- This article relates to the connection bar used in railways. For the type of Greek pottery, see Fish plate.
In rail terminology, a fishplate, splice bar or joint bar is a metal bar that is bolted to the ends of two rails to join them together in a track. The name is derived from fish, a wooden bar with a curved profile used to strengthen a ship's mast.[1] The top and bottom edges are tapered inwards so the device wedges itself between the top and bottom of the rail when it is bolted into place.[2] In rail transport modelling, a fishplate is often a small copper or nickel silver plate that slips onto both rails to provide the functions of maintaining alignment and electrical continuity.
[edit] History
The first railway fishplate, patented by William Adams and Robert Richardson in 1847
The device was invented by William Bridges Adams[3] in May 1842, because of his dissatisfaction with the scarf joints and other systems[4] of joining rails then in use. He noted that to form the scarf joint the rail was halved in thickness at its ends, where the stress was greatest.[5] It was first deployed on the Eastern Counties Railway in 1844, but only as a wedge between the adjoining rails. Adams and Robert Richardson patented the invention in 1847,[6] but in 1849 James Samuel, the engineer of the ECR developed fishplates that could be bolted to the rails.[7]
[edit] Electrical connection
Electrically bonded main line 6-bolt rail joint on a segment of 155 lb/yd rail
When railway lines are equipped with track circuits, or where the line is electrified for electric traction, the electrical connection provided by fishplates is poor and unreliable and has to be supplemented by bonding wire fixed to the two rails either side of the joint by spot welding or other means.
[edit] Welded rail
Even though fishplates strengthen the weak points represented by rail joints, improvements can still be made. For example, the joints can be welded together using the thermite welding process.
[edit] Turnouts
The moving blades of a set of points can be connected to the stock rails by looser than normal fishplates. This is called a heeled switch. Alternatively, the blade and stock rail can be a one piece heel-less switch, with a flexible thinned section to create the moving heel.
[edit] Examples of fishplates
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A connector that matches rails of different heights
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Fishplate and electrical connecting wire
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Short rail, sometimes known as a "Dutchman"
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Rusty line across end of the left-hand rail, indicates right-hand rail is higher (mismatch)
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[edit] References
- ^ "Fish 2". Oxford English Dictionary (Second ed.). Oxford, England: Oxford University Press. 1989.
- ^ Morgan, C. D. (1946). "Permanent way". In Pendred, Loughan. The Engineer's Year-Book for 1946 (52 ed.). London: Morgan Brothers. p. 2015.
- ^ Ransom, P. J. G. (1990). The Victorian Railway and How it Evolved. London : Heinemann. p. 224.
- ^ Ransom, P. J. G. (1990). The Victorian Railway and How it Evolved. London : Heinemann. pp. 224 - 229.
- ^ Manby, Charles (ed.) (1857). "Permanent Way". Minutes of proceedings of the Institution of Civil Engineers (London: Institution of Civil Engineers) XV1: 289. http://books.google.com/?id=wx4AAAAAMAAJ&pg=PA273.
- ^ Manby (1857: 273)
- ^ Marshall, C.F. Dendy; revised by R. W. Kidner (1963). A history of the Southern Railway Vol.1. London: Ian Allan. pp. 212.
- Ellis, C. Hamilton (1958). Twenty Locomotive Men, Ian Allan Ltd, London.
[edit] External links
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| Permanent way |
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| Trackwork and track structures |
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| Signalling and safety |
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| Buildings |
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