suffered from this at various points, but the one I’ve experienced it with was early Life-Like Proto2000. I believe it was fairly common with their E8 model, to the point that people would look for cheap E8s (back when they sold for as low as $30) to harvest spare frames from. It’s also come up recently on a couple forums involving Walthers freight cars, specifically the Greenville wood chip hopper and their RTR 89’ flatcars. People have discovered that their 89’ flats have bowed in the middle over time, and when they try to straighten them, they snap in half. Someone posted photos on FB of two Greenville hoppers he bought secondhand - the frames had shattered into many pieces. I have a Walthers Bethlehem 4000 cuft triple hopper (BN prototype) that I bought off eBay that has a broken frame, but I need to tinker with it to see it’s zinc pest or was just severely damaged somehow. I suspect it’s zinc pest though, because the plastic body doesn’t seemed damaged. It’s important to point out that this didn’t happen consistently with every model from a given manufacturer. It seems to have been confined to certain times in their production over the years, when the factory used a bad batch of metal. It does seem like some manufacturers had bigger issues with it than others though. Dave
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Post by carrman on Jun 11, 2022 7:15:27 GMT -8
I've seen a few Atlas U33C frames crumble.
Dave
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Post by Mr. Trainiac on Jun 11, 2022 7:31:04 GMT -8
On the subject of metal fatigue developing in die-cast zinc or Zamac components. e.g loco frames, etc. This phenomena is not due, as commonly stated, to a bad mix of the metals used in the alloy. Contamination in the mix might cause a bad casting, but not fatigue. The cause of the fatigue which sometimes develops in die-castings is due to incorrect settings or parameters during the molding process. i.e. the temperature of the melt, the mold temperature and the injection pressure. When the mold/melt temperatures are correct the melt will flow easily into the mold at a relatively low pressure, and a stable casting will result. When the temperatures are too low the melt flows badly and a much higher injection pressure has to be used to force the sluggish melt into the mold. This causes stresses in the casting and these stresses will eventually work their way to release and thereby to deform or destroy the casting. The same can be true of injection molded thermoplastic parts. But since thermoplastic is a more malleable material, the finished part will warp and maybe develop cracks, but only very seldom will a thermoplastic item disintegrate or crumble. That makes sense from the standpoint of residual stress. I can understand some high-stress components failing under high tension or compression, but it doesn't really explain the metal reducing itself to powder. Once the stress is relieved in the initial few deformations or breakages, you would think the stress drops below the metal's yield point and further deterioration would stop. I think the title of this thread is a bit misleading, as the original poster seemed a bit confused about the terminology. Your explanation for fatigue failure makes sense, but I think you need to make a clarification in your post. Are you saying Zinc Pest and residual stress are the same thing? The consensus in the hobby is that Zinc Pest is caused by lead contamination; do you have any evidence of Zinc Pest occurring in the absence of lead?
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Post by NS4122 on Jun 11, 2022 7:36:42 GMT -8
I did this exact thing with my Proto 2000 Conrail OCS E8. Three years ago, I picked a now forgotten road name one up at the Springfield show for $30 just to get a new frame. I couldn't believe how bad the frame on the Conrail unit just crumbled into pieces unlike the Walthers flatcar that just warped. What are some of the brands suffering from this issue? I know several manufacturers suffered from this at various points, but the one I’ve experienced it with was early Life-Like Proto2000. I believe it was fairly common with their E8 model, to the point that people would look for cheap E8s (back when they sold for as low as $30) to harvest spare frames from. It’s also come up recently on a couple forums involving Walthers freight cars, specifically the Greenville wood chip hopper and their RTR 89’ flatcars. People have discovered that their 89’ flats have bowed in the middle over time, and when they try to straighten them, they snap in half. Someone posted photos on FB of two Greenville hoppers he bought secondhand - the frames had shattered into many pieces. I have a Walthers Bethlehem 4000 cuft triple hopper (BN prototype) that I bought off eBay that has a broken frame, but I need to tinker with it to see it’s zinc pest or was just severely damaged somehow. I suspect it’s zinc pest though, because the plastic body doesn’t seemed damaged. It’s important to point out that this didn’t happen consistently with every model from a given manufacturer. It seems to have been confined to certain times in their production over the years, when the factory used a bad batch of metal. It does seem like some manufacturers had bigger issues with it than others though. Dave
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Post by edwardsutorik on Jun 11, 2022 7:55:58 GMT -8
