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Train Glossary

Tablet - A device serving the same purpose as a staff but being in the shape of a flat disc.

Tail Board - An appropriately-marked board, at one time hung on the end of the last vehicle of a train, to indicate to a signalman that the train had not become divided. Later replaced by a lamp.

Tail Lamp - A lamp which all trains must carry on the end of the last vehicle, to indicate to a signalman that the train had not become divided.

Tamping Machine - A permanent-way maintenance machine, consisting of a number of vibrating rods, which, when dug into the ballast, cause the ballast material to pack more firmly under the track.

Tank Locomotive - A steam locomotive that carries its own water supply, rather than towing a separate vehicle for the purpose. Usually indicated by a `T' appended to wheel arrangements when describing locomotives (e.g. 0-6-0T)

Tappet - A valve actuating mechanism used in some early types of valve gear. An oscillating rod would have one or more dogs connected to the rod, each of which would make contact with and move a lever at a pre-determined point of the rod's travel. The movement of the lever would then open or close a valve.

Target - The round disc, which is part of the indication on a ground signal.

Target - A large disc, usually red in colour, which is attached to the gates of a level crossing so that they may be seen from a distance.

Tender - A railway vehicle which is permanently coupled to a steam locomotive, and in which water and fuel are carried.

Tender Locomotive - A steam locomotive that carries its water supply and coal in a tender.

Test Cocks - Taps fitted at various heights to the back-head of a boiler to enable the approximate water level to be ascertained. May also be referred to as try cocks.

TGV - Train a Grande Vitesse is France's high speed electric train with a top speed of 300 kilometres per hour.

Theatre-Box - Theatre-type route indicator. A route indicator in which the indication is made up from a grid of lights.

Thermic Siphons - Longitudinally flattened arch-tubes which are expanded in cross-sectional area near their top ends.

Third Rail - A system of railway electrification in which the traction current is picked up by a skate or shoe which makes contact with a third rail located between or to one side of the running rails, and returned via both or either of the two running rails.

Three-Link Coupling - A coupling between vehicles which consists of three links of a chain. See couplings for more details.

Three-Way Point - Two interlaced sets of points whose combination branches one track into three tracks.

Throat Plate - A downward extension of the front of a locomotive firebox below the boiler barrel.

Tie - A frame or girder member which is under tension.

Tie Bar - A bar joining two points blades together.

Time-Interval Signalling - A long-ago-discontinued system of train signalling, where a signal would be put at danger after a train had passed, but then cleared again after a prescribed interval of time. This system might still be used in emergencies, but only where other safety precautions are taken.

Token - Another term for a staff or tablet.

Top Feed - Some, mainly earlier, designs of steam locomotive fed water to the boiler from the sides or bottom. This resulted in localised cooling and unequal contraction of boiler plates. Many later designs used top feed which fed water through the boiler top onto shallow trays, the water would thus be heated before coming into contact with boiler parts.

Top-light - A small non-opening window above a drop-light.

Track - A pair of parallel rails on which trains run.

Track Circuit - An electrical circuit that includes an insulated section of track. A train occupying the track will complete the circuit by connecting the two rails together via its wheels and axles thus signalling the trains occupation of that section of track.

Track Formation - The under soil on top of which the ballast and track is laid.

Track Gauge - A device for setting the rails of a track the required distance apart.

Track-Gauge - The distance between the inside contact faces of the running rails of a track. The standard track gauge used in the UK is 4 foot 8 inches.

Track Mile - Unit of measure used to indicate how much track is between two places.

Track Possession - Temporary closure of a section of track to normal traffic for maintenance purposes.

Traction Motor - Motor used to rotate the axle of an electric or diesel electric locomotive.

Traction Motor Blower - Fan system used to provide cooling air to the traction motors on electric or diesel electric locomotives and multiple units.

Tractive Effort - A calculated mean draw-bar-pull which a locomotive could exert when working at maximum capacity. Frictional losses in the locomotive itself and its tender (if any) are neglected when formulating tractive effort.

Trailer Car - A coach on a multiple-unit train which does not incorporate driving motors.

Trailing Point - A matter of perspective. If a train would have to reverse its direction of travel to change lines, that would be described as a trailing point. A point which allows a train to change lines without reversing the direction of travel is known as a facing point.

Trailing Wheels - Locomotive carrying-wheels which are in rear of the driven wheels.

Train - A collection of railway vehicles coupled together, with at least one of the vehicles being self-propelled.

Train Approaching - A signalling bell-coded message which is sent to the signal-box in-advance immediately a signalman receives the train- entering-section message from the signal-box in-rear. However, this message is only used at locations where the block section in- advance is very short.

