CAPACITY
The nominal load in pounds or gallons which the car is designed to carry. See "Load Limit."

CAR BODY
The portion of the car structure above the trucks.

CAR MILE
A unit used in comparing freight earnings or expenses; the amount earned from, or the costs of hauling a car of freight one mile.

CAR NUMBER
A number stenciled on each car which, together with the reporting marks, conveys a unique identity to each car. See "Reporting Marks."

CAR SEAL
A security device consisting of a thin metal strip or metal cable usually attached to tank or hopper car closures. A broken seal indicates possible tampering or unauthorized tank entry.

CAR SERVICE AGREEMENT (CSA)
The legal contract between lessor and lessee defining all terms of the rental agreement.

CARBON STEEL
A general term applied to steels that contain relatively small amounts of alloying elements. Also, a term commonly used to distinguish between stainless steel and non-stainless steel.

CARLINE
One of a series of framing members which extend across the top of a car (covered hopper or box car) from one side to the other to support the roof.

CARLOAD
The quantity of freight required for the application of a carload rate.

CASTING
A general term applied to any part made by pouring molten metal into a mold.

CENTER ANCHOR
See "Tank Anchor."

CENTER BAND
A thicker or more chemically resistant vertical paint band around the center of the tank to protect against possible commodity spills.

CENTER BOWL
The area in the center of the truck bolster into which the body center plate sits.

CENTER BOWL WEAR LINERS
A metallic or synthetic liner placed between the body center plate and the truck center bowl to minimize wear of these two parts.

CENTER FILLER
The structural arrangement designed to transfer the center plate load into the car body, located within the center sill just above each center plate.

CENTER LINE
A line passing through and defining the center of the object.

CENTER PIN
The large steel pin which passes through the center of the body center plate and the truck center bowl.

CENTER PLATE (BODY CENTER PL.)
See "Body Center Plate."

CENTER SILL
The main longitudinal structural member of a car underframe. The couplers are mounted into the center sill at each end of car.

CERAMIC FIBER
A high temperature tank insulating material generally used in combination with another insulation, such as fiberglass. The ceramic fiber is necessary in order to meet the AAR requirements for "J" cars.

CERTIFICATE OF CONSTRUCTION
The bottom portion of form AAR 4-2. After the approved Application for Approval is returned by the AAR, the builder signs the bottom portion thereby certifying that the cars will be built per the approved design. The completed form is now submitted to the B.O.E. and the AAR. Cars cannot be placed in service until the Certificate of Construction has been submitted. See "Application for Approval."

CERTIFIED FACILITY
A shop or other facility certified by the AAR to construct or perform certain other types of operations on tank cars and/or tank car fittings.

CFR
See "Code of Federal Regulations."

CHARPY TESTED STEEL
Steel, intended for low temperature service, that has been tested to verify compliance with a specific low temperature toughness standard.

CHECK VALVE
A valve which automatically closes to stop the flow of liquid or vapor in one direction. Also known as excess flow valve.

CHEMTREC
Chemical Transportation Emergency Center.

CHLOROBUTYL
A type of rubber used to line the interior of tank cars.

CLASS I RAILROAD
A railroad in US whose operating revenue exceeding $277.7 million per year.

CLASS II RAILROADS
Regional - A railroad operating at least 350 miles or whose operating revenue is at least $40 million per year.
Local - A non regional railroad, with line-haul service.
Switching - A railroad which switches between other railroads.

CLASSIFICATION YARD
A railroad facility where cars are made up into trains according to their destinations and are also made ready for proper and safe movement.

CLEANING
Removal of foreign matter from the surfaces exposed to the commodity by chemical, thermal, or mechanical means.

CLEARANCE DIAGRAM
An outline or cross section drawing showing the maximum limiting dimensions to which railcars can be built. See "Plate B" and "Plate C."

CLEARANCE LIMITS
The dimensions beyond which the size of, or projections on a shipment may not extend in order to clear obstructions along railway tracks, such as switchstands, platforms, tunnels, mail cranes, water tanks, third rails, low bridges, signal stands, etc.

