Model Railroad Glossary:
AAR:
Association of American Railroads, the trade association that represents the common interests of the railroad industry in such areas as standards, public relations, and advertising.
AC:
See Alternating Current.
ACC:
See CA.
Access Hatch:
A hole in the benchwork and scenery, sometimes concealed with a lift out section of scenery, for emergency access to parts of the layout.
Accessory Decoder:
Decoder that provides power and operational control of one or more layout accessory devices, such as turnouts, signals, cranes, animation devices, lighting, etc. Also known as a stationary decoder.
ACI:
Automatic Car Identification; see Kar Trak.
Address:
Used by the command station to communicate with a specific decoder. It can be either 2- or 4-digit, depending on the system, and is typically part of the locomotive’s road number. Addresses are unique to each decoder.
Airbrush:
A miniature paint sprayer that gives a controlled application of thinned paint.
All in One Track:
Model track that includes simulated roadbed or ballast. Also called combination or "click" track.
Alternating Current: (AC)
An electric current that reverses its direction of flow at regular intervals. Each move from zero to maximum strength and back to zero is half a cycle. A full cycle includes excursions in both the positive and negative direction.
Ammeter:
Meter used to measure current strength - for example, how many amps a locomotive draws when it stalls.
Ampere or Amp:
Unit used to determine the amount of an electrical current.
AREA:
The American Railway Engineering Association is the prototype railroad organization which establishes right of-way material specifications and track construction standards.
Articulated:
A steam locomotive with two engines (i.e., cylinders, rods, and wheels) under one boiler.
Automatic Reversing:
A circuit that senses short circuits and reverses the polarity. Used commonly with reversing loops, wyes, and turntables.
Backdrop:
A painting or scenic photograph on the wall behind the layout. It can be as simple as a cloudless sky or it can echo the scenery of the layout and create an illusion of great distance.
Bad Order:
A freight car that's defective or out of order.
Ballast:
On real railroads, a layer of material - usually crushed rock, cinders, or gravel - on top of the roadbed that holds the ties in position and facilitates drainage. On a model railroad, ballast is simulated by fine gravel spread between the ties and alongside the track.
Balloon Track:
See Return loop.
Benchwork:
Supporting framework for a model railroad layout. L girder and open grid (sometimes called butt joint) are two popular types.
Big Hook:
Wrecking crane.
Block:
On a real railroad, a section of track defined for the purpose of controlling trains. On a model railroad, a block is an electrically isolated section of track.
Block Signal:
A signal at the entrance to a block (See Block) indicating whether the block is occupied by a train.
Bolster:
The crosswise member of the frame of a car at the truck (body bolster) or the crosswise piece at the center of a truck (truck bolster).
Boomer:
An experienced railroad man who moves from railroad to railroad.
Booster:
In DCC, the booster takes the low-current signal from the command station and "boosts" it to the high-current signal needed by locomotives to operate DC motors, etc., in conformance with NMRA Standards S-91. Also referred to as power stations or power boosters.
Branch Line:
Secondary line of a railroad.
Brass: (also brass hat, brass collar)
Railroad executives and officials.
Bridge:
A structure that supports a track passing over a depression in the terrain or a stream. A through bridge has a floor structure, which supports the track between its side beams or trusses, while a deck bridge has its supporting structure below track level.
Bridge Guardrail:
A set of steel rails mounted inside the running rails on a bridge or other structure to keep derailed cars in line.
Bridge Pier:
An intermediate support used between bridge spans.
Bridge Shoe:
An iron or steel casting which transfers the weight of a bridge to its supports. One end is normally a solid mounting while the opposite end allows for expansion and contraction.
Bright Boy:
(brand name) An abrasive rubber block used to clean track.
Bumper:
A braced, coupler height blocking device that keeps cars from rolling off the end of a track.
Bunk, Camp, or Outfit Car:
A passenger or freight car converted into movable living quarters for track workers.
Bus, or Bus Wire:
A main wire, or trunk wire, running under a model railroad. Shorter branch wires, such as track power feeders, are connected to it.
CA:
Short for cyanoacrylate adhesive, also known as super glue. A high strength adhesive that can be used on metal and styrene plastic. Sometimes seen as ACC for alphacyanoacrylate cement.
Cab:
Usually a handheld piece of equipment with necessary controls to send speed, direction, and other information to the locomotive. Frequently referred to as "throttle". On the prototype, the part of the locomotive that houses the crew.
Cab Bus:
Used to connect handheld and stationary cabs to a command station. Wireless cabs are indirectly connected to a cab bus via their companion wireless base.
Cab Control:
A method of independent control of two or more trains in which the throttle for each train is connected to the sections of track or "blocks" in which that train will run. A block is an electrically insulated section of track. Only one engine or set of engines can be independently controlled in each block.
Cab Forward:
An articulated steam locomotive peculiar to the Southern Pacific, built with the cab in front for visibility in tunnels and snowsheds.
Cab Unit:
A diesel locomotive built with a full width body. Sometimes called a "covered wagon".
Caboose:
The car that carries the crew of a freight train. It’s almost always at the rear of the train. Slang terms for the caboose include buggy, bouncer, bobber, cabin, cage, crummy, hack, palace, and way car.
Camelback:
A type of steam locomotive with the cab astride the boiler. The Camelback was a solution to the problem of forward visibility past the wide firebox required for burning anthracite.
Can Motor:
A round-cross section motor with a circular field magnet.
Catenary:
A structure built above railroad tracks to carry overhead wire for electric locomotives.
Circuit:
The path of an electrical current.
Circuit Breaker:
A switch that automatically protects the Digital Command Control system and all the decoders on the layout in the event of a current overload.
Class One Railroad:
The seven major U.S. railroads with average operating revenues in excess of $250 million or more are known as Class I; railroads with revenue of between $20 and $250 million are Class II; less than $20 million earns a Class III rating.
Classification Lights:
Lights on the front of the locomotive that indicate the type of train. White lights show that the train is an extra; green indicates that another section of the train is following.
Clear Board:
Green or proceed signal.
Clearance:
The space that’s required for rolling stock to pass an object or other equipment. Vertical clearance is the space between a car roof and an overhead object or structure.
Clearance Point:
The location near a turnout frog where equipment on one track may safely pass equipment on the adjacent track.
Click Track:
See All-in-one track.
Climax:
A type of geared steam locomotive used primarily by logging railroads. The two cylinders drive a jackshaft parallel with the axles. Power is transmitted to each truck through bevel gears and a driveshaft; rods couple the axles on each truck. See also Shay and Heisler.
Closure Rails:
The rails connecting the points and the frog of a turnout.
Coaling Station:
A structure for storing coal and transferring it into locomotive tenders.
Code:
Height of model rail as measured by thousandths of an inch. Code 83 is .083" tall, code 70 is .070", and code 55 is .055".
Combination Track:
See All in one track.
Command Control:
A way of controlling model trains by sending electronic signals through the rails or by wireless link, either radio or infrared. Each locomotive has a decoder or receiver that responds only to the messages specifically directed to it. Engines can be controlled independently anywhere on a layout.
Command Station:
The "brains" of the DCC system. It receives information from the cab, forms the appropriate DCC "packet," and transmits this information in an NMRA DCC-compliant signal to the track via the booster.
Common Rail Wiring:
A wiring system wherein one rail is electrically continuous. A single wire connected to it serves as a common return for two or more cabs.
Configuration Variable: (CV)
In DCC, number programmed into a decoder that controls its behavior. These numbers remain stored until they are reprogrammed. An address is an example of a configuration variable.
Consist: (pronounced CON-sist)
Cars which make up a train; also a list of those cars. A locomotive consist is a group of diesel units put together to pull a train. Also known as "m.u.-ing" (from multiple units). In DCC, with basic consisting, the command station sends the same commands to each loco in the consist. With advanced consisting, each decoder-equipped locomotive responds to the address of the consist, enabling the command station to control the consist with a single command.
Consist Address:
In DCC, the address to which all digital decoders in a consist respond.
Continuous Rail: (also welded rail, ribbon rail)
On the prototype, rails that have been welded together to form a single rail hundreds of feet long, eliminating most rail joints, which are the weakest part of the track.
Control Bus:
A cable connecting the command station to its boosters.