Train Describer - An electrically-operated instrument, by which the type or destination of a train can be passed from signal-box to signal-box in areas of heavy traffic. On older instruments the display usually resembles a clock face around which a pointer moves.

Train Entering Section - A signalling bell-coded message given by a signalman to the signal-box in-advance when a train, which has been accepted by the signalman in-advance, is passing the signal-box of the signalman giving the message.

Train Heating - The heating of coaches has been traditionally supplied by taking steam from the locomotive and piping it through radiators in the coaches. With the introduction of diesel and electric locomotives in the UK special water boilers were fitted to supply the train. More recently electric train heating (ETH) has been fitted to locomotives and coaches, this uses power from the diesel set (usually from a separate generator) or a separate feed from the main transformer on electric locomotives. Electric train heating supplies also power the air conditioning in more modern coaching stock.

Train Pipe - Refers to the continuous brake pipe running throughout a train. See the entries for air brakes or vacuum brakes for details.

Train Out of Section - A signalling bell-coded message given by a signalman to the signal-box in-rear when a train is passing the signal-box of the signalman giving the message.

Train Register - A bound book which is used to record the activities of a signal-box, including each communication sent and received by that signal-box, train movements, staff signing on and off duty, equipment failures and any other significant events.

Train Shed - That area of a railway station in which the platforms and tracks are under the cover of a roofed structure.

Tram Engine - A small steam locomotive in which the boiler is enclosed in an all-over cab, and in which the driving gear is hidden behind all- round protective plates or skirts which reach down almost to rail level.

Tramway - A railway route, usually un-signalled and un-fenced, on which speeds are restricted and on which only tram engines are permitted.

Transition Curve - A curve in a length of railway track in which the entrance and exit to the curve are of larger radius of curvature than the centre of the curve.

Trap Points - A point which is used to deliberately derail vehicles that pass over it when set against them. Typically used to protect running lines from runaways in sidings, it being safer to derail vehicles at slow speed than to allow them onto running lines where they could collide with trains running at higher speeds.

Traverser - A length of railway track secured to a framework which may be moved transversely along rails. Such a device is sometimes constructed outside a wide locomotive-shed so that a locomotive entering from a single approach track can move onto the traverser and then be moved sideways to line up with any one of the shed lines. The purpose of such an arrangement is to save the space needed for a fan of points. Traversers might also be used for the transverse movement of goods vehicles or coaches.

Trevithick, Richard (1771 to 1833) - Richard Trevithick built the first steam locomotive that on 21 February 1804 hauled a load of 10 tons and 60 people over 91/2 miles of tramway from Merthyr Tydfil to Abercynon. With a cylinder bore of 81/2 inches and weighing 6 to 7 tons it was controlled by walking alongside.

Tri-Composite - A carriage with seats for First, Second and Third Class ticket holders. This type of coach is represented in preservation by a LSWR Tri-composite Brake carriage in the National Railway Museum. Second class was abolished, with the exception of Boat trains, in the early years of the century. The Midland Railway started the trend by upgrading all their third-class seats to second-class standard. In 1956 Third Class was re-named "Second", and then again more recently as "Standard".

Trimming - The upholstering of carriage seating.

Trimmings - Wicks made from woollen or other materials which can feed oil by capillary action from a reservoir to a bearing.

Truck - Part of a railway vehicle having its own separate frame and wheels, which is pivoted to the main frame, or suspended from the main frame with a degree of side play.

Truck - Another term for a wagon. An American term for a bogie.

Try Cocks - Cocks fitted at various heights to the back-head of a boiler to enable the approximate water level to be ascertained.

TT Gauge - The Track width of TT Gauge is 12mm.

Tubes - The firebox is the main area for generation of steam, but the products of combustion must then be conveyed to the smoke-box, through tubes. These tubes must be designed to extract the maximum amount of the remaining heat and transfer it to the surrounding water. Too small tubes impose too much restriction on the flow of gasses, too large and not enough of the hot gasses will be in contact with the walls. Similarly if they are too long.

Tumblehome - The curve inwards towards the bottom of the sides of a carriage body. Does not apply to vehicles such as SR Bulleid or BR standard stock which have a continuous curve.

Tunnel Van - A flat-roofed van on the top of which are positioned strike gauges made to the contour of a tunnel interior. By passing this van through a tunnel, any subsidence of the roof or walls will be evident.

Turnout - Another term for a set of points.

Turntable - A length of railway track secured to a pivoted framework which may rotate 360 about a central axis







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