An upper quadrant automatic semaphore mounted on a 30ft post. The signal can take 2 positions over the upper quadrant: horizontal (STOP) and vertical (PROCEED).
Home and distant 2-position automatic semaphore signals appeared in NSW in the 1900s. Later (1920s?) a 3-position variant for use in areas with higher traffic densities started to appear. These were double-light semaphore signals where the lower light had a red/green spectacle arm in place of a distant semaphore. The semaphore had 3 positions but the 3 spectacles showed only 2 colours (red, green, green). By day, CAUTION was indicated by the semaphore at 45 degrees, while at night the light indication was green over red.
In country areas where the distance beteen station limits was large, semi-automatic, double-light absolute signals could be used within station limits. The signals operated automatically when the station was unattended.
Starting signals protected entry into the section beyond the station limits. Where the signal in advance of a starting signal was a distant signal, then the former had no need to indicate CAUTION (because this function was provided by the distant signal). The signal employed the same semaphore lenses as the automatic distant signal (red,red,green). The semaphore operated in 2 positions: STOP (semaphore horizontal, lights red over red) and CLEAR (semaphore vertical, lights green over green). The intermediate 45-degree position of the semaphore was not used.
Each signal was controlled by a nearby relay hut ('NSWGR automatic signal relay hut', kuid:368725:20070) in which track-circuit detections were converted into signal-motor instructions to set the semaphore position. The spectacle arm of the lower light was driven from a jointed rod that connected it to the semaphore. The complex movement of this rod is beyond my skill to animate, so it has been omitted from the model.
The signal has a black name board mounted on the pole with white characters aligned vertically. This board can be populated by the user via the Properties editor in Surveyor mode. Actual names used for these signals followed the format <single alphabetic line code (optional)><distance from Sydney Central to the first decimal place>. Line codes were only used in the Sydney and Newcastle(?) suburban networks where there was parallel running of different lines.
Тип: Сигнал