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Hornby Glossary

Hornby model railways are a traditional and endlessly rewarding hobby, but boy are there a lot of words involved! Sometimes it’s difficult to know you’re ballast from your louvers, or your splashers from your pantograph. That’s why we’ve compiled this handy glossary of all things Hornby, the perfect tool for any budding conductor! (Pro tip: if you know the word you’re looking for, simply press Ctrl + F and type it in).

Terms that refer only to DCC layout will have an asterisk (*) next to them.


Acceleration Delay* – The time it takes for a locomotive to go from a stationary position to its desired speed.

Accessory Decoder* – A decoder designed to be used with track side accessories (signals, points, etc).

Address* – The number that is given to an accessory or locomotive that is linked to or equipped with a decoder.

Alternating Current/AC – An electrical current which flows alternately though each wire. It flows in a rapid sequence called a “cycle”. Mains electricity is Alternating Current/AC.

Ampere/Amp – The current in an electrical circuit.

Armature – The part of an electric motor that revolves.


Back-to-back – The distance between the backs of running wheels on rolling stock.

Ballast – Material that supports sleeps by holding them in place on the ground. Usually stone chippings, or something similar.

Baseboard – Quite literally the base of your layout, the structure that everything is built on.

Big Four – The four companies formed on 1 January 1923 that ran freight and passenger trains across the country. These were GWR (Great Western Railway), SR (Southern Railway), LNER (London and North Eastern Railway) and LMS (London, Midland and Scottish Railway).

Bogie – The underside of a freight wagon, coach or locomotive. Basically, the piece that supports the wheels. Typically each bogie will hold 2 or 3 pairs of wheels.

Brushes – Pieces of carbon that fit on either side of a commutator on an electric motor. Often phosphorous bronze or copper strips that touch both sides of the commutator.

Buffer Beam – A headstock, essentially. The beam at either end of a locomotive, wagon or coach that carries the buffers.

Bus* – Wires which carry an electrical signal around a model layout.


Catch Point - A single trailing point blade set into an ascending track. The aim is to derail wagons that have come uncoupled and are running backwards down the hill. A catch point prevents runaways colliding with a following train, which is always nice.

CDU (Capacitor Discharge Unit) – Stores power so that several motors can work simultaneously.

Catenary – Overhead wires and their supports which carry electricity above the railway.out

Chair - Metal clips which are bolted or spiked to sleepers that hold the rail in place.

Check-Rail – A rail that runs inside the two running rails on curves and points. It keeps the flanges of the wheel from riding up the opposite rail, keeping them in check.

Colour Light Signal – A signal that indicates how far in front of the train the line is clear using only coloured lights.

Command Station* – The smart bit of a DCC system, this is a micro-computer that communicated with decoders located in locomotives and accessories. It sends signals that tell the decoders what to do (accelerate, brake, turn lights on, etc).

Common Return – A wire which connects one side of the running rail, returning the current from the entire track.

Commutator - The slotted copper segments at the end of the armature on an electric motor, which transfers the current from the brushes to the coils wound on the armature.

Configuration Variable (CV)* – Refers to the operating information of a locomotive (or accessory) that is stored on the specific decoder. This information won’t change unless you do so using the Command Station.

Connecting Rod – On locomotives, this is the rod which connects the piston rod to the driving wheel.

Consist/Consisting* – An American term, in the UK it is known as Double or Triple Heading. When two or more locomotives join to function as one. There are three types of Consisting (1) Basic consisting where the locomotive decoders in the Consist have the same address.(2) Universal Consisting where the Consist information is stored in the Command Station. (3) Advanced Consisting is where the Consist information is stored inside the decoder.

Controller – This controls the direction and speed of a locomotive on an analogue layout through variable resistance, variable transformer or electronic circuit.

Coupling Rod – The rod connecting the large wheels on a locomotive.

Crank – The pin or pivot point where the connecting rod joins the driving wheels.

Crosshead - The two parallel pieces of metal connecting the piston rod which slide in the side bar and transmit power to the connecting rod.

Crossing – The point where two tracks cross each other.

Crossover – A crossing from one set of rails to another.

Cutting – A section of countryside that is at a higher level than the track which runs through it, the ground having been removed to lay the line.

Cut-Out – A switch the cuts all power to the layout in the event of an overload or short circuit. These can usually be reset by pressing a button.


DCC (Digital Command and Control)* - The application of computer technology to control the movements of locomotives. Each locomotive is fitted with a decoder (or ‘chip’) which is uniquely programmed and recognises its own identity and responds only to those control signals which are addressed to it. DCC also allows a wide range of extras including controllable lighting and on-board sound.

