Sunday, 25 December 2011

Sedgeley Junction (again)

I introduced this fascinating signal box in the post Sedgeley Junction. I hadn't located my early notes so I produced a (not very good) box diagram from memory for this post. Because of interest from my friend Phil, I started to expand on this theme in the post Sedgeley Junction Remembered. Eventually, I located a notebook containing notes on traffic movements at Sedgeley Junction which got issued in a whole series of posts called 'Traffic Movements at Sedgeley Junction 1962-1963'. Later still, I found a train register book with detailed timings of some of my visits. I've described this in the post Jan's Train Register Book with a link to the complete document. If this all seems a little backwards, well, it is but after losing the information for half a century, it seems better to try to nail it down in a less-than-ideal manner now.

All this is leading up to saying that I've found more contemporary notes and sketches relating to Sedgeley Junction. Rather than wait another fifty years for these to be converted into a better form, I'll post them as they stand. Once you're familiar with the way a signal box is laid out, it becomes easier to understand any other signal box. In the earlier post Deepfields in Detail, I give an explanation of some of the features of an L&NWR box, and it may be worth referring to that post for more information.

Box Diagram & Block Shelf

The best way to orient yourself in any signal box is to study the box diagram. I've also sketched the layout of the block shelf:-

Sedgeley Junction - Copy of box diagram and sketch of block shelf layout. Click on sketch to enlarge.

At Sedgeley Junction, the block shelf only extended between levers 1 to 30 - the last ten lever positions had no block shelf above. The four L & NWR Block Instruments and the Block Switch (allowing the box to 'switch out') huddled together near the left end of the shelf. The order, from left to right, was Horsley Fields, Dudley Port Junction, Block Switch, Dudley East (Main Lines), Dudley East (Loop Line). To the right of the block instruments, the Box Diagram was suspended from the roof and to the right of the diagram there was the antique telephone and L & NWR Single Stroke Bell communicating with Conygree Siding Ground Frame.

The front face of the block shelf mounted a number of Signalling Repeaters. From left to right there was the Distant repeater for lever 1 (a miniature yellow arm on a brass 'signal post'), the Track Circuit Indicator for TC2205 (discussed below) and the Weight Bar Repeater for lever 7 (the Up Distant from Dudley Port High Level direction). The right hand end of the block shelf was fitted with an indicator for the track circuit. This was in the form of a pointer moving between 'LOCKED' and 'FREE'. To the left of this indicator was a Sealed Release. The front face of the block shelf was also furnished with a number of protruding nails to suspend a number of reminder links used as Lever Collars and 'Train Waiting at Signal' reminders for the commutator of block instruments. As far as I remember, lever 35 (the Down Slot protecting Conygree Siding) and lever 39 (the Down Distant) also had repeaters. In the absence of a block shelf above these levers, each repeater was mounted on top of a vertical tube rising out of the floor behind the frame.

Looking at the box diagram, note that, with the point levers 'normal', both Up and Down roads are set towards Dudley Port High Level (not as shown in my earlier posts). Presumably, this is considered 'safer' as any vehicles running away would be diverted onto a rising, rather than falling, gradient. However, when I was visiting levers 20 and 21 were left reverse for most of the time because that was the way most trains went.

Facing points 18 and 21 were each provided with a mechanical locking bar (to prevent attempted movement of the points when vehicles were passing over). Facing point 30 had been modernised and protection was provided with a track circuit (T1). This track circuit controlled a Back Lock on lever 29 and the associated Locked/Free indicator mentioned above.

Track circuit TC2205 was something of an oddity. I believe it indicated the presence of a train in Dudley Port Low Level station on the Down Line. Since this was in Horsley Fields block section, it wouldn't normally be of interest to Sedgeley Junction. It might have been involved in the control of the electric lock on the Down Walsall Home (lever 38 - the only signal in the box with an electric lock) but I don't know. I can't remember our taking a lot of notice of this track circuit although you'd hear a 'click' as a down train left the track circuit and the indicator moved back to 'TRACK CLEAR'. Originally, the L.M.S. numbered all its track circuits in a single series, hence the rather large number 'TC2205'. But as track circuits started to proliferate, a change was made so that the track circuits for each box were in a 'local' series, starting with T1, without renumbering any existing track circuits.

Levers and Pulls

Then, you need to study the layout of the levers. The colour indicates the function, of course, for instance red for stop signals, black for points and so on. Fixed to the front of each lever is the 'Pull Plate' showing which other levers need to be reversed before that lever can be pulled. Further guidance was given by the text on the Back Plates fixed on a board behind the levers.

Sedgeley Junction - Lever Pulls (First column is lever number, next columns list the 'Pulls', final column gives description as on the Back Plates) Click on sketch to enlarge.

This is fairly straightforward, although I suggest that the pull 'Lever 24 requires Lever 36' is a transcription error for 'Lever 24 requires Lever 35'.

Gradient profiles

It's important that the signalman has a clear idea of prevailing gradients. If a train becomes divided, particularly a 'loose coupled' freight without continuous brakes, it's important that the signalman understands what may happen to any vehicles running away. Gradient profile information is included on the box diagram and is given below.

Sedgeley Junction - Gradient Profiles. Click on sketch to enlarge.

It was a tough slog for freight trains from Great Bridge up to Dudley. The diagram above shows a section of 1 in 62 just outside Sedgeley Junction box. That, combined with weight transfer on the wheelsets of locomotives passing through common crossings on poinwork near the box resulted in many engines 'losing their feet' near the box. In contrast, the line from Sedgeley Junction to Dudley Port High Level was, according to the diagram, a bit of a switchback.