Jan Ford's World: 4 Jan 2012

Wednesday, 4 January 2012

Deepfields Electrical Controls

Deepfields was one of the mechanical signal boxes I got to work (unofficially) in the early 1960s. The box is described in the posts Deepfields and Deepfields in Detail

Click on image to enlarge.

In a series of articles about Spring Vale Sidings box (which was the next box to Deepfields), I discuss the electrical controls applied to this type of signal box. Part 1 and Part 2 are published, other parts are in preparation. I didn't manage to obtain prints of the electrical controls for Deepfields, but I did make rough manuscript copies which appear below. Click on any picture for a larger image.

The principles of electrical control apply everywhere so, if you're familiar with the arrangements at Spring Vale for instance, it's much easier to understand the Deepfields controls.

Drawing Symbols and Labelling Conventions

The symbols for the various circuit elements are, in general, peculiar to railway signalling. Whereas the Spring Vale drawings use the 'old' symbols, some of the Deepfields drawings use the 'simplified' symbols which are probably harder to follow, until you get used to them. The student also has to become familiar with the letter codes used to label components. As in the Spring Vale drawings, a group of letters and figures is used to identify each component. For instance, the designation '20RGCR' means [20][Red][Signal][Proving][Relay]. Once you've mastered the principal codes, understanding diagrams becomes much easier.

The Drawing Set

The set of drawings for Deepfields was numbered CW.125/59/x, where 'x' was the sheet number. These drawings were prefaced by a Contents and Ordering page. The 'Contents' gave details of the drawing pages and I'd got as far as producing a typed version of this list:-

'Ordering' was a brief stores description of the various electrical items:-

Sheet 1 Controls

This information is presented as a table comprising a row for each running line and various columns:-

Line: There is a row of entries for each running line, Up Main, Down Main and Up & Down Goods.
Block Control: Shows that the Berth Track Circuit on the Up Main controls the Block.
Line Clear: Lists the conditions which must be satisfied to be able to give a 'Line Clear'. These conditions are divided into levers in the frame which must be proved 'normal' and actual signal indications which must be proved (by electrical contact boxes attached to signal arms or weight bars for semaphore signals or 'lamp proving' for colour lights).
Annunciator: Shows that the Berth Track Circuit triggers an audible warning if a train approaches the Home Signal when 'on' and shows the time (in seconds) for which the alarm sounds before the lever lock on the home signal is released.
Track Circuits: Lists the Track Circuits associated with each running line.

A second table details the requirements for electric lever locks. A row is provided for each lever requiring a lever lock or circuit controller and various columns:-

Lever and type: Lever Locks [L] may hold the lever Normal [N] or, in the case of Facing Point Locks, Reverse [R}. Lever 1 has a circuit controller for the Green [D] relay [R] controlling Bloomfield's Down Starter. Lever 39 has a circuit controller for the Yellow [H] relay [R] controlling Deepfield's Up Starter.
Lock Proving Contacts: Lists other levers which must be proved via Lock Proving Contacts [LCC].
Track Circuits: Lists Track Circuits which must be Clear or, in the case of certain home signals, occupied before the lock is released.
Block: Lists signals controlled by the Block.
Signals: Lists signals which must be On or, in the case of the distant signal prior to the colour light, Off before the lock is released.
Replaced: Records the criteria for the colour light to be automatically replaced to danger, even when the controlling lever is still reverse.
Notes: Records that lever 1 is a control on a Bloomfield signal and that Sealed Releases are provided for the Facing Point Lock levers.