Cookie Cutter:
A type of table construction in which the plywood tabletop is cut alongside the track and then elevated above the level of the rest of the layout (or dropped below).
Coupler:
The device that fastens cars and locomotives together.
Covered Wagon:
A diesel cab unit, A or B, as opposed to a hood unit.
Cowl Unit:
A diesel unit that looks like a cab unit but differs structurally in that the carbody is merely a full-width hood rather than a structural part of the locomotive.
Crossing:
A track arrangement that permits two tracks to cross but does not allow trains to move from one track to the other. (Also called a "diamond" from its shape.) A level intersection between two tracks or between a track and a highway.
Crossover:
Two turnouts laid frog to-frog to allow trains to move from one track to another parallel track.
CTC:
Centralized Traffic Control, remote control of turnouts and signals by a dispatcher or control operator.
Cut:
Roadbed dug into the surrounding terrain to maintain a relatively even grade.
Cut and Fill:
A right of way construction method that removes earth or stone above grade and uses it to fill in gaps below grade.
Cut of Cars:
A number of cars coupled together. The addition of marker lamps and an engine makes the cut of cars a train.
CV:
See Configuration variable.
DC:
See Direct Current.
DCC:
See Digital Command Control.
DCC Bus:
Heavy-gauge copper wire used to distribute the electrical power from the booster around the layout. Each booster has its own set of track bus wires. Accessory decoders may be connected to a track bus. The wire gauge of a track bus must be appropriate to the rating of the associated power station and load.
Deadhead:
A car or train, usually passenger, moving empty; a passenger traveling on a pass. Empty freight cars are referred to as empties.
Decal:
A type of lettering material for models. The letters and numbers are printed on specially prepared paper and then coated with varnish. The lettering is applied by soaking the decal in water to dissolve the film between the ink and the paper and placing the layer of varnish and ink on the car.
Deck:
A bridge floor which may be either ballasted or open (with the track bolted to the supports).
Decoder:
In DCC, small circuit board that receives digital packets of information addressed to it by the command station in accordance with NMRA standards. Mobile decoders are mounted inside locomotives and control the motor, lights, and sounds. Accessory decoders are used to control non-locomotive items such as turnout motors, signals, etc.
Derail:
(verb) to leave the rails; (noun) safety device placed on the track, usually on a siding, to prevent cars from rolling onto the main line - a minor derailment is preferable to a major collision. It may have a cast steel frog that diverts one wheel up and over the rail to stop a car well short of the clearance point. Some derails consist of a single switch point that’s normally left open to stop any moving car clear of the main track.
Digital Command Control:
Method of controlling multiple trains and accessories using digital communications packets to send commands.
Direct Current:
Electrical current that flows in only one direction. Used for control of most model railroads before command control.
Division:
A portion of a railroad considered as an operational and administrative unit.
Double Crossover:
Adjacent trailing and facing-point crossovers allowing trains to pass from one parallel track to the other in either direction.
Double Slip Switch:
A special condensed track component that combines the functions of two turnouts in a shorter distance.
Doubleheader:
A train pulled by two locomotives, each with an engine crew, as opposed to diesel or electric locomotive units operating in multiple as a single locomotive with one crew.
Doubling a Hill:
Splitting a train and taking it up a steep grade in two parts, one at a time.
DPDT:
Double-pole, double-throw. Switch used on model railroads to allow you to change the polarity of the current for reverse loops or for complex block control. Some DPDT switches have a "center-off" feature.
Draft Gear:
The mechanism which connects the coupler to the frame of the car. In the model world, the coupler mounting box is sometimes called the draft gear.
Drawbar:
Any coupling, either a solid bar or couplers, between two pieces of rolling stock.
Drawbridge:
A movable bridge that spans a navigable waterway.
Dry Transfer:
Transferable lettering or images on waxy clear film. The lettering material is made of thin plastic with pressure sensitive adhesive, and the letters or images are released from the waxed carrier sheet when rubbed onto a model.
Dry-Brushing:
A painting and weathering technique in which most of the pigment or paint is removed from the brush before the brush is touched to the model. The "dry brush" is then stroked lightly over the model to bring out raised details and textures.
Duckunder:
A passage underneath layout benchwork requiring ducking or crawling to reach another part of the layout.
Electrostatic Grass:
Flock that simulates grass. A charge of static electricity makes the fibers stand upright.
Elevated:
A reference to a high-level right of way, often constructed on a fill, to provide clearance underneath for another track or a roadway.
Elevation:
The measured height of a specific location above a base line.
Enginehouse:
A building in which locomotives are serviced and/or stored.
Epoxy:
A two part resin and catalyst adhesive that cures rather than dries. The most useful for model building is the type that sets in 5 minutes, called "5-minute epoxy".
Expansion Joint:
A special slip joint that includes an open space in the center to allow the rails to expand or contract.
Extra:
A train not authorized by a timetable schedule.
Facing Point:
A track turnout positioned so its points face oncoming traffic.
Feeder:
Electrical power wire attached to rail.
Fill:
Roadbed built up above the surrounding terrain to maintain a relatively even grade.
Fixed Cab:
A cab or throttle permanently mounted to one location.
Flange:
The part of the wheel that runs below and inside the top of the rail to guide the wheel.
Flange-Way:
The space between a running or stock rail and a guardrail for wheel flanges.
Flash:
A thin web of material on a cast part, the result of mold sections not meeting tightly.
Flexible Track:
Track in long sections (usually 3 feet or 1 meter) that can be bent to any desired curve. Also called "flextrack".
Flextrack:
See Flexible track.
Freelance:
Modeling that does not follow a prototype railroad.
Frog:
The X shaped rail assembly where rails cross in a turnout or crossing.
Function Buttons:
Buttons on a throttle that control locomotive accessories such as lighting and sound.
Function Mapping:
In DCC, changing a decoder’s CVs to determine which function button controls which function output.
Function Outputs:
Wires on a decoder that power locomotive accessories such as lighting. Function outputs are most commonly used to control sound effects and the front and rear headlamps of a locomotive.
Gandy Dancer:
A track worker.
Gantlet Track: (not "gauntlet" track)
Overlapping parallel tracks which share a single roadbed and track structure to pass through a narrow obstruction like a tunnel or bridge.
Gap:
A slot cut through the rail to break the electrical path.
Gas Electric:
A self propelled car powered by a gasoline engine driving a generator, which supplies current to motors on the axles. Gas electrics were often used for branchline and local passenger service from the 1920s through the 1950s.
Gauge:
The distance between the inside of the heads of track rails. Most railroads in North America and Europe are built to a standard gauge of 4'-8½". Narrow gauge means track with a width less than standard gauge. For example, On3 means O scale trains with 3 scale feet between the rails.
Geep:
See GP.
Glad Hand:
The metal coupling on the end of an air hose.
Gondola:
An open car with a flat bottom.
GP:
General Motors’ designation for its four-axle "general purpose" locomotives. Also referred to as Geep.
Grab Iron:
Handholds on the sides, ends, and roofs of cars.
Grade:
The vertical rise or fall of a track per 100 units of distance, expressed as a percentage. A 2" rise in 100" is a 2 percent grade.
Grade Crossing:
Arrangement that allows track to cross a road or highway on the same level.
Ground Foam:
Synthetic foam rubber ground up and dyed for use as a texture element in scenery.
Ground Throw:
A low level manual switch stand used to move and lock the switch points to select a route through a turnout.
Guardrail:
An additional rail used on the inside of rails to help wheel flange follow the proper route (as in a turnout or crossing), or to keep derailed cars on the track structure (as on a bridge).
Hand Laying:
Process of laying model track using individual ties, rails, and track spikes.
Hardshell:
A technique for building scenery made by dipping paper towels in plaster and laying them over a temporary support structure, creating a rigid, self supporting form.
Head End Cars:
Mail, baggage, and express cars, usually run at the front of a passenger train.
Headblocks:
The pair of extended ties that support a switch stand.
Heisler:
A type of geared steam locomotive used by logging railroads. It had two cylinders arranged in a V connected to a driveshaft which in turn was connected to the trucks. See also Climax and Shay.
Helix:
A rising curve which turns around an axis like a corkscrew. Used on some multilevel layouts to allow trains to go from one level to another.
Helper:
A locomotive added to a train to help it climb a grade.
High Iron:
The main line.
Highball:
A proceed signal.
