SVR S&T Dept.
SIGNALLING NOTES - Chris. Hall
In the last article, I reported that the rewiring of Bridgnorth box had been completed and the ground frame at Foley Park had been commissioned. Troughing between the motor points and the outer advanced starting signal is now complete. A group of 18 Network Rail staff on a volunteer day pulled a 37-core cable into it, this has the extra cores needed to control the key release instrument at the ground frame, the new location cupboard housing this equipment is ready for installation, just waiting on the Annet‘s key to be engraved (and for the RRV to be available). The telecomms cable for the operators’ phone was also installed.
Approximately ¼″ has been shaved off the left hand side of this lock (designed for 5¼″ lever spacing) by the GWR in 1947 so that it fits snugly between tappets 10 and 11 when lever 10 is reversed. The lock has been ‘posed’ in its midway position but would be driven right by the movement of tappet 10 to its left to butt up against tappet 11 out of sight under top bar 1. [Photo: Author]
A view under the box at Highley showing the existing mechanical locking: above the operating floor all you can see is the original McKenzie & Holland frame. [Photo: Author]
the new fixed locks have been milled to size and here one of them is being drilled so that it can be rivetted to a top bar. Doing this on the radial drill at a relaxed pace in the workshop is more accurate and less stressful than doing it in situ. [Photo: Author]
Once the RRV is available, we will transport the cupboard to site, connect it up and commission it. We must now await another place in the queue to do this vital work. The door on one side of the cupboard will provide access for operational staff to the key release instrument and local indication that the points have been restored to normal after use. The electrical detection box which proves that the points controlled by the ground frame are set and locked correctly has been replaced as the original had been damaged.
In order to allow the ground frame to be electrically released from Kidderminster signal box, a significant amount of re-wiring will be required in the relay room there with six new relays being provided, with a new lever 55 and associated circuit controller, all of which will need to be comprehensively tested before the new location will be able to do more than offer local indication.
The lineside cabinet at the North end of platform 2 at Bridgnorth is reaching the point of needing significant repairs. It was decided to renew the cabinet completely and relocate it in a slightly different position to provide for the signal at the end of platform 2 to be moved further Northwards. This will also allow us better access to the rear of the cabinet as the new cladding on the loco shed currently prevents us fully opening the doors.
The replacement cabinet has now been assembled and is in the final stages being wired and tested in our workshop at Kidderminster prior to being transported to site. The project will also involve the renewal of some of the cables back to the signal box, along with those to the adjacent signals and track circuit connections. It anticipated that this will take place ready for changeover and commissioning during the non-running period next winter.
Making changes to the mechanical locking at Highley (which is GW 5-bar vertical tappet) in connection with the provision of a new disc signal at the north end of the layout has proved a bit of a challenge. The lever spacing is non-standard: although GW 5-bar frames had levers at 4″ spacing, there were many places where older pattern GW frames with spacings of 5¼″ and 4″ were converted to ‘5-bar’. Extra-special locking trays at Highley were needed to accommodate the 5″ spacing of the original 1883 McKenzie & Holland frame. We have therefore had to procure some gunmetal bar from which we can machine the nine fixed locks required by the design. We have plenty of spare sliding locks for 4″ frames and these can be used with a 1″ block screwed to the side. In 1947 the GW solution was to machine down standard locks for 5¼″ spacing - choosing locks that had sufficient material to allow this.
Seven of the nine new fixed locks have been either rivetted or screwed to suitable lengths of locking bar ready for the commissioning in November. The two remaining new locks plus one being reused in a different position will have to be fitted in situ, as will the studs to drive the sliding locks. The shunt signal by the Up Home has been installed, tested and connected to the lever but the lever is secured normal until November - the signal thus remains out of use with no face.
The cam box from lever 6 has been refurbished and fitted to lever 1 and dummy tappets will be fitted in positions 6 and 9. A lever contact box (similar to that fitted to lever 13) has been prepared to fit to lever 5 - this will provide a release for 7 signal when the route is set for the headshunt: at present it is only released for a move onto the single line, once a token has been withdrawn as it can (until November when it will acquire a red face instead of its present yellow face) be passed at Danger for moves into the headshunt.
The platform 1 starting signal at Bridgnorth was straightened up with help from Dave Evans and a RRV. The result of making this signal (nearly) vertical is that the wires then would rub on the sleeping coaches, so these had to be altered as well. Compensators and pins have been renewed at the south end of Arley to rectify a points adjustment problem on warm mornings, seemingly to good effect.
New 110V power supply cables have been installed at Kidderminster box with the intention of removing an earth fault. It turned out the earth fault was elsewhere, and easily remedied, however the cables, some 40+ years old, were not in a good state and so this renewal was worth doing anyway. We have a new volunteer, Steve Pratt, an S&T man with decades of experience, to whom we wish a warm welcome. He got stuck in with this work on his second day working with us.
Presentation of our beautiful signals remains a high priority, so much use has been made of the MEWP earlier in the year to repaint finial balls (the red fades quickly), clean and/or change signal arms and scrub off the green algae that clings to the posts. We have now renewed all the calling on arms on the gantry at Kidderminster with resprays as the old had faded. Bruce Strong and friends are tackling ground discs and locs with wire/paint brushes which is greatly appreciated. The old S&T shed at Bewdley is being smartened up - few seem to know that this is a historic building in its own right, not just a “shed”. It’s all cosmetic of course, but the visitors that come here will hopefully notice and appreciate the effort!
In several places across the railway the track has sunk, meaning that our rodding and signal wires are now rubbing against the rails. This adds friction to the lever and can cause track circuits to fail. We have had to dig and level rollers in places or change rodding joints for deeper sets to counteract this. We assisted Howard Bowling, the Deputy Signalling Manager in strain gauge testing all the levers on the railway and are pleased to report that everything was within specification as “acceptable” even though some pulls, we already knew, are at the heavier end of the range.
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