An upper quadrant motor-worked semaphore mounted on a 12ft doll that is cantilevered 5ft to the right from the top of an 18ft post. The signal can take 3 positions over the upper quadrant, but only 2 positions are valid: horizontal (SIGNAL FAILED), 45 degrees (CAUTION, OBSTRUCTION AHEAD or DIVERTING PATH SET) and vertical (CLEAR AHEAD on main line).
Home (absolute) and distant (