Homasote:
A pressed-paper construction board often used for model railroad roadbed.
Hood Unit:
A roadswitcher, so called because of the construction of the locomotive, with the machinery covered by a hood rather than a full-width cab.
Hopper Car:
An open top car with funnel like bins and unloading doors or gates in bottom of car. Covered hoppers have roofs to loads that need protection from weather.
Hostler:
A workman who services locomotives between runs and moves them around an engine teminal.
Hotbox:
An axle bearing that has become hot because of lack of lubrication.
Hi Cube:
A boxcar that is taller than standard and thus has a higher cubic capacity.
Hydrocal:
A hard, quick-setting plaster often preferred for model railroad scenery and made by U.S. Gypsum.
In the Hole:
In a siding to meet or be passed by another train.
Industry Track:
Side track where freight cars can be left so a railroad customer can load or unload them.
Instruction Packets:
In DCC, the regular packet format used for most digital commands.
Insulated Joint:
A mechanical rail joint that doesn’t pass electricity.
Insulated Rail Joiner:
A plastic rail connector used to insulate joints.
Interchange:
A junction of two railroads where cars are transferred from one line to the other.
Interlocking:
A mechanical or electrical system of signaling which ensures that only one train at a time is allowed to move through a junction.
Intermodal:
Shipments carried by more than one mode of transportation, mainly containers and piggyback trailers.
Interurban:
An electrically operated light railway between cities and towns, as opposed to local streetcar service.
Johnson Bar:
The manual reversing lever of older steam locomotives.
Joint:
An end to end mechanical rail connection using a rail joiner to maintain precise alignment.
Joint Bar:
A formed-steel bar, bolted in place, used to join sections of prototype rail.
Journal:
The load bearing part of an axle. The weight of the axle is carried by the journal bearing, which is enclosed by the journal box.
Junction:
A location where main and/or branch lines diverge or cross each other.
Kar Trak:
An outdated system used to keep track of all railroad equipment. It employed ACI (automatic car identification) reflective labels on all rolling stock, trackside scanners, and computers.
Kingpin:
Pin or screw used to mount model railroad trucks to locomotive or car body. Center pin is the more common term for the prototype.
Kitbash:
To combine parts from different kits to produce a model unlike the straight kit models.
Kitbashing:
Taking one or more model railroad kits (often structure kits) and changing the construction process or combining parts to make a personalized model.
Lap or Three Way Switch:
A special track component that combines two overlapping turnouts to connect one track to three tracks.
LCL:
Less than Carload Lot, any shipment of freight too small to fill an entire car.
Lichen:
A plant used to model trees and bushes.
M.U. :
Multiple unit, a method of controlling several diesel or electric cars or locomotives from one cab. M.U. cars are electric passenger cars for operation on electrified portions of a steam or diesel railroad, as in a suburban district. Interurbans, subway cars, and RDCs are technically M.U. cars, but the term is usually reserved for steam road electric cars.
Main Line:
The track serving as the main route for trains. Some heavy-use lines have two or more main tracks.
Maintenance of Way Equipment:
The machinery and rolling stock used to keep track and roadbed in good condition.
Markers:
Lamps formerly hung on the rear of the last car of the train to show that the cars are indeed a train and to indicate its status. Later substitutes were used, such as reflector paddles. Now replaced on freight trains by end-of-train (EDT) devices; passenger trains now typically have built-in marker lights.
Matte Medium:
An artist’s material used as an adhesive for ballast and scenery materials.
Milepost:
A trackside sign with a number indicating the distance from an established starting point.
Module:
A section of a layout built following a standard pattern or dimensions. Each module can be connected interchangeably with any other module built to the same standards. Ntrak is an organization that has developed standards for N scale modules.
MOW:
Maintenance of way, the job of keeping track and roadbed in good condition.
Narrow Gauge:
Track with a gauge less than 4'-8½" (standard gauge). In the U.S., 3-foot and 2½-foot gauges were used. In modeling, narrow gauge is labeled first with the scales, followed by an n (for narrow), followed by the track gauge in feet (e.g. Hon3).
Nickel Silver:
A silvery colored alloy of brass used for model railroad rails.
NMRA:
National Model Railroad Association, a worldwide organization of hobbyists who gather to exchange information and promote creative development and fellowship in model railroading. The NMRA’s standards and recommended practices ensure compatibility of mechanical and electrical components from different model railroad manufacturers.
NMRA Gauge:
Flat steel standards gauge issued by the National Model Railroad Association for checking track gauges and clearances in some scales.
On the Ground:
In railroad slang, derailed.
Operation:
Running trains on a layout to simulate the movement of freight and passengers.
Operations Mode Programming:
In DCC, also known as "programming on the main". Changing the CVs of an individual locomotive on a track other than the programming track. Not all decoders or DCC systems support this.
Packet:
The sequence of bits used to encode the instructions upon which a decoder operates.
Pantograph:
A current pickup device for electric locomotives and cars.
Piggyback:
The movement of truck trailers on flatcars. Also called trailer-on-flatcar (TOFC).
Platform:
A loading dock for freight or passengers. A high platform is even with the car floor, while a low platform may be at any height below floor level.
Points:
The two connected short rails in a turnout that move to change a train’s route.
Portal:
An entrance to a tunnel or the framing at the ends of a truss bridge.
Power District:
An area of the layout connected directly to its own booster, electrically isolated from any other boosters or power districts.
Power Pack: (or supply)
A model railroad control device containing, at the minimum, a transformer and rectifier to reduce 120-volt AC house current to a lower DC voltage for running model trains.
Profile:
A scale drawing which shows the grade alignment for a section of main track.
Programming Track:
A short piece of track electrically separated from the main trackage. It is used to program any CV, including the decoder’s address. CVs may also be read back to the cab from a decoder on the programming track.
Prototype:
The real, full-sized object after which a scale model is made.
Pull the Pin:
Operate the uncoupling lever.
Pullman:
A sleeping car or parlor car operated by the Pullman Co.; by extension, any sleeping car.
Pulse Width Modulation: (PWM)
Used to control the speed of a DC motor by applying pulses of a constant voltage of varying width. The wider the pulses, the faster the motor turns. This is the method of motor control used by DCC decoders.
Puzzle Switch:
A slang term referring to the special track components, including single or double slip switches used in extremely congested areas.
Radius:
The size of a curve measured from its center point to the center line of a curved track.
Rail:
A specialty shaped rolled steel beam with a wide base that’s fastened to crossties to guide trains along the right of way and carry their weight.
Rail Code:
The height of model rail in thousandths of an inch: code 100 measures .100" tall, code 83 is .083" tall, code 70 is .070", and code 55 is .055."
Rail Diesel Car: (RDC)
A self propelled passenger car built by the Budd Company.
Rail Joiner:
A formed sheet-metal mechanical connector used to join model rails end to end.
Rail Nipper:
Flush-cutting pliers used to make clean, square cuts in soft metal rail.
Railfan
A person who enjoys riding, watching, photographing, and reading about trains.
Railhead:
The wider, top portion of a rail that the wheels run on.
Rectifier:
A device inside a decoder for converting electrical AC current into DC current.
Red Board:
A train order signal indicating orders to be delivered.
Reefer:
A refrigerator car. Similar in appearance to a boxcar but has ice or mechanical cooling equipment.
Relay:
An electromagnetic switching device commonly used to control polarity, power, and signal circuits.
Re-Railer:
Section of model track used for getting cars and locomotives back on the rails.
Resistor:
Restricts the flow of electrical current to lower its voltage or limit its current.
Return Loop:
A section of track that reverses the direction of a train running through it; on the prototype more often called a "balloon track".
Reverse Loop:
See "return loop".
Reverse or "S" Curve:
Opposing curves connected end to end.
Right-of-Way:
The track, roadbed, and property along the track owned by the railroad. On a model railroad, the term refers to track, roadbed, and subroadbed.
Rip Track: (repair-in-place)
The track in a yard where minor car repairs are made.
Riser:
A vertical piece in the benchwork that supports a track board or subroadbed.
Road Switcher:
A general purpose diesel that can be used for both yard switching and road duties. Also called a hood unit.
Roadbed:
On real railroads, the foundation layer of earth on which the track is built. On a model railroad, a strip of wood, cork, foam, or other material that simulates the ballast profile of a real railroad.
