Monday, October 7, 2013

Nene Valley Railway - the lever frame at Wansford, 2013

Deutsche Version dieses Postings

After the Epping-Ongar Railway, my next "heavy duty signalling visit" was at Nene Valley Railway's Wansford station, west of Peterborough. Here is the signal box:

Signal box behind gates, Wansford (NVR), 22.8.2013

Here is its long lever frame:

Lever frame, Wansford (NVR), 22.8.2013

At the very right, four levers deal with the gates of the level crossing just below the signal box. The two rightmost ones are for the small gates, whereas the two on the left unlock the large vehicle gates and the wheel that opens or closes them. Even though the numbers of the levers go up to 60, the frame does not have that many levers—it has been reduced in size when it was installed here, so that the levers now start at 17, and the active ones at 22 ("up first home"):

Gate levers, Wansford (NVR), 22.8.2013

Here are the signal levers for the station's west side. In between, there is a blue-and-brown release lever for the ground frame in the "loco yard," which has the typical shortened handle of an electric release. At the bottom of the levers, one can see that there is a gap between lever 45 and 46. It therefore seems that this type of frames uses units of 15 levers; these units are then installed side by side. This fits nicely with the number of 60 levers (four units), but it does not fully explain that the levers now start at 17: Obviously, the first unit with levers 1 to 15 has not been installed; but somehow, an additional lever with number 16 also got lost somewhere in the process:

Right side of lever frame, Wansford (NVR), 22.8.2013

Here are the levers for the up starter and the shunting signal for leaving the station's main track towards Yarwell Junction in a western direction. Near them, there is an additional lever 35 called "interlocking lever:" Actually, it reversed two trailing points connecting the platform tracks. However, these points proved to be troublesome more than they were useful, and so they were removed. In order to keep the locking logic the same, their lever was kept as an "interlocking lever:"

Signal levers, Wansford (NVR), 22.8.2013

Here are detailed photos of the track diagram. One can see that there are a few track circuits for track segments on the west side that cannot be seen well or at all from the signal box—all other tracks must be visually checked for occupation:

Right side of track diagram, Wansford (NVR), 22.8.2013

Center of track diagram, Wansford (NVR), 22.8.2013

On the left, there is a small gradient diagram of the line (the distances are given in the old miles and chains units), and one can see that the points to a storage siding are not (yet; or no longer) connected to the signal box, but clamped in place:

Left side of track diagram, Wansford (NVR), 22.8.2013

Many levers are not only controlled by mechanical tappet locks, but also by electric circuits. Here is the row of locking bars going through the electrical locks. One can see that most levers can only be locked in their normal position; but that there are two that can be locked reversed, namely the fourth and the tenth. Why would that be so? Counting down the levers in the picture of the signal levers above, one finds that the first one is the release lever for the ground frame: And of course, it has to be locked in reverse if the corresponding release lever on the ground frame has been pulled, so that no conflicting routes can be set at the signal box. As for the tenth locking bar, "I leave the determination of the reason for its reverse locking to the reader."

Many of the locks seen here carry the symbol "SGE," meaning "Siemens and General Electric Railway Signal Co., Ltd." It is interesting that Siemens did some signalling business in the UK, but never defined how signalling circuits are designed there, as they definitely did in many parts of Central Europe:

Electric locks and catch handle switches, Wansford (NVR), 22.8.2013

Besides the electrical locks, there are also many catch handle switches on this frame. The contacts in these switches are used to energize the locking circuits so that the batteries are only cut in when a lever is to be reversed; this considerably reduces the amount of current needed by the signal box's circuits:

Circuit activation contacts (activated by pulling catch handle), Wansford (NVR), 22.8.2013

Like the EOR, the NVR does not (yet?) use Tyer's instruments for block working, but only a single key as a staff on each of the two sections west and east of Wansford. Here is the Annett's key that is used as staff towards the line's end at Yarwell. Locking is accomplished mechanically here:

Annett's key used as staff, Wansford (NVR), 22.8.2013

The key for the section to Peterborough is locked in this electrical lock behind the lever frame:

