The Swing Bridge stands on the site of the Old Tyne Bridges of 1270 and 1781, and probably of the Roman Pons Aelius.
The previous bridge on the site was demolished in 1868 to enable larger ships to move upstream to William Armstrong's works.The hydraulic Swing Bridge was designed and paid for by Armstrong, with work beginning in 1873. It was first used for road traffic on 15 June 1876 and opened for river traffic on 17 July 1876. At the time of construction it was the largest swing bridge ever built. The construction cost was £240,000
The hydraulic power still used to move the bridge is today derived from electrically driven pumps. These feed a hydraulic accumulator sunk into a 60 ft (18 m) shaft below the bridge; the water is then released under pressure which runs the machinery to turn the bridge. The mechanism used for this is still the same machinery originally installed by Armstrong.
It has an 281 ft (85.6 m) cantilevered span with a central axis of rotation able to move through 360° to allow vessels to pass on either side of it.
The busiest year of operation was 1924 when the bridge was rotated 6,000 times unlike current use where it is only required to turn occasionally to allow yachts and pleasure craft to pass by and on the first Wednesday of each month as a maintenance exercise.
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