Rolling stock
Non-powered railroad cars; freight and passenger cars.
Roundhouse:
An engine-house like a sector of a circle in shape, and usually surrounding a turntable.
RS:
American Locomotive Co. (Alco) "road switcher" diesel locomotive.
Ruling Grade:
The maximum grade that controls train size on a given route.
Runaround:
A switching maneuver in which the locomotive uncouples from its train, pulls ahead, backs past on an adjacent track, and moves forward to couple onto the rear of the train; also the track itself where the move takes place.
Running Board:
Walkway along roof or along sides of tank cars and steam locomotives.
Saw By:
A maneuver by which two trains can meet at a siding that’s too short to hold either one of them.
(If neither train fits, it’s a double saw-by.)
Scale:
The size of things on a model railroad relative to things on a real railroad. For example, in the most popular scale, HO, models are 1/87th full size. More Information.
Schedule:
That portion of a timetable that lists the class, direction, number, and timings of regular trains.
Scissors Crossover:
Two crossovers interlaced with a crossing in the middle which allow trains to pass from one parallel track to the other in either direction.
Scratchbuilding:
Making a model from raw materials and parts, not using kits.
SD:
General Motors’ designation for its six-axle "special duty" diesel locomotives.
Sectional Track:
Track in short, rigid pieces (fixed length and curve radii) that are easily joined to each other.
Shay:
A type of geared steam locomotive used extensively in logging, mining, and industrial railroading. It had three cylinders mounted vertically on the right side of the boiler driving a crankshaft geared to all the axles.
Short Line:
A small railroad, generally Class II. See Class I railroad.
Siding:
A side track with a turnout at each end. Passing sidings are long enough to let trains meet each other.
Single Slip Switch:
A special condensed track component that combines the functions of two turnouts in a short distance. Allows only three possible routings, not the four of a double-slip.
Slug:
A weighted locomotive unit with traction motors but no diesel engine or generator. Used in conjunction with a diesel locomotive for additional tractive force.
Smoke-Jack:
A chimney on a car or building.
Snowshed:
A structure built over the track in mountainous areas to protect the tracks from snow and avalanches.
SPDT:
Single-pole, double-throw. A type of electrical switch used in model railroading. See DPDT.
Speed Table:
In DCC, table of parameters specifying the motor voltage in response to a speed and direction command. Individual speed tables can be programmed for each locomotive, allowing locomotives from different manufacturers to work together in a consist.
Spike:
On a prototype railroad, a forged steel fastener with an offset head that’s driven into the ties to secure the rails.
Spiral Curve or Easement:
A curve of gradually increasing radius that makes the transition between a tangent or straight track and a fixed-radius curve.
Spot a Car:
To place a car in its designated position, as at an industry or on a station track.
Spring Switch:
A turnout held in one position by a spring so that facing point traffic always takes the same route but trailing point traffic can run through the turnout from either track.
Spur or Spur Track:
A dead end track, one with a turnout at only one end.
Standard Gauge:
In North America, the standard gauge between rails is 4' 8½".
Stub Switch:
A pointless turnout that changes its route by gently bending the approach or "fly" rails sideways.
Styrene:
Short for polystyrene, a versatile plastic commonly used for modeling. Comes in sheets, blocks, and rods of many different thicknesses and sizes.
Sub-Road-Bed:
The bottom or foundation layer of model track, usually made from plywood.
Super-Elevation:
Raising the outside rail of curved track to help trains negotiate curves more easily and at higher speeds.
SW:
General Motors’ designation for its diesel switchers.
Switch:
Electrical switches are usually called toggles. In a turnout, the "switch" is the assembly of moving points that select one route or the other.
Switch Lock:
A padlock or an interlocking device that secures a switch so it cannot be moved.
Tango:
A type of lightweight passenger train now operated by Amtrak in the Northwest. In the model world the term is applied to truck mounted couplers.
Tangent:
A straight track.
Tank Engine:
A steam locomotive that carries its fuel and water supply in tanks hung over or alongside the boiler or on a frame extension at the rear instead of in a tender.
Tender:
A car attached to a steam locomotive that carries extra fuel and water for the locomotive.
Third Rail:
An extra rail mounted alongside the running rails to supply current for electric locomotives or traction cars.
Throttle:
The speed control of the locomotive; in the model world, a potentiometer or other speed controller.
Tie:
The structural element placed at right angles to the track center line to support and hold the rails in gauge. Most ties on real railroads are still hardwood, but increasingly some are made of prestressed concrete. On a model railroad ties are either plastic or wood.
Tie Plate:
A forged steel plate used between the rail base and the tie top to help spread the load.
Timber:
Any heavy wood beam used in railroad construction.
Timetable:
The authority for the movement of regular trains subject to the railroad’s operating rules.
Toggle: (switch)
An electrical switch with a lever control and snap action (as opposed to a slide switch or push buttons). The household light switch is a 110 volt example of a toggle switch.
Track:
Two parallel rails affixed to wooden or concrete ties; plastic or wood in model form.
Track Bus:
See Bus, or bus wire.
Track-Board:
The horizontal wood support beneath model roadbed and track; subroadbed.
Traction:
Public utility transportation; by extension, all electrically operated trains.
Trailing Point:
A turnout with its points facing away from the direction of travel.
Transformer:
Changes high-voltage 110-volt AC house current into low-voltage AC current to power your DCC system.
Transition Curve:
See Spiral curve or easement.
Truck:
The wheel axle frame assembly under each end of a car or locomotive; the framework supporting railroad wheels.
Turnout:
A section of track with movable rails to divert a train from one track to another. Also "switch," although technically the switch is only the moving parts of a turnout. "Turnout" also avoids confusion with electrical devices. Referred to by number. For example, a no. 6 turnout spreads one unit for each six units of travel measured from the point of the frog.
Turntable:
A revolving bridge commonly used to turn locomotives in an engine terminal.
Uncoupling Lever:
Also called a cut lever. The device which raises the locking pin in a coupler to allow the knuckle to open for uncoupling.
Unit:
A single diesel locomotive.
Unit Train:
A freight train that carries a single commodity from source to destination and returns empty.
USRA:
United States Railroad Administration. The USRA was responsible for the operation of the country’s railroads during World War I.
Varnish:
A passenger train. Wooden passenger cars used to be given many coats of varnish.
Vestibule:
The enclosed area at the end of a passenger car where the side doors are located. Early passenger cars had only an open platform. Around the 1880s narrow-vestibule cars came into use, with a vestibule only as wide as the passageway between the cars. The full-width vestibule followed soon after.
Volt:
A unit of electrical pressure. Commonly, 0 to 9 volts of DC are used for Z scale model railroading, 0 to 14 volts DC for N and HO scale, and 0 to 20 volts DC for large-scale model railroading.
Walk-Around Cab:
A cab or throttle that is handheld and connected by a cable to a plug connected to the cab bus at multiple points around the layout. Memory-equipped walkaround cabs allow a train to maintain speed and direction while the cab is unplugged from the cab bus.
Walk-Around Control:
A system that allows the model railroad operators to walk along with their trains.
Walkaround Railroad:
A railroad you can walk around in the course of operation without having to duck under any part of the benchwork. Walkaround controls may be built into the benchwork.
Water Column:
A standpipe adjacent to the track and connected to a water supply for filling steam locomotive tenders.
Weathering:
Making shiny new models look more realistic by dirtying them up to simulate road grime, the action of sun and rain, and general evidence of use.
Welded Rail:
Real rail sections that have been welded together to eliminate track joints. Also called continuous rail.
Wheel Stop:
A wedge shaped device mounted on the railheads to keep a car from rolling off the end of a track.
Wheelset:
A pair of wheels connected by an axle.
White Glue:
An adhesive primarily for joining wood and paper materials.
Wireless Cab:
A handheld cab that has no cable connection to the layout. Wireless cabs use infrared or radio waves as a method of transmitting information.
Wireless Cab Base:
A base station for one or more wireless cabs. Connected to the command station via a cab bus.
Wye:
Type of turnout where the two legs curve away equilaterally, forming a Y. Also a triangular track configuration for turning a locomotive or a train or for joining a branch to a main line for operation in both directions.
Wye Switch:
A turnout that diverges equally in both directions.
Yard:
Collection of tracks used for sorting and storing cars.
Yard engine: (also yard goat)
A switching locomotive.
