Electric train staff: Difference between revisions
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== Operation == |
== Operation == |
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The staff instruments at either end of a section are connected by a pair of wires, which may also be used for a telegraph or telephone circuit. With no staff out, the two machines have the same polarity, which allows a staff to be extracted at one end or the other. Once extracted, the instruments have opposite polarity, which |
The staff instruments at either end of a section are connected by a pair of wires, which may also be used for a telegraph or telephone circuit. With no staff out, the two machines have the same polarity, which allows a staff to be extracted at one end or the other. Once extracted, the instruments have opposite polarity, which prevents another staff being extracted, hence the safety element of the system. |
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Each staff is labelled with the names of the stations at either end of the section, plus a number. |
Each staff is labelled with the names of the stations at either end of the section, plus a number. |
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Revision as of 11:13, 20 October 2016
Electric Train Staff is an improved and more flexible version of the older Train Staff and ticket system.
Two machines are installed at either end of a single line section, and while each machine can hold several staffs, the machines are electrically interlocked so that only one staff can be released at a time.
Operation
The staff instruments at either end of a section are connected by a pair of wires, which may also be used for a telegraph or telephone circuit. With no staff out, the two machines have the same polarity, which allows a staff to be extracted at one end or the other. Once extracted, the instruments have opposite polarity, which prevents another staff being extracted, hence the safety element of the system.
Each staff is labelled with the names of the stations at either end of the section, plus a number.
Staffs in a section have a particular arrangement of rings, a bit like the wards on a key, which prevents a staff being restored incorrectly to an adjacent section. There are typically three wardings so that sections can be amalgamated or divided as required, without having to alter the wardings of all sections in a cascade fashion.
The original Electric train staffs were quite large and heavy, but a miniature version was eventually introduced.
When a train arrives to make a crossing, the staff should not be handed directly to the waiting train in the opposing direction, but rather, should be put through the machine, extracting a staff of a different number. This rule is necessary to give the opposing station a chance to decline to accept that train for any reason.
Intermediate ETS
Where there are intermediate sidings, and it is desired to lock away a train, clear of the single line section, intermediate machines can be provided.
The siding points may be released by an Annett Key mounted on the end of some or all of the Electric Train Staffs, or a Drawer-lock Release.
Electric Tablet
Slightly older than ETS is the electric tablet system, which also has two machines at either end of a single line section.