Identification & quantity of components on fret:
1. 4ft plain distant arm (1)
2. 4ft plain home arms (2)
3. 4ft lipped-edge home arms (2)
4. 3ft plain home arm for sidings etc. (1)
5. 3ft lipped-edge home arm for sidings etc. (1)
6. 3ft backing arm (no more installed after 1947) (1)
7. 2ft4in disc for use under platform canopies (1)
8. Goods line arm ring (1)
9. Cranked balance levers (7)
10. Spectacle plates (8)
11. Rule 55 track circuit diamond (1)
12. Backlight blinders (6)
13. 2-way route indicator (1)
14. 2-doll bracket (1)
15. Disc signals (2)
SN15 2mm scale Great Western Railway/BR Western Region lower quadrant signal arm fret (including 2-doll bracket and route indicator)
This pattern of steel arm was introduced by the GWR in 1930, replacing the wooden design (SN14) which had been in use since 1887. These signal arms were used for all new installations after 1930, and although usually associated with tubular steel posts (SN30), also gradually replaced the wooden arms on their original wooden posts (SN17). The design was adopted by BR and Railtrack, and a very few lower quadrant semaphore signals are still being installed by Network Rail today, where replacement by colour lights is inappropriate. A few signals combined the new pattern arm with the old pattern spectacle plate.
The actual size of the fret is 42½ x 27mm; it is etched in 0.008" brass. For clarity, the photo shows the equivalent 4mm scale fret.
To see exactly what is involved in using these parts, download the instruction sheet as an Adobe Acrobat® file (185kb).