The following glossary is arranged alphabetically with each term catalogued by first letter. Select a letter below to begin.
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 thats 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.
Rerailer
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 (repair-in-place) track
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
Nonpowered railroad cars; freight and passenger cars.
Roundhouse
An enginehouse 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.
