Trains glossary

This article is intended to contain a list of terms that are likely to appear in discussions about LEGO trains. Any term here should link to the internal article (where one exists) or to an external article on Wikipedia or elsewhere.

You are encouraged to add to this list even if you don't know the meaning of the term, just put it in the list.

Top - 0–9 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

Linking here

If you wish to link to a term on this page, you should include a link using [[trains glossary#T|Term]] where T will be the first letter of the term and must be a capital letter. This will link as follows: Term. A simpler alternative is to use the TGL template as {{TGL|T|erm}} which is a little clearer on the page and links as Term. When linking HERE, we used bolded terms so use TGLB instead of TGL, same syntax...

Definition Sources

The following places are good places to seek definitions: (note, some may be US centric, you are encouraged to add more)

• Rail Terminology article in Wikipedia
• UK railfan jargon article in Wikipedia
• US railfan jargon article in Wikipedia
• Train FAQ from LUGNET
• LEGO train terms
• Lar's glossary
• Railway Technical index page, other pages on this site are great resources as well
• US FTA glossary US Federal Transit Authority
• German/English dictionary of rail terms

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A Glossary of Train Terms

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0-9

• 2-foot gauge - Often used on light industrial lines. The only North American common-carrier railroads to use this gauge were all in the state of Maine.
• 27-inch gauge - Like it sounds. Rare. Found on a very few steam-era shortlines in the UK.
• 3-foot gauge - Used by the most famous narrow-gauge railroads in the US: the Denver & Rio Grande Western, the Rio Grande Southern, and the Colorado & Southern.

A

• A1A - a Truck or Wheelset consisting of 3 axles, the middle one unpowered, in a rigid (or at best, steerable, but not articulated) frame.
• A1A-A1A - a two truck locomotive with two A1A trucks. The Alco PA and many other early passenger diesels were A1A-A1A, meaning they had two trucks, each with two outboard axles with traction motors and a center idler axle. North American Usage. Contrast CoCo which might be A1A-A1A, or it might be C-C...
• A1A-B - a two truck locomotive with an A1A lead truck and a B trailing truck. The FL9 is almost unique in that it is A1A-B, the trucks are different, this was done to make room for an electric pickup on the lead truck (the FL9 is bipower, electric when inside NYC, due to anti smoke requirements, diesel when outside the range of third rail territory, either, as convenient, when outside NYC but inside third rail territory). North American nomencature. See Bo, CoBo (which might be C-B or it might be A1A-B, no way to tell...) et. al. for non NA nomenclature.
• Abt railway - A less-used variant of the Cog railway. Named after Dr Roman Abt, the German inventor who designed it, the rack on an Abt Railway consists of two sets of staggered teeth side-by-side, and uses two coaxial drive pinions on the locomotive.
• Action red - A somewhat orangish red, used by Canadian Pacific when they were called CP Rail and used the Multimark logo.
• Air brakes - A form of Continuous brakes which use air pressure to release the brakes. A compressor on the locomotive provides the pressure. A triple valve senses changes, with reductions in line pressure resulting in corresponding applications of the same amount of brake effort, and increases resulting in releasing the brakes (and recharging the reservoir). Thus a break in the air system, (meaning maximum difference in pressure) applies the brake to the maximum extent possible (an "Emergency application" or when done on purpose "big-hole-ing"), and thus the system is failsafe. The system was developed by George Westinghouse, and led to the founding of the Westinghouse company. First used in North America. Not sure where else but I think the UK at least do not use this, preferring vacuum brakes instead.
• Allegheny (US) - A steam locomotive type; 2-6-6-6 in Whyte notation. Used by the Chesapeake & Ohio.
• Aspen Gold - Actually light orange. Used by the Denver & Rio Grande Western starting in 1956 to replace yellow in their paint scheme.

