Left.The sending instrument in the loco yard. The box on the
left contains a "speaking instrument" (telephone). Note the levers outside
the dial of the instrument making it resemble a ship's steering wheel!
Right.The receiving instrument situated on the shelf in the
Signalbox. The bell on the top strikes once for each position the pointer
passes.
When the running foreman (or other authorised person) needs to send a
request to the signalman for a particular move to be set up he has to carry
out the following procedure:-
First he will need to pull towards himself the lever adjacent to the
appropriate tablet and then he has to push away from himself the lever by
which the pointer is currently resting. The pointer will now run around the
dial until it reaches the lever that was pulled and then remain in that
position. The "Receiving" instrument in the Signalbox will step on in unison
with the "Sending" instrument whilst a bell will sound one beat as it reaches
each tablet. If the destination tablet occurs less than five points from
where the pointer is resting then the mechanism and pointer must be allowed
to travel a complete circuit of the dial to the "new" description. To do this
the levers are worked in the opposite order so that the lever adjacent to the
appropriate new description is pulled out after the pointer has passed that
description.
Upon receipt of a destination (other than "Cancel") the signalman must acknowledge the receipt by sending five beats on the appropriate bell key regardless of whether or not he is in a position to make the described movement. Upon receipt of the "Cancel" indication, the signalman will acknowledge this by one beat on the appropriate bell key.
As with all things mechanical, it does sometimes happen that the two instruments can become out of phase. In this situation the instrument should not be used until such time as an engineer from the S&T Department has corrected it.
Text and Photos Copyright © Peter Richards.