Operation
The system required each station at the end of each section to be staffed, the staff member would communicate with the staff member at the other end of the section with a bell code to release a tablet.
To release a tablet at station A to send a train to station B:
- Both machines must be in a closed state
- Operator at station A sends a bell code to station B asking if line is clear for the train.
- If clear operator at station B will repeat the bell code to acknowledge.
- Station A operator holds down the bell plunger
- Station B operator presses his/her switch plunger with one hand, and with the other pulls out the bottom slide half-way; the instrument now shows a "Train Approaching" indication
- Station B operator holds down the bell plunger
- Station A operator presses his/her switch plunger with one hand, and with the other pulls the bottom slide to its full extent; the instrument now shows a "Train on Line" indication and also releases a tablet from the lower slide
- Station A operator hand the tablet to the driver of the train heading to station B
To close up each machine once the train has arrived at station B from station A:
- The train driver hands the tablet to station B operator
- Station B operator draws out the top slide, places the tablet in it, and closes the top and then the bottom slide; the instrument now shows a "Line Closed" indication
- Station B operator sends a bell code to station A (denoting "Train out of Section"), holding the plunger down on the last stroke
- Station A operator holds down his switch plunger, and closes the bottom slide; the instrument now shows a "Line Closed" indication
- Both machines are now in closed states ready for the process to start again for another train
The Tyer's No. 6 instrument was originally a non-restoring design which meant once the tablet had been removed, it had to travel through the single line section and be replaced in its companion instrument to release the section again. This meant that should a train failure occur in the single line section or a shunt beyond station limits, the tablet had to travel to the receiving instrument by foot or horse.
However, there was a way in which a shunt could be performed without removing the tablet. This was achieved by a very similar means of the staff and ticket working system.
Later on as shunting became more complex and the trains longer requiring frequent movements on to the single line section to complete the shunt, many instruments were converted to restoring types, which enabled the tablet to be placed back into the issuing instrument for shunting out of station limits. This increased flexibility and did not compromise safety. It also dispensed with the written authority in the staff and ticket system.
Read more about this topic: Tyers Electric Train Tablet
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