SVR S&T Dept.
SIGNALLING NOTES - Chris. Hall
During the operating season there is usually less to report while we carry out the routine mnaintenance and testing and attend to any reported defects. The larger jobs tend to happen in the close season.
A spare token machine has been refurbished and used to replace one of the token machines at Hampton Loade - this job was done on a non working day mid-week so that the necessary disconnection and testing could be performed without interrupting the service. The section signal post at Bridgnorth has received a coat of paint and the backstop casting changed. A new white sighting board has been fited to the Down Home signal there. This sort of work is like most of our work - invisible to passengers and staff - but is part of routine refurbishment and replacement of worn equipment.
Bewdley North Down Main Inner Home signals have their balance levers out of sight in a pit under the platform and these had become extremely work so that the main and drive pivots were operating in elongated holes. In September the Tenbury signal was disconnected and a temporary balance lever fitted to the main signal to allow the two worn balance levers to be removed. A much needed coat of paint was applied to the hidden parts and the worn holes were machined and re-bushed. These were refitted on October 23rd between trains, diverting one train to use the Back Road during the work.
Looking ahead, we will be installing a temporary Up Distant at Arley consisting of a reflectorised board mounted on point rodding. This is to allow the existing signal to be removed, the post cut down and reinstated in a metal 'boot'. The FPL bars on the yard points at Arley will be removed to allow the worn hangers to be replaced by refurbished ones - this will be a November job requiring a possession whilst the service is not running south of Hampton Loade (Steam in Lights).
In November the points from platform 2 to EL2 (42 points) at Kidderminster are being renewed like-for-like involving us in the disconnection and recommissioning. It has not been possible to take the opportunity to move the fouling point for platform 2 closer to the footbridge, so the installation of the Radyr bracket is still waiting in the wings. The temporary platform 1 starting signal has lasted well, now some 38 years on.
In January there will be some major work at Bridgnorth as the pointwork at the south end of the station is renewed and the switches on the bridge (12 points) brought sixty feet closer to get them off the bridge. This involves minor alterations to the rodding run and a lot of temporary recoveries and replacement of cranks and will allow a temporary speed restriction to be removed. This is at the planning stage with both P-Way and Signal Engineering Departments involved. We are pleased to welcome new volunteer Simon Hopkins to our ranks who brings a wealth of mechanical signalling expeertise with him.
It is easy to think that all of the mechanical interlocking takes place inside the signal box. In fact any signal reading over facing points will have detection at each set of points to prove that the points are closed up correctly and any FPL is properly engaged. This means that pulling the signal lever may result in the Signal remaining at Danger (or, in the case of electrical detection, the signal lever not being released). In such a situation the view of the operating and engineering functions differ: we know the equipment is working correctly and preventing the signal from being cleared whereas the operators will see this as a failure.
During a failure the Rules prescribe the precautions to be taken before any movement can be authorised (ensuring the points are set correctly and applying a point clip if necessary). Apart from the feel on the signal lever, the symptoms are the same as if the signal wire had broken. In the case of a broken wire, it is important to ensure that any mechanical detection slides are pulled clear of the point detection before moving the points.
A 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.