Diamond - The centre portion of an acute angled crossing.

Direct Current/DC – The opposite of AC. Direct current flows in only one direction and is what most model railway locomotives work on.

Disk Wheels - Solid wheels that have no spokes, though some will have holes around the edge.

Distant Signal - A semaphore signal giving the driver advanced warning of the position of the next home signal, allowing him to slow the train if it were at danger. The facing arm of the distant signal is yellow with a fish tail.


Embankment – A section of line where the surrounding countryside is lower than the rail line.


Facing Point – A point or turnout which faces the oncoming trains.

Fiddle Yard - A place on a layout to store complete trains which are ready to run onto the main circuit layout. IT can also be used to changed trains.

Fine Scale - A smaller scale nearer to the true scale of the prototype. I.e. Fine Scale ‘00’ gauge is often described as EM Gauge.

Fishplate - A metal plate which clamps on the end of two abutting rails to make sure the rail is in line. On a model railway a metal fishplate will conduct electricity across the gap. If an isolated section is required then a plastic fishplate is used.

Flyover – A bridge that carries one railway line over another.

Footplate – The floor of a locomotive.

Four Aspect Signal - A colour light signal using four lights. From top to bottom in order, the lights are yellow, green, yellow, red. A red indication means the next section contains a train. A single yellow light (using the lower yellow aspect) means the next section is clear but there is a train in the following section. A double yellow means the next two sections are clear but there is a train in third section. A green indicates that the next three sections are clear.


Gantry – Walkway/bridge over tracks on which signals are mounted.

Gauge – The distance between running rails of the railway track.

Gears – Toothed or cog wheels which work together to increase or decrease speed.

Ground Frame - Small signal box or lever frame often seen in shunting yards. It does not usually control signals or points for a main line but for sidings and yards.

GWR - Great Western Railway


Handrail - A handgrip along the boiler of a locomotive that serves as a grip for crew. Also found on brake vans and cab sides for passengers.

Handrail Knob – Fixes the handrail to the locomotive boiler.

Home Signal – Controls entry into a section. If the arm is up then the line is clear, if it is horizontal there is a train ahead.


Inner Home Signal - A home signal within station limits where an outer home signal is positioned. The inner home signal is in advance of the outer home and usually to the rear of the signal box.

Inoperable Signal – A signal at the lineside which permanently set to caution or stop.


Jinty – A nickname for a six wheel side tank locomotive designed by Sir Henry Fowler for shunting and light freight duties.

Junction Signal - Any signal that has more than one route and is capable of displaying an indication of which route has been selected. A junction indicator will also be fitted to a junction signal to inform the driver which way a junction is set, by means of white lights.


Kettle – A lineside boiler that fills locomotive boilers directly.

King Lever - A lever in a signal box which cuts out the box’s control and allows its signals and points to be controlled remotely from another box or automatically via track circuits.

Kip - A hump at the top of a rope-hauled railway to prevent wagons or carriages accidentally running back down the incline; An incline on which wagons are built to be run off by gravity as required, usually at a colliery, to feed a loading point.


Lever Frame - The assembly which holds the signal and point levers in a signal box or ground frame. A lever frame is made up of slots for the levers to operate in and allows for them to be locked together.

Live Steam – An alternative method of powering a locomotive as opposed to electric current.

LMS – London, Midland and Scottish Railway.

LNER – London and North Eastern Railway.

Loading Gauge - The size limit for locomotives, freight and passenger rolling stock over a specific stretch of railway. This is measured horizontally in relation to position of platform edges and tunnel walls, for example, and vertically in relation to bridge and tunnel heights. The loading gauge can vary considerably for the same track gauge, especially in other parts of Europe and North America; a metal frame, often found in freight yards, suspended over the track to indicate the limit an open freight wagon may be safely loaded.

Locomotive Decoder* - A small PC board which contains a ‘chip’ that stores control information; normally fitted in locomotives. The Command Station sends coded information to the decoder which can then control the locomotives speed, direction and any operating functions that the locomotive may have e.g lights. Locomotive Decoders can be fitted to accessories that have a motor as a drive for example the R8131 Hornby Operating Conveyor or the R813 Hornby Tipper set.

Lower Quadrant Signal – A semaphore signal. When the arm is lowered, the line ahead is clear.

Louvers – Ventilation slots found in the sides of diesel and electric locomotives (and occasionally goods vans).


Main Frame - The strong metal sides of the chassis of a locomotive in which holes are drilled for axles. They also carry the spacing pieces and fixings for the locomotive’s motor.

