I recently posted a summary of the rules for air brake servicing, and in particular the stenciling on the freight car which recorded this service, because that’s the part that we as modelers can and should reproduce. The post can be found at this link: http://modelingthesp.blogspot.com/2014/04/brake-service-rules-and-modeling.html . Partly in response to inquiries I’ve received, I want to expand on the topic in the present post.
Guy Wilbur was kind enough to send me a complete version from 1952 of AAR Interchange Rule 60, which governs air brake servicing and stenciling (and charging of car owners for the service, if performed off-line). Here are the graphics showing where and how to stencil the brake equipment:
And also the arrangement for the combined reservoir in AB systems:
The lettering size, 1-1/2 inches, is also indicated here.
As I mentioned in Part 1 of this thread (cited above), and as is noted on these drawings, if the reservoir were so located as to be difficult to see clearly from the car side, it was suggested that the brake servicing stencil be placed on the side of the car near the reservoir location.
Prior to 1958, the maximum interval between brake servicing was 36 months. One would thus simply add three years to the year shown in the stencil, and see if the validity period had expired. As with reweigh intervals, the month shown in the stencil is the last month of validity, in that third year.
Prototype photos of freight cars, in which reservoirs are fully visible, show that workmen stenciling this information by no means always followed the rules as to location and arrangement. One possible reason for that would be simple convenience, since a repacking stencil is similar, and might already be prepared; just apply it to the brake reservoir. Part (a) of Interchange Rule 60 states that “standard air brake markings, as shown [above] . . . are required on all cars,” but this evidently means the content specified is required, not the arrangement. Or else it means that exceptions were tolerated.
Those prototype photos also show, in many cases, that the reservoir stencil cannot be read, and is either partially or entirely obscured by dirt. Accordingly, I would not try to have a visible stencil on every visible model reservoir, just because the same was true of the prototype.
As I mentioned in the first post on this topic, we modelers can choose whether we want to stencil all the reservoirs (or nearby car parts) of our model fleet of freight cars, or not. Personally, my choice is to apply brake stencil decals to some of the most visible reservoirs, with no effort to do anywhere near all of them. But you, of course, can choose the course that works best for you.