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- ‘A’ 0-8-0 Locomotive Class
- Webb’s first type of 0-8-0 goods engine, of which 111 were built from 1893. They were 3-cylinder compound engines with a huge low pressure cylinder between the frames. The designation ‘A’ was applied retrospectively from 1911. They were all rebuilt by Whale or his successors into 2-cylinder simple engines of classes ‘C’, ‘C1’, or ‘D’. In modified form some lasted into BR ownership.
- Absolute Block System
- The railway signalling system which is based on the principle of dividing a line into sections or blocks. Normally, no train is allowed to enter a section occupied by another.
- Adhesion traction
- Reliance on the weight of the locomotive to provide sufficient grip on the rails for it to draw its train – as distinct from rack and pinion.
- Advance Starting Signal
- A signal in advance of the starting signal, necessary where another line – for example a separate platform line or an exit from a goods yard – converges on to the main line beyond the station.
- Assistant Goods Manager’s Office
- Agricultural Implement Wagon
- A wagon primarily intended to carry agricultural implements.
- Ahrons, Ernest Leopold (1866—1926)
- Author of ‘The British Steam Railway Locomotive 1825–1925’ (Locomotive Publishing Company 1927). A standard work on the subject, for long regarded as a classic. His earlier writings were under the pen name ‘Meteor’.
- Air Brake
- A braking system in which the brakes are applied by compressed air acting on a piston. These brakes are controlled by variation of the pressure in the train pipe actuating a 'triple valve' which causes compressed air from a local reservoir to enter the brake cylinders to apply the brakes or vents the cylinders to release them.
- Association of Independent Railway Preservation Societies — now called the Heritage Railway Association (H.R.A.).
- Alfred the Great Locomotive Class
- A development of the Jubilee class of 4-cylinder compound passenger engine but with a larger boiler. 40 examples were built at Crewe Works between 1901 and 1903. They superseded the Jubilee engines on the heaviest express trains. In 1903 one engine (No.1952 Benbow) was modified to have four independent sets of valve gear in place of the two sets as originally fitted and all forty engines were converted before the end of 1907. See also Benbow class.
- Allan Valve Gear
- A form of valve gear patented by Alexander Allan in 1859 when Locomotive Superintendent of the Scottish Central Railway at Perth and also known as ‘straight link’ motion. Movement is derived from eccentrics on the driving axle. Generally similar to the Stephenson gear but the valve-rod is raised as the link is lowered and the link itself is straight, whereas on the Stephenson gear it is curved. Allan valve gear was used by Webb for many of the passenger engines used on the LNWR.
- Allan, Alexander (1812—1878)
- Works Manager at Crewe Works 1843–53, under Francis Trevithick.
- American Special (1)
- American Specials were the boat trains from Euston to Liverpool Riverside in connection with Cunard line and White Star line sailings (before the companies were amalgamated) mainly to New York. These were afternoon sailings from Liverpool and, before the First World War, down boat trains left Euston at 9.50, 11.00 or 12.00, depending on the sailing time. Up trains left Riverside as soon as possible after the arrival of the ocean liner.
- American Special (2)
- LNWR carriages, of great comfort and with doors at the ends only, similar to The Corridor carriages, built at Wolverton for the American Special trains.
- Anglesey Central Railway (ACR)
- Incorporated 1863. Transferred to the LNWR in 1876.
- Annett’s Lock
- A device on a ground frame which prevents the point levers on that frame from being reversed unless first unlocked by a special key. Once unlocked, the key cannot be removed until the point levers are returned to normal. A similar device, operated by the same key, is situated in the main signal box, but in this case the signals protecting the area operated by the ground frame are locked.