A Trains Model Railroading - Glossary 

Acute Frog The two frogs in a crossing which are less than 90 degrees.
Ammeter A device which is used to measure amperes.
A.C. (Alternating Current) An electric current that reverses direction in a circuit at regular intervals.  Ordinary house current is alternating current.
Ampere A unit of electric current.
Block An electrically isolated section of track that can be independently operated.
Brass A yellow metal alloy consisting of copper and zinc.
Bumper An obstruction placed at the end of a railroad track to prevent rolling stock from derailing.
Cab A power pack.
Cab Control A method of wiring a layout to allow control of electrical blocks, which may be passed back and forth between cabs
Circuit A closed path through which an electrical current may flow.
Common Lead A wire from the power supplyu to the common, or ungapped rail.
Common Rail The one rail in model railroad track without electrical gaps.
Common Rail Wiring A method of wiring your layout where one rail has electrical continuity throughout the layout.
Connector A device manugactured by Atlas to turn electrical power on or off to track sections or accessories.
Controller An electrical device manufactured by Atlas, which provides the proper operation of reversing loops and turntables.
Control Rail The rail in a model railroad layout which has electrical gaps.
Crossing The point where two railroad tracks cross each other without joining.
Current Electricity flowing in a circuit.  Current flows from positive(+) to negative(-).
Cut A group of freight or passenger cars.
Cycle The number of times that alternating current completes a total reversal of direction in a given interval of time, normally one second.
D.C. (Direct Current) An electrical current that flows in one direction only.
Dogbone A configuration of model railroad track which looks like a dogbone.
Double Pole Double Throw (DPDT) An electrical switch that can be adapted to reverse the flow of electric current.
Double Track Wye A track configuration in which two parallel tracks both create wyes.  Traversing the complete double track wye will result in the train running on the opposite track.
Drill To switch a train or cars from one track to another.
Flange The protruding edge on a wheel which acts as a guide against the rail.
Flux A paste used in soldering to assist the molten solder to flow freely.
Frog The location where two rails cross in a turnout or crossing.
Gap An electrical break in a rail.
Gauge The distance between the rails of a railroad, measured from the inside of the railheads.
Actual Railroad: 4' 8 1/2"
N Scale Railroad: 9mm
HO Scale Railroad: 16.5mm
O Scale Railroad: 31.8mm
HO Scale A scale of model railroads and equipment that is 187th the size of the real items.
Homasote A wallboard material of compressed newspaper useful for its sound deading property and ease of insertion of track nails.
Insulated Joiner A Plastic clip that joins two sections of track mechanically but isolates them electrically.
Insulated Frog A frog that is electrically isolated from the rails.
Ladder Track The track in a ladder yard from which all other tracks originate.
Layout A model railroad.
Main Line The promary railroad track that carries through traffic.
Multi-meter An electrical instrument consisting of an ammeter, ohmmeter and voltmeter, all contained in one casing.
N Scale A scale of model railroads and equipment that is 1/160th the size of the real items.
NMRA National Model Railroad Association
4121 Cromwell Rd.
Chattanooga, TN 37421

The NMRA sets standards for the compatibility of model railroad equipment and is dedicated to the promotion and improvement of the hobby.
Nickel Silver A silvery colored metal alloy consisting of copper, zinc, and nickel.
Ohm A unit of electrical resistance.
Ohmmeter A device used to measure ohms.  Also used to find a short circuit.
Passing Siding A double-ended siding, long enough for two trains to pass one another.
Pier set A Number of graduated plastic piers that enables model railraod track to gain elevation by suppoerting the track at graduated intervals.
Points The moving portion of a turnout.
Polarity The movement of electricity from a power source (a power pack or battery, for example) to the place where it is used (a motor, for example) and then back to the power source to complete the circuit.
Power The work done by an electrical current.  The unit of power is the watt.
Power Pack An electrical device that plugs into a household outlet and converts 110 volts AC current into 12 volts DC current.  HO and N scale model railroads use 12 volts DC current.
Prototype The actual object that your model railroad equipment is patterned after.
Radius A line from the center of a circle to any point along it's outer edge.  In model railroading it is a line from the center of an imaginary circle to the center of a curved section of track.  Radius is alwasys measured to the center of the track, mid-way between the rails.
Rail Joiner A small metal clip used to join two sections of track mechanically and electrically.
