page_title: Glossary of rail transport terms
section_title: W
hierarchical_section_title: Glossary of rail transport terms / W
caption_attribution_description: English: A Double whistle post located on the Grand Trunk Western Railroad in Battle Creek, Michigan. Free for use on any Wiki Trains Project
context_page_description: Rail terminology is a form of technical terminology. The difference between the American term railroad and the international term railway is the most significant difference in rail terminology. There are also others, due to the parallel development of rail transport systems in different parts of the world.
  Various global terms are presented here; where a term has multiple names, this is indicated. The abbreviation "UIC" refers to standard terms adopted by the International Union of Railways in its official publications and thesaurus.
context_section_description: Standpipe
  A device used for delivering a large volume of water into the tank or tender of a steam locomotive
  Water gauge or water glass
  A device showing the level of water in the boiler
  Way car
  An alternate term for a caboose used by the Chicago, Burlington and Quincy Railroad, Chicago and North Western Railway, and Atchison, Topeka and Santa Fe Railway
  Wayobjects or wayside objects
  Trackside objects or any structures at the wayside or beside the rail tracks usually within the right-of-way, such as railway signals, third rails, overhead lines and their supports, electrification systems, platforms, or boom barriers
  Well tank
  A type of tank locomotive. The water tank is mounted between the frame plates, beneath the cab and boiler.
  Well wagon (UIC)
  A flat wagon with a depressed centre used for carrying extra tall loads
  Wheel
  The rolling component typically pressed onto an axle and mounted on a rail car or locomotive truck or bogie. Wheels are cast or forged (wrought) and are heat treated to have a specific hardness. New wheels are trued to a specific profile before being pressed onto an axle. All wheel profiles must be periodically monitored to insure proper wheel to rail interface. Improperly trued wheels increase rolling resistance, reduce energy efficiency and may create unsafe operation. A railroad wheel typically consists of two main parts: the wheel itself, and the tire around the outside.  A railway tire is itself steel, and is typically heated and pressed onto the wheel, where it remains firmly as it shrinks and cools.
  Wheel climb
  The process of a wheel climbing up and often off the inside or gauge side of the rail. It is a major source of derailments. Wheel climb is more likely to occur in curves with wheels whose flanges are worn or have improper angles. See also: Adhesion railway
  Wheel flange
  The inner section of a wheel that rides between the two rails. The angle between the wheel tread and flange is often specific to the rail to prevent wheel climb and possible derailments. The wheel flange is part of the wheel tire. See also: Adhesion railway
  Wheel–rail interface
  The on-contact interaction between wheels and rails. The term is used in connection with the design and management of their interaction.
  Wheel slip
  The loss of traction due to a slippery rail or wheel. Wheel slip was common with steam engines as they started to move due to the excessive torque often generated at low speed. Steam engines carried sand dispensing gear to increase traction at the start of motion.
  Wheeltapper
  An historical railway occupation; people employed to tap train wheels with hammers and listen to the sound made to determine the integrity of the wheel; cracked wheels, like cracked bells, do not sound the same as their intact counterparts. The job was associated with the steam age, but they still operate in some eastern European countries. Modern planned maintenance procedures have mostly obviated the need for the wheel-tapper.
  Wheel tread
  The slightly conical section (often with a 1 in 20 slope) of a railroad wheel that is the primary contact point with the rail. See also: Adhesion railway
  Whistle
  Train whistles are used as a safety warning and also by the engineer to communicate to other railroad workers. See train whistle for a description of the whistle code used to communicate. Also a nickname for an air horn on a diesel locomotive. Steam engine whistles were historically known as chimes in the US during the 19th century.
  Whistle post
  An advance warning to the engineer of an upcoming grade crossing. It is the point at which the engineer should begin sounding the whistle or horn.
  Whyte notation
  A system of describing steam locomotive wheel arrangements (e.g. 4-6-4, 2-10-2). The first number indicates the number of "pilot" wheels that help lead the engine into turns. The second is the number of coupled wheels ("drivers"). Third are the trailing idler wheels, usually to provide support to larger fireboxes. Articulated locomotives are similarly described. For example, a Union Pacific "Big Boy" would be described as a 4-8-8-4, wherei
caption: A double whistle post
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