CLM
This is an acronym for "car location message." Car location messages are used in the railroad industry to track car movement. CLM's may be used to find lost cars, identify load/empty status, or when and where car was last placed.

CLOSING PRESSURE
Pertains to safety valves; the pressure measured at the valve inlet, at which the valve closes.

COATING
See "Interior Coating."

COATING/LINING ABUSE
Damage to coatings or linings caused by means not definable such as cuts.

COATING/LINING MECHANICAL DAMAGE
Damage to coatings or linings caused by repairs to the car.

COATING/LINING NORMAL WEAR & TEAR
Damage to coatings or linings caused by use and due to age.

CODE OF FEDERAL REGULATIONS (CFR)
Regulations issued by various branches and agencies of the federal government under the authority of statutes. Title 49 CFR pertains to transportation.

COIL SPRING
A spring made by winding round wire or bar in a helical pattern around a circular core. This type spring is used in trucks and safety valves.

COILED
A general term that refers to a tank car that is equipped with some type of interior or exterior heater coil system.

COILS (TANK CARS)
A general term used to describe various types of heater pipe systems for tank cars. See "Heater Pipes."

COLUMN WEAR PLATE
The replaceable steel wear plates mounted to the truck side frames that transmit frictional forces caused by vertical movement between truck bolster and side frame.

COMBINATION DEVICE
A spring loaded safety valve with a frangible disc or a breaking pin mounted below it.

COMMERCIAL BLAST
See "Blast."

COMMODITY
A general term used to describe the contents of a car.

COMMODITY STENCILING
Lettering placed on the sides of the car describing the commodity contained in the car. Commodity stenciling is the responsibility of the shipper.

COMMON CARRIER
A transportation line engaged in the business of transporting goods impartially for all shippers.

COMPARTMENT TANK CAR
A tank car in which the tank is divided into several sections for the purpose of carrying different commodities or smaller shipments.

CONICAL JACKET HEADS
Regarding tank cars; refers to the general shape of a jacket head that was fabricated by means other than pressing in the head press.

CONSTANT CONTACT SIDE BEARING
A side bearing designed to eliminate the normal clearance gap between it and the body side bearing.

CONTROL VALVE
"See Air Brake Control Valve."

CONVENTIONAL BRAKES
A brake system whose brake cylinder is mounted on the car body rather than on the trucks.

CONVENTIONAL UNITS
Unit of Measurement from the English system (customary in the U.S.) rather than the Metric System.

CONVERSION
A change in tank or fittings that changes the DOT or AAR specification. Sometimes used to refer to any physical change to a tank car.

CORROSION
The deterioration or eating away of metal through chemical action.

COT&S
An acronym for the periodic servicing of brake system components and indicating "Clean, Oil, Test and Stencil."

COUPLER
A standard device located at both ends of all cars whose function is to provide a means for connecting railcars to one another.

COUPLER CROSS KEY
The large flat steel member that is inserted through the center sill and the coupler shank thereby attaching the coupler to the car. Type "E" couplers only.

COUPLER HEIGHT
The distance from the top of the rail to the center of the coupler, nominally 34 1/2 inch.

COUPLER KNUCKLE
The pivoting hook-like casting that fits into the head of a coupler and rotates about a vertical pin between open and closed positions.

COUPLER RELEASE RIGGING
See "Uncoupling Lever."

COUPLER SHANK
The part of a coupler behind the head that extends into the center sill. The shank contains a slot or hole to facilitate attachment to the car.

COUPLER, TYPE E
See "E Coupler"

COUPLER, TYPE F
See "F" Coupler.

CROWN
The highest point on the top curved surface of a tank car.

CSA
See "Car Service Agreement."

CUBIC CAPACITY
The load carrying capacity of a car expressed in cubic feet or cubic meters. More commonly used in reference to hopper cars than to tank cars.

CUSTOMS BROKER
A person who processes customs service documentation for import shipments.

CUTOUT
Generally refers to an access opening in a tank or jacket which will later be either permanently covered or closed by a removable closure.

CUTTING TORCH
Refers to the oxy-acetylene device used to cut carbon steel.

CYLINDER LEVER
In a conventional brake system, the lever attached directly to the brake cylinder rod.