Staff lock to Peterborough, Wansford (NVR), 22.8.2013

Lever 43, which controls electric points 43A and 43B, is reversed here:

Points+FPL lever 43 is pulled, Wansford (NVR), 22.8.2013

English signals are traditionally moved by single wires. This makes it hard to invent a device that adapts the wire's length with changing temperatures, and so this task is delegated to the signalman. Here is a a wire tensioner, with the corresponding handle inserted for turning the large wheel via the worm gear:

Wire tensioner, Wansford (NVR), 22.8.2013

Wire tensioner, Wansford (NVR), 22.8.2013

On the block shelf, there is a row of signal repeaters—here is one of them for the signal farthest away from the signal box. This instrument is crucial when the wire is shortened or lengthened: When it is pulled so short that the arm starts moving upwards (which might be interpreted as clear by a driver!), the repeater moves to the "wrong" position and hence indicates to the signalman that he must not shorten the wire that far:

Signal repeater, Wansford (NVR), 22.8.2013

Bell and signal repeater, Wansford (NVR), 22.8.2013

Electric cabinets on the back wall contain some of relays for the various circuits:

Relays, Wansford (NVR), 22.8.2013

Relays, Wansford (NVR), 22.8.2013

And here is a Tyer's instrument waiting for its future duties.

Tyer's instrument (not yet operational), Wansford (NVR), 22.8.2013

In the next NVR posting, a train will arrive from Peterborough and continue on to Yarwell Junction!

London double deckers and a few lorries, 2013

Deutsche Version dieses Postings

In contrast to many other countries, the UK does not have a statutory limit on the height of vehicles. There is only a recommendation that the height should be limited to 4.95m (16'3"), because new bridges are built with a height of at least 5.03m (16'6"). But even this height is larger than the limits of most other European countries, and so one can see quite high lorries of all kinds on British roads:

A lorry on the A1, 30.8.2013

Another lorry on the A1, 30.8.2013

And a very high one, 30.8.2013

The recommended limit of almost 5m allows the construction of double decker buses with a genuine upper level. If I remember correctly, the most common type of London's double deckers has a height of 4430mm—well below the 5m limit, but still with ample headway for passengers on both decks. Here are a few photos of this famous type of transport:

13 near Tottenham Court Road, 21.8.2013

Rainy weather, 24.8.2013

Rainy weather, 24.8.2013

4 and 25 at St.Paul's, 28.8.2013

25 near St.Paul's, 28.8.2013

Another 25 near St.Paul's, 28.8.2013

220 at Willesden Junction, 28.8.2013

Stratford, 28.8.2013

Friday, October 4, 2013

London Underground, 2013

Deutsche Version dieses Postings

Here are a few pictures from the London Underground.

Piccadilly Line train towards Uxbridge, King's Cross – St.Pancras, 21.8.2013

Even though it is an "underground," it sometimes travels overground:

Central Line trains meet near Hanger Lane, 24.8.2013

On the Bakerloo line, one can see that Underground and Overground are totally compatible, as they are travelling on the same track (and because Overground and usual trains use common tracks at Euston, this means that Underground and "big railway" trains are compatible)! However, the electrical details of this compatibility are a little tricky, as is explained in this Wikipedia paragraph about "fourth rail" electrifications.

Bakerloo Line Underground train at Queen's Park, 28.8.2013

Overground train at Queen's Park, 28.8.2013

But let's again dive into the dark tunnels!

Signal A.781, Northern Line, Embankment, 24.8.2013

Station sign, Northern Line, Embankment, 24.8.2013

A train navigates the tight curve at Embankment on the Northern Line:

Northern Line, Embankment, 24.8.2013

Northern Line, Embankment, 24.8.2013

When the doors open, it is indeed necessary to "mind the gap"—the central door of each car is almost half a yard away from the platform edge:

Northern Line, Embankment, 24.8.2013

And at last, here are a few pictures from the end of the Northern Line at High Barnet:

Northern Line, High Barnet, 28.8.2013

Northern Line, High Barnet, 28.8.2013

Northern Line, High Barnet, 21.8.2013

Thursday, October 3, 2013

Epping-Ongar Railway, 2013 - North Weald with a tour on the 4141

Deutsche Version dieses Postings

Here we are at North Weald again—4141 has pulled our train back from Ongar:

4141 has arrived at North Weald, 19.8.2013

Having been in North Weald's signal box before, I wandered around the station to get a few shots of signals and other bits and pieces.

