Some people say you can find almost anything on the internet nowadays. But I often find nearly zero when it comes to reference items for historical railroad maintenance. Too odd a topic I guess. Well, a couple days ago, while working a night shift I spent quite a bit of time trying to find diagrams or information to trouble shoot a 24RL brake system. I found some 26 brake information (actually NYAB has some good pdf's) and even a 6BL system but very little about the 24RL.
Granted is is an antiquated system but a lot of us deal with antiques. Anyway since I knew I had some information at home I thought maybe someone besides me might need to reference some diagrams.
The one which was hand colored by a BAR employee years ago come with some papers given to me when the ARHS bought BAR F3 #46. I have often looked at it almost as a work of art. The other is a diagram for a 24RL brake system for a B unit. This was not found in every 24 brake manual.
All the various groups probaly have libraries of various reference material. To me a website that would have the various brake manuals, wiring diagrams, "Alco Notes" and EMD MI's etc would be a great reference.

Most people who maintain large technical libraries and scan a lot of that information to PDF files for easier reference have discovered that virtually everything posted on the internet as free information will end up being pirated and sold on pay for viewing websites, or packaged on CD's and sold on eBay. Consequently there is much less enthusiasm for putting a lot of time into making technical information available on the internet. Several groups tell me that they cannot get anybody to produce content for their websites anymore, nobody wants to put a lot of work into stuff that others are going to steal and sell. In a couple of those groups the webmasters are virtually the only members of the organizations left that write for the website.

PC

Railswap.org has some technical info. online, but it doesn't appear that they have added anything else lately. George Gelwood's Fallen Flags website also has a lot of operators manuals. I am sure if you were to scan an air brake instruction book George or Railswap would put it up on their sites.

Your prayers have been answered, check out the resource library on the Railroad Passenger Car Alliance website at www.rpca.com