You're way off on the timing of hump yards. Enola yard was built in 1905 with two humps. I'd put that as close to the beginning of the era of common use.
Do not hump cars were anything that couldn't hand the coupling OR anything that might "hang up" on either the hump or the bowl, so typically extra-dimension loads were "Do Not Hump" as well. Explosives, glass, delicate machinery, etc... all got do not hump.
My 16" 50 cal Mark VII naval rifle barrels certainly get a "DO NOT HUMP" placard, just like the prototype loads.
Special handling cars were often placed at the front (or back) of the train so that they would be cut out of the string before it was sorted on the hump. If a do not hump car got too the hump, somebody screwed up. If the crew cared, it was likely either
switched into a pocket or the locomotive would take it over the hump rather than let it run free. On an extra dimensional load, they'd have to back it off the hump and put it where it belonged.
Valuable specialty cargos often had accompanying riders who would ensure that the cargo was handled properly in just this sort of a situation as well. Typically, they rode in the cabin car (caboose) with the crew but sometimes, companies would lease a coach
or could own their own "rider car" for their person to accompany loads.
From: STMFC@... on behalf of jimbetz@... [STMFC]
Sent: Sunday, June 25, 2017 10:21 AM
Subject: [STMFC] Speaking of "Do Not Hump" ...
Every once in a while we see cars that are labeled "Do Not Hump" - often with some
lettering on a white background attached to a tack board but also, every once in a
while, just marked in chalk on the sides or doors of the car.
This prompts me to ask the following questions:
1) When were hump yards "invented" ... and when were they in common use?
I'm guessing post WW-II for the second part ... ???
2) Why were cars marked "Do Not Hump" - what was the reason for it? The kind
of load it was carrying? Something about the car itself? I'm guessing that
this was done to avoid damage ... but what kinds of loads/cars would be
damaged by going thru the hump?
3) What did the RR do if a car was coming up over the hump and the hump operator
saw that marking/warning on it? Did they send it down an empty track? Stop
the shove and take the cut back down the way it came up and 'side track' the
4) If you were establishing a "no earlier than 19__" date for "Do Not Hump" to be
on any of your cars (because your layout represented that date or earlier)
what year would you use?
- Jim B.