page_title: Glossary of North American railway terms
section_title: S
hierarchical_section_title: Glossary of North American railway terms / S
caption_attribution_description: A privately-owned speeder on display at the Mad City Model Railroad Show and Sale in Madison, Wisconsin, February 2004.
context_page_description: This page contains a list of terms, jargon, and slang used to varying degrees by railfans and railroad employees in the United States and Canada. Although not exhaustive, many of the entries in this list appear from time to time in specialist, rail-related publications. Inclusion of a term in this list does not necessarily imply its universal adoption by all railfans and railroad employees, and there may be significant regional variation in usage.
context_section_description: Safety Appliance Act (US)
  A law mandating air brakes, grab bars, and automatic couplers
  Screamer or screaming thunderbox
  An EMD F40PH locomotive, in reference to it operating in a constant state of full throttle (in order to provide head-end power to passenger cars).
  Sergeant Stripes
  A Canadian National locomotive in the 1970s and 1980s paint scheme featuring light-gray stripes on the locomotive's long hood
  Shoofly (US)
  A temporary stretch of track that takes trains around construction or an accident scene
  Shove
  To push a cut of cars backward with a locomotive
  Shunting neck (US)
  A length of track feeding a number of sidings that permits the sidings to be shunted without blocking the main line, or where two lines merge into one before ending with a buffer, to allow a run-round procedure to take place
  Siding (US)
  A second parallel track (running for a short distance) on single-track railway lines, allowing a train to pass another
  Skate
  A wheel chock
  Slack action (US)
  Looseness in a train caused by mating clearances in couplers
  Slug
  A locomotive, with or without an operator's cab, which lacks a diesel engine, and draws power for its traction motors from a normal locomotive, known as a "mate" or "mother"
  Smokestack or stack (US)
  A chimney
  Smurf (Smurf Unit)
  A BNSF locomotive in a blue and white livery, named after their vague resemblance to the blue-and-white creatures in The Smurfs
  Snail
  A locomotive with a diesel engine, but does not have traction motors, often used for external power for a rotary snow plow
  Snake head
  A section of strap rail that has come loose and curled upward due to the weight of railway cars passing over it
  Speeder, motorcar, trackcar, putt putt, or golf cart
   A small, motorized track inspection vehicle
  Spur (US)
  A stretch of rail that branches off the main line, often to an industry that is serviced by freight trans
  Stacks
  A nickname for double-stacked cars or trains
  Steeplecab (US)
  An electric locomotive with a central cab and sloping "noses" on each end
  Subway (US)
  A railroad that runs underground, generally in a large city
  Switch (US)
  Points
  Switcher (US)
  A small locomotive used for assembling trains and moving railroad cars around
caption: A privately owned speeder on display
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