SVR S&T Dept.
http://www.svrsig.org/svr/Iss198.htm

SIGNALLING NOTES - Chris. Hall

S & T Notes - issue 198

SIGNALLING NOTES - Chris. Hall

SIGNALLING NOTES - Chris. Hall

The last article covered our activities up until Half Term week which means that I am so up to date that I am only trying to describe nine weekends of work. Luxury! Re-timbering the deck of the Down Homes at Arley is complete, newly painted signal arms and spectacles have been fitted and the structure repainted (at the moment in undercoat but should be finished by the time you read this).

Down Homes at Arley on 27th March: new timbers have been fitted but the metalwork and dolls are still to be painted. By now they are in undercoat.[Photo: J. Smith]

We have also been refurbishing cranks so that we now hold a number of spare, refurbished cranks and compensators in store. This means that we can replace worn items before they cause any significant problems. It is the Department's responsibility to ensure that the signalling system is operating correctly and safely and that any wear and tear does not affect its safety function. This sometimes means that signals are correctly held at Danger where the signalling system is unable to establish that it is safe for them to be cleared. For example, the electrical locking on the Up Inner Homes at Bewdley North is only released if the electrical detection on the facing points immediately ahead (6B points) is correctly made up (indication is provided in the signal box). Otherwise the running disc (which is ahead of the points concerned) might be cleared but the main arm would be locked at Danger. The indication on the block shelf is provided so that the Signalman would know, after pulling the points but before trying the signal, that the points were not correctly locked and thus be able to restroke the faing point lock (FPL) lever until the points were correctly set and locked.

Some time ago the FPL stretcher on 36 points at Kidderminster (the Platform 1/Engine Line 1 points near the box) had been damaged again and there was a case for it to be replaced by a brand new stretcher. We had procured half a dozen brand new GW insulated FPL stretchers from a local supplier - these make up the majority of the component, leaving just the short piece from the insulation to the switch to be manufactured from 3" x 5/8" steel plate. This has to be a precision job but includes two 90 degree bends - in fact we were within 1/32" after the two bends - and the uncut stretcher was taken to site for the FPL plunger slots to be marked up. A Sunday afternoon possession of platform 1 was arranged with the Signalman to make the necessary disconnections so that we could mark up the new stretcher. After machining the slots, undersized in width and with the safety critical face exactly as marked, another afternoon session allowed us to mark up any further machining required so that the slot would be exactly to specification. On the third visit the new stretcher was fitted, tested and commissioned in little more than an hour.

The brand new insulated FPL stretcher has just been fitted (4 April) and has been tested with the necessary gauges to ensure it is within specification. [Photo: J. Smith]

With the Northern Belle operation now under way - a large source of revenue for the Railway which the Department's work at Kidderminster from 2007 to 2012 had facilitated at fairly nominal cost - we became aware that some problems were being reported on getting 52 points at Kidderminster (the Platform 1/Engine Line 1 points at the buffer stop end) to close up reliably. We knew that long trains were going to be run round in the early hours and that such problems would be particularly difficult to overcome with few staff on hand.

The rodding run to these points is a popular target when coaling engines at Kidderminster, during ash disposal and being driven over by JCBs but this does not normally cause major problems. The only way to track down such a problem is by disconnection so yet another Sunday afternoon disconnection was needed. The same signalman was on duty again so we took great care not to disrupt his breaks, leaving 52 points lever mid-stroke and the points disconnected for most of the day. The 'lead off' crank (outside the box) and the pin joints which connect the crank to the point rodding proved to be badly worn and the pin joint at the compensator, half way along the run, was lifting and jamming. It was a fairly straightforward job to replace the lead off crank with a refurbished spare and to fit new pin joints but the jamming required a new length of point rodding to be cut and the roller casting block had to be dug out and lowered. It took all four of us until 5.30pm to get it reconnected but it was then closing up reliably and correctly every time.

The van that contained the contents of our Bridgnorth stores building when we were evicted from there has now been emptied of all signalling equipment. The new shed at Kidderminster is full to capacity so a major sort out is needed - a wet day job.

Cable corrosion - this time at Bewdley South Down Distant - had caused some minor disruption to signalling. This has been rectified by complete retermination using slack cable which was provided when the cables were installed over 30 years ago - they owe us no favours!

A final reminder that this article, as well as other information on Signal Engineering, can be viewed in full colour here on the unofficial Signal Engineering web site.

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