On the subject of metal fatigue developing in die-cast zinc or Zamac components. e.g loco frames, etc. This phenomena is not due, as commonly stated, to a bad mix of the metals used in the alloy. Contamination in the mix might cause a bad casting, but not fatigue. The cause of the fatigue which sometimes develops in die-castings is due to incorrect settings or parameters during the molding process. i.e. the temperature of the melt, the mold temperature and the injection pressure. When the mold/melt temperatures are correct the melt will flow easily into the mold at a relatively low pressure, and a stable casting will result. When the temperatures are too low the melt flows badly and a much higher injection pressure has to be used to force the sluggish melt into the mold. This causes stresses in the casting and these stresses will eventually work their way to release and thereby to deform or destroy the casting. The same can be true of injection molded thermoplastic parts. But since thermoplastic is a more malleable material, the finished part will warp and maybe develop cracks, but only very seldom will a thermoplastic item disintegrate or crumble. That makes sense from the standpoint of residual stress. I can understand some high-stress components failing under high tension or compression, but it doesn't really explain the metal reducing itself to powder. Once the stress is relieved in the initial few deformations or breakages, you would think the stress drops below the metal's yield point and further deterioration would stop. I think the title of this thread is a bit misleading, as the original poster seemed a bit confused about the terminology. Your explanation for fatigue failure makes sense, but I think you need to make a clarification in your post. Are you saying Zinc Pest and residual stress are the same thing? The consensus in the hobby is that Zinc Pest is caused by lead contamination; do you have any evidence of Zinc Pest occurring in the absence of lead? So he responded to the title of the topic, and not the posts therein, where there does not seem to be any discussion about metal fatigue. If he's talking about metal fatigue, it's odd that he would lead off with the line: "This phenomena is not due, as commonly stated, to a bad mix of the metals used in the alloy." I don't recall much discussion anywhere in the model railroad world, about metal fatigue, or its causes. As stated here: en.wikipedia.org/wiki/Fatigue_(material)metal fatigue is caused by "cyclic loading" (commonly described as "bending back and forth a lot"). This does not match the explanation in the post. So I suggest that his explanation for fatigue failure does NOT make sense. Ed
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Post by edwardsutorik on Jun 11, 2022 8:08:57 GMT -8
If you love zinc pest, the best way to increase its prevalence is to say nothing about it when it happens to you--just accept it as "one of those things and move on".
If YOU don't care, why should anyone up the chain care?
To solve the problem, you must use alloys of the proper purity. That is generally achieved by dealing with reputable suppliers and by doing testing. Yes, it adds cost. So is declining to purchase from the lowest bidder.
I suppose it depends on just how high a quality item you want to sell. And be known for.
The Walthers flats are cars I am a bit knowledgeable on. I found one deformed flat car that I reported on here, and where I presented a photograph. I recently found one more. I would guess I have a total of about 30-40 of them. My concern is whether these two are the beginning of a very long list, or just a couple of bad apples. It's not a huge problem for me to sacrifice two out-of-the-box for these two, that I have modified.
So I do wonder "When will it stop?" (accompanied by person screaming).
I did talk to a Walthers person on the phone about this matter. I got the impression that they took the problem quite seriously.
Regarding the Walthers part bowing rather than crumbling: The underframe casting that I removed from the first flat broke into pieces very easily. It was unusually brittle. I think it was/is in the early stages of zinc pest. I expect at some point it will start crumbling all by itself.
Ed
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Post by Deleted on Jun 11, 2022 9:37:04 GMT -8
Metal fatigue occurs with steel bridges after repeated truck loading cycles where cracks develop in the steel with sometimes disastrous results. We in engineering actually equivalate all trucks to multiples of 18,000 pound (or 18 kip) equivalent single axles, and then we track the lifetime number of equivalent 18 kip axles (ESALS) the bridge is exposed to. We have computer programs that can analyze the remaining life of the bridge based upon known periodic traffic counts. Those programs are used to make decisions about when to replace or rehabilitate (if possible) the bridge.
Metal fatigue should not ever happen with model trains. They are not subject to millions of loading cycles as real steel girders and beams are.
Zinc pest when it is advanced does result in brittle failure and metal pieces that literally crumble to dust in your hands. Some Pre-WWII Lionel wheels are known for doing this and my past employer witnessed this on numerous occasions. Bowser for many years cast identical replacement wheels in pure zinc for those old Lionel trains and offered them painted in matching colors.