B

• B - a Truck or Wheelset consisting of 2 axles, both powered, in a rigid (or at best, steerable, but not articulated) frame. Many early diesels were B-B (2 trucks on a common frame, all 4 axles powered). Modern practice tends toward C-C. North American usage. See Bo.
• B-B - wheel arrangement consisting of two B trucks. North American usage. See BoBo.
• B Unit - cabless booster: A locomotive without a cab. Never a Steam locomotive, and almost never an electric. Sometimes called a Booster Unit. More common among first generation units, and more common among carbody units than hood units. Railroad financial officers specified B units to save money on the cost of the cab. Railroad operating departments prefer the flexibility of being able to operate any unit in the lead, and studies have shown that the initial capital savings do not outweigh the operational efficiency savings.
• Baby Boat (US) - A GE U18B locomotive; so called because it was the lowest-horsepower U-boat.
• Bay platform - A Platform in which the track ends, often with a Buffer stop or Bumper. A bay platform is not as long as the platform it ajoins. Note that in a Terminus station the platforms are not referred to as bay platforms unless they are short and at the outer end of the station.
• Bay window caboose (US) - A Caboose without a cupola, instead having overhanging secions on the sides allowing the conductor to see along the sides of the train.
• Bo - A Wheelset with two axles (four wheels). Non North American nonenclature. See B
• Bobber caboose (US) - A very short four-wheel caboose from the 19th century.
• BoBo - A train with two Bo wheelsets (eight wheels in total). Many North American trains are BoBo and all official 9V LEGO trains are BoBo. Non North American nonenclature. See B-B
• BoBoBo - A train with three Bo wheelsets (twelve wheels in total). Quite common in Japan
• BoCo - A train with one Bo and one Co wheelset. Quite rare although more common in fan created LEGO trains where the motor is often left as Bo even when the prototype should be Co
• Brunswick green - A very dark, almost black green used by the Pennsylvania Railroad. No close Lego counterpart.
• Buffers (UK/Europe) - Sprung or damped devices to cushion the impact between train vehicles. Usually used in pairs at either end of the Bufferbeam with a central hook and chain, but sometimes used singly centrally with a pair of Sidechains.

C

• C - a Truck or Wheelset consisting of 3 axles, all powered, in a rigid (or at best, steerable, but not articulated) frame. See Co.
• C-C - wheel arrangement consisting of two C trucks. North American usage. Most, although not all modern diesels in NA are C-C as they have grown heavier over time and this allows the weight to be spread and maximum tractive effort applied to the rails. North American usage. See CoCo.
• C-Liner (US) - slang term for any of the diesel-electric cab units in Fairbanks-Morse's "Consolidation Line"; all their model designations began with C. Most were B-B; a few were B-A1A.
• Cab unit - Also Carbody unit. A locomotive (generally diesel) with a full-width body. Structural strength comes from the body, not the underframe. Can refer to both A units and B units, though only A units actually have cabs.
• Cabin (US) - A Caboose. Term used only by the Pennsylvania Railroad.
• Calf (US) - A switcher Booster unit. Distinct from a Slug.
• Cape gauge - 42 inches between the rails. So named because of its use in South Africa. It qualifies as narrow gauge, but in many places it's used, it's the most common gauge. Found in many African countries, Australia, Japan, and elsewhere. Rare in continental Europe and North America. (The main North American user of Cape gauge was the now-defunct Newfoundland Railway.)
• Carriage - A passenger railroad car (UK usage.)
• Cascade green - The green paint used by the Burlington Northern, and the paint scheme using it. Similar to standard Lego green.
• Catenary - Overhead electricity supply wires. May carry AC or DC current in a variety of voltages. Named after the shape the supporting Messenger wire forms between supports (although some argue that technically, it doesn't QUITE follow that shape since it has a load, see Wikipedia:Catenary for some discussion of that). Also know as OCS, OLE and OHW.
• Century (US) - A diesel locomotive from Alco's Century series made in the 1960s.
• Chinese red - The red paint used by the Chicago Burlington & Quincy, and the paint scheme using it. Similar to standard Lego red.
• Co - A Wheelset with three axles (six wheels)
• CoCo - A train with two Co wheelsets (twelve wheels in total). Common in British diesels. See A1A-A1A and C-C for North American nomenclature.
• CoBo - Like BoCo but in reverse. Rare but not as rare as BoCo at least in North American usage. See A1A-B for North American nomenclature.
• Cog railway (US) - A system for climbing steep Gradients. A powered cog or gear on the Locomotive meshes with a run of toothed rack placed between the rails. Also known as a Rack railway . See also Abt railway .
• Color scheme - the particular colors and markings/striping chosen for a railway's locomotives and rolling stock. Usually chosen to be distinctive but economical. Also known as Livery (UK) or Paint scheme (US). See also the full article on liveries.
• Consolidation - A steam locomotive type; 2-8-0 in Whyte notation. Regarded as a heavy freight engine in the 19th century and a light freight engine in the 20th.
• Covered hopper - A closed freight car loaded through hatches in the top and unloaded through hatches in the bottom. Some of the earliest examples were converted from (closed) Hoppers. Used for carrying grain, sand, cement, potash, plastic pellets, etc.
• Cowl unit - A locomotive (generally diesel) with a full-width body. The body is not load-bearing, unlike in a cab unit. Typically built on the frame of a Hood unit.

