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- Arc Roof Carriage
- 19th century carriage with the roof formed of a simple (fairly flat) arc, sometimes known as a “compass” roof. Like most other railways, the LNWR in the 20th century built larger carriages with low elliptical (”cove”) or high elliptical roof profiles.
See examples in this part of the Carriages exhibtion (and following pages) which show examples of Arc and Cove roofs.
- At Danger
- A signal in the On position I.e. horizontal with a red lamp showing.
- Atlantic Wheel Arrangement
- A generic name for the the 4-4-2 wheel arrangement. See Whyte wheel arrangement.
- Automatic Warning System (AWS)
- A device which indicates the position of a distant signal , or colour light signal, in the cab of a locomotive, and applies the brakes if a caution indication is not acknowledged.
- The steel shaft on which the locomotive wheels are mounted. The axle not only holds the wheels to gauge, but also transmits the load from the Axle-boxes to the wheels.
- 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 Guard
- A modeller’s term (often one word) to describe the hornguides, springs, spring hangers, axleboxes and everything else to hold an axle in place beneath a solebar. The term originated when early models represented this by a single casting.
- Axle Load
- The static weight carried by an individual axle. This determined the routes over which vehicles (especially locomotives) might run taking into account the strength of the infrastructure, that is bridges and track work. From the 1930s it was realised that the dynamic axle load (allowing for the “hammer blow” effect of reciprocating parts) was more relevant and significant.
- 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.
- Aylesbury Railway (AR)
- Incorporated 1836. Transferred to L&B in 1846.