Railroad Legal Glossary: S

SBU: Sense and Brake Unit.

Scab: Non-union members doing work usually contracted by railroads for railway union labor contracts. 

Schedule: That part of a timetable which prescribes class, direction, number and movement for a regular train. 

Section: One of two or more trains running on the same schedule, displaying signals or for which signals are displayed. 

Semaphore Signal: A signal in which the day indications are given by the position of a semaphore arm. 

Service of Process: Providing a formal notice to the defendant that orders him to appear in court to answer plaintiff]'s allegations. 

Shock: The effect of a sudden change in speed of a car, locomotive or train, or part of a train. 

Shoe Fly Track: A temporary track built around a train wreck or washout. 

Side Track: This is a track auxiliary to the main track. 

Siding: This is a track auxiliary to the main track which is used for meeting or passing trains. The timetable will indicate stations at which sidings are located. 

Signal Aspect: The appearance of a fixed signal conveying an indication as viewed from the direction of an approaching train; or the appearance of a cab signal conveying an indication as viewed by an observer in the cab. 

Signal Dolly: A train that delivers supplies to towers. 

Signal Indication: The information conveyed by the signal aspect. 

Signalman: The man who controls the signals and authorizes the movements of trains on running lines 

Single Track: A main track upon which trains are operated in both directions. 

Single-Car Test Device: Is used to test the air brake equipment on car that is sent to a repair track 

Skipper: The conductor 

Slack Action: Movement of part of a coupled train at a different speed than another part of the same train. 

Slack: The motion, forward or back, that one or more cars, locomotives, or parts of a train has without moving other coupled cars, locomotives, or parts of the train. Loose slack is the free movement or lost motion between parts of a train. Spring slack is the movement beyond the free or lost motion brought about through compressing the draft gear springs. Slack is necessary so as to start one car at a time and so that the train may be operated around curves and over high and low places. 

Slug: A small, ballasted, four or six axle unit, semi-permanently coupled to a locomotive that does not have a prime mover, but does have traction motors. Generally used in yard duty where the switcher has enough horsepower, but not enough traction to push long strings of cars up a hump. 

Spring Switch: A switch equipped with a spring mechanism to restore the switch points to original position after having been trailed through.

Station: A place designated in the timetable station column by name. 

Statute of Limitations: The time period within which a plaintiff must file his action against the defendant. This time frame varies by state. In North Carolina, the statute of limitations is three years.

Strict Liability: The defendant is liable to the plaintiff regardless of fault.

Stub Track: A form of side track connected to a running track at one only and protected at the other end by a bumping post or other obstruction. 

Subdivision: A portion of a division designated by timetable. 

Subpoena: A form issued by the court requiring someone to appear in court and/or bring documents. (Also referred to as a "Summons.")

SUNA: Initials of Switchmen's Union of North America 

SBU: Sense and Brake Unit.

Scab: Non-union members doing work usually contracted by railroads for railway union labor contracts. 

Schedule: That part of a timetable which prescribes class, direction, number and movement for a regular train. 

Section: One of two or more trains running on the same schedule, displaying signals or for which signals are displayed. 

Semaphore Signal: A signal in which the day indications are given by the position of a semaphore arm. 

Service of Process: Providing a formal notice to the defendant that orders him to appear in court to answer plaintiff's allegations. 

Shock: The effect of a sudden change in speed of a car, locomotive or train, or part of a train. 

Shoe Fly Track: A temporary track built around a train wreck or washout. 

Side Track: This is a track auxiliary to the main track. 

Siding: This is a track auxiliary to the main track which is used for meeting or passing trains. The timetable will indicate stations at which sidings are located. 

Signal Aspect: The appearance of a fixed signal conveying an indication as viewed from the direction of an approaching train; or the appearance of a cab signal conveying an indication as viewed by an observer in the cab. 

Signal Dolly: A train that delivers supplies to towers. 

Signal Indication: The information conveyed by the signal aspect. 

Signalman: The man who controls the signals and authorizes the movements of trains on running lines 

Single Track: A main track upon which trains are operated in both directions. 

Single-Car Test Device: Is used to test the air brake equipment on car that is sent to a repair track 

Skipper: The conductor 

Slack Action: Movement of part of a coupled train at a different speed than another part of the same train. 

Slack: The motion, forward or back, that one or more cars, locomotives, or parts of a train has without moving other coupled cars, locomotives, or parts of the train. Loose slack is the free movement or lost motion between parts of a train. Spring slack is the movement beyond the free or lost motion brought about through compressing the draft gear springs. Slack is necessary so as to start one car at a time and so that the train may be operated around curves and over high and low places. 

Slug: A small, ballasted, four or six axle unit, semi-permanently coupled to a locomotive that does not have a prime mover, but does have traction motors. Generally used in yard duty where the switcher has enough horsepower, but not enough traction to push long strings of cars up a hump. 

Spring Switch: A switch equipped with a spring mechanism to restore the switch points to original position after having been trailed through. 

Station: A place designated in the timetable station column by name. 

Statute of Limitations: The time period within which a plaintiff must file his action against the defendant. This time frame varies by state. In North Carolina, the statute of limitations is three years.

Strict Liability: The defendant is liable to the plaintiff regardless of fault.

Stub Track: A form of side track connected to a running track at one only and protected at the other end by a bumping post or other obstruction. 

Subdivision: A portion of a division designated by timetable. 

Subpoena: A form issued by the court requiring someone to appear in court and/or bring documents. (Also referred to as a "Summons.")

SUNA: Initials of Switchmen's Union of North America 

Superior Train: One train having precedence over another. 

Swing Man: The rear brakeman. 

Switch Point Indicator: A light type indicator used in connection with facing point movement over certain switches to indicate switch points fit properly. One train having precedence over another. 

Swing Man: The rear brakeman. 

Switch Point Indicator: A light type indicator used in connection with facing point movement over certain switches to indicate switch points fit properly.