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| What is AAR M302 Grade B? https://www.rypn.org/forums/viewtopic.php?f=1&t=48605 |
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| Author: | mldeets [ Tue Mar 11, 2025 1:28 pm ] |
| Post subject: | What is AAR M302 Grade B? |
The title pretty much says it all. The C&NW specified this material for drawbar pins and we are looking for the modern equivalent. Thanks in advance for any help.............mld |
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| Author: | M Austin [ Tue Mar 11, 2025 3:37 pm ] |
| Post subject: | Re: What is AAR M302 Grade B? |
Attachment: AAR-Specs 222.jpg [ 144.24 KiB | Viewed 6826 times ] Attachment: AAR-Specs 223.jpg [ 195.01 KiB | Viewed 6826 times ] Attachment: AAR-Specs 224.jpg [ 208.79 KiB | Viewed 6826 times ] Attachment: AAR-Specs 225.jpg [ 172.04 KiB | Viewed 6826 times ] |
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| Author: | NYCRRson [ Tue Mar 11, 2025 4:31 pm ] |
| Post subject: | Re: What is AAR M302 Grade B? |
I think you will likely have a hard time sourcing wrought iron bars in 2025. I would look to some of the medium strength modern steels maybe some 1045, that should be much stronger than the M302. The wrought iron probably "rusts" less than a 1045. You could look for a chrome moly steel like a 4140 to "rust" more slowly. Good Luck Kevin |
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| Author: | mldeets [ Tue Mar 11, 2025 4:53 pm ] |
| Post subject: | Re: What is AAR M302 Grade B? |
Matt, THANK YOU very much for posting that pamphlet. It will be of great help. Do I read it correctly that the only chemical composition requirement is no more than 0.06% manganese? NYCRRson - Those materials have already been mentioned but I'll leave it up to those in our group better versed in material selection than I. This gives us a great starting place to determine what we'll use for the C&NW 1385. Thanks to all for the input.......mld |
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| Author: | NYCRRson [ Tue Mar 11, 2025 6:12 pm ] |
| Post subject: | Re: What is AAR M302 Grade B? |
Also, Iron products (Wrought Iron, Cast Iron and Sheet Iron) "rust" or oxidize and form an outer shell or black skin. Once this forms the surface is "inactive" and does not continue to "rust" (unless you scrape the skin off the surface, then the skin reforms). Simple steel oxidizes and turns to that orange crap which flakes off and the rusting process continues until the original metal no longer exists (unless painted/protected). Same process; oxidation, but different outcome. True Wrought Iron is no longer mass produced after about 1970 (steel got cheaper). There are modern products in the Architectural field (railings, benches, gates, etc.) that are referred to as Wrought Iron but most new ones are actually steel that is "textured" to look like old historic True Wrought Iron. |
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| Author: | JeffH [ Wed Mar 12, 2025 1:52 pm ] |
| Post subject: | Re: What is AAR M302 Grade B? |
Surely the AAR must have a current spec for what material to use on drawbars and pins. Just follow that. It's nice to see the specs from 100 years ago, but very often they reference materials that are no longer manufactured, or use terminology which has been superceded. |
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| Author: | Adam Phillips [ Wed Mar 12, 2025 3:49 pm ] |
| Post subject: | Re: What is AAR M302 Grade B? |
Based on historical standards, you should be able to find an appropriate material. I no longer have a copy of the AAR Manual of Standard and Recommended Practice to post and I didn't see anything in the CFR other than "safe and suitable for service". Some interesting info on drawbars, pins, and safety chains can be seen here. https://www.google.com/books/edition/Pr ... frontcover |
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| Author: | M Austin [ Thu Mar 13, 2025 12:19 am ] |
| Post subject: | Re: What is AAR M302 Grade B? |
All the BIG power on UP had FORGED pins meeting UP CS-1-A/mild steel. Drawbar pins from 1903 and before were wrought iron or open hearth steel. Wrought iron was not that strong but was immune from shear fracture. And, yes, the only chem requirement for testing was manganese. However, the physical tests to pass were BRUTAL. Attachment: UP-FEF-DB-Pin.jpg [ 91.43 KiB | Viewed 6061 times ] Attachment: UP-CS-1-A-MS.jpg [ 114.67 KiB | Viewed 6061 times ] High-Res version 1903 Dwg. Attachment: UP-1903-DB-Pins.jpg [ 89.64 KiB | Viewed 6061 times ] |
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| Author: | M Austin [ Thu Mar 13, 2025 12:23 am ] |
| Post subject: | Re: What is AAR M302 Grade B? |
The most historic material selection would be to take a vintage car axle (probably anything with plain bearings) and turn it down from that. |
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