Zinc pest still DOES happen, and I KNOW the manufacturers care about it. However, model trains are NOT built by LOW BID. They are NOT highways or bridges built on government contract with government mandated wage rates.
You folks are being extremely disingenuous to even begin to suggest that model trains are built in China by LOW BID. You are completely forgetting the years of time invested with the manufacturers to get them to a point where the model quality is what it generally is now (which sometimes isn't even what some of us might want). One does not simply replace a retired manufacturer with the next guy down the street and not have a couple year learning curve.
I'm positive the North American importers TRY to get pure metal the best they can for their Asian builders, but we live in an imperfect world, and especially in the Far East, one cannot always trust the material suppliers. We can't trust their word in other areas of life. They have massive civil engineering failures that kill thousands of people (recent Chinese dam failures). Why on earth would you trust them to supply 100% pure metal for model trains? Seriously.
Also, Ed, customer service reps will take you very seriously and truly pretend to care, until you are done venting. That is their job--to let the customer believe the customer is always right.
There are good reasons we do not use foreign made steel on public construction projects in the US. So why then should any of us expect our models or toys to be 100% pure when you could never get pure steel out of the very same countries these models come to us from?
John
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Post by edwardsutorik on Jun 11, 2022 11:24:26 GMT -8
Metal fatigue occurs with steel bridges after repeated truck loading cycles where cracks develop in the steel with sometimes disastrous results. We in engineering actually equivalate all trucks to multiples of 18,000 pound (or 18 kip) equivalent single axles, and then we track the lifetime number of equivalent 18 kip axles (ESALS) the bridge is exposed to. We have computer programs that can analyze the remaining life of the bridge based upon known periodic traffic counts. Those programs are used to make decisions about when to replace or rehabilitate (if possible) the bridge. Metal fatigue should not ever happen with model trains. They are not subject to millions of loading cycles as real steel girders and beams are. Zinc pest when it is advanced does result in brittle failure and metal pieces that literally crumble to dust in your hands. Some Pre-WWII Lionel wheels are known for doing this and my past employer witnessed this on numerous occasions. Bowser for many years cast identical replacement wheels in pure zinc for those old Lionel trains and offered them painted in matching colors. Zinc pest still DOES happen, and I KNOW the manufacturers care about it. However, model trains are NOT built by LOW BID. They are NOT highways or bridges built on government contract with government mandated wage rates. You folks are being extremely disingenuous to even begin to suggest that model trains are built in China by LOW BID. You are completely forgetting the years of time invested with the manufacturers to get them to a point where the model quality is what it generally is now (which sometimes isn't even what some of us might want). One does not simply replace a retired manufacturer with the next guy down the street and not have a couple year learning curve. A careful reading of what I said about low bidding will see that I was not referring to the importers choosing who manufactures their stuff, as you seem to think. I was referring, in particular, to alloy suppliers. I could be wrong, but it's my impression that quality materials cost more to supply than lower quality materials. Thus, if one is getting low quality materials, it might well be that the supplier is cutting corners. Alternately, he might be overcharging. Ya know, I've heard "...one cannot always trust the material suppliers." All the more reason to do better work at finding those that CAN be trusted, and detecting those that can't. You could point out that that costs money (Oh, the horror). Yup. Delivering quality products always costs more than delivering crap. Interesting that you just KNOW I was "venting". And that you KNOW I can't figure someone out after talking to them for awhile. I assume you are talking about after the San Francisco Bay bridge replacement was built. For that matter, almost every container crane in the United States was a part of a public construction project. Lotsa steel there. How much from the US? Ed
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Post by Deleted on Jun 11, 2022 11:40:39 GMT -8
I cannot speak for construction contracting in Commifornia.
I can speak for Pennsylvania, where the use of steel from outside the Unites States on a Department of Transportation project is absolutely 100% prohibited. It is the same in, to my knowledge, MOST states of the US. In fact, I'm pretty sure the Federal Government prohibits the use of foreign steel in ANY of their construction projects, unless der fuhrer has changed it recently.
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Post by Baikal on Jun 11, 2022 11:40:49 GMT -8
Odd how you KNOW that also. I suppose the use of foreign steel in building the replacement for the San Francisco Bay bridge is thus a surprise to you. Ed
U.S. Icons Now Made of Chinese Steel
etc 1,000 times.
No way this guy is a Civil P.E. as this info is easy to find.
