"On down brakes"
I might have told you when I hired out in May 1955, we still had some 1904 and 1905 men working. The oldest "brakies" on the "seni" lists said, necessarily, the cars with "the Westinghouse" were all on the head end of a freight train and those withou air brakes were on the rear end. Some freight trains were mostly without operable air brakes. Thus, the engineer would whistle "down brakes" (o o o o o o o o) when he wanted to stop, say, to head in to a siding for a meet at the end of track authority. The head, swing, and rear men would run along the car tops tightening the staff brakes with their "staffs of ignorance" (brake clubs). Too tight and the car wheels would pick up at low speed and slide flat and "walk" (ker plunk, ker plunk). Too loose and the point would run past the heading-in switch thereby violating track authority for a while, until brakes could be released and the train backed under flag protection, usually by the conductor. While "lapping authority," the head end had to be protected by the "tallow pot," who made a spot fire and, then, left the cab with a flagging kit, because the "brakies" were busy.
[from the R&LHS Newsgroup.]