- This article relates to the connection bar used in railways. For the type of Greek pottery, see Fish plate.
In rail terminology, a fishplate or joint bar is a metal bar that is bolted to the ends of two rails to join them together in a track. 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.
The device was invented by William Bridges Adams
in May 1842, because of his dissatisfaction with the scarf joints
then in use. It was first deployed on the Eastern Counties Railway
in 1844. He patented his invention in England, Ireland and Scotland but, supposedly by some underhand means, the patent shortly afterwards passed to James Samuel
, the engineer of the ECR.
When railway lines are equipped with track circuits, or where the line is electrified for electric traction, the electrical connection provided by fishplates is too poor and unreliable and has to be supplemented by bonding wire which is spot welded to the two rails either side of the joint.
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
- Ellis, C. Hamilton (1958). Twenty Locomotive Men, Ian Allan Ltd, London.