Just some thoughts on this subject.
1. In general, the practice when running engines with trains down hill would be to make the reduction and release the engine & tender brakes with the independent in quick release. Mountain brake and drifting of engines not considered in this discussion.
Since engines have greater braking effort than cars (one for one), then letting the engine brakes come on will generally bunch the train.
Build up of driver brake pressure will be at a greater rate than in the cars. Longer the train, the longer of the setting time at the rear end.
Now imagine having two engines on the head end and the road engine hogger (2nd man) not paying attention to what the helper man is doing and when the air is set, the brakes on the second engine apply. As brakes set front to rear, this could could do quite a job of undesired bunching of the train.
If (just for the discussion), the train consist is comprised of a long train of mixed loads & mtys, with more of the loads on the rear end, the rear end running in bunching the slack could give the head end one good "kick".
If the head end were in some tight curvature, and mtys on the head end you could find the cars "spit out" toward the ROW fences.
Part of the reason for not running two engines on the head end down hill. This was not done on all roads. Long trains add to this problem. Curves and straights can also help to keep a train slack mixed and requires indepth knowledge of the physical charateristics of the railroad.
2. If the bunch train method is used then the train would be gently bunched with the independent brake valve before the set is made, then allowing the BC pressure to remain on or at least come up easily on the second reduction of a split application.
This was used especially when stopping on down grades and on the level to pevent run out. This not all to discuss on this method.
But, as for the two engine business, until the train brakes have set at the rear end, one should be careful to control the amount of BC pressure developed on the engine(s).
Obviously, this is only the tip of the iceberg on this subject. Lots of variables, facts and personal preferences on how to do it.
Slack is wonderful for starting, but when handling passengers it can sure bounce 'em around out on the road.
Next item.
Wish I could remember what the practice was on the slim gauge, but since crews were called ist in first out. (Obviously.) My inclination would be that the road crew would be the 1st out crew, unless the helper was an assigned job. This primarily because it (Road job) would be the higher paying of the two.
I haven't been following the "call sheets" too much, but that should tell part of the tale.
Maybe they would show if an engine crew could be trapped in Chama on helper or Cumbres turns.
This will be another subject that varied because of management operational decesions due to traffic demands, and the union agreements.
Chris