When I approached the up loop starter, the diesel engine just pulled in with its train:

2012 arrives from Epping Forest, North Weald, 19.8.2013

Here is the signal again, first its top ...

Up loop starter, North Weald, 19.8.2013

... and then the tension weight at the bottom:

Counterweight at up loop starter, North Weald, 19.8.2013

The following short video shows the—obvious—movements when the signal is cleared so that 4141 can leave its train and move back to the main track:



For flank protection of the main, there is a derail in the loop track at this place:

Derail, North Weald, 19.8.2013

The derail is moved by a electro-hydraulic motor:

Derail hydraulic motor, North Weald, 19.8.2013

Derail hydraulic motor, North Weald, 19.8.2013

Going to the platform on the other side, I took this photo of the large diesel and the ongoing work on the water crane:

D6729 and water crane foundation, North Weald, 19.8.2013

At the shed tracks, a ground frame controls a set of points and two shunt signals. The frame is released from the signal box via lever no.6, which is of course only possible if the points 5a and 5b are in their normal position, i.e., aligned for the main track and providing flank protection for moves there:

Ground frame, North Weald, 19.8.2013

Here is the up bay starter and, below it, the shunt signal controlled from the ground frame:

Up bay starter and shunt signal, North Weald, 19.8.2013

The counterweights are higher up, and two angled cranks deflected the signal wires' movements by 90 degrees:

Counterweights at up bay starter, North Weald, 19.8.2013

Here are the wheels that send the signal wires to their corresponding frames:
  • On top, the wire for the shunt signal goes towards the ground frame.
  • On bottom, the wire for the up bay starter is deflected to the signal box.

Chain wheels for shunt signal and up bay starter, North Weald, 19.8.2013

More signals: The up starters for the loop and the main, ...

Up starters, North Weald, 19.8.2013

... a fog repeater for the down loop starter, ...

Fog repeater of down loop starter, North Weald, 19.8.2013

... and at last the down starters towards Ongar (as one can see, the EOR has quite a mixture of signals: Upper quadrants and colour lights at North Weald, a lower quadrant at Ongar ...):

Down starters, North Weald, 19.8.2013

When I went back to the station, I asked the driver of the 4141 something about its valve gear—which netted me an invitation to a ride on the engine! Here is the engine, waiting for its next turn:

4141 rests at platform 2, North Weald, 19.8.2013

Shortly later, the reversing lever has been moved fully backwards (in the background, two of the green buses of the EOR can be seen):

Reversing lever on 4141, North Weald, 19.8.2013

A short time later, the down starter is cleared by the signalman for the move, ...

Down main starter cleared for 4141, North Weald, 19.8.2013

... and we move out of the station:

4141 shunts at North Weald, 19.8.2013

We run behind the shunt signal and wait for its clearing—I have used the video of this in my first posting. A moment later, we start moving towards our train—and even though we do not move that fast, the leaves outside seem to fly by on this picture:

Engine driver of 4141, North Weald, 19.8.2013

We pass the storage sidings on the east side ...

4141 shunts to its train, North Weald, 19.8.2013

... and rumble over the points into the loop track:

4141 shunts to its train, North Weald, 19.8.2013

The driver brakes the engine with the air brake ...

(Main valve) and brake handle, North Weald, 19.8.2013

... and finally, using a few short jerks of the main steam valve, moves the engine against the coaches:

Driver moves 4141 to train, North Weald, 19.8.2013

And that's it from the EOR—at this point, the battery of my camera was totally depleted, and so I had to stop taking pictures!