Signalling & Track
Signalling at Leadhills
The signalling at Leadhills has developed over a number of stages. The points at the north (yard) end of the Down Loop had originally been hand worked. The points at the south (Glengonnar) end required to be fitted with a facing point lock (FPL) because they are on a part of the line used by loaded passenger trains. The FPL originally only locked these points in the ‘normal’ position, i.e. set for the Platform Line. As an interim arrangement, by 1992 the points and FPL were worked from a two-lever ground frame which was released by the train staff. The hand points giving access to the single line from the engine shed and yard area were fitted with an Annett’s lock in 1994. To release the points, the train staff had to be inserted in the lock and turned, then a slide drawn across. The staff could only be removed from the lock once the points and the slide were returned to the normal position.
The re-assembly of the lever frame in the new signal box was completed in 1996. It is a ‘Saxby & Farmer 1888 Duplex’ frame of 17 levers, which are set at 102mm (4″) between centres. Originally it was envisaged that a major locking alteration could be avoided by designing the track and signalling layout at Leadhills along similar lines to that which the frame had formerly worked at Arrochar. The first signalling equipment to be worked from the signal box was based on that assumption.
To improve operational flexibility, two additional signals were brought into use in 2000.
As the layout at Leadhills evolved and consideration was given as to how it would be used in the future, it became clear that the interlocking would have to be redesigned to correspond with a revised layout of signals. In order to more sensibly group the levers together and seeing as a complete re-lock had to be undertaken, the opportunity was taken to rearrange the levers working all but one of the five signals already in use. The south loop points and the facing point lock continued to be worked by levers 7 and 13 respectively, to avoid having to alter their rodding runs. Luckily these numbers fitted in quite well with the new numbering scheme.
The lever frame was re-locked in 2003 to our own design, the locking work being carried out by members of the Bo’ness and Kinneil Railway.
All opposing signals are locked against each other, except when the ‘king lever’ (lever 12) is reversed. This enables the signal box to continue to be left unattended if desired, while the passenger train runs back and forth. When the king lever is reversed, the south loop points are locked in the normal position and signals 2 and 3 cannot be cleared, to prevent a second train being signalled from the yard towards the station. The wooden train staff is to be replaced by an Annett’s key and an Annett’s lock will be fitted to lever 12 to ensure that it can only be moved while no train is occupying the single line section.
Because the signalman’s view of signals 5 and 6 can be obstructed, electric repeaters were provided in the signal box (brought into use in 2004). The ‘calling-on’ signal (number 15) was also commissioned in 2004. This signal is used to admit a train into the Platform Line when it is already occupied by vehicles, e.g. when the locomotive is running round its train.
When completed, the signalling will be as shown.
The Signal Box
Above the lever frame is the signal box diagram showing all the signals and points along with their lever numbers.
The diagram was drawn in the later style used on the former Scottish Region of British Rail, using Computer Aided Design (CAD). In the photograph, all the levers are seen in the ‘normal’ position. When a lever is pulled to the forward position, it is said to be ‘reverse’. Each lever is fitted with a badge stating its number and description, as listed below. The badges also show the ‘pulls’, meaning any other levers which must first be pulled reverse before that lever can be pulled.
1 – (Spare)
2 – Sidings to Platform Line
3 – Sidings to Down Loop (Pull 4)
4 – Sidings and Down Loop
5 – Down Loop to Sidings (Pull 4)
6 – Platform Line to Sidings
7 – Up Facing
8 – Down Loop Starting (Pull 7)
9 – Platform Line Starting
10 – Down Advanced Starting
11 – (Spare)
12 – King Lever (Pull 13)
13 – No.7 Points F.P.L.
14 – Single Line to Down Loop (Pull 7,13)
15 – Up Calling On (Pull 13)
16 – Up Home (Pull 13)
17 – Up Outer Home (Pull 13)
The levers are interlocked with one another so as to enforce correct operation of the frame and guard against human error.