Model Railway Language

2004-3-13

One of the first steps in building a model railway is to read and read and read to gather information. This inevitably means you will come across terminology you do not understand. So I have put together a list of some of the most common terms. This list is by no means exhaustive, but I hope covers the basics.

If you want an explanation of a term not included or you feel something is missing, you can leave a message in the "model railway section of the forum" and I will be pleased to help.



AC - Alternating current. Electric current which changes polarity in a regular cycle. It is the normal mains supply.

Advanced Uncoupling - A system of automatic uncoupling where the rolling stock are pushed over an actuating mechanism which uncouples the locomotive/wagons.

Auto-coupler - A device for automatically coupling locomotives and rolling stock when pushed together.

Baseboard - The platform on which a model railway is built.

Ballasting - The prototype track is laid on a bed of loose rock chippings, to provide drainage and support for the sleepers. In the model version this may be simulated by a foam rubber inlay or to be much more realistic, loose chippings held together with a dilute PVA mix.

Bracket signal - A semaphore signal array with two or more arms indicating different routes ahead. Often termed a junction signal.

Broad Gauge - Any railway with a gauge wider than 4ft8½in.

Buffer Stop - Placed at the end of a section of track to prevent the locomotive over-running.

Controller - A device that modifies a 12 volt DC supply to control speed and direction of a locomotive.

Centre third - A system of current collection using a central third rail. Now virtually obsolete.

Command control - A system of model railway control where a constant voltage is applied to the rails. Each locomotive is fitted with a decoder, which interprets a command sent over the rails. The control unit uses advanced electronics and requires a microprocessor. It permits independent operation of two or more trains in the same section of track.

Crossing - 1) A track formation that crosses one track over another without any connection, as at a double junction. Frequently termed a diamond crossing. 2) In strict railway parlance, the part of a turnout where the rails cross.

Culvert - A small bridge or large drain carrying a stream under a railway.

Cutting - A large trench with sloping walls and railway tracks at the bottom.

DC - Direct current. Electric current of constant polarity as supplied by batteries or from AC supplies via a rectifier.

Diesel Era - A more accurate term for Modern Image.

Fishplates - Also known as rail joiners. Metal clips used to join track together to provide an unbroken electrical circuit.

Flexi-track - As the name suggests this is flexible and can be cut and curved to suit your track plan, where a standard radius of track will not fit.

Gauge - The distance between the inner faces of the rails.

Distant signal -A warning signal, normally ¼ mile in front of a home signal giving the driver time to slow down and stop.

Embankment - A bank of soil to carry a railway line (or other track) above the natural ground level.

Fiddle Yard - A series of offstage storage tracks used to hold trains so they can emerge in turn on the layout proper.

Flanges - The projection/lip on railway wheels, which keeps them on the track.

Flatbottom Rail - The standard rail section in use on all modern systems. The rail has a wide base and, originally, was spiked directly to the sleeper. With increasing train loadings, baseplates were introduced to spread the load and on all but lightly laid track now has the rail secured either by bolts and clips or patent clips.

Frog - The part of a turnout where the inner rails cross. Also known as a crossing.

Gantry Signal - A lightweight bridge structure crossing several tracks carrying many signal posts or colour light heads.

Gradient - The slope of a railway. It can be expressed as a percentage (%), as per mile (0/on) or, more commonly in the UK, as a ratio (1 in xxx). centimetres or metres).

Home signal - The semaphore signal controlling entry into a block section.

Level Crossing - A road crossing on the level. Formerly closed by gates, but today lifting barriers are preferred.

Livery - The paint scheme for a locomotive or coach.

Modern Image - A term introduced in the 1960s to describe the then new diesel hauled and electrified trains on British Rail. The object was to distinguish between current practice and the steam hauled system. Over the past few years it has become necessary to distinguish between current practice and 'Historic Modern Image.'

Narrow Gauge - Any prototype railway with a gauge less than 4ft 8½ in is 'narrow' gauge.

Occupation Bridge - A small underbridge maintaining access between parts of an estate or farm bisected by a railway embankment or cutting.

Occupation Crossing - A level crossing provided to maintain access between parts of an estate or farm bisected by a railway.

Overbrldge - A bridge carrying a road or canal over a railway.

Overhead Supply - Most prototype electrified railways have an overhead feed, the rails forming the return. On models of modern electrified railways should be so equipped, but in most instances the overhead is only a cosmetic feature.

Point - Where two tracks are linked to allow trains to be diverted to one of two tracks. Also known as turnout.

Prototype - The full size original on which a model is based.

Ready to Run - Commercially produced locomotives and rolling stock, for
use 'straight from the box'.

Rectifier - An electronic device which converts AC current to DC.

Scale - The ratio between sizes on the prototype and model, expressed either as a ratio (1 :76) or linear equivalent (4mm to 1 feet).

Signal box - A structure housing a lever frame controlling points and signals on a section of track. Early systems were wholly mechanical and only controlled a limited area. Modern electro-mechanical installations control large sections of track the signalmen rely on illuminated panels and monitors to follow the position of trains.

Steam Age - Used to encompass all model railways set in a period prior to dieselisation.

Track - An assembly of two rails set at a fixed gauge held in fixings to a series of wooden cross beams termed sleepers.

Track Pins - Used to fix the track in place. They are placed at intervals in predrilled holes in the sleepers.

Train Turntable - A form of fiddle yard where the entire yard turns around a central pivot.

Transformer - A device to change the line voltage of an electric current. It will only work with AC supplies.

Two-rail - The common system of current collection on model railways, where the rails are insulated one from another and the current fed to each rail. All wheels must be insulated.

Underbridge - A railway bridge spanning a road or waterway.