Air Brakes and Train Handling Rules - Alaska Railroad

GlossaryQuick ServiceThe local venting of brake pipe pressure at each car. This ventingoccurs every time the control valve on a car moves from therelease position to the service position.Radial TruckA steerable truck with axles mechanically coupled throughsteering linkage. Axles deflect a few degrees within the truck.RDUReceiver display unit; part of the Glenayre Digitair end-of-traintelemetry device.Reduction (of the brake pipe)A decrease of brake pipe pressure at a rate and amount sufficientto initiate an automatic brake application or increase it.Reduction Relay ValveA device on long cars that helps reduce brake pipe pressureduring service and emergency brake applications. The valvecompensates for the added length of brake pipe on long cars.Regulating ValveAt the automatic brake valve, a device that controls the maximumpressure put into the equalizing reservoir and brake pipe.The air controlled is supplied by the locomotive main reservoirand delivered to the automatic brake system.Run-InThe rapid change of the train’s coupler slack to buff (compressed).Run-OutThe rapid change of a train’s coupler slack to draft (stretched).G-12 ARRC Air Brakes and Train Handling Manual June 1, 1996