D

• D - a Truck or Wheelset consisting of 4 axles, all powered, in a rigid (or at best, steerable, but not articulated) frame. North American usage.
• D-D - Wheel arrangement consisting of two D trucks. Very rare to see this used. EMD locomotives DD35 and DDA40X, and the narrow-gauge DDM45 used in Brazil, are of this type. Note that the U50 and C855, the contemporaneous GE and Alco competitors, went with a B+B-B+B arrangement using Span bolsters instead, as D trucks are very hard on trackage. The Soviet (now Russian) T3M7 diesel shunter also is D-D. North American usage.
• Decapod - A steam locomotive type; 2-10-0 in Whyte notation. Term sometimes extended to include 2-10-2s (Santa Fe) as well.
• Deck (US) - Engineers' slang for a 2-10-2 steam locomotive; derived from the (mis?)use of the name Decapod. Used (only?) on the Southern Pacific.
• Diesel - power source for Locomotives. Most Diesels are actually Diesel Electrics. Diesel Hydraulics were common in Germany and could be found in scattered other locations. Some small industrial switchers are Diesel Mechanical.
• Deadheading (US) - Moving an empty passenger car. Partly equivalent to Stock train (UK).
• DMU - like an EMU but diesel powered (rarer than EMUs) UK/european term. US equivalent is RDC or, earlier, "Gas Electric".
• Doubleheading (US) - Operating a train with two locomotives on the front. Only used when engines involved are steam.
• Double-unit diesel (US) - When the early Cab units and Booster units were being built, some railroads regarded a cab/booster set (or even a cab/booster/booster/cab set) as one locomotive. The set would not be uncoupled except for maintenance. The seperate units would receive the same road number with different letter suffixes. A cab/booster pair might be numbered 100A and 100B (fitting with the use of the terms "A unit" and "B unit"). A cab/booster/booster/cab set might be numbered 101A, 101B, 101C, 101D from front to back. Some engines were built with this concept in mind - early production runs of the EMD FT came as Drawbar-coupled sets. Some of them actually could not operate separately even if the drawbar were to be removed - even though each unit had a prime mover, the necessary electrical equipment was divided between the A and B units.
• Drawbar - A bar used to achieve a permanent coupling. Used between a a steam locomotive and its tender, on some early two-, three- or four-unit diesels, between some Well cars and between the components of a Miniquad.

E

• Eight-Wheeler (US) - A steam locomotive type; 4-4-0 in Whyte notation. Also known as American Standard.
• EMU - Electric Multiple Unit - electrically powered set of permanently joined carriages
• Electric - power source for locomotives.
• Extended-vision caboose (US) - Commonly termed wide-vision caboose. A Caboose with a cupola that overhangs on the sides.

F

• Fallen Flag denotes a railroad that is no longer in operation.
• First generation diesel (US) - A diesel locomotive built in the 1950s or earlier.
• Fishplate - Short metal plates bolted to the ends of two rails to join them end to end. Also "rail joiner".
• Fitted train - A train consisting entirely of vehicles which are fitted with Continuous brakes.

G

• Geep - US railfan slang for a four-axle EMD hood unit, based on their model designations beginning with "GP".
• Gondola - An open freight car loaded and unloaded from the top. Traditionally low-sided; modern ones often aren't. Used to carry gravel, coal, ore, scrap metal, wood chips (in very high-sided cars), etc.
• Grade (US) or Gradient (elsewhere) - the slope of the railway line. This is notated in different ways in different countries. A gradient of 1 in 100 (1/100 1:100) is equivalent to 1% (US) or 100 º/oo or 0.6º. The "ruling grade" of a line is the highest value for the grade across the entire line or section; the grade that limits an engine's pulling power. For example if one reads that Sherman Hill (on the UP Cheyenne westbound main) has a ruling grade of 1.6% that doesn't mean it's all 1.6%, just that there is nothing higher than 1.6%. There may even be sections of downgrade, depending on the terrain. To be more precise, "ruling grade" usually refers to "ruling grade over a train length" - the highest average grade over a train length. There may be brief sections of steeper grade, but if the entire train cannot fit on them at once, they have less effect on hauling capacity. In the LEGO train hobby grade is usually expressed as number of plates per track section. 16 LDU (2 plates) per section is considered quite extreme (equating to 5% or 1 in 20), with 8 LDU preferred and 4 LDU even better. 4.5V and 12V trains, with their ridged rails and traction tires, are sometimes tasked to climb 1-brick-per-section (7.5%) grades.
• Gravitation yard - Australian term for a Hump yard.
• The Grouping (UK) - The 1923 consolidation of the UK rail system into four railways: the Great Western Railway (not to be confused with the Colorado shortline of the same name), the London and North Eastern Railway, the London, Midland and Scottish Railway, and the Southern Railway (not to be confused with the US Southern Railway). It lasted until the four companies merged into British Railways in 1948.

