The Field Service Manual was supplemented by the Master Technicians Service Conference. This was an ongoing monthly training program started in 1948 that went through at least 1973. The material was supplemental to the FSM and was intended to make the process even simpler and easier to understand by the man working in the service bay on the customer's car. The FSM comes after these for good explanations that you can really use, rather than before in my experience.
If you hit any bumps in the future, I'd suggest looking in the MTSC section of the website. the entire 1948 manuals are in our posession and coming soon, but fortunately the brake one has already been put up on the website for your convenience.
The good news is that this module tells it like it is about the 1948 brakes, I should think, and explains everything with really easy to understand graphics and explanations.