Association of American Railroads, the trade association that represents the common interests of the railroad industry in such areas as standards, public relations, and advertising.
AC:
See Alternating Current.
ACC:
See CA.
Access Hatch:
A hole in the benchwork and scenery, sometimes concealed with a lift out section of scenery, for emergency access to parts of the layout.
Accessory Decoder:
Decoder that provides power and operational control of one or more layout accessory devices, such as turnouts, signals, cranes, animation devices, lighting, etc. Also known as a stationary decoder.
ACI:
Automatic Car Identification; see Kar Trak.
Address:
Used by the command station to communicate with a specific decoder. It can be either 2- or 4-digit, depending on the system, and is typically part of the locomotive’s road number. Addresses are unique to each decoder.
Airbrush:
A miniature paint sprayer that gives a controlled application of thinned paint.
All in One Track:
Model track that includes simulated roadbed or ballast. Also called combination or "click" track.
Alternating Current: (AC)
An electric current that reverses its direction of flow at regular intervals. Each move from zero to maximum strength and back to zero is half a cycle. A full cycle includes excursions in both the positive and negative direction.
Ammeter:
Meter used to measure current strength - for example, how many amps a locomotive draws when it stalls.
Ampere or Amp:
Unit used to determine the amount of an electrical current.
AREA:
The American Railway Engineering Association is the prototype railroad organization which establishes right of-way material specifications and track construction standards.
Articulated:
A steam locomotive with two engines (i.e., cylinders, rods, and wheels) under one boiler.
Automatic Reversing:
A circuit that senses short circuits and reverses the polarity. Used commonly with reversing loops, wyes, and turntables.
Backdrop:
A painting or scenic photograph on the wall behind the layout. It can be as simple as a cloudless sky or it can echo the scenery of the layout and create an illusion of great distance.
Bad Order:
A freight car that's defective or out of order.
Ballast:
On real railroads, a layer of material - usually crushed rock, cinders, or gravel - on top of the roadbed that holds the ties in position and facilitates drainage. On a model railroad, ballast is simulated by fine gravel spread between the ties and alongside the track.
Balloon Track:
See Return loop.
Benchwork:
Supporting framework for a model railroad layout. L girder and open grid (sometimes called butt joint) are two popular types.
Big Hook:
Wrecking crane.
Block:
On a real railroad, a section of track defined for the purpose of controlling trains. On a model railroad, a block is an electrically isolated section of track.
Block Signal:
A signal at the entrance to a block (See Block) indicating whether the block is occupied by a train.
Bolster:
The crosswise member of the frame of a car at the truck (body bolster) or the crosswise piece at the center of a truck (truck bolster).
Boomer:
An experienced railroad man who moves from railroad to railroad.
Booster:
In DCC, the booster takes the low-current signal from the command station and "boosts" it to the high-current signal needed by locomotives to operate DC motors, etc., in conformance with NMRA Standards S-91. Also referred to as power stations or power boosters.
Branch Line:
Secondary line of a railroad.
Brass: (also brass hat, brass collar)
Railroad executives and officials.
Bridge:
A structure that supports a track passing over a depression in the terrain or a stream. A through bridge has a floor structure, which supports the track between its side beams or trusses, while a deck bridge has its supporting structure below track level.
Bridge Guardrail:
A set of steel rails mounted inside the running rails on a bridge or other structure to keep derailed cars in line.
Bridge Pier:
An intermediate support used between bridge spans.
Bridge Shoe:
An iron or steel casting which transfers the weight of a bridge to its supports. One end is normally a solid mounting while the opposite end allows for expansion and contraction.
Bright Boy:
(brand name) An abrasive rubber block used to clean track.
Bumper:
A braced, coupler height blocking device that keeps cars from rolling off the end of a track.
Bunk, Camp, or Outfit Car:
A passenger or freight car converted into movable living quarters for track workers.
Bus, or Bus Wire:
A main wire, or trunk wire, running under a model railroad. Shorter branch wires, such as track power feeders, are connected to it.
CA:
Short for cyanoacrylate adhesive, also known as super glue. A high strength adhesive that can be used on metal and styrene plastic. Sometimes seen as ACC for alphacyanoacrylate cement.
Cab:
Usually a handheld piece of equipment with necessary controls to send speed, direction, and other information to the locomotive. Frequently referred to as "throttle". On the prototype, the part of the locomotive that houses the crew.
Cab Bus:
Used to connect handheld and stationary cabs to a command station. Wireless cabs are indirectly connected to a cab bus via their companion wireless base.
Cab Control:
A method of independent control of two or more trains in which the throttle for each train is connected to the sections of track or "blocks" in which that train will run. A block is an electrically insulated section of track. Only one engine or set of engines can be independently controlled in each block.
Cab Forward:
An articulated steam locomotive peculiar to the Southern Pacific, built with the cab in front for visibility in tunnels and snowsheds.
Cab Unit:
A diesel locomotive built with a full width body. Sometimes called a "covered wagon".
Caboose:
The car that carries the crew of a freight train. It’s almost always at the rear of the train. Slang terms for the caboose include buggy, bouncer, bobber, cabin, cage, crummy, hack, palace, and way car.
Camelback:
A type of steam locomotive with the cab astride the boiler. The Camelback was a solution to the problem of forward visibility past the wide firebox required for burning anthracite.
Can Motor:
A round-cross section motor with a circular field magnet.
Catenary:
A structure built above railroad tracks to carry overhead wire for electric locomotives.
Circuit:
The path of an electrical current.
Circuit Breaker:
A switch that automatically protects the Digital Command Control system and all the decoders on the layout in the event of a current overload.
Class One Railroad:
The seven major U.S. railroads with average operating revenues in excess of $250 million or more are known as Class I; railroads with revenue of between $20 and $250 million are Class II; less than $20 million earns a Class III rating.
Classification Lights:
Lights on the front of the locomotive that indicate the type of train. White lights show that the train is an extra; green indicates that another section of the train is following.
Clear Board:
Green or proceed signal.
Clearance:
The space that’s required for rolling stock to pass an object or other equipment. Vertical clearance is the space between a car roof and an overhead object or structure.
Clearance Point:
The location near a turnout frog where equipment on one track may safely pass equipment on the adjacent track.
Click Track:
See All-in-one track.
Climax:
A type of geared steam locomotive used primarily by logging railroads. The two cylinders drive a jackshaft parallel with the axles. Power is transmitted to each truck through bevel gears and a driveshaft; rods couple the axles on each truck. See also Shay and Heisler.
Closure Rails:
The rails connecting the points and the frog of a turnout.
Coaling Station:
A structure for storing coal and transferring it into locomotive tenders.
Code:
Height of model rail as measured by thousandths of an inch. Code 83 is .083" tall, code 70 is .070", and code 55 is .055".
Combination Track:
See All in one track.
Command Control:
A way of controlling model trains by sending electronic signals through the rails or by wireless link, either radio or infrared. Each locomotive has a decoder or receiver that responds only to the messages specifically directed to it. Engines can be controlled independently anywhere on a layout.
Command Station:
The "brains" of the DCC system. It receives information from the cab, forms the appropriate DCC "packet," and transmits this information in an NMRA DCC-compliant signal to the track via the booster.
Common Rail Wiring:
A wiring system wherein one rail is electrically continuous. A single wire connected to it serves as a common return for two or more cabs.
Configuration Variable: (CV)
In DCC, number programmed into a decoder that controls its behavior. These numbers remain stored until they are reprogrammed. An address is an example of a configuration variable.
Consist: (pronounced CON-sist)
Cars which make up a train; also a list of those cars. A locomotive consist is a group of diesel units put together to pull a train. Also known as "m.u.-ing" (from multiple units). In DCC, with basic consisting, the command station sends the same commands to each loco in the consist. With advanced consisting, each decoder-equipped locomotive responds to the address of the consist, enabling the command station to control the consist with a single command.
Consist Address:
In DCC, the address to which all digital decoders in a consist respond.
Continuous Rail: (also welded rail, ribbon rail)
On the prototype, rails that have been welded together to form a single rail hundreds of feet long, eliminating most rail joints, which are the weakest part of the track.
Control Bus:
A cable connecting the command station to its boosters.
Cookie Cutter:
A type of table construction in which the plywood tabletop is cut alongside the track and then elevated above the level of the rest of the layout (or dropped below).