H

• H-Liner (US) - Slang term for a Fairbanks-Morse hood unit, since their model designations began with H.
• Hogger (US) - Slang term for an engineer.
• Hood unit or Roadswitcher (both US)- A locomotive (generally diesel) that does not have a full-width body. Structural strength comes from the frame. Open walkways run along the sides.
• Hopper - An open freight car loaded through the top and unloaded through hatches in the bottom. Used to carry coal, ore, rock, etc.
• Hump Shunting(UK?) or Humping - a method of Shunting or Switching which uses gravity to sort freight vehicles (US "cars"). The vehicles are propelled up one side of a hump (or hill), and then seperated and allowed to run down the other side through a set of Points or Switches to their required location where they are slowed by Retarders. In the US a place where this is done is called a hump yard (as opposed to a "flat yard" where locomotive power does all the work), and freight cars (this is never used for sorting passenger cars in the US) put through this process are said to have been "humped". You will sometimes see "NO HUMP" stencilled near the reporting marks, as a note that the car (or customary cargo) cannot take the collision shock inherent in this process, cars strike already sorted strings going anywhere up to 5 km/h (3 mph) which can be too much for some delicate cargos. Some very long cars, such as Schnabel cars, cannot handle the vertical curvature of a hump.

I

• Island platform - A Platform that has tracks on both sides. Access to the platform is by Footbridge or Subway or by crossing the tracks, possibly on a Barrow crossing.
• Island layout - A model layout that is freestanding and away from the walls.

J

• Javanic - A steam locomotive type; 2-12-2 in Whyte notation. Not a well-known or widely used term, since the wheel arrangement it refers to is rare.
• Jenny (US/Can.) - Also Jimmy. Slang term for the smallest Hopper cars (about 25 feet long); used to carry dense ores.

K

• Kodachrome (US) - Railfan slang for a Santa Fe or Southern Pacific diesel in the red and yellow scheme both railroads used when they planned to merge in the late 1980s. The name comes from the scheme's supposed resemblance to packages of Kodak film.

L

• Lap switch (US) - A Three-way switch.
• Livery (UK) - See Color scheme

M

• Maintenance of way (US) - The repair of track and roadbed; the equipment used to do so.
• Mastodon - A type of steam locomotive; either 4-8-0 or 4-10-0 in Whyte notation. In the US, only one 4-10-0 ever existed: the Central Pacific's "El Governador" in the 19th century.
• Miniquad (US/Can.) - A set of four ore Jennies connected by Drawbars.
• Mixed train - A train containing both freight and passenger cars. Obsolete in NA and UK; still found in many Third World nations.
• Mohawk - A steam locomotive type; 4-8-2 in Whyte notation. Term used only by the New York Central.
• Mountain - A steam locomotive type; 4-8-2 in Whyte notation. Used for fast freight and passenger service.

N

• Niagara (US) - A steam locomotive type; 4-8-4 in Whyte notation. Term used only by the New York Central and National of Mexico.
• Northern - A steam locomotive type; 4-8-4 in Whyte notation. Used mostly for passenger service.

O

• OCS (Europe and US) - Overhead Contact System. See Catenary.
• OLE (UK) - Overhead Line Equipment. See Catenary.
• OHW (Aus) - Over Head Wiring. See Catenary.

P

• Paint scheme - See Color scheme

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• Pantograph - One possible kind of the apparatus on the roof of an Electric train to collect power from the Catenary. Different from a Trolley Pole in that a pantograph is multiple section, and can typically be raised and lowered by remote control. The pictured part (2881: Hinge Train Pantograph Shoe ) is used in construction of a Pantograph.