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Post by Baikal on Jun 11, 2022 11:44:34 GMT -8
I cannot speak for construction contracting in Commifornia. I can speak for Pennsylvania, where the use of steel from outside the Unites States on a Department of Transportation project is absolutely 100% prohibited. It is the same in, to my knowledge, MOST states of the US. In fact, I'm pretty sure the Federal Government prohibits the use of foreign steel in ANY of their construction projects, unless der fuhrer has changed it recently. I worked for Caltans as a planner, managing funding for rail projects, including bridges. Chinese steel is common, even on Fedrally funded projects.
As a not-a-professional-engineer, where are you getting your info from?
Laws also "prohibit" driving drunk or over the speed limit or school shootings. Reality says otherwise.
Reminds me of the Pompey quote to the Mamertines in Messana, complaining about Pompey's legal jurisdiction after their city was retaken: "Stop quoting laws, we carry weapons!"
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Post by Deleted on Jun 11, 2022 11:47:02 GMT -8
I just checked FHWA's website: The Federal Highway Administration.
Foreign steel is allowed in only deminimus quantities...minimal use... on American transportation projects.
Under the NAFTA agreement, certain allowances were made to allow deminimus use. I just searched that up on FHWA's website.
That still means, generally speaking, we CANNOT use foreign steel.
I've spent 30 years as a designer (20 years as a licensed PE) on projects for DelDot, MDSHA, PennDOT, & Pennsylvania Turnpike. Foreign steel is generally speaking, not allowed. It's specified in PennDOT's construction material list. But then we are more conservative about the materials we allow here in the East than Commifornia.
Apparently FHWA allows minimum use and petitions can be filed, I guess where a steel product is not readily available, to allow exceptions.
Every single lot of material is tracked and signed off on in Pennsylvania. They do not use foreign steel in bridges.
AND if you use foreign steel in a PennDOT project here in Pennsyltucky, and john q public finds out about it, the press will absolutely NOT be good. Paving over a dead deer factually got the crew 3 days in the street without pay. We've already lost too many steel jobs overseas. People in certain parts of PA have severe issues with foreign made steel.
Also you all are apparently very trusting. I come on here to talk about trains, and you think you can trust people half a world away, in a culture that generally speaking, hates the US but tolerates us because they need our money to buy their goods, to be 100% honest about manufacturing? When we can't trust anything they say about some other issues in life that are bigger???
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Post by Deleted on Jun 11, 2022 12:19:07 GMT -8
The only way to retard--slow down--zinc pest is to keep all sides of the piece of metal painted with some kind of relatively moisture resistant coating.
The toys where the paint chipped off the most were the ones most likely to crumble to dust the soonest. A collector who had more than 1 million dollars of Lionel Trains told me this. He's long gone now.
This of course means that unpainted metal frames or weights, or those items painted on only one side, will be the first to show evidence of zinc pest.
Some P2K frames are also brittle, and if you attempt to bend them in your bare hands, as I have on one SD45 frame that was not straight, they will just snap. That is different and not necessarily a result of zinc pest. Some metal frames are not intended to be bent. Maybe poor heat tempering...or brittle alloy.
Trains that are kept sealed in their boxes, stashed away in a closet for some future layout construction date, will be least likely to exhibit zinc pest, too.
As was clearly stated above, not every flat car or weight or frame will be bad, only those from individual batches.
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Post by edwardsutorik on Jun 11, 2022 12:36:29 GMT -8
...a culture that generally speaking, hates the US... Please explain. I've been there, and didn't notice any hatred. Sometimes they looked a little bewildered by us, but not in a mean way. Yeah, I think that's called "trade". We buy some of those little trains with dollars. They'd like some wheat that we have, and they buy it. Or high tech secret stuff, if we'll sell it to them. Ed
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Post by edwardsutorik on Jun 11, 2022 12:41:58 GMT -8
Some P2K frames are also brittle, and if you attempt to bend them in your bare hands, as I have on one SD45 frame that was not straight, they will just snap. If you need to bend a zinc alloy casting, I strongly recommend never bending it with your bare hands. You cannot adequately control the force application, and you may unnecessarily break the casting. I have written a lot about this, earlier. Ed
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Post by edwardsutorik on Jun 11, 2022 12:47:59 GMT -8
That still means, generally speaking, we CANNOT use foreign steel. That would include German steel. Which is also well known to be crap. And those Japanese--also making "foreign" steel. It is indeed a wonder that NO ONE ELSE in the whole world can make steel good enough to be used here. Definitely a lesson to be learned, there. Ed
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Post by Deleted on Jun 11, 2022 12:50:26 GMT -8
Ed--
Yes, you wrote an excellent post about one good method to straighten a zinc frame, which perhaps I wish I had seen a few years ago before breaking said frame.
