I was trolling around the online DeGoyler Library at SMU web site. Lots of neat info. But I stumbled upon this and thought the group might be interested.

https://digitalcollections.smu.edu/digi ... wy/id/3737

I had always wondered how the builders arrived at component sizes on locomotives. Now I have a lot better understanding of why things are as they are. Thanks.

Yup, back before computers the engineers found out by experience "well sheet,,, that part was not strong enough" and came up with "rules of thumb" about how big/thick parts needed to be to survive without "yielding / deformation" (permanent bending).

And they where cautious and made everything about 5x or 10x bigger/thicker than than it needed to be "just in case".

As the ability to produce better metals with more predictable "strength" the 5x to 10x factor went down. And modern computer analysis can get the "margin of safety" down to 2x - 3x. That results in much less mass per unit of horse power.

For "rocket ships" the factor of safety is sometimes as low as 110% of the actual strength of the material. That requires careful tracking of the actual metals used and very complete analysis of computer models.

Cool to see strength (yield) tables for wrought iron, nobody even lists that as a suitable metal for fabricating any moving \ structural parts in any modern assembly.

Nice find, Kevin.

Wow.

This 'looks like' it predates the Baldwin Standard Practice documents, although some of the formulas appear to be the same.

But wow, it struck me that this is like the Dead Sea Scrolls of steam engineering principles.
And entirely handwritten from the looks of things.

Having worked in some of these formulas, and being an ex-IT guy, I'm just in amazement at not just the formulas, but what it took to get there, and this is the DNA trail for at least some of them.

I'll second that WOW and add a Holy Moley! Fantastic reference and I'm so glad it can be shared.......mld