andersley Wrote:Not sure about the second air line, but could be for the hopper doors, see below.

I would imagine that in this case (just a guess) the second air line is for the hopper doors. If you would use train line air you would probably keep putting the train in "emergency" evey time you opened or closed a door.
Charlie

Just had a reply from a train driver I know (passenger trains, though). He says we use a two-pipe brake system, one for brake operation, the other to keep reservoirs at full pressure. I suppose this reservoir air could be used for the hopper doors, or maybe there is an installed air supply at the discharge site (coal fired power station).

andersley Wrote:Just had a reply from a train driver I know (passenger trains, though). He says we use a two-pipe brake system, one for brake operation, the other to keep reservoirs at full pressure. I suppose this reservoir air could be used for the hopper doors, or maybe there is an installed air supply at the discharge site (coal fired power station).

That was too obvious, of course they could use the resovoir line for both purposes.
Charlie