I like John Bush was never in the operating dept except on occasional helper service, and as he said others are more qualified to speak than I on this subject but I have had a hand in setting up the trains so that they handle well coming down hill off Cumbres so here I go any way.
The objective is to use as small of sets or BP reductions as possible or as necessary. Allow the train to all stabilizes into the set, then recharge the brake pipe letting the retainers hold the set while the brake pipe & auxiliary reservoirs recharge. Then do it again and so forth.
After a brake test at the top of the hill and confirmation from the conductor that retainers have been set to the engineer’s instruction and a go ahead you start downhill. Very soon you will need to do a set; it takes about 3 lbs reduction just to get the system to react so generally you would start at about 5 lbs set. If you feel a response you let it ride, if not better take some more till it responds. Let it ride a few seconds then back to the engine hold so that the tender brakes stay on and the rest of the system recharges. The retainers keep it tight till while you recharge. If you are able to cycle with small sets the recharge time is less. Then cycle again.
The size of the train and the skill or lack their of the car toad maintaining the brake system and speed are a big part of timing and size of sets. The train should work at 5 to 7 lbs sets at the top of the hill and at 10 to 12 lbs sets on down the hill after things heat up. If the train is working at 15 to 20 lbs sets after things get hot the cars are in need of adjustment and should have the cylinder travel adjusted.
The ROW is changing all the way down the hill so there are times you let it ride longer or you take more or less air in a set. There is no set combination that is correct. Also trains have differing consist and handle a little different plus weather and speed are also a big variable factor for timing & size of sets.
If the train is short, you have a rotary, dead engine or some cars cut out for some reason use the driver brakes and compression with the drifting throttle along with cycling.
How a person can consistently react with the tools available to maintain a smooth consistent ride is testament to the skill level of the engine man managing the ride.
madjack
