This and the next few postings in my blog show pictures from our 2013 vacation. Via the forum at signalbox.org, I got a list of perfect locations to visit in the vicinity of our stay at South Mimms, and at all these locations I found nice people also interested in that strange hobby of signalling. As always, I'll interleave my pictures with some text that explains what's going on. However, because England is not really my home turf, I hope that I do not make too many errors—and I'd be happy if I get comments that help me to correct at least the grossest ones! The order in which I present the pictures is a mixture of "by topic" and "by time," so don't be astonished if photos taken obviously in one place and at one time turn up in two postings far apart.
My first visit was to the Epping-Ongar Railway just north of London. A helpful conductor, two well-informed signalmen and finally a driver who gave me a ride made this the first pleasant experience.
Here is North Weald's signal box on platform 1, on the opposite side of the station building:
Signal box, North Weald, 19.8.2013
Signal box, North Weald, 19.8.2013
Inside, there is a Saxby and Farmer lever frame in bright colours, as you can see in the next picture.
Lever 17 has an interesting inscription: Calling on to the main track requires points 14 reversed, and shunting into the storage tracks needs points 16 reversed; but a move into the loop is possible without reversing any other lever, which is indicated with the (originally Latin) word "nil."
As is customary on English frames, the levers for colour light signals have been shortened a little bit. However, the levers for all the points have kept their long handles, even though all the points at North Weald use electric (actually, if I observed it correctly, electro-hydraulic) point machines—from my limited knowledge of English practices, I would have expected that also their levers would have been cut back:
Lever frame and signal repeaters, North Weald, 19.8.2013
Here is a proof of the Saxby & Farmer origin:
Lever frame detail, North Weald, 19.8.2013
The track diagram shows the layout of the station—the up calling signal, which is cleared by lever 17, is right below the up inner home, marked 20, at the end of track circuit "LN." On the diagram, one can see that the loop at platform 1 is occupied, and also the bay at platform 3. The latter is steam engine 4141, which will be going in front of the train in the loop and hence has to zig-zag through the station soon:
Track diagram, North Weald, 19.8.2013
A short time later, steam engine 4141 starts its zig-zag tour. First, the pair of points leading from the bay to the main are reversed with lever 5, and the up starter of the bay track is cleared:
Lever frame, North Weald, 19.8.2013
On the east side of the station, points 14 have already been aligned for running through on the main track:
Lever frame, North Weald, 19.8.2013
But nothing is moving out there yet:
Looking outside on the east side, North Weald, 19.8.2013
Over the coaches of the train, one can see the cleared bay starter and a tiny puff of steam where 4141 starts to move:
4141 moves, North Weald, 19.8.2013
Shortly later, its axles shortcut track circuit DN on the main track, which lights the corresponding double lamps (a wagon left in the bay keeps the lamps on there):
4141 occupies main, North Weald, 19.8.2013
On the other side, the down main starter is already cleared. Its signal wire is a little long, so the arm seems a little hesitant to go all the way up to the clear position:
Down main starter cleared for 4141, North Weald, 19.8.2013
And here's the engine coming down the main track:
4141 on its way, North Weald, 19.8.2013
Now it is going over points 14 (or has already gone past them), which occupies track circuit KN:
4141 occupies KN, North Weald, 19.8.2013
However, we have to wait until it is past the up calling signal (that lever 17 from above) until we can safely reverse the points—ok, now:
4141 at LN, 14 can be returned to normal, North Weald, 19.8.2013
Signal 17 can be cleared to the loop:
And a short time later, 4141 moves up to its train:
4141 arrives at train, North Weald, 19.8.2013
In the signal box, I was allowed to take a look below the floor. The covered tray which has those "spokes" is the lower locking bed; there is a second, upper one whose cover can be seen looking out under the boards just a little bit. Two levers have been reversed, and their corresponding "tappets" have been pushed through the locking beds:
Frame with open locking bed, North Weald, 19.8.2013
Here are the two tappets of reversed points lever 14. One can see a cut-out in the lower tappet, but the magic of the locking bed is below its cover. In a later posting, I will reveal a little bit of how this type of mechanical logic does its work:
Reversed points lever and tappets, North Weald, 19.8.2013
Here is another view of a part of the locking bed. The upper tappet obviously consists of two bars on top of each other: I do not know the reason for that—is it for "repairing" the superfluous cut-out visible in the lower bar? But surely, making a new tappet would not have been too much work. Another idea!: The upper bar is narrower than the actual tappet—could it move from side to side a little to achieve some additional locking which would have required too much space in the existing locking bed? Might be—one would have to take a look at the locking charts to find out!
At the upper end of the picture, one can see a few of the relays used for controlling the points machines and the colour light signals:
Locking bed, North Weald, 19.8.2013
Here are the tappets of reversed lever 21, which have quite a lot of cut-outs. This indicates that this is a signal lever, which is locked in its stop position by quite a lot of other levers of the frame—a look at the track diagram (or the lever plates) confirms this: This is the up outer home, which here has been cleared for a train from Ongar:
Tappets of lever 21, North Weald, 19.8.2013
And here it comes: The signalman has gone out to the level crossing to get the staff (one can see the driver at the open door, if one looks carefully). In the meantime, 4141's driver is busy oiling the top hinge of the Stephenson gear:
Staff passing and oiling going on, North Weald, 19.8.2013
A short time later, the signalman carries the token (actually, currently, a key is used) in his right hand to the signal box:
The staff is brought in, North Weald, 19.8.2013
So much for a first series of pictures that I have described with some connecting stories. I took some more photos—below are some of the more interesting devices and instruments at the signal box; other parts and pieces will follow in another posting soon.
Here is the "king lever" which can be used to cut out the box after having aligned all points and signals for the main track (a virtually identical device on Austrian interlockings is the "Nachtsperre" or "nightly closing" which can been seen on photos in my blog in German). When I find time, I might describe its working—but not until I have understood how its locking (or rather unlocking) actions are accomplished, which seem to me somewhat tricky because they have to override otherwise necessary locks between conflicting signals:
King lever and neighbours, North Weald, 19.8.2013
The EOR owns a few Tyer's instruments that have been set up at the signal boxes. However, they are not yet operational—instead that key shown above is used, which however limits shunting at Ongar severely; but plans are already drawn for upgrading signalling at Ongar and cutting in the token instruments:
Tyer's instrument, North Weald, 19.8.2013
Of course, a precise clock is important for railway operations. The key for winding it up is right next to it (but I wonder: Does someone come over and wind the clock every day, even when there are no operations going on? Or is the clock allowed to stop, and is wound and set anew if operations start after a few days?):
Clock, North Weald, 19.8.2013
The level crossing below the overpass has small gates for pedestrians, but also large ones for vehicles. As these swing into the track clearance, they need to be locked when signals are cleared. Here are the respective keys for these large gates, which are electrically interlocked with the rest of the frame:
Gate keys, signal repeaters, North Weald, 19.8.2013
Finally, at the signal box, there is also a diagram of the line, using this newfangled idea of kilometres instead of miles and chains for marking the distance from Ongar. One can see that North Weald is the only level piece of the whole railway!
Gradient profile, North Weald, 19.8.2013
This was the first of three postings showing signalling, but also other equipment from the EOR—two more will come soon!
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