Explanation requested above would get too political and would definitely be beyond the scope of these model train forums. Can we return the discussion to model trains?
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Post by Deleted on Jun 11, 2022 13:07:21 GMT -8
That still means, generally speaking, we CANNOT use foreign steel. That would include German steel. Which is also well known to be crap. And those Japanese--also making "foreign" steel. It is indeed a wonder that NO ONE ELSE in the whole world can make steel good enough to be used here. Definitely a lesson to be learned, there. Ed Ed-- PennDOT and other state DOT's are notoriously conservative. We were not allowed to use plastic pipes for cross pipes under a PennDOT roadway for many years because when they tested the plastic pipes, back about 25 to 30 years ago for the first time, they factually placed them under 80 feet of fill material, and of course they failed due to just the dead load on top of them. Additionally, it took years to learn a better way of placing the backfill envelope around plastic pipes to give them a better opportunity to survive. You can't just throw them in a ditch and start putting dirt on top of them. It's a bit more complicated than that. As a result plastic pipes of ANY kind were forbidden as a crosspipe for many years (though select PennDOT maintenance districts did begin using plastic pipes on back roads). As designers we were absolutely forbidden from using them on a PennDOT project. Because it takes so many years after initial pipe installation before PennDOT will likely ever touch the pipe again, we are required to design most roadway cross pipes for a minimum 50-year design life, and under high type arterial roadways, like interstates and US routes, they require 100-year design life. Plastic pipes, until relatively recently, could not meet those standards adequately enough for PennDOT. Pennsylvania has more than 22,000 state owned bridges, about 3rd place in the US for total state-owned bridges, if I recall. Since this was pretty much THE steel-making state in the US, there is tremendous public pressure not to use foreign steels on a state-owned highway project. Whatever the Department of General Services does is whatever they do, but PennDOT does an awful lot of steel bridges (where it makes more sense than concrete--certain span lengths lend themselves to steel). GSA doesn't build that many buildings... So you have a very conservative state with regard to any acceptance of foreign steel on a public transportation project. Civil engineers are also very conservative. If a bridge fails or a road or dam or airport, we civil engineers, who are required to be licensed due to our work directly affecting public safety (so we are the most licensed engineering profession) can be very easily sued. All of that contributes to why we just don't like foreign steels. Again--it's not even up to me--I specify the materials and alternates that I am required to provide. We even have alternate bridge designs--prestressed concrete versus steel versus other alternatives--that can be required based upon the project. The design bridge engineering consultant will prepare detailed final design plans for one alternative, but the contractor may be able to substitute his own plans for two other alternatives if he chooses to do so. I'm the roadway geometry person so I am involved with the grades and grading around the bridge, what is possible and what isn't or can't fit. So I work directly with the bridge designers, and generally, I don't do their job (***I did for one year when roadway work was slow and got to size beams for a bridge to a PPL Power Plant.) Now back to trains, please.
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Post by edwardsutorik on Jun 11, 2022 13:34:18 GMT -8
It's a wonder that the Pennsy conservatism didn't extend to maintenance of the Forbes Avenue bridge that collapsed in January.
But we were talking about how "we do not use foreign made steel on public construction projects in the US" and how that appears not to be so. Or not.
And now back to trains.
Ed
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Post by kentuckysouthernrwy on Jun 13, 2022 13:42:02 GMT -8
FWIW, Canadian National has a lot of Japanese steel rails thru Michigan, the Grand Trunk Western line.
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Post by Deleted on Jun 14, 2022 14:39:03 GMT -8
FWIW, Canadian National has a lot of Japanese steel rails thru Michigan, the Grand Trunk Western line. As a privately owned company, or rather not a US-publicly-owned transportation company, that generally carries freight and is not a public or common carrier of passengers, they are free to use any rails they desire. That freight railroad is privately owned, would most likely be considered privately funded so far as the US is concerned, and CN pays real estate taxes to the US government and applicable states along the way. They can do as they please with their privately owned land. Things might be a bit different if they were a public hauler of passengers, funded with US tax dollars and under the control of USDOT and FHWA. The funding source agency has the right to dictate use of US or North American steel. No less than 21 federal and state agencies must sign off on any new highway construction here, in my state. That is the way the laws are set up in America. We are going out of the way to avoid a historic farm, that can legally be bulldozed tomorrow for a private housing development (actually planned). For our road project we are required to consider all avoidance alternatives at whatever the cost (I'm doing the roadway alignment study on behalf of PennDOT). The property owner of the farm can do whatever they want with it tomorrow, but we consultants acting on behalf of PennDOT cannot. That is the law. Who builds first does matter.
