I am looking for technical design standards for locomotive driving axles. All I am finding is articles on modern axles for cars and diesel/electric locomotives. I am looking for safety factors and dimensional recommendations.

This is what you want. I gave all my books away so I don't have a copy but you should be able to track one down with this info.
https://catalog.hathitrust.org/Record/101794960
Good luck.

The original design of US railway axles comes out of a German book, The Constructor. The first detailed analysis comes from the MCB proceedings, I believe it is the 1897 conference minutes. Continued development is based mostly on failure reports and destructive testing. The next hard technical look at the axle comes from Oscar Horger, VP engineering at Timken steel. He developed the raised wheel seat axle, which is the current standard. His next project was to be crank pin failures. However, this efforts was interrupted by WWII and when he got back to it the steam loco was well on its way out. His next project was the development of the AP tapered roller bearing. Oscar then left Timken and started a competing company, Brenco.

Most of Oscar’s work, and other work on the railway axles, is published as meeting papers from the Rail Transportation Division of the American Society of Mechanical Engineers. ASME also put out several books after the war which contain works by Oscar Horger. In maybe the mid 1980s David Blane (?), mechanical engineer with Southern Pacific wrote a ASME paper in which he tracks the development of the US railway axle. This includes a list of the significant papers on the subject. The AAR standard M-101 is the current standard for railway axles, but it is a design standard and contains no information on the development of the design. The detailed information of the AAR’s development of the M-101 would be in the notes of the AAR WABL committee. But these notes are private and not available to the public.

M Austin was kind enough to put this on the web for me perhaps it will help you.
http://hsengco.com/aar/AAR-Specs.pdf

Robby

I downloaded the material specs and saved them in my collection of tech data for Alaska Railroad 557.

The BLW card index for the USATC Consolidations includes a number of specifications that were apparently interim specifications for metals created as part of the war effort. Some examples are:

EM-201-2, GR. B. cast steel
AAR EM-201-42 Gr. B cast steel
AAR-EM-503-42 medium bronze
ARR EM-117-43 steel

Is there a collection of this group of interim specifications or a cross-reference to more commonly used standards?

The MSRP is one of the Holy Grails of info. It is comprised by many Sections. Section A is material specifications which is great if you want to know the composition of materials such as firebox steel, bronze shoes or axles. If you want axle profiles, condemning limits, etc, you will want Section F. If someone could post a pdf of that, they will have done the industry a service!

Heritage Rail (aka TRAIN, ATTRM, AARM) assembled a wonderful DVD several years ago of various manufacturers standard procedures. The Baldwin section is relatively exhaustive. They are scanned TIFF's of the BSP pages and as many of the others as were assembled at that time.

The really critical stuff that's in there is some of the dimensional tolerances, chamfering radii on axles, etc. What's not in there are specific material specs equal to modern materials, a reference may be made to 'Baldwin Standard Steel' or something, takes digging and equal discussion to match up material specs with what was in the BSP's.

On axles, that stuff is critical. Our case had journals worn to condemnable limits so it was literally a do-over on that issue alone. But the previous axles were cut angle-square at the hub, and yeah, some surface cracking had developed as well.

The more time I spend in these the more I gain a respect for the steam-era machinists; part science and part empirical experience. I enjoy commenting that 'why do you spec a 1/2" bolt there? when the answer is that "well, 3/8" failed, why?". And I'd also recommend that you be willing to get some technical advice (and pay for it) from some of the qualified machine shops out there that do this kind of work.

Unfortunately to truly understand the wear limits you also need to understand the materials used. For instance, the piston rod for a steam is a hammer forged item and they want the cross head end machined 0.020 inches over where the crosshead interfaces with the crosshead. This is to promote a marrying of the surfaces as the two are pressed together. Since forgings are not as easily found today one tourist railroad has taken to using 4140 steel as the "substitute" because the tensile strengths are the same. Unfortunately that is not the only material behavior they were using in the design. A forging has an overall behavior and a localized behavior with respect to the location within the metal. The harden surface will act differently than the softer sub surface. They understood this back then and took advantage of these different properties. So now the modern "steam expert" does not and sees part of the specs and creates his own mess. The result is a piston rod that will not marry with the crosshead and the key winds up taking the load which it should not. The keys eventually fail and the results are dramatic. So yes the wear spec is not exactly in this document but understanding the material behavior is important to understanding the wear spec.

There is a critical lack of appreciation of engineering of the steam locomotive in todays preservation world by too many involved in it. It is further complicated by the fact that the world of engineering has changed and too any professional engineers are not of the level of the engineers of the past. This is due to social pressures on how many hours a university can require of a student. All of us need to take a broader view of the technical world wefind ourselves in.

Robby Peartree

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Thanks Kelly, that's pretty much what I suspected.

And a tip of the hat to Kelly, he led me through the entire mess including these exact steel spec issues of old vs. new. Reconciling original manufacturer materials with what is available today is an art and a science.