Friday 13 June 2014

Yangon Central Power Signal Box

Click on any picture below to see an uncropped image.

In 2008 I made my first visit to Myanmar (formerly Burma) and travelled on Yangon's suburban railway. The railway trip is described in the post The Circle Line, Yangon.

In a later post, Yangon Area Railways, I described the colour light signalling on the railways around Yangon. I'd discovered that in January 1946, following severe damage to the railways around Yangon during World War II, an order was placed with Westinghouse Brake and Signal Company for two Style 'L' miniature lever frames for Burma Railways. They were intended for 'Rangoon' and 'Kemmendine'. At that time, I hadn't found the signal box at Yangon (as Rangoon is now called) and I was puzzled about Kyee Myin Daing (as Kemmendine is now called) because I'd seen two mechanical signal boxes there, still apparently in use.

In February 2013, shortly after writing the Yangon Area Railways post, I made another visit to Yangon. This time, I located Yangon Central Power Signal Box and, although confined to public areas, confirmed that the Style 'L' miniature lever frame was still in use. I wrote about this discovery in a post here.

Yangon Central Power Signal Box in 2013.

On my next trip to Burma, my friend Doctor Hla Tun made arrangements on 25th April 2014 for me to visit Yangon Central Signal Box and make a cab ride around the Circle Line. The day is briefly described in the post Exploring Yangon's railways.

The Style L Power Frame

Early miniature-lever Power Frames retained mechanical interlocking between the levers, in a similar fashion to purely mechanical lever frames. But as installations became more complex, the problems of providing mechanical interlocking in the limited space available increased. The Style L Frame introduced by Westinghouse Brake and Signal in 1929 interlocked the miniature levers electrically. This meant that a large frame could be installed in two or more sections, if that was operationally more convenient. For instance, the frame at Waterloo was divided into three sections and that at Crewe North Junction into two sections. In addition, all the interlocking was on the operating floor of the signal box. In front of each lever an engraved description or lead plate was provided. Behind each lever, on an almost vertical panel, are the repeater lamps.

Movement of a lever has two actions:-
1) Through a link piece, the lever moves a horizontal lock slide extending to the rear of the frame. Suspended below the lock slide is a sealed Interlocking Magnet which allows or prevents lever movement. A second, smaller Indication Magnet is also provided.
2) Through bevel gearing, movement of the lever rotates a vertical shaft through 120 degrees. Each shaft can mount up to 36 phosphor-bronze electrical contact bands. Where additional contacts are required, a further bevel gear is provided at the rear of the lock slide, rotating a second vertical shaft at the rear of the frame, allowing a further 36 contacts to be fitted.

For more detailed information, refer to Mr. Francis' excellent book [reference 1].

My visit to Yangon Central Power Signal Box

I was made very welcome by two signalmen, a senior signalman, a regulator and a train announcer. Most had some English. Just as well, because the frame, the illuminated diagram and all the lever description plates were in English. That made it a lot easier for me to work out what was going on. I've noticed before when overseas that because most railways work in similar ways, it's possible to work out quite a lot even if you can't ask questions of the local staff, so I quickly felt at home.
The lever frame dominated the signal box - 143 minature levers in one straight line with an illuminated track diagram behind.

General view of the Style L Power Frame and Illuminated Track Diagram at Yangon.

There were some signs that the frame might be getting 'tired' - occasionally a signalman would 'jiggle' a lever, perhaps because of a sticky lock. The lever description plates appeared to be engraved brass, filled white. All the repeater lamps were, as normal, fitted on the nearly-vertical panel behind the levers. Points displayed the usual 'N' (normal) or 'R' (reverse).

Detail of left end of the frame.

The front access panels were plastic glazed, so all the electrical contacts on the front vertical shafts were visible.

Vertical contact shafts at the front of the frame.

Looking from the rear of the frame, there were similar access panels plastic glazed across the top allowing the lock slides and the associated mechanics to be seen. The interlocking magnets themselves were below the top plate but the positions they occupied were visible. Finally, there were vertical rear access panels, plastic glazed (similar to those at the front), allowing inspection of the electrical contacts on the rear vertical shafts.

Conventionally, the relay room was below the operating floor but I was only able to see it through the vision panel on the padlocked door.

