For those of you interested in how the brakes work on a train, here is a few links to get you started.
Description of air brake systems with cutaway views of the equipment: http://www.catskillarchive.com/rrextra/chapt21.Html
Train brakes and description: http://www.sdrm.org/faqs/brakes.html
Air brake testing procedures and rules (70 page PDF document):
http://www.utu32.com/Rules/air_brake_30_to_34.pdf#search=‘locomotive%20air%20brakes’
http://www.mtmuseum.org/jsr/roster/RockIslandAirBrakes.html
How about an Operator’s Manual for the U34CH:
http://www.hobokenterminal.com/u34ch/u34ch_03.html
GP7-9 pre-trip inspection:
http://cqpa.steelvalleywebdesign.com/gp9manual/GP9_Section2_Operation.htm
More GP7-9 stuff: http://cqpa.steelvalleywebdesign.com/gp9manual/GP9_Section1.htm