Sunday, 26 May 2013

First solo in Consall 'box

Less than a year ago (see this blog 10th July 2012) as a member of  the Churnet Valley Railway I considered volunteering on the railway with the ambition of becoming a signalman. About a month ago I qualified in that role in Consall signal box (see entry for 27th April on the blog). Today I got to exercise that privilege, rostered as unsupervised signalman at Consall for the very first time.

First time as rostered signalman at Consall

But when I switched on the 'box this morning, it threw me a curved ball. All indications on the instruments were normal, except track circuit '5'. That showed 'Line Occupied', although clearly there were no trains running yet and I could physically see down the line that the section was unoccupied. Track circuits show the signalman the whereabouts of trains under the control of the 'box, and if they fail they 'fail safe', detecting a train that isn't there rather than failing to detect one that is. T5 had clearly failed.

The problem for me was.... the track circuit also informs the 'box's electrical interlocking of the whereabouts of trains. The interlocking therefore 'thought' there was a train in that section, and so would not allow me to clear any signal to allow 'another' train in. The critical signal I would not be able to clear was the up loop starter, signal 9. Oh, and the up main line starter; but that signal would not normally be used today so that wasn't a problem.

The Consall 'layout' (please click on the picture for a larger image). Track circuit 5 is shown as 'T5' in this diagram, and when it is 'on' it is indicating that the orange section of track adjacent to T5 on the diagram is occupied. Signal 9 is the up loop starter, and signal 13 is the up main line starter. With T5 occupied, neither of these signals can be cleared (moved from the 'stop' position) as to do so would allow a train from the up main or up loop lines to enter the occupied section. Note also 'point 6' which controls the route at the 'up' end of the layout. In normal operation, we accept 'down' trains from Kingsley & Froghall (left hand end of the layout) to the main line platform, and dispatch 'up' trains from the loop line platform to Kingsley & Froghall. So signal 13 is not normally used, but signal 9 is crucial.

Since I was unable to clear signal 9, I had to advise drivers of trains about to depart to Kinsley & Froghall that "I am authorising you to pass signal 9 at 'danger', but please visually check that point 6 is correctly set as you approach it since it is no longer protected by the signal" (normally, if point 6 is incorrectly set for an 'up' loop departure, signal 9 would not be able to be cleared. But I've just told the driver to ignore signal 9, so we need to be very careful about point 6!). 

Indicators and lever frame at Consall. T5 track circuit indicator is on the extreme left of the row of instruments above the levers.

Close up of T5 track circuit indicator. It is showing 'Track Clear' (no train present). When a train is present (or the indicator has failed) the black bar swings horizontal exposing the text 'Track Occupied'. That's how it was this morning when I switched on the 'box!

Signalmen are wary of over-ruling the interlocking by authorising train movements that the interlocking is prohibiting. In so doing, you are literally 'unprotected' from making a mistake. On the same day that I passed out as a signaller at Consall about a month ago, a signalman on the Great Central Railway found that he could not clear a signal. He authorised the driver to pass the signal at danger. Click on this link to see what happened:

Derailment at Great Central railway

It seems the reason the signalman couldn't clear the signal is that the point and the trap point it was protecting had not been set. The driver whistles to acknowledge he is passing the signal at danger, but he hasn't visibly checked that the trap point is correctly set.

I certainly didn't want my first day as a qualified signalman to end like that!

The track circuit problem fixed itself by lunchtime, so I was able to take full advantage of the protection provided by the electrical and mechanical interlocking and fully enjoy my first ever day as a Consall signalman!

Just under a year ago, on my first visit to this railway as a potential volunteer, I wrote on this blog:

 Now I have to decide - can I commit enough time to volunteering at the Churnet Valley Railway to make a go of being a signalman there, alongside my volunteering at MoSI and Styal Mill and my tour guide and education work at the Manchester Airport Runway Visitor Park, alongside all my other interests? Today has been a bit of a jolly - a look at the operation as an outsider, enjoying the valley on a gorgeous summer day, riding on the trains, and even a footplate ride on the steam loco. And I got to go home early as well!
The reality will be some turns as trainee, then qualified crossing keeper with fairly long days before getting the opportunity to train in a signal box. The weather will not always be warm and sunny, and in winter it will be dark at both ends of the day and the journey to and from home might be problematical in bad weather.

However, it really would be good to end up a qualified signalman working Consall 'box!

Food for thought!

