It is interesting regarding all this "communication" regarding "grease burners".
During my formative years on the Georgetown Loop and Colorado Central, I don't remember any of the old heads hollering at me as to when he was going to pull out the throttle or shut it down. I figured it out pretty quick for each engineer based on our location on the railroad and eventually learning the territory. After awhile, I was just slightly ahead of the engineer and throttle position when coming to a grade or shutting off for a level stretch or down grade. Exceptions were in an unusual situation or emergency. Except for drifting, I was taught to watch the stack regarding the fire and not to spend to much time looking into the peep hole.
I never experienced this "inter cab communication" until I went to the Grand Canyon Railway in 1989. I figured at that time it was because we were all learning the railroad (engineer and fireman) and helping each other out. After a year or two, I knew the railroad well enough from both sides of the cab, and I was in sync with the engineer most of the time, and usually, as the engineer, never hollered to the fireman regarding my impending throttle position.
Same for a coal burner. After awhile, I was taught to know the territory so as to anticipate when I needed to get up and start shoveling, when to sit down and where I needed to have my water at any given location. Understanding and knowing the territory as a fireman really helped me when I was learning to run as an engineer as well. On this longer and/or more complicated operations, I always though that the ones who spent a lot of time on the left side of the cab and became good fireman, usually also made better engineers.
MD Ramsey