Single Line Instruments

Described below are more of the many forms of Single Line Instrument that have been used by the Southern railways over the years. Once again, this is more of an informative introduction than an in-depth tutorial. These notes are a brief reference to the operation of the Instruments, there are other requirements to fulfil before a Train may be allowed into the section.

An Electric Key Token Instrument

Electric Key Token Instrument This instrument, the Tyer's Key Token, was the most widely used by the Southern Railway and carries out exactly the same function as the Electric Train Staff Instrument, though on a smaller scale. Instead of the Train Staff there are Key Tokens that fit into the Instruments and are carried between block posts in leather pouches attached to a leather-clad metal hoop. To obtain a Key Token, all other requirements having been met, the Signalman raises a Key Token and places it on the spindle under the top indicator. When the Signalman at the other 'box gives him a release, using the chrome plunger on the right of his Instrument, the galvanometer needle in the top indicators will deflect, allowing him to turn the Key Token two quarter turns anti-clockwise and withdraw it from the Instrument, which will set his left-hand indicator to 'Train Going To'. Once the galvanometer needle has returned to the normal position he must give one beat on his plunger that will set the left-hand dial in the other 'box to 'Train Coming From'.

photograph by Peter Richards

Key Token Left: The Key Token. Adjacent sections will have a different colour and shape as well as having each end of the section engraved.

Right: The leather pouch for holding the Token. The Token is inserted so that the colour, shape and section ends are visible through the open window.

photographs by Peter Richards

Token Pouch

Example of Electric Train Staff Instruments | Examples of Electric Train Tablet Instruments
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This page was created 2 January 2004

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