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Trains Big Boy
Railroading Glossary
The following glossary is arranged alphabetically with each term catalogued by first letter. Select a letter below to begin.
A | B | C | D | E | F | G | H | I | J | K | L | M
N | O | P | Q | R | S | T | U | V | W | X | Y | Z
Saddle-tank
A steam locomotive which carries its water supply not in a separate tender but in an upside-down U-shaped tank on the boiler.
Sawtooth profile
A railroad line with a series of relatively short up- and down-grade segments.
Scale test car
A special car having a precisely known weight and used to verify the accuracy of track scales that weigh cars for billing purposes.
Seal
Fastening device used to keep the doors on a car or trailer shut.
Searchlight signals
Signals having a single lamp, but which are capable of displaying more than one color.
Second-generation diesel
From the point of view of the railroad, second-generation units were those that replaced the diesel engines that replaced steam. Builder by builder, though, the situation and opinions differ and there is no accepted definition. For Electro-Motive, the beginning of the second generation can be marked by the introduction of the 645 engine in 1966 (EMD's first major design change) or by the introduction of the SD24 in 1958 and the GP20 in 1959 (respectively, EMD's first turbocharged units and the first hood units marketed for road service). Alco's second (and last) generation was the Century series. General Electric's first large unit, theU25B, was clearly second-generation in concept-a high-horsepower hood unit intended to replace cab units. GE's first generation could be said to be the use of GE electrical equipment in Alco locomotives.
Section house
A company-owned residence provided to a track maintenance worker.
SEPTA
Southeastern Pennsylvania Transportation Authority.
Set out
The process of switching out a car or group of cars from the consist of a train.
Shay
Type of geared steam locomotive conceived by Ephraim Shay and built by the Lima Locomotive Works. The most common of the geared steam engines, it featured a set of vertical cylinders (usually three) on the right of a boiler offset to the left. The cylinders drove a longitudinal shaft that drove the axles through bevel gears.
Shoofly
Temporary track constructed to allow trains to pass around an obstacle that blocks movement on the main track.
Short line
A railroad company that can originate and terminate traffic on its line, and is generally less than 100 miles in length. There is no official or legal definition of the term. This is the criterion used by the railroad industry and the American Short Line Railroad Association.
Shorthaul
To move traffic a shorter distance than the maximum possible for a given railroad between two points. For example, Burlington Northern Santa Fe would shorthaul itself if it turned over Seattle-Chicago traffic to Wisconsin Central at St. Paul instead of taking it all the way to Chicago on its own rails.
Short-time rating
Maximum allowable amperage for a locomotive over a limited period of time (15-minute rating, 30-minute rating, etc.) beyond which the traction motors will be damaged. It is higher than the continuous rating.
SI
Spokane International Railroad
Siding
An auxiliary track connected to the main track used to meet or pass trains.
Signal aspect
The appearance of a lineside or cab signal.
Signal indication
The information conveyed by the signal aspect, which the train crew must act on.
Single-line haul
Shipment over one railroad.
SIT
Storage in transit.
Slack action
Sometimes violent movement of cars in a train relative to each other because of the "give" in each coupler.
Slip switch
Combination of a diamond crossing of two tracks plus a connecting track permitting movement between the two through tracks.
Slug
A unit of motive power with traction motors but without a diesel engine. Electricity for the motors is provided by a standard locomotive with which the slug is mated. Usually used in hump, transfer, or other low-speed service. The engine-the prime mover-of a diesel locomotive can produce more electric power than its traction motors can absorb at low speeds. A slug can use this excess current to provide additional tractive force. Other terms for "slug" are MATE, TEBU, yard booster unit, remote power unit, and drone.
Smoke deflector
An object placed on both sides of a steam locomotive's boiler near the smokestack that would create air currents to lift the smoke above the boiler. Eliminated problems associated with smoke drifting into the engine cab and improved visibility from the cab. Also called smoke lifters.
Smoke jack
Chimney in an enginehouse that collects locomotive exhaust gases and directs them up through the roof to the outside.
Smoke lifter
See Smoke deflector.
Solid-state inverter
Computerized device in a locomotive that generates and regulates alternating current for the traction motors.
SP&S
Spokane, Portland & Seattle Railway.
Spare-board
Canadian equivalent of "extra board", a list of jobs not held down by a specified person.
Spark arrestor
Devices fitted over the smokestacks of diesel locomotives designed to catch hot, partially combusted material as it was exhausted out the smokestack. Used to prevent hazards such as lineside fires.
Spartan cab
The standard EMD nose/cab configuration used before most railroads began adoption of the wide-nose safety-cab style in the 1990's. The nose is low enough to see over from the window of the cab, and narrow enough for walkways on either side; the cab roof is flat in the center and beveled on each side.
SPCSL Corporation
Southern Pacific Railway subsidiary, which bought the former Gulf, Mobile & Ohio Chicago-St. Louis line in 1989.
Sperry car
Specialized car owned by Sperry Rail Services used to detect defects in the rail.