• Penn Central green - Also called New York Central green. A paint color very similar to Lego teal. Unlike many famous paint schemes and colors, the use that gave it its name was freight cars, not locomotives. (Penn Central locomotives were black.)
• Permanent way (UK) - Roadbed and track; usually, the equipment used to maintain them. Equivalent to Maintenance-of-way.

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• Platform - A space between tracks at stations for passengers to board. These can vary in height from ground level to level with the train floor. Raised platforms can be solid, wooden or concrete. Most modern platforms have painted lines to stand behind parallel to the edge, or in some cases, embedded yellow plastic with raised nubs which can be felt by those who are visually impaired. The LEGO parts 2617 and 2642 are used in LEGO sets such as Metro Station to realise these.

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• Point (UK) - A track having movable rails and necessary crossings or frogs); used to turn a train from one track to another. Also known as a Turnout or a Switch. In US usage, the point is the movable part or parts (usually paired except in prototypically rare cases such as a stub switch) that actually effect the change in routing.

• Prairie - A steam locomotive type; 2-6-2 in Whyte notation.
• Pullman green - A dark green typically used on heavyweight passenger cars.
• Pumpkin - Railfan slang for a diesel in a paint scheme featuring orange. Most often applied to BNSF locomotives, also used for ICG's all-orange scheme and CSX and Amtrak Maintenance-of-way locomotives. Not usually applied to Milwaukee Road, Indiana Harbor Belt, or South Shore Line engines, though they are also orange.

R

• Rack railway - See Cog railway.
• Railfan (US) or Trainspotter (UK) - A person interested in real-life trains.
• Rolling stock - A term used to refer to train Engines and Carriages (in the UK) or freight and passenger cars but not engines (US).

S

• Santa Fe (US) - A steam locomotive type; 2-10-2 in Whyte notation. Sometimes erroneously termed Decapod.
• Schnabel car - The largest freight cars in the world. They can actually split in half; the load is carried between the halves of the car and serves as the structural connection. Usually used to carry transformers, reactor vessels, and other very heavy high-and-wide loads. They have from 10 to 36 axles. Used worldwide, they are one of the rarest types of freight car wherever they exist.
• Second generation diesel (US) - A diesel locomotive built in the 1960s or 1970s. The EMD GP20 (produced 1959-62) and SD18 (starting in 1958) are often called the first second-generation units.
• Selkirk (Can.) - A steam locomotive type; 2-10-4 in Whyte notation. See Texas.
• Sergeant stripes - Railfan slang for the CN paint scheme with a red cab and white diagonal stripes on a black body. Sometimes also called Zebra stripes.
• Sleepers (UK) - The planks of wood (or concrete or steel) which lie crosswards beneath the rails and above the Ballast or Roadbed on a railway. Also known as Ties
• Slug - A locomotive with no main diesel or electric power source. It does have traction motors, allowing it to tap power from a diesel it's coupled to. It increases tractive effort but not horsepower, and is therefore only useful at low speeds. The majority are intended for yard use, though there are road slugs. Slugs are not (usually) made by diesel manufacturers, but built by railroads from obsolete diesels. They often (but not always) don't have cabs.
• Stock rail or Running rail - The non-moving rails that run continuously through a Point.
• Stock train (UK) - A train comprised of empty Carriages.
• Stock train (US) - A train transporting livestock.
• Stub switch (US) - A Switch without the distinction between point rails and Stock rails. It relies on bending the stock rails to shift from one route to the other. Obsolete before the end of steam.
• Subway (UK) - (US: Underpass or Pedestrian Tunnel) An underground passageway, it may connect different platforms and the headhouse, or may connect two sides of the street.
• Subway (US) - (UK: Tube, Europe: Metro) An An Underground railway line, primarily intended for commuter or center city transit, used in areas where street railways or elevated railways would be too disruptive, and where the traffic density is high enough to justify the higher initial capital cost and running costs. The term is highly city specific. New York City lines are Subways even when running above surface, and Chicago lines are "the EL" even when running subsurface, while Washington DC lines are "the Metro" regardless of where they run.
• Switch (US) - See Point

