Mechanical railway signalling installations rely on lever frames for their operation to interlock the signals, track locks and points to allow the safe operation of trains in the area the signals cont
A mechanical lever frame inside the signal box at Knockcroghery in Ireland
Waterloo station A signalbox, LSWR (Howden, Boys' Book of Locomotives, 1907)
Lever frame of the signal box Hausen im Tal, Germany: the signals are operated by the red levers, black levers with Arabic numerals are for points and blue levers with Roman numerals are for track locks. The box on the right of the lever frame is used for manual block signalling; the smaller green levers are used for operating the route locks. The interlocking apparatus is in the box behind the levers.
A three-lever ground frame at Kyle of Lochalsh, released by Annett's key
Severn Bridge Junction is the area of railway lines just south east of Shrewsbury railway station, in Shropshire, England. It is controlled by a mechanical interlocked signal box of the same name, whi
Severn Bridge Junction as viewed from Shrewsbury Castle
A 1912 Railway Clearing House Junction Diagram showing (right) railways in the vicinity of Shrewsbury. Severn Bridge Junction is indicated as S.&H. & S.&W.'TON JN
The signal box as viewed from Shrewsbury station. Shrewsbury Abbey is in the background.