Stewart Marchant, 26/08/2010
This bridge was marked as a Hydraulic Swing Bridge on the 1928 OS map. It had been recorded on earlier maps, but not identified as a movable structure.
Most of the swing bridges in Birkenhead Docks were replaced by identical bascule bridges around 1928-31.
All of the swing bridges that I have found details and images for in Birkenhead Docks at that time were hydraulically operated bridges of plate girder construction. Old photogrpahs show most of them as having a double roadway with railway tracks laid in the surface and outside walkways.
Modern maps show that the entrance lock from the Mersey to Morpeth Dock has been filled in, as has the western access to Egerton Dock, so there is no longer any water access to Morpeth or Egerton Docks, which have become an isolated pool. This bridge is still in place although in a very poor state.
The Scherzer Bascules in Birkenheada docks were built to a different design from any other Scherzer Bascules that I have been able to visit. Most Scherzer Bascules - including those crossing the Royal Canal in Dublin, the ones in the old Surrey Docks in London and the Stanley Dock bridge in Liverpool - are operated by a pinion wheel at the pivot point rolling along a rack. In the Birkenhead bridges the beam that is equivalent to the rack acts as a drawbar. At the bridge end these bars are attached to the pivot point and when they are drawn back through or under the motor room the bridge is rolled back on its 'heels'.
|Related Website :