T

• Ten-Wheeler (US) - A steam locomotive type; 4-6-0 in Whyte notation.
• Texas (US) - A steam locomotive type; 2-10-4 in Whyte notation. See Selkirk.
• Ties (US) - See Sleepers
• Tieplate - (US only??) Rectangular cast metal plate, with spike holes, and often with ridges for each side of the rail web, that the rail sits on when spiked. The function is to spread the weight of the rail onto the wooden tie. The spike holes ensure that the spike head tops, when driven in, grip the web of the rail firmly. There is no analogous thing in LEGO, since the 9V track has sleepers and rails cast together, with metal rail facings and this detail (as well as the spikes) is presumably below the resolution of the LEGO track.
• Tiger stripes - An early Southern Pacific diesel paint scheme, primarily black with some orange diagonal stripes.
• Tinplate - Model railroad term. It's very old (dates back to the 1920s at least, if not farther) with a large variety of meanings, usually discernable from context. The term derives from the way that early toy trains were often made, they were pressed from tin (tin can stock, allegedly) and plated, then painted. This made for very crude details, although some remarkable Lionel,American Flyer, and other companies models were made this way. In transition, some details were cast and attached, but many mass production modern models are cast... whew. Strangely enough, really high value models are now fabricated from many parts, sort of reinventing things a bit... Anyway... Tinplate can be used in a pejorative way to denote toylike and low quality, or as a badge of pride (referring to oneself as a "Tinplate collector"), but typically refers to items that are not to any particular scale, and which may have exaggerated features, or exaggerated operating things like large flanges, high profile rails, 3 rail power, very sharp curves, shortened rolling stock, lots of operating accessories, etc. The similarity in approach and philosophy to LEGO is quite pronounced. Official LEGO trains rather resemble Lionel O-27 trains (the most famous tinplate line in the US): they both have roughly O-scale track gauge, roughly S-scale train width, compressed length, and similar standard curve radius. When a scale modeler approaches one at a show, drawing the analogy to tinplate is quite useful, they then "get it" and stop thinking of LEGO as just a toy. Talk about collectibility and rarity, and then follow that up by pointing out that unlike Tinplate or scale, if something takes an unplanned floor excursion, usually there is little or no damage... Usually.
• Turnout - See Point Many North American model railroaders will avoid calling them "switches", reserving that word for electrical switches.
• Tube - The vernacular name for the Underground railway serving London. The name is not used for any other underground rail systems in the UK (or indeed other countries) and refers to the tubular shape of the tunnels. See The Tube for more information.
• Tuscan red - A dark red/maroon used most famously by the Pennsylvania Railroad. No Lego color is a very close match; dark red is the closest, but modellers are sometimes forced to use regular red due to the more limited part selection in dark red.
• Twelve-Wheeler (US)) - A steam locomotive type; 4-8-0 in Whyte notation.

See Mastodon.

U

• U boat - North American slang for an early second generation (1960s) GE diesel. All of these early road switcher units had model numbers starting with U (U23B a 2300 horse B-B, U30C a 3000 horse C-C etc), standing for "Universal". Replaced by the Dash 7 line in 1976.
• Underground railway - Underground railways are inner city railway systems which run partially or entirely beneath street level. Many cities have underground railway networks and names vary wildly from place to place. Some of the more famous are: the London Tube, the New York Subway and the Paris Metro. In Europe these networks tend to be called Metros (although not exclusively), while in the US they tend to be called Subways (again not exclusively).
• Underground (The) - Another name for the London Tube.
• Unfitted train - A train consisting of vehicles which are not fitted with Continuous brakes.

V

• Vacuum brakes - A form of Continuous brakes which use negative air pressure or vacuum to release the brakes. An ejector on the locomotive provides the vacuum. A break in the vacuum system applies the brake, thus the system is fail-safe.
• Van (Can.) - A Caboose.
• Viaduct - A long bridge with multiple piers carring a railway line over a section of lower lying land.

W

• Web - The bottom, and widest part, of the rail.
• Westinghouse brake - See Air brakes.
• Wheelset - A grouping of wheels on a locomotive or power car, typically sharing a common rotation point to the main chassis. The terms Bo and Co are often used to describe wheelsets. (note: North American nomenclature is different, dropping the o and focusing on wheel arrangements of the entire unit, and distinguishing between powered and unpowered axles) At least among model railroaders, "wheelset" can be used to refer to a single axle and pair of wheels.
• Whiskers (US?) - Slang term for short straight tracks extending from a Turntable that don't lead to anything.

Z

• Zebra stripes - Railfan slang for an early Santa Fe diesel paint scheme. Engines were primarily black, with white diagonal stripes on some areas. Term sometimes also applied to a CN paint scheme.

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