I know that all people present in the cab of a locomotive are required to repeat the signal when it is announced by the engineer but my question goes back to steam locomotive days when the engineer had no vision of the tracks on a left hand curve. If the fireman saw some obstacle on the track ahead was there a standard order or command to the engineer to immediately go into emergency braking or was a blood curdling scream sufficient?
Well "STOP!!" would work, although a common term used would be "WASHOUT!!" meaning the track ahead was washed away, and you had to do an emergency stop. I believe the hand signal for STOP, waving a lantern back and forth or moving both arms back and forth (kinda like an NFL referee signalling that a field goal attempt was no good) was commonly called a "washout signal" IIRC.