Coupler:
The device that fastens cars and locomotives together.
Covered Wagon:
A diesel cab unit, A or B, as opposed to a hood unit.
Cowl Unit:
A diesel unit that looks like a cab unit but differs structurally in that the carbody is merely a full-width hood rather than a structural part of the locomotive.
Crossing:
A track arrangement that permits two tracks to cross but does not allow trains to move from one track to the other. (Also called a "diamond" from its shape.) A level intersection between two tracks or between a track and a highway.
Crossover:
Two turnouts laid frog to-frog to allow trains to move from one track to another parallel track.
CTC:
Centralized Traffic Control, remote control of turnouts and signals by a dispatcher or control operator.
Cut:
Roadbed dug into the surrounding terrain to maintain a relatively even grade.
Cut and Fill:
A right of way construction method that removes earth or stone above grade and uses it to fill in gaps below grade.
Cut of Cars:
A number of cars coupled together. The addition of marker lamps and an engine makes the cut of cars a train.
CV:
See Configuration variable.
DC:
See Direct Current.
DCC:
See Digital Command Control.
DCC Bus:
Heavy-gauge copper wire used to distribute the electrical power from the booster around the layout. Each booster has its own set of track bus wires. Accessory decoders may be connected to a track bus. The wire gauge of a track bus must be appropriate to the rating of the associated power station and load.
Deadhead:
A car or train, usually passenger, moving empty; a passenger traveling on a pass. Empty freight cars are referred to as empties.
Decal:
A type of lettering material for models. The letters and numbers are printed on specially prepared paper and then coated with varnish. The lettering is applied by soaking the decal in water to dissolve the film between the ink and the paper and placing the layer of varnish and ink on the car.
Deck:
A bridge floor which may be either ballasted or open (with the track bolted to the supports).
Decoder:
In DCC, small circuit board that receives digital packets of information addressed to it by the command station in accordance with NMRA standards. Mobile decoders are mounted inside locomotives and control the motor, lights, and sounds. Accessory decoders are used to control non-locomotive items such as turnout motors, signals, etc.
Derail:
(verb) to leave the rails; (noun) safety device placed on the track, usually on a siding, to prevent cars from rolling onto the main line - a minor derailment is preferable to a major collision. It may have a cast steel frog that diverts one wheel up and over the rail to stop a car well short of the clearance point. Some derails consist of a single switch point that’s normally left open to stop any moving car clear of the main track.
Digital Command Control:
Method of controlling multiple trains and accessories using digital communications packets to send commands.
Direct Current:
Electrical current that flows in only one direction. Used for control of most model railroads before command control.
Division:
A portion of a railroad considered as an operational and administrative unit.
Double Crossover:
Adjacent trailing and facing-point crossovers allowing trains to pass from one parallel track to the other in either direction.
Double Slip Switch:
A special condensed track component that combines the functions of two turnouts in a shorter distance.
Doubleheader:
A train pulled by two locomotives, each with an engine crew, as opposed to diesel or electric locomotive units operating in multiple as a single locomotive with one crew.
Doubling a Hill:
Splitting a train and taking it up a steep grade in two parts, one at a time.
DPDT:
Double-pole, double-throw. Switch used on model railroads to allow you to change the polarity of the current for reverse loops or for complex block control. Some DPDT switches have a "center-off" feature.
Draft Gear:
The mechanism which connects the coupler to the frame of the car. In the model world, the coupler mounting box is sometimes called the draft gear.
Drawbar:
Any coupling, either a solid bar or couplers, between two pieces of rolling stock.
Drawbridge:
A movable bridge that spans a navigable waterway.
Dry Transfer:
Transferable lettering or images on waxy clear film. The lettering material is made of thin plastic with pressure sensitive adhesive, and the letters or images are released from the waxed carrier sheet when rubbed onto a model.
Dry-Brushing:
A painting and weathering technique in which most of the pigment or paint is removed from the brush before the brush is touched to the model. The "dry brush" is then stroked lightly over the model to bring out raised details and textures.
Duckunder:
A passage underneath layout benchwork requiring ducking or crawling to reach another part of the layout.
Electrostatic Grass:
Flock that simulates grass. A charge of static electricity makes the fibers stand upright.
Elevated:
A reference to a high-level right of way, often constructed on a fill, to provide clearance underneath for another track or a roadway.
Elevation:
The measured height of a specific location above a base line.
Enginehouse:
A building in which locomotives are serviced and/or stored.
Epoxy:
A two part resin and catalyst adhesive that cures rather than dries. The most useful for model building is the type that sets in 5 minutes, called "5-minute epoxy".
Expansion Joint:
A special slip joint that includes an open space in the center to allow the rails to expand or contract.
Extra:
A train not authorized by a timetable schedule.
Facing Point:
A track turnout positioned so its points face oncoming traffic.
Feeder:
Electrical power wire attached to rail.
Fill:
Roadbed built up above the surrounding terrain to maintain a relatively even grade.
Fixed Cab:
A cab or throttle permanently mounted to one location.
Flange:
The part of the wheel that runs below and inside the top of the rail to guide the wheel.
Flange-Way:
The space between a running or stock rail and a guardrail for wheel flanges.
Flash:
A thin web of material on a cast part, the result of mold sections not meeting tightly.
Flexible Track:
Track in long sections (usually 3 feet or 1 meter) that can be bent to any desired curve. Also called "flextrack".
Flextrack:
See Flexible track.
Freelance:
Modeling that does not follow a prototype railroad.
Frog:
The X shaped rail assembly where rails cross in a turnout or crossing.
Function Buttons:
Buttons on a throttle that control locomotive accessories such as lighting and sound.
Function Mapping:
In DCC, changing a decoder’s CVs to determine which function button controls which function output.
Function Outputs:
Wires on a decoder that power locomotive accessories such as lighting. Function outputs are most commonly used to control sound effects and the front and rear headlamps of a locomotive.
Gandy Dancer:
A track worker.
Gantlet Track: (not "gauntlet" track)
Overlapping parallel tracks which share a single roadbed and track structure to pass through a narrow obstruction like a tunnel or bridge.
Gap:
A slot cut through the rail to break the electrical path.
Gas Electric:
A self propelled car powered by a gasoline engine driving a generator, which supplies current to motors on the axles. Gas electrics were often used for branchline and local passenger service from the 1920s through the 1950s.
Gauge:
The distance between the inside of the heads of track rails. Most railroads in North America and Europe are built to a standard gauge of 4'-8½". Narrow gauge means track with a width less than standard gauge. For example, On3 means O scale trains with 3 scale feet between the rails.
Geep:
See GP.
Glad Hand:
The metal coupling on the end of an air hose.
Gondola:
An open car with a flat bottom.
GP:
General Motors’ designation for its four-axle "general purpose" locomotives. Also referred to as Geep.
Grab Iron:
Handholds on the sides, ends, and roofs of cars.
Grade:
The vertical rise or fall of a track per 100 units of distance, expressed as a percentage. A 2" rise in 100" is a 2 percent grade.
Grade Crossing:
Arrangement that allows track to cross a road or highway on the same level.
Ground Foam:
Synthetic foam rubber ground up and dyed for use as a texture element in scenery.
Ground Throw:
A low level manual switch stand used to move and lock the switch points to select a route through a turnout.
Guardrail:
An additional rail used on the inside of rails to help wheel flange follow the proper route (as in a turnout or crossing), or to keep derailed cars on the track structure (as on a bridge).
Hand Laying:
Process of laying model track using individual ties, rails, and track spikes.
Hardshell:
A technique for building scenery made by dipping paper towels in plaster and laying them over a temporary support structure, creating a rigid, self supporting form.
Head End Cars:
Mail, baggage, and express cars, usually run at the front of a passenger train.
Headblocks:
The pair of extended ties that support a switch stand.
Heisler:
A type of geared steam locomotive used by logging railroads. It had two cylinders arranged in a V connected to a driveshaft which in turn was connected to the trucks. See also Climax and Shay.
Helix:
A rising curve which turns around an axis like a corkscrew. Used on some multilevel layouts to allow trains to go from one level to another.
Helper:
A locomotive added to a train to help it climb a grade.
High Iron:
The main line.
Highball:
A proceed signal.
Homasote:
A pressed-paper construction board often used for model railroad roadbed.
