Locomotive parts glossary

Terms that come up when you specify, buy and exchange locomotive parts.

Power assembly: On EMD engines, the cylinder head, liner, piston, piston carrier, rings and connecting rod supplied and changed out as one unit.
Prime mover: The diesel engine of a diesel-electric locomotive. It drives the main generator or alternator, which feeds the traction motors.
Roots blower: A gear-driven positive displacement blower that supplies scavenging air on non-turbocharged EMD two-stroke engines such as the 567C and 645E.
Turbocharger: An exhaust-driven compressor that raises intake air pressure. On EMD two-stroke engines the turbocharger is also gear-driven through an overrunning clutch at low engine speeds.
Traction motor: The electric motor geared to a locomotive axle. EMD D77 and D78 and GE 752 are common direct-current types.
Main generator: The direct-current generator driven by the prime mover on older locomotives. Later units use an alternator with rectifiers, such as the EMD AR10.
Dynamic brake: Braking that turns the traction motors into generators and sheds the energy as heat in resistor grids.
Unit exchange (UX): A rebuilt component supplied in exchange for the customer's worn one of the same type. The worn part is the core.
Core and core charge: The core is the worn part returned for rebuilding. A core charge is a deposit billed until the core arrives and is accepted.
Running take-out (RTO): A used part removed from a locomotive that was running when it was retired or dismantled.
Used serviceable: A used part that has been inspected and judged fit for further service without a rebuild.
Remanufactured: A used part rebuilt to the maker's dimensions and tested, with worn components replaced.
AAR M-1003: The Association of American Railroads quality assurance specification for suppliers of railway parts and services. Certified shops are audited against it.
Certificate of conformance: A supplier's signed statement that a part meets the specification it was ordered to. Buyers keep it with the maintenance record.
COT&S: Clean, oil, test and stencil. The periodic overhaul of air brake valves, after which the date and shop are marked on the equipment.
26L brake equipment: The Westinghouse Air Brake locomotive brake schedule fitted to most diesel locomotives built from the late 1950s until electronic brakes replaced it.
Multiple unit (MU): Control of two or more locomotives from one cab through a 27-point jumper cable and air hoses between units.
Glad hand: The quick-connect coupling on the end of an air brake hose.
Angle cock: The valve at each end of the brake pipe that opens or closes the air passage to the hose.
Knuckle: The pivoting jaw of a coupler that locks with the knuckle of the next vehicle.
Draft gear: The cushioning unit behind the coupler that absorbs pulling and buffing forces.
Wheelset: Two wheels pressed on an axle. On a locomotive it usually carries the axle gear and bearings as well.
Condemning limit: The wear measurement at which a part, such as a wheel flange or tread, must be removed from service.
Railcar mover: A road and rail vehicle with couplers used to move railcars in plants, terminals and yards. Trackmobile and Shuttlewagon are common makes.
Blue card: In the United States, form FRA F 6180-49A, the locomotive inspection and repair record kept in the cab.
Request for quote (RFQ): A buyer's list of parts and quantities sent to a supplier, who answers with price, condition and lead time for each line.