Rectifier An electrical device which converts AC current to DC current.
Relay A power operated electrical switch.  (See also, "Snap-Relay")
Remote Control Turnout A turnout (switch) whose points are electrically operated from a remote position.
Rerailer A section of straight model railroad track resembling a road crossing, which is used to put rolling stock on the rails.
Resistance The property of a conductor which limits or opposes the passage of an electrical current.  The amount of resistance is measured in ohms.
Resistor An electrical device which limits the passage of an electrical current.  The value of a resistor is expressed in ohms.
Reverse Loop A section of track that goes around in a circle and comes back on itself and is joined by a turnout at this point.  A reverse loop resembles a balloon on the end of a string.
Rheostat An electrical device which limits the amount of voltage delivered to a motoe, thus acting as a speed control.  Also called a variable resistor.
Right of Way The track and land owned by a railroad.
Scale The proportional size of model railroad items compared to the real thing. (prototype).
N Scale - 1/60th the size of the real item.
HO Scale - 1/87th the size of the real item.
O Scale - 1/48th the size of the real item.
Selector An Atlas electrical device that enables the operation and control of two trains at the same time.
Short Circuit A usually unintended flow of current between two points, bypassing the normal electrical circuit.
Single Pole Single Throw (SPST) A simple "On-Off" electrical switch.
Siding A side or secondary track, also called a "spur".
Snap-relay A DPDT relay with actuating mechanism driven by a momentary-power, twin coil solenoid.
Snap Switch A turnout, manufactured by Atlas, whose straight (through) leg is 9" in length and whose diverging (branching) track has a radius of 18".
Snap-Track .A system of sectional track components in HO scale, manufactured by Atlas
Solder A soft, wirelike metal comprised of tin and lead, which, when melted, is used to join two pieces of metal or wire.
Soldering iron A device used to melt solder and accomplish the act of soldering.
Solenoid A cylindrical coil of insulated wire in which an iron core is made to move back and forth by a flow of electric current.
SPDT An electrical switch that can be adapted to route power.
Spur See Siding.
Stock Rail The two outer rails in a turnout.
Stub Track A track that comes to a dead end.  Used for storing locomotives and/or cars, or to lead to a structure on your layout.
Switch 1) A device to route train wheels from one set of rails to another by means of moveable points.  Also called "track switch" or "turnout".
2) An electrical device that routes, reverses or interrupts the flow of electric current.
Switch Machine A device either manual or electrical (remote), connected to the points of a turnout to change the setting of the route.
Tender The car directly behind a steam locomotive that carries the fuel and water for the engine.
Terminal Joiner A rail joiner with a section of wire attached which is used to supply power to the track.
Terminal Section Also known as terminal track.  A section of model railroad track with attachments for wire.  Used to conduct electricity from the power pack to the rail.  Terminal sections may be straight or curved.
Terminal Strip A series of screw or clip-on wire terminals mounted on a strip of insulating material.
Throwbar The bar connecting the two point rails in a turnout.
Tie A timber laid crosswise to support railroad tracks.
Tin (or Tinning) In soldering, a thin coat of solder on the tip of a soldering iron, on the surfaces of two pieces of metal to be joined, or on a piece of wire.
Toggle Switch One of many variations of electrical switch.  Other types of toggle switches include double pole, double throw; single pole, single throw, etc.
Track Section See "Block".
Transformer An electrical device which either increases or, more commonly, decreases electrical voltage.
Trunks The device beneath railroad cars or locomotives that hold the wheels.
Trunk Line The main protion of a railroad.
Turnout Same as a switch; that point where two diverging tracks come together.
Twin An Atlas electrical component consisting of two double pole, double throw reversing switches wired in parallel.
Volt/Voltage A unit of electromotive force, comparable to pressure in a water pipe.
Voltmeter A device used to measure volts.
Watt A unit of work done by an electrical current (power).
Wye A triangular shaped track arragement, using three turnouts, where trains my be reversed.  Can also refer to one turnout with two curved diverging routes instead of one straight and one curved route, as is commonly found.
Way-Freight A freight train consisting of a locomotive and one or more freight cars to be delivered to local undustries.
X-sections A section of track, electrically isolated, used to temporarily "x"-tend the length of adjacent sections (blocks).
Yard A group of side tracks where railroad cars are stored or where trains are made or broken up prior to or after a run.