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Southern Signals
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 |
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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 |
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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 |
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This page was created 2 January 2004
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