Air Brakes and Train Handling Rules - Alaska Railroad
Air Brakes and Train Handling Rules - Alaska Railroad
Air Brakes and Train Handling Rules - Alaska Railroad
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67.8 Control Valve67 Car Equipment <strong>and</strong> ComponentsThe control valve applies <strong>and</strong> releases car brakes in relation tochanges in brake pipe pressure.Control valves respond rapidly during brake applications <strong>and</strong> releases,allowing the safe operation of long, heavy freight trains.67.8.1 Control Valve ComponentsThe control valve has three basic components:A. Pipe BracketThe pipe bracket:• Attaches to the car <strong>and</strong> connects various piping to components• Filters the air supply using its internal strainer• Connects the service <strong>and</strong> emergency valve portionsB. Service PortionThe service portion includes the service piston, slide, <strong>and</strong> graduatingvalve. It functions as follows:• Allows the emergency <strong>and</strong> auxiliary reservoirs to charge• Performs all service brakingC. Emergency PortionThe emergency portion includes a piston, slide, <strong>and</strong> graduating valvesimilar to the service portion. When the emergency portion sensesthat brake pipe air is reduced at greater than a service rate, it movesto vent brake pipe air directly to the atmosphere <strong>and</strong> directs emergencyreservoir air pressure to the brake cylinder.NOTE: An emergency brake application is a result of a rapiddrop in brake pipe pressure. The emergency brake applicationwill apply the brakes quickly <strong>and</strong> evenly throughout the train.June 1, 1996 ARRC <strong>Air</strong> <strong>Brakes</strong> <strong>and</strong> <strong>Train</strong> H<strong>and</strong>ling Manual 67-7
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