Hood Unit:
A roadswitcher, so called because of the construction of the locomotive, with the machinery covered by a hood rather than a full-width cab.
Hopper Car:
An open top car with funnel like bins and unloading doors or gates in bottom of car. Covered hoppers have roofs to loads that need protection from weather.
Hostler:
A workman who services locomotives between runs and moves them around an engine teminal.
Hotbox:
An axle bearing that has become hot because of lack of lubrication.
Hi Cube:
A boxcar that is taller than standard and thus has a higher cubic capacity.
Hydrocal:
A hard, quick-setting plaster often preferred for model railroad scenery and made by U.S. Gypsum.
In the Hole:
In a siding to meet or be passed by another train.
Industry Track:
Side track where freight cars can be left so a railroad customer can load or unload them.
Instruction Packets:
In DCC, the regular packet format used for most digital commands.
Insulated Joint:
A mechanical rail joint that doesn’t pass electricity.
Insulated Rail Joiner:
A plastic rail connector used to insulate joints.
Interchange:
A junction of two railroads where cars are transferred from one line to the other.
Interlocking:
A mechanical or electrical system of signaling which ensures that only one train at a time is allowed to move through a junction.
Intermodal:
Shipments carried by more than one mode of transportation, mainly containers and piggyback trailers.
Interurban:
An electrically operated light railway between cities and towns, as opposed to local streetcar service.
Johnson Bar:
The manual reversing lever of older steam locomotives.
Joint:
An end to end mechanical rail connection using a rail joiner to maintain precise alignment.
Joint Bar:
A formed-steel bar, bolted in place, used to join sections of prototype rail.
Journal:
The load bearing part of an axle. The weight of the axle is carried by the journal bearing, which is enclosed by the journal box.
Junction:
A location where main and/or branch lines diverge or cross each other.
Kar Trak:
An outdated system used to keep track of all railroad equipment. It employed ACI (automatic car identification) reflective labels on all rolling stock, trackside scanners, and computers.
Kingpin:
Pin or screw used to mount model railroad trucks to locomotive or car body. Center pin is the more common term for the prototype.
Kitbash:
To combine parts from different kits to produce a model unlike the straight kit models.
Kitbashing:
Taking one or more model railroad kits (often structure kits) and changing the construction process or combining parts to make a personalized model.
Lap or Three Way Switch:
A special track component that combines two overlapping turnouts to connect one track to three tracks.
LCL:
Less than Carload Lot, any shipment of freight too small to fill an entire car.
Lichen:
A plant used to model trees and bushes.
M.U. :
Multiple unit, a method of controlling several diesel or electric cars or locomotives from one cab. M.U. cars are electric passenger cars for operation on electrified portions of a steam or diesel railroad, as in a suburban district. Interurbans, subway cars, and RDCs are technically M.U. cars, but the term is usually reserved for steam road electric cars.
Main Line:
The track serving as the main route for trains. Some heavy-use lines have two or more main tracks.
Maintenance of Way Equipment:
The machinery and rolling stock used to keep track and roadbed in good condition.
Markers:
Lamps formerly hung on the rear of the last car of the train to show that the cars are indeed a train and to indicate its status. Later substitutes were used, such as reflector paddles. Now replaced on freight trains by end-of-train (EDT) devices; passenger trains now typically have built-in marker lights.
Matte Medium:
An artist’s material used as an adhesive for ballast and scenery materials.
Milepost:
A trackside sign with a number indicating the distance from an established starting point.
Module:
A section of a layout built following a standard pattern or dimensions. Each module can be connected interchangeably with any other module built to the same standards. Ntrak is an organization that has developed standards for N scale modules.
MOW:
Maintenance of way, the job of keeping track and roadbed in good condition.
Narrow Gauge:
Track with a gauge less than 4'-8½" (standard gauge). In the U.S., 3-foot and 2½-foot gauges were used. In modeling, narrow gauge is labeled first with the scales, followed by an n (for narrow), followed by the track gauge in feet (e.g. Hon3).
Nickel Silver:
A silvery colored alloy of brass used for model railroad rails.
NMRA:
National Model Railroad Association, a worldwide organization of hobbyists who gather to exchange information and promote creative development and fellowship in model railroading. The NMRA’s standards and recommended practices ensure compatibility of mechanical and electrical components from different model railroad manufacturers.
NMRA Gauge:
Flat steel standards gauge issued by the National Model Railroad Association for checking track gauges and clearances in some scales.
On the Ground:
In railroad slang, derailed.
Operation:
Running trains on a layout to simulate the movement of freight and passengers.
Operations Mode Programming:
In DCC, also known as "programming on the main". Changing the CVs of an individual locomotive on a track other than the programming track. Not all decoders or DCC systems support this.
Packet:
The sequence of bits used to encode the instructions upon which a decoder operates.
Pantograph:
A current pickup device for electric locomotives and cars.
Piggyback:
The movement of truck trailers on flatcars. Also called trailer-on-flatcar (TOFC).
Platform:
A loading dock for freight or passengers. A high platform is even with the car floor, while a low platform may be at any height below floor level.
Points:
The two connected short rails in a turnout that move to change a train’s route.
Portal:
An entrance to a tunnel or the framing at the ends of a truss bridge.
Power District:
An area of the layout connected directly to its own booster, electrically isolated from any other boosters or power districts.
Power Pack: (or supply)
A model railroad control device containing, at the minimum, a transformer and rectifier to reduce 120-volt AC house current to a lower DC voltage for running model trains.
Profile:
A scale drawing which shows the grade alignment for a section of main track.
Programming Track:
A short piece of track electrically separated from the main trackage. It is used to program any CV, including the decoder’s address. CVs may also be read back to the cab from a decoder on the programming track.
Prototype:
The real, full-sized object after which a scale model is made.
Pull the Pin:
Operate the uncoupling lever.
Pullman:
A sleeping car or parlor car operated by the Pullman Co.; by extension, any sleeping car.
Pulse Width Modulation: (PWM)
Used to control the speed of a DC motor by applying pulses of a constant voltage of varying width. The wider the pulses, the faster the motor turns. This is the method of motor control used by DCC decoders.
Puzzle Switch:
A slang term referring to the special track components, including single or double slip switches used in extremely congested areas.
Radius:
The size of a curve measured from its center point to the center line of a curved track.
Rail:
A specialty shaped rolled steel beam with a wide base that’s fastened to crossties to guide trains along the right of way and carry their weight.
Rail Code:
The height of model rail in thousandths of an inch: code 100 measures .100" tall, code 83 is .083" tall, code 70 is .070", and code 55 is .055."
Rail Diesel Car: (RDC)
A self propelled passenger car built by the Budd Company.
Rail Joiner:
A formed sheet-metal mechanical connector used to join model rails end to end.
Rail Nipper:
Flush-cutting pliers used to make clean, square cuts in soft metal rail.
Railfan
A person who enjoys riding, watching, photographing, and reading about trains.
Railhead:
The wider, top portion of a rail that the wheels run on.
Rectifier:
A device inside a decoder for converting electrical AC current into DC current.
Red Board:
A train order signal indicating orders to be delivered.
Reefer:
A refrigerator car. Similar in appearance to a boxcar but has ice or mechanical cooling equipment.
Relay:
An electromagnetic switching device commonly used to control polarity, power, and signal circuits.
Re-Railer:
Section of model track used for getting cars and locomotives back on the rails.
Resistor:
Restricts the flow of electrical current to lower its voltage or limit its current.
Return Loop:
A section of track that reverses the direction of a train running through it; on the prototype more often called a "balloon track".
Reverse Loop:
See "return loop".
Reverse or "S" Curve:
Opposing curves connected end to end.
Right-of-Way:
The track, roadbed, and property along the track owned by the railroad. On a model railroad, the term refers to track, roadbed, and subroadbed.
Rip Track: (repair-in-place)
The track in a yard where minor car repairs are made.
Riser:
A vertical piece in the benchwork that supports a track board or subroadbed.
Road Switcher:
A general purpose diesel that can be used for both yard switching and road duties. Also called a hood unit.
Roadbed:
On real railroads, the foundation layer of earth on which the track is built. On a model railroad, a strip of wood, cork, foam, or other material that simulates the ballast profile of a real railroad.
Rolling stock
Non-powered railroad cars; freight and passenger cars.
