Block Bell Codes - SignallingWA

What were Bell Codes?
Bell Codes were not the same as the Morse Code used in Telegraphy and Telephony which consisted of series of 'short and long' buzzes or rings. Bell codes used by the Western Australian Government Railways (W. A. G. R.) consisted of a series of 'Beats' separated by a pause of time. An aubible example is given at the bottom of this page.

Why were they used?

How did they work?

Bell Codes were sent by the pressing in of a plunger. A plunger could be fitted into its own wooden case, or in the case of Winter's and Dowson's Block instruments, included in these instruments. For single line working, typically using Electric Staff Instruments, (either miniature or Large type) the plungers were not used, as a 'tapper key' or button was provided on each instrument. In both Electric Staff and Block Instrument systems, Bell Codes were received from the distant station on Block Bell units.

Each press of the plunger or key, resulted in the Bell at the remote location would give one ring, with the reverse also being true.

Note: Some models of early W. A. G. R. Instrument Shelf Block Bells show evidence of their being fitted with 'tapper keys' similar to those used in English Signal Cabins.

When there was more than one Block Bell, how did a Signalman know which one rang?
There were several shapes of Block Bells, each giving its own tone. In most signal boxes, there would only be two Block Bells, and they were set up in such a fashion in each signal box so that the same shape / tone of the bell would indicate the direction of the signal being sent. An example of this, is that that on the Perth to Fremantle line, each signal cabin had the 'round' bell on the 'Up' (Fremantle end) of shelf over the levers, and all of the 'oval' shaped bells were positioned on the 'Down' (Perth end) of each signal cabin. This aided Signalmen whenever they worked in the various signal cabins along the line, and it did not matter whether the signal cabin was orientated differently to its neighbour. The Bells usually had a letter stamped inside to denote the tone of bell they were. The shape of the bells on the South West (S. W. R.) line differed from the Eastern (E. R.) line bells by being a 'conical' (Up End) and a 'cylindical' (Down End) shape as can be seen here in this photo of the bells fitted to the Winters Block instrument at Cannington.