LEAD TRACK. An extended track connecting either end of a yard with the main track.
LOAD LIMIT. The maximum weight of lading that a railcar is designed to carry. For cars
meeting standard AAR design criteria, the load limit is equal to the maximum allowable gross
weight on the rails (determined by axle and wheel size), less the light weight of the car. Load
limit is stenciled on every freight car in conjunction with the capacity and lightweight and is
LOCOMOTIVE. A self-propelled rail vehicle designed to convert electrical or mechanical
energy into tractive effort to move railcars.
MAIN RESERVOIR. A cylindrical tank, carried on a locomotive, to hold a supply of
compressed air. The main reservoir is distinct from the auxiliary and emergency reservoirs under
MAIN TRACK. A track extending through yards and between stations, upon which trains are
operated by centralized control.
MU. Multi-unit locomotive. More than one power unit connected together, and controlled by
any one of the power units.
NEW. Net explosive weight.
NET. Net explosive tonnage.
PC SWITCH. A pneumatic control switch that automatically opens during an emergency brake
application and reduces the power output of the locomotive. The PC switch automatically resets
itself provided the throttle is returned to idle and control of the brake is recovered. It is often
referred to as the power cutoff switch.
PLAIN BEARING. (See BEARING.)
RESERVOIR, AUXILIARY. A compressed air storage tank that is a part of the air brake
equipment on each railcar. Compressed air is stored in the auxiliary reservoir and is admitted to
the brake cylinder to apply train brakes when brake pipe pressure is reduced. The auxiliary
reservoir is isolated from the emergency reservoir by a separator plate bolted between them.
RESERVOIR, EMERGENCY. A compressed air storage tank which is a part of the air brake
equipment on each car. Air stored in the emergency reservoir is used to apply the brakes during
an emergency application, and to assist in releasing the brakes and recharging the system during
brake release operations.
RIGHT OF WAY. The strip of land on which a railroad track is built.
ROLLER BEARING. (See BEARING.)
ROLLING STOCK. Any equipment that rolls on wheels which includes cars, trucks, heavy
equipment, material handling equipment, etc. but excludes skid-mounted equipment-- for
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