Air Brakes and Train Handling Rules - Alaska Railroad

GlossaryHand BrakeAn assortment of levers, chains, rods, and gears. When appliedmanually by wheel or lever, the hand brake forces the brakeshoes against the braking surfaces (wheel tread or disc) tocontrol car or locomotive movement.Harmonic RockingThe excessive lateral rocking of cars and/or locomotives thatmay result in wheel lift. Harmonic rocking usually occurs atspeeds between 13 and 21 MPH on jointed rail.Hauled-In-TowSee “Dead-in-Train.”Head End Power (HEP)The system on a locomotive that supplies electrical power to atrain for air conditioning, heat, light, etc. HEP includes thefollowing power sources:Normal HEP: The head-end power alternator supplies 480 VAC(volts AC) to the train.Shore Power: Any external (nonlocomotive) source that supplies480 VAC to the train.Standby HEP: The main alternator supplies 480 VAC to thetrain.HelperOne or more manned locomotives added to a train to assistmovement.In-Train ForcesAny force occurring within a train. Examples include buff, draft,run-in, and run-out. Excessive in-train forces may result inbreak-in-two, jackknifing, stringlining, damage to lading, etc.G-8 ARRC Air Brakes and Train Handling Manual June 1, 1996