The wheeled undercarriage assembly beneath a railcar consisting of two axles, four wheels, the frame, springs, and brake components. Railcar trucks allow the car body to pivot over curves and absorb track irregularities. Truck maintenance is a major source of bad-order repairs.
The mechanical device at each end of a railcar that links cars together into a train. North American railroads use the AAR standard E or F knuckle coupler, which engages automatically when two cars are pushed together. Coupler failures are a leading cause of train separations and bad orders.
The pneumatic braking system used on all North American freight cars, based on George Westinghouse's fail-safe design in which brakes apply automatically if air pressure is lost. The system uses a continuous brake pipe running the length of the train, fed by a locomotive compressor. FRA regulations govern brake testing requirements before each departure.
A railcar that has been removed from service because it has a mechanical defect, damage, or other condition that makes it unsafe or unsuitable to move loaded. Bad-ordered cars are set out at a repair facility until they are inspected and restored to serviceable condition. The term is used as both a noun and a verb in railroad operations.