Well here we are less than a year later - a qualified signalman working Consall box! It took a bit of commitment achieving all the steps along the way (anything worthwhile always does, and it's all on the blog). But hats off to the CVR for supporting me in my ambition, particularly Kevin and Knotty Ted (the rosterers) who gave me the opportunities. Daz on Cheddleton and Apesford crossing training, Pete on checking me out on those and on 'the rules', which enabled me to start signaller training. Howard (especially Howard!), Roger, and the other signalmen who gladly shared their 'box at Consall and their knowledge to train me, and Nick for checking me out in the 'box. I'm so glad I persevered and did it about as quickly as it could be done, I think!

Please click twice on this picture for a fuller image (apologies for the poor quality - it was taken on my phone; but it captures the day!).
It was a lovely summer's day in the valley today; cyclists and walkers on the towpath of the Cauldon Canal making their way to and from the Black Lion pub, the occasional narrow boat on the 'cut' itself, a couple of canoes gently paddling by, and the soothing sound of water tumbling over the weir from the canal into the gently flowing River Churnet. In between train movements I could sit out on the steps and enjoy the peaceful scene; just the thing to maximise enjoyment of my 'first turn' in the 'box!


Monday, 13 May 2013

More grist to the mill

Stretton Watermill
(click on any picture for a larger image)

Last weekend was ' National Mills Weekend' and Stretton Watermill south east of Chester celebrated it with 'Enthsiast Days' on Saturday, Sunday, and Monday. On the last two days, guest millwright Malcolm Cooper was present. I was occupied with Nimrod and Concorde tours at the Runway Viewing Park all day yesterday, so went to Stretton today to meet the millwright to pick up some knowledge about dressing mill stones, and anything else Malcolm could impart. My mate, also named Malc, came with me.

The mill building showing the external overshot waterwheel. There is another such wheel in the opposite end of the building.

The mill pond is formed by the dam, which also acts as the back wall to the mill building

Mill guide Kate Harland explains the operation of the Pit Wheel (the gear attached to the water wheel axle) and the Wallower (the gear that meshes with the Pit Wheel). The large gear at the top of the picture is known as the Great Spur Wheel; it transfers the drive to the mill stones via the small pinions on the Runner Stone drive shafts (the upper, rotating one of the two mill stones in each grinding set). These small pinions are known as Stone Nuts. The frame that contains this mechanism is the Hurst frame; ours at Nether Alderley is relatively new and made of cast iron, whereas this one above is wooden.

The other water wheel at Stretton; this one is inside the mill building and was replaced in the 1800s, so uses cast iron in its construction

One of two sets of stones (inside their wooden encasement, or 'furniture') with a 'horse' frame on top supporting the grain hopper. The stones are driven by the internal water wheel. There are two more sets driven by the external water wheel, though these are not in use at present.

A  mill stone, showing the pattern of cutting grooves in the surface. The stones are used in pairs, the bottom or 'Bed Stone' does not rotate, while the upper or 'Runner Stone' does. The grain is fed into the centre of the Runner Stone and works its way to the edge, getting ground steadily finer as it goes. The surface of the stone is concave, being about 1/4 of an inch lower near the centre than at the edge. This forms a 'reservoir' for the grain to be poured into and 'dressing' the stones (a skilled job done by the Millwright) is mainly concerned with cutting out this 'reservoir', which gets shallower as the stones wear. The outer section of the stones generally wears to match the other stone of the pair and the Millwright will not wish to lose this ideal 'interface', but will perhaps deepen and sharpen the edges of cutting grooves in the stones .

Kate demonstrates the Sifter, which separates the white flour from the courser components of the the output from the mill stones

Two Malcolms! Millwright Malcolm Cooper explains the finer points of the mill's gears
to my mate Malc.

Malc and Malcolm discuss the dressing of mill stones. The length of wood that Malcolm is holding is used to find 'high points' on the stone's surface.

Here's a video of one of the sets of stones in action. The grain is fed in down the 'shoe' which is agitated by the 'damsel' (a 4-sided 'cam' device).
Mill stones working

This video shows the sack hoist in operation. This lifts the sacks of grain to the top of the mill where they can be loaded into the grinding hoppers.
Sack lift in operation

It has been a most informative day out, and enjoyable, too. Thanks to Kate of Cheshire West Council (who run the mill) and to millwright Malcolm Cooper for imparting their knowledge. I know I'll find that useful in my work as a volunteer at our local Nether Alderley Mill (see 16th March 2013 entry on this Blog).

Today was one of cumulus cloud build ups and isolated but heavy showers, so we had left the bikes at home and driven to Stretton in my MX5. We had the top down in lovely sunshine for the outward journey, especially lovely as we went the pretty way through Peover, Lach Dennis, Whitegate, and over the Peckforton hills to Broxton and Stretton. By the time we were coming home, however, the heat of the sun had kicked off the showers and we kept the roof up.