Spine car
Special type of articulated three- or five-unit flatcar designed to carry trailers or containers.
Spiral
A section of track whose curvature changes at a constant rate over its length; provides transition from tangent (straight) track to curved track
Split the switch
When a rail car approaches a facing-point switch and one pair of wheels follows a course different from all the other wheels, generally resulting in a derailment, the car is said to have split, or "picked" the switch.
Spot a car
To switch a freight car to a specific location, usually for loading or unloading.
Spring switch
Standard track switch equipped with a spring mechanism that automatically returns the switch points to a normal position after they have been displaced by the passage of cars in a trailing point movement. Eliminates the need for train crews to reset the switch to a normal position.
Spur
Segment of track branching off the main, used to reach a customer or facility, or to store equipment.
SSW
St. Louis Southwestern Railroad (aka the "Cotton Belt").
Stabbing
The unexpected delaying of a train, particularly by another train movement.
Stack train
A train made up all or largely of double-stacked containers.
Staff system
An early method of train control by which authority to enter a section of track is granted by the train crew's possession of a designated object, which, in early times, was a wooden staff.
Staggers Act
The Staggers Rail Act, named for Rep. Harley O. Staggers of West Virginia, was signed into law by President Jimmy Carter on October 14, 1980. It permitted massive deregulation of the railroads, including provisions to raise any rate that falls below 160 percent of out-of-pocket costs (later 180 percent) and to enter into contracts with shippers to set price and service, both without ICC approval.
Standard gauge
The track gauge used throughout North America and most of Europe of 4 feet 8-1/2 inches, as measured from the inside vertical surface of the top, or head, of the rail.
Station
Location with a specific name designation in a timetable.
STB
Surface Transportation Board. Independent federal agency housed in the U.S. Department of Transportation that is responsible for regulatory matters affecting railroads, motor carriers, bus lines, steamship companies, and other transportation firms engaged in interstate commerce. Established on January 1, 1996, after the Interstate Commerce Commission was abolished. The board mediates rate and service disputes between shippers and transportation companies; and regulates railroad mergers, line sales, line abandonments, and line construction.
Steam generator
A compact boiler installed in a diesel or electric locomotive to provide steam for heating passenger cars. It burns diesel fuel from the main fuel tank. It required a substantial supply of water, since typical consumption is 1500 to 3000 pounds (200 to 400 gallons) per hour. Steam heat has been replaced by electric heat.
Steam railroad
A term still used by regulatory bodies to differentiate ordinary railroads from "electric railways"-interurbans and streetcar companies.
Stillwell, Lewis B.
Designer of passenger cars, in particular suburban coaches for the Erie and the New York, Westchester & Boston.
Stilwell, Arthur
Builder of the Kansas City, Pittsburg & Gulf Railroad and the Kansas City, Mexico & Orient Railway, and also of the city of Port Arthur, Texas.
Stock rail
The rail against which the point of a switch rests.
Stroke
In diesel locomotives, the distance a piston moves in a cylinder
Stub switch
A track switch in which the rails of the single-track end of track move sideways to meet the two (sometimes three) pairs of rails from the other end. Stub switches are long since obsolete, replaced by the conventional switch with movable tapered rails called points.
Subsidiary
A company wholly controlled by another that owns more than half its voting stock.
Sunnyside yard
Large passenger-car yard serving Penn Station, New York, located across the East River in Queens, N.Y.
Sunset route
The New Orleans-Los Angeles line of the Southern Pacific Railroad.
Superelevation
On segments of curved track, the vertical distance the outer rail is raised above the inner rail to counteract the centrifugal force of moving trains.
Superheater
A series of coils containing freshly created steam that pass through flue gasses to increase the temperature of the steam and make it more powerful. Once steam has passed through superheater coils, it adds 25 to 30 percent more power to an engine.
Surface Transportation Board (STB)
Independent federal agency housed in the U.S. Department of Transportation that is responsible for regulatory matters affecting railroads, motor carriers, bus lines, steamship companies, and other transportation firms engaged in interstate commerce. Established on January 1, 1996, after the Interstate Commerce Commission was abolished. The board mediates rate and service disputes between shippers and transportation companies; and regulates railroad mergers, line sales, line abandonments, and line construction.
SW1200RS
Canadian variant of the SW1200 switcher equipped with large number boards and Flexicoil trucks for road service.
Switch
(noun) a track structure with movable rails to divert rolling stock from one track to another; (verb) to sort cars by destination on more than one track (also "classify", "drill", or "marshal"). Electrical switches are also called toggles; track switches are also called turnouts.
Switchback
An arrangement of track, usually with two switches, that requires a change of direction, usually to climb a steep grade.
Switcher
A unit designed specifically for yard service, which calls for good visibility from the cab and pulling power rather than speed.
Switching district
An area within which a shipper located on one railroad has equal access to other railroads, either through a terminal or switching railroad or through reciprocal switching agreements among line-haul railroads.
Switching railroad
See Terminal Railroad.
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