Roundhouse:
An engine-house like a sector of a circle in shape, and usually surrounding a turntable.
RS:
American Locomotive Co. (Alco) "road switcher" diesel locomotive.
Ruling Grade:
The maximum grade that controls train size on a given route.
Runaround:
A switching maneuver in which the locomotive uncouples from its train, pulls ahead, backs past on an adjacent track, and moves forward to couple onto the rear of the train; also the track itself where the move takes place.
Running Board:
Walkway along roof or along sides of tank cars and steam locomotives.
Saw By:
A maneuver by which two trains can meet at a siding that’s too short to hold either one of them.
(If neither train fits, it’s a double saw-by.)
Scale:
The size of things on a model railroad relative to things on a real railroad. For example, in the most popular scale, HO, models are 1/87th full size. More Information.
Schedule:
That portion of a timetable that lists the class, direction, number, and timings of regular trains.
Scissors Crossover:
Two crossovers interlaced with a crossing in the middle which allow trains to pass from one parallel track to the other in either direction.
Scratchbuilding:
Making a model from raw materials and parts, not using kits.
SD:
General Motors’ designation for its six-axle "special duty" diesel locomotives.
Sectional Track:
Track in short, rigid pieces (fixed length and curve radii) that are easily joined to each other.
Shay:
A type of geared steam locomotive used extensively in logging, mining, and industrial railroading. It had three cylinders mounted vertically on the right side of the boiler driving a crankshaft geared to all the axles.
Short Line:
A small railroad, generally Class II. See Class I railroad.
Siding:
A side track with a turnout at each end. Passing sidings are long enough to let trains meet each other.
Single Slip Switch:
A special condensed track component that combines the functions of two turnouts in a short distance. Allows only three possible routings, not the four of a double-slip.
Slug:
A weighted locomotive unit with traction motors but no diesel engine or generator. Used in conjunction with a diesel locomotive for additional tractive force.
Smoke-Jack:
A chimney on a car or building.
Snowshed:
A structure built over the track in mountainous areas to protect the tracks from snow and avalanches.
SPDT:
Single-pole, double-throw. A type of electrical switch used in model railroading. See DPDT.
Speed Table:
In DCC, table of parameters specifying the motor voltage in response to a speed and direction command. Individual speed tables can be programmed for each locomotive, allowing locomotives from different manufacturers to work together in a consist.
Spike:
On a prototype railroad, a forged steel fastener with an offset head that’s driven into the ties to secure the rails.
Spiral Curve or Easement:
A curve of gradually increasing radius that makes the transition between a tangent or straight track and a fixed-radius curve.
Spot a Car:
To place a car in its designated position, as at an industry or on a station track.
Spring Switch:
A turnout held in one position by a spring so that facing point traffic always takes the same route but trailing point traffic can run through the turnout from either track.
Spur or Spur Track:
A dead end track, one with a turnout at only one end.
Standard Gauge:
In North America, the standard gauge between rails is 4' 8½".
Stub Switch:
A pointless turnout that changes its route by gently bending the approach or "fly" rails sideways.
Styrene:
Short for polystyrene, a versatile plastic commonly used for modeling. Comes in sheets, blocks, and rods of many different thicknesses and sizes.
Sub-Road-Bed:
The bottom or foundation layer of model track, usually made from plywood.
Super-Elevation:
Raising the outside rail of curved track to help trains negotiate curves more easily and at higher speeds.
SW:
General Motors’ designation for its diesel switchers.
Switch:
Electrical switches are usually called toggles. In a turnout, the "switch" is the assembly of moving points that select one route or the other.
Switch Lock:
A padlock or an interlocking device that secures a switch so it cannot be moved.
Tango:
A type of lightweight passenger train now operated by Amtrak in the Northwest. In the model world the term is applied to truck mounted couplers.
Tangent:
A straight track.
Tank Engine:
A steam locomotive that carries its fuel and water supply in tanks hung over or alongside the boiler or on a frame extension at the rear instead of in a tender.
Tender:
A car attached to a steam locomotive that carries extra fuel and water for the locomotive.
Third Rail:
An extra rail mounted alongside the running rails to supply current for electric locomotives or traction cars.
Throttle:
The speed control of the locomotive; in the model world, a potentiometer or other speed controller.
Tie:
The structural element placed at right angles to the track center line to support and hold the rails in gauge. Most ties on real railroads are still hardwood, but increasingly some are made of prestressed concrete. On a model railroad ties are either plastic or wood.
Tie Plate:
A forged steel plate used between the rail base and the tie top to help spread the load.
Timber:
Any heavy wood beam used in railroad construction.
Timetable:
The authority for the movement of regular trains subject to the railroad’s operating rules.
Toggle: (switch)
An electrical switch with a lever control and snap action (as opposed to a slide switch or push buttons). The household light switch is a 110 volt example of a toggle switch.
Track:
Two parallel rails affixed to wooden or concrete ties; plastic or wood in model form.
Track Bus:
See Bus, or bus wire.
Track-Board:
The horizontal wood support beneath model roadbed and track; subroadbed.
Traction:
Public utility transportation; by extension, all electrically operated trains.
Trailing Point:
A turnout with its points facing away from the direction of travel.
Transformer:
Changes high-voltage 110-volt AC house current into low-voltage AC current to power your DCC system.
Transition Curve:
See Spiral curve or easement.
Truck:
The wheel axle frame assembly under each end of a car or locomotive; the framework supporting railroad wheels.
Turnout:
A section of track with movable rails to divert a train from one track to another. Also "switch," although technically the switch is only the moving parts of a turnout. "Turnout" also avoids confusion with electrical devices. Referred to by number. For example, a no. 6 turnout spreads one unit for each six units of travel measured from the point of the frog.
Turntable:
A revolving bridge commonly used to turn locomotives in an engine terminal.
Uncoupling Lever:
Also called a cut lever. The device which raises the locking pin in a coupler to allow the knuckle to open for uncoupling.
Unit:
A single diesel locomotive.
Unit Train:
A freight train that carries a single commodity from source to destination and returns empty.
USRA:
United States Railroad Administration. The USRA was responsible for the operation of the country’s railroads during World War I.
Varnish:
A passenger train. Wooden passenger cars used to be given many coats of varnish.
Vestibule:
The enclosed area at the end of a passenger car where the side doors are located. Early passenger cars had only an open platform. Around the 1880s narrow-vestibule cars came into use, with a vestibule only as wide as the passageway between the cars. The full-width vestibule followed soon after.
Volt:
A unit of electrical pressure. Commonly, 0 to 9 volts of DC are used for Z scale model railroading, 0 to 14 volts DC for N and HO scale, and 0 to 20 volts DC for large-scale model railroading.
Walk-Around Cab:
A cab or throttle that is handheld and connected by a cable to a plug connected to the cab bus at multiple points around the layout. Memory-equipped walkaround cabs allow a train to maintain speed and direction while the cab is unplugged from the cab bus.
Walk-Around Control:
A system that allows the model railroad operators to walk along with their trains.
Walkaround Railroad:
A railroad you can walk around in the course of operation without having to duck under any part of the benchwork. Walkaround controls may be built into the benchwork.
Water Column:
A standpipe adjacent to the track and connected to a water supply for filling steam locomotive tenders.
Weathering:
Making shiny new models look more realistic by dirtying them up to simulate road grime, the action of sun and rain, and general evidence of use.
Welded Rail:
Real rail sections that have been welded together to eliminate track joints. Also called continuous rail.
Wheel Stop:
A wedge shaped device mounted on the railheads to keep a car from rolling off the end of a track.
Wheelset:
A pair of wheels connected by an axle.
White Glue:
An adhesive primarily for joining wood and paper materials.
Wireless Cab:
A handheld cab that has no cable connection to the layout. Wireless cabs use infrared or radio waves as a method of transmitting information.
Wireless Cab Base:
A base station for one or more wireless cabs. Connected to the command station via a cab bus.
Wye:
Type of turnout where the two legs curve away equilaterally, forming a Y. Also a triangular track configuration for turning a locomotive or a train or for joining a branch to a main line for operation in both directions.
Wye Switch:
A turnout that diverges equally in both directions.
Yard:
Collection of tracks used for sorting and storing cars.
Yard engine: (also yard goat)
A switching locomotive.
