RISC OS S.V.R. S&T Department RISC OS
http://www.svrsig.org/ diags/S225.htm

Oxford Station North (formerly Oxford Engine Shed)

The box diagram is reproduced with the kind permission of Kidderminster Railway Museum and shows the position in May 1953. Oxford Engine Shed box dates from around August 1915, when a 3-bar tappet locked frame of 96 levers was installed. In December 1930 a facing slip to provide access to the shed from the Down Main was installed and the dog chart and associated locking table, derived from the dog chart, show the situation immediately following this change. A contemporary box diagram (December 1930) is also now included, although this is based on the later diagram so the format of signals cannot be relied upon (for example Down Bay Starting was probably a bracket, not a route indicating signal and the elevated disc reading from the Down Bay Sidings was a bracket). The box was renamed Oxford Station North when the frame was relocked and renumbered, using 5 bar locking in May 1944. In January 1945 the access to the engine shed was improved.

The dog chart and associated locking chart, derived from the dog chart, show the situation in July 1956. The principal changes between May 1953 and July 1956 (i.e. those not shown on the box diagram but included on the locking chart), are the provision of track circuits 12T, 16T and 57T in lieu of F.P.L. bars. This would have affected the locking on signals reading over the F.P.L. in the trailing direction (each way locks removed) and 12 leads 16 (mechanical locking removed and provided electrically). Subsequently 25T was installed in lieu of F.P.L. bar (1957) completing the replacement of F.P.L. bars with track circuits.