Abt System
A rack-and-pinion system where the rack has two closely-adjacent
staggered rows of teeth.
Adams, W
Chief Mechanical Engineer for London & South Western Railway (1878-1895)
Adhesion factor
The ability of a locomotive to pull a heavy train without slipping.
Mathematically this factor is given as the ratio of the total weight resting
on the driving wheels of the locomotive to the tractive effort
of the locomotive.
Advance direction (or in advance)
Forward from the location, in the normal direction of travel, for the line in
question.
Advanced-starting signal
Where it is necessary to have two or more consecutive starting signals
within station limits for any particular line, the furthest advanced of
them is the "advanced starter".
Air bags
Slang term for the flexible pipes used to connect air brake systems between
vehicles.
Air brakes
Each vehicle of an air braked train will have a cylinder with pressurized air
on both the `train pipe' and `reservoir' sides of the piston while the brakes
are off. The brakes are applied
by releasing the pressure in the train pipe side, the resulting pressure
differential will put the brakes on. The pressure is originally supplied from
the locomotive via the train pipe and a one-way valve ensures that the
reservoirs on each vehicle are pressurized. The train pipe runs the length of
the train thus providing a fail-safe system should the train part.
Airfield Line
Marketing name for the Coventry Steam Railway Centre, a standard gauge
railway line in Warwickshire built on a `greenfield' site.
ALCO
See entry for American Locomotive Co.
Alexandra (Newport & South Wales) Docks & Railway
A standard gauge railway with only 9 miles route, but with running powers over
a further 100 miles. The company was incorporated in 1865. From 1897 it
included the Pontypridd, Caerphilly and Newport Railway.
It was absorbed into the Great Western Railway on 1 Jan 1922 as a result
of the grouping.
Allan straight-link motion
A valve gear combining the features of Stephenson and
Gooch valve gear, but where the expansion link
and radius link move up or down together in opposite
directions to obtain reverse. The name arises from the fact that the
expansion link is straight in this valve gear instead of curved as in other
valve gears.
Allgemeine Eletricitaets Gesellschaft (AEG)
A locomotive building company.
American wheel arrangement
A locomotive which according to the Whyte classification
is of the 4-4-0 wheel arrangement.
American Locomotive Co. (ALCO)
A locomotive building company.
Andrew Barclay & Son
A locomotive building company based in Kilmarnock, Scotland.
They took over John Fowlers in 1968 and were themselves later taken over
by Hunslet.
Annett's Lock
A device on a ground frame which prevents the points
levers on that frame from being reversed unless first unlocked by a special
key. Once unlocked, the key
cannot be removed until the points levers are returned to normal. A similar
device, operated by the same key, is situated in the main signalbox, but in
this case the signals protecting the area operated by the ground frame are
locked.
Archbutt, R.C
Chief Mechanical Engineer from 1913 to 1930 for the former
Somerset & Dorset Joint Railway.
Armstrong Witworth & Co. Ltd
A locomotive building company based in Newcastle upon Tyne.
ARPS
See Association of Railway Preservation Societies
Arrols
A locomotive building company based in Glasgow.
Articulated locomotive
A locomotive which is made up of several units, with each unit being pivoted
to the next unit. Each unit is on a separate frame which is free to swivel
relative to the frame of the next unit.
Ash Pan
Fitted below the firebox of a steam locomotive to catch the hot ashes falling
from the grate. Typically a flattish tray with flaps known as dampers, which
are used to control the admission of air to the fire from
below. Later steam locomotive designs had hopper type ash pans which could be
emptied much easier than the older type.
Ashford Works
Main works for the former South Eastern & Chatham Railway.
Ashover Light Railway
A former 2 foot narrow gauge railway in Derbyshire, it was built in 1925 and
closed down in 1950.
Aspinall, John A.F
Chief Mechanical Engineer from 1886 to 1899 for the former
Lancashire & Yorkshire Railway, he then became General Manager until his
retirement in 1919. Born 1839. Died 1937.
Associated Equipment Co. (AEC)
A locomotive building company based in Southall, London.
Association of Independent Railways (AIR)
Now merged with the Association of Railway Preservation Societies to form the
Heritage Railway Association
Association of Independent Railways and Preservation Societies
Former name of the
Heritage Railway Association
Association of Railway Preservation Societies (ARPS)
Now merged with the Association of Independent Railways to form the
Heritage Railway Association
Atlantic Locomotive
A locomotive which according to the Whyte classification
is of the 4-4-2 wheel arrangement.
Atmospheric railway
A long-ago-obsolete system of railway motive power where traction is achieved
by special vehicles which have a piston hanging underneath their bodywork
fitting into a continuous tube located between the running rails. These tubes
have a continuous slot along their upper surface which is sealed by a leather
flap. Air is sucked out of the tube by stationary pumping engines in such a
way that atmospheric air on one side of the piston drives the vehicle along
against the vacuum on the other side of the piston.
Auto-train
A locomotive-powered train which may be driven with the locomotive either
hauling or propelling one or more coaches. When propelling coaches, the train
is driven from a special compartment at the front of the leading coach, where
some of the driving controls are duplicated.
Automatic block
A block section in which operation of the signals is fully controlled
by track circuits.
Automatic block signal
A signal controlling the entrance to an automatic block.
Automatic Train Control (ATC)
An early system invented by the Great Western Railway in 1910
to give drivers an audio warning of the status of the signal ahead.
Automatic Warning System (AWS)
A system provided to drivers to give an audio visual indication in the cab of
the status of the signal ahead.
In the UK this system briefly works as
follows; As the train approaches the signal it passes over a ramp between the
rails, in which are placed two electromagnets (or a permanent magnet and an
electromagnet). If the signal is green both magnets are detected by a receiver
mounted between the axles. This causes a bell to ring and a warning disk shows
a black aspect. If the signal is anything other than a green, only one
magnet is detected which sounds a horn and a black and yellow aspect is shown.
In this case the driver needs to accept the warning by pressing a button,
otherwise the brakes will be automatically applied to stop the train.
Auxiliary signal
Early name for a distant signal.
Auxiliary Steam Valve
Controls the supply of exhaust steam to the exhaust steam injector.
See Injector for diagram and more details.
Aveling Porter
A locomotive building company based in Canterbury, Kent. They are better
known for building traction engines and steam rollers, than railway
locomotives.
Avoiding line
A railway route which diverges from a main route and rejoins it again at
another location after avoiding an area of congestion.
Avon Valley Railway
A preserved standard gauge railway near Bristol.
Avonside Engine Co.
A locomotive building company based in Bristol, they were taken over by
the Hunslet Engine Co. in 1935.
Axle-hung
A system of electric motor suspension in which the weight of the whole motor
is taken on the axle which is being driven.
Axlebox
This provides the bearing between the axle and locomotive frame. These were
usually simple bearings designed to take the load (for driving wheels) of the
alternating piston thrusts as well as the weight of steam locomotive. They were
mounted in vertical slides within the frames and sprung to allow for uneven
track. Relying upon a simple film of oil for lubrication, it was not
uncommon for an axle box to overheat and seize (hence the term `hot box').
Later designed steam locomotives and diesels use roller bearings.
Axle Weight
The weight carried on any axle of a train. The maximum allowed would be
limited by the track design, bridges and other structures on the line.