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Post by kentuckysouthernrwy on Jun 14, 2022 15:05:51 GMT -8
Was just stating a fact...btw it IS an Amtrak Midwest Service line from Port Huron to Battle Creek where the passenger trains divert onto the Amtrak owned line to the West, old MichCent/NYC/Conrail/NS Chicago-Detroit line. Actually a look at local records in my area, reveals that a big chunk of the taxes are actually paid by the Saint Clair Tunnel Corporation...to the local jurisdictions, cities and townships. not state or federal governments. Ranging way off topic, but I have seen some CN locos with seemingly bent frames but have no idea about the causation.
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Post by lvrr325 on Oct 21, 2022 20:52:43 GMT -8
Just wanted to throw out there I bought a box lot of stuff at a show last weekend and there are two what appear to be Stewart F-unit frames, post-Kato drive by the looks of the motors, which have pretty bad zincpest. One appears to have broken right in half ahead of the fuel tank and was glued back together, and the front is heavily filed down to fit whatever shell they were trying to use, maybe the stock one. I've never seen that before, although I don't handle Stewart F-units very often either.
In an irony there's a Varney F3B in the box too, and it's fine.
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Post by upcsx on Oct 22, 2022 5:15:16 GMT -8
Two of mine Intermountain ES4400's the frames are bowed up.
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Post by edwardsutorik on Oct 22, 2022 6:20:41 GMT -8
Being "bowed" doesn't necessarily mean zinc pest. Sometimes it's just shaped that way. Those Athearn auto racks from awhile ago appear to be that way. Also, zinc pest takes time to happen.
I doubt the Intermountain stuff has been around long enough to develop zinc pest. White powder on the surface doesn't mean it's got it, either. Without seeing the one Stewart frame, there being a break MIGHT mean the guy tried to work on it and screwed it up. Zinc alloy castings don't enjoy being bent, and are willing to break if pushed too far.
Zinc pest is characterized by cracking, brittleness, swelling, and distortion. Do an image search for examples.
Yeah, I have yet to see zinc pest in a Varney casting. Looks like Gordon made it a point to use good alloy.
Ed
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Post by lvrr325 on Oct 22, 2022 9:03:39 GMT -8
These Stewart frames are swelled and cracked, one is much worse than the other but both have it.
I have seen Walthers B40-8 locos with swelled frames and those aren't particularly old.
Varney is usually good, but late, 60s era Varney I have seen it in, some Casey Jones/Old Lady frames and the bright colored Docksider must have been really bad because all I ever find are the shells. (they did a run in 62-63 to commemorate selling over one million Dockside switchers, of six roadnames in more or less diesel paint schemes; FEC red, Mopac blue, NH black with orange cab, NYC green, SP grey and UP yellow. Been trying to collect a set).
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Post by edwardsutorik on Oct 22, 2022 9:10:53 GMT -8
How old, Johnny? Touring Youtube, it looks like they showed up about 8 years ago. That does seem like a pretty short time for it to happen--I've been guessing it would take 10-20 years (or more, of course). I would imagine the crappier the alloy, the sooner it would happen.
I have the impression that the Intermountain can't be older than a year or two.
Ed
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Post by Baikal on Oct 22, 2022 9:36:27 GMT -8
How old, Johnny? Touring Youtube, it looks like they showed up about 8 years ago. That does seem like a pretty short time for it to happen--I've been guessing it would take 10-20 years (or more, of course). I would imagine the crappier the alloy, the sooner it would happen. I have the impression that the Intermountain can't be older than a year or two. Ed
I haven't seen any of the models discussed in this thread, so not addressing any specific issue.
But some of the problems seen in castings are not "zinc pest". These include cracking due to who-knows-what impurities, improper cooling, bad mix, whatever. Or the inability to take more than one bend. Not just in models- Last week I bought a cheap cast mystery-metal lemon squeezer. The handle snapped on the 5th lemon, not that surprised.
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