View of the relay room. Racking with large shelf-type relays on the left and cable termination panel on the right.

Operations at Yangon Central Station

It's always interesting to watch operations around Yangon Central station but, of course, the Power Signal Box gives the best view. There are two balconies at the front of the signal box and the signalmen make frequent use of them to check exactly where trains are.

Subsequent changes

Since the visit in 2014 described in this post, the signalling around Yangon has been modernised. The new arrangements are described in the post Railway Operation Control Center, Yangon.

Books

[reference 1] 'The Style L Power Frame' written and published by J. D. Francis 1989 (ISBN 0 9514636 0 8).

My Pictures

Yangon Central Power Signal Box.
You can find all my albums of pictures showing Burma Railways here.

More

Myanma Railways (Index)
You can select all my posts about railways in Burma (in reverse date-of-posting order) here.


There's a post about Crewe North Junction Signal Box here with a little more information about (and more photgraphs of) the Style L Power Frame.

[Minor update & link to 2020 post added 31-Mar-2020]

Peak Rail Update

Click on any picture below to see an uncropped image.

I returned from a trip to Burma on 9th May 2014. There's a series of posts describing the trip (starting at Back to Burma with links to later posts in order). This wasn't a railway holiday but I did manage a visit to the power signal box in Yangon and a diesel cab ride around Yangon's Circle Line (there's a brief description in Exploring Yangon's Railways with links to my pictures).

I had a few days to recuperate before my next footplate turn at Peak Rail on Sunday 18th May.

Events of Sunday 18th May 2014

I was booked with Harvey and we started the day with a footplate experience course. Our trainee was a very pleasant young man who, we discovered, had just married and was with his charming wife. It seemed an odd format for a honeymoon but after the course, they both enjoyed a ride on the train and I managed a picture of them both on 'Lord Phil' at Matlock Town. We extend our best wishes for the future to this couple.

Newly-weds Mr. and Mrs. Yeend on the footplate of 'Lord Phil' at Matlock Town.

The format for the passenger service was five rounds between Rowsley and Matlock Town, top and tailing with 'Penyghent'. The only exceptional event was that the weather remained hot all day and at times it was a bit warm on the footplate.

Before our final departure of the day from Rowsley, the station staff asked us to do our best to be 'right time' at Matlock Town as two lady passengers were hoping to make the connection with the East Midland Trains service at Matlock and make a further connection at Derby as they were travelling back to London. We didn't let them down.

'Lord Phil' at Matlock Town standing next to an East Midlands Trains Class 153.

Events of Sunday 26th May 2014

My next turn was with Dave on Sunday 26th May. We were joined by Jacob, on his first Cleaning Turn. The weekend had been advertised as the Mixed Traffic Weekend. Heritage Shunters Trust were running brake van rides at Rowsley, and they rang the changes on the motive power in use, providing an excellent attraction. But shortage of motive power for the service trains meant than it had been decided to operate only the normal service of five top and tailed round trips between Rowsley and Matlock. 'Lord Phil' was on the south end of the train, with Peter Briddon's preserved 'Teddy Bear' locomotive 14 901 on the north end. Wikipedia has a description of the 'Class 14' here.

It was as well I'd taken my heavy overcoat because the weather was quite different from that on my previous turn described above. On my arrival, the rain was sluicing down and it remained pretty wet all day. When it's raining, it's impossible to prepare a steam locomotive standing in the open without getting thoroughly bedraggled and it took me some time to dry out afterwards. But, leaning out of the cab for better visibility when on the move and taking water periodically during the day at Rowsley means that, as soon as you've dried out, you get drenched again. As I often say "Anyone can work on a locomotive when it's fine but it takes an engineman to do it when it's wet".

Fortunately, by the time we arrived back at Rowsley on the last trip, the rain had stopped, so we were able bring the light engine 'on shed' and dispose without another soaking. Disposal is unattractive enough at the best of times - the fire has to be 'knocked out', ash removed from the ashpan, char removed from the smokebox. There's a brief description of the process in the post MIC - Disposal


Jacob beside 'Lord Phil' at the end of his first turn as a Cleaner.

My Pictures

Peak Rail, May 2014.
You can find all my Peak Rail Pictures here.

More

You can find all my Peak Rail Posts here.