Merry-Go-Round (MGR) – MGR trains deliver coal to electric power stations. MGR trains consist of permanently coupled hopper wagons, fast loading of coal from a storage hopper at a colliery and automatic discharge over the power station’s receiving hopper. The advantages of an MGR system include doing away with the need for extra locomotives and wagons, and special sidings for loading and unloading coal.

Modern Image – Refers to the railway scene of today. Someone who models on today’s railways is known as a ‘modern image’ modeller.

Multiple Unit – A self-powered set of coaches with a driving compartment at each end. Usually powered by electric or diesel motors.


Narrow Gauge - A railway running on tracks having a closer distance between the rails than normal.

NEM Coupling - A standard universal type of coupling that can be fitted by means of a small socket on the underside of most locomotives and rolling stock. It enables models from different manufactures to be run coupled together.


Occupancy Decoder - A unit that can detect the presence of a locomotive on a specific section of track and can provide the appropriate information as ‘return’ data.

Ohm – The measurement of resistance in an electrical circuit

Outer Home Signal - An additional signal placed before the home signal that protects trains shunting back past the home signal. It also indicates station limits at the approach end of a station.

Overload - Where the electrical load (i.e. several model locomotives running at the same time) requires more power than the transformer or controller can give.


Pantograph - A metal assembly on the roof of an electric unit to collect current from overhead wire.

Point - One railway track turning into two or three tracks, or the crossing of one track with another.

Point Motor - An electric motor or solenoid used for changing the points.

Point Rodding - The rodding or wires which move the point either from an electric motor or solenoid or from the lever in a signal box.

PO (Private Owner) Wagons - Private Owner wagons are vehicles owned privately and not by the railway company running them. In the steam era, many PO wagons were owned by private collieries and coal merchants before the rail and coal industries became nationalised in 1948. Tank wagons are often owned by the oil company whose name appears on the side.

Power Booster/Power Station* - A Power Booster or Power Station is as the name implies, there to provide a boost of power to the track. This can occur if a larger than normal quantity of locomotives are required to be running on the track at the same time. If the transformer already fitted cannot handle this number then it will be necessary to section the layout and fit a Power Booster. This Booster will not only provide more ampage to drive the locomotives but also boost the signals to the Decoders. All Boosters fitted must still be connected to the Power Station.

Power Bus* - Copper strip or wires that can relay power from a Power Booster to the track.

Programming* - The process of assigning an Address to a locomotive or accessory (points or signals).The process of programming sends a signal containing a numerical identifier to the locomotive being programmed.

Programming Track - A section of track isolated from the main layout purposely for programming locomotives. A Programming Track negates the requirement of removing other locomotives from the main layout.

Power Unit - Transformer and rectifier used to convert the mains electricity (normally 240V AC) to the smaller voltage required by a model railway controller (normally 12V DC) or Digital Command and Control systems (DCC).

Prototype - The full size locomotive, coach or wagon; Full size railway practice.

Push/Pull - A type of train where the carriages are kept permanently coupled to the locomotive which pulls them in one direction then pushes them in the other.


Q Train - A special train manned by British Transport Police officers that can be stopped at any time to deal with cases of vandalism, trespass or other crimes on the railway.


Rain Strips - Curved pieces of wood or metal fixed on a coach roof to prevent the rain running down the sides when the doors are opened.

Ramp - The sloping end of a station platform; Sloping object in the centre of the running rails in model railways usually used for uncoupling.

Ready-To-Run - A model which can be taken straight out of the box, placed on your layout, and run. All Hornby locomotives and rolling stock are manufactured as ‘ready-to-run’.

Rectifier - An electrical item used for changing Alternating Current (AC) to Direct Current (DC).

Relay - An electrical device for switching currents to other circuits; the opening or closing of a circuit. A relay can also be used in place of a point motor.

Resistance - A measurement of electricity; a substance which reduces the flow of electricity.

Reverse Loop - A model railway track which loops 180° to turn trains round to the direction from which they came.

Reversing Switch - Electrical switch which changes the polarity of the electrical supply to the model railway and thus reverses the direction of the locomotive.

Rolling Stock - Anything with wheels on it which can run on the track including locomotives, carriages, freight wagons and maintenance vehicles.


Saddle - The cradle in which the smokebox end of the boiler of a locomotive rests.

Scale - The relationship in size between the model and the full size item.

Scissors Crossover - The facing and trailing crossovers between two adjacent tracks.

Section - In railway terms a length of track, usually between two signals.

Semaphore Signal - A signal that uses a moving arm to indicate the state of the line ahead. Having the signal arm pointed horizontally usually indicates that the next section contains a train. A raised or lowered arm indicates the line is clear. The arm also has coloured filters fitted which are moved in front of a lamp when the signal arm moves to help drivers see the signal at night.

Short Circuit - The negative and positive wires of an electrical supply touching one another. One example of a short circuit is when a metal object, i.e a screwdriver, is placed on the track providing a path for electricity from one electrical circuit to another.

Shunting - The movement required to re-arrange the position of wagons or coaches in a train; to pick-up and set-down wagons in a goods train.

Shunting Signal - A smaller than normal signal that is used specifically to indicate whether or not particular shunting moves may take place. A shunting signal is usually represented on a modern image layouts with a colour light ground signal.

Signal Box - A building from which the surrounding points and signals are operated. May contain either a lever frame or in more modern signal boxes a panel containing switches and coloured lights.

Six-foot Way - The distance between two railway lines on a railway.

Sleeper - The wooden or concrete beam on which the rails rest and are kept in position by a chair.

Slide Bar - The two parallel metal bars or strips in which the crosshead slides, forming part of the valve gear.

Solenoid - The effect of a current passed round the coil of a solenoid producing a forced magnetism which pulls the solenoid’s centre core down, providing energy to operate points and signals. A solenoid is similar in action to a relay.

Spectacle Plate - Windows at the cab front enabling the driver and fireman to have forward vision.

Speed Steps* - A variable voltage increase used to control motor speeds. Decoders can set the output power for each speed step.

Splashers - The coverings on the upper part of a footplate protecting the driver and fireman from being splashed by rain or mud.

Spur Drive - The drive through a chain of gears.

Spring Motor - A clockwork mechanism.

SR – Southern Railway

Stall Current* - Stall Current is the maximum current draw in amperes that a locomotive is capable of when stalled. If the armature of a motor is prevented from turning and the maximum voltage is applied the current draw of the motor is known as the “Stall Current”.

Starting Signal - An extra signal placed at the departure end of a platform to allow trains to run into the station and stop, even though there is a train in the next section.


Three Aspect Signal - A colour light signal using three lights. From top to bottom, in order, the lights are green, yellow and red. A red light means the next section contains a train. A yellow light means the next section is clear but there is a train in the following one. A green indicates the next two sections are clear.

Throttle Notches - Determines whether a locomotive is controlled with 8,14, or 18 speed steps.

TOPS (Total Operations Processing System) - A computer-based program developed by British Rail to monitor the movements of all freight and passenger rolling stock, and locomotives. The system was introduced in the early 1970s to record every movement of freight traffic and non-multiple unit passenger trains. The information is broadcast live to a central computer to form a comprehensive and up-to-the-minute picture of the freight and passenger traffic situation over the whole of the rail network.

Trailing Points - Turnouts (points) or crossovers which are against the direction of travel, i.e. a train has to reverse to pass over them.

Two Aspect Signal - A colour light signal using two lights. A two aspect signal can either be yellow and green, or red and green. As with other colour light signal formations, a yellow aspect means the next section is clear but there is a train in the following one. A green indicates the next two sections are clear.

Turnout - See point.


Uncoupling Ramp - A ramp fitted under or between the rails on a model railway to remotely uncouple rolling stock. It is not a prototypical example, but uncoupling ramps can often be seen in hump shunting yards.

Underframe - The chassis of a wagon or coach.

Upper Quadrant Signal - A semaphore signal which raises its arms to indicate the line ahead is clear.


Valve Gear - The mechanism used to power the driving wheels and pistons of a locomotive. In most steam locomotives the valve gear is exposed, although in Bulleid’s West Country Class, for example, the chain-driven valve gear is enclosed within the body.

Vestibule - The corridor connection between coaches, usually a flexible gangway to enable passengers to pass between coaches in a train.

Volt - An electrical measurement meaning the pressure of electricity in the supply.


Watt - A unit of electrical measurement to describe the energy produced. A watt is the number of volts multiplied by the number of amps.

Wheel Arrangements - The arrangement of wheels on a locomotive. There are many varieties of wheel arrangements for steam and diesel locomotives depending on the number of leading, driving, trailing or load bearing wheels there are.


XpressNet* - A high-speed communication protocol used for connecting Digital input devices together.

XPT - An Australian high speed train with diesel power units at each end similar to the BR Intercity 125 trains seen in the UK. These trains were specifically adapted for Australian conditions, and were introduced in New South Wales in 1982.


‘Y’ Point - A turnout in the shape of a letter ‘Y’; A single track turning into two parallel tracks.


Zoo Keeper - A nickname for a railwayman or woman checking tickets at station barriers.

Z Stop - A comfort stop for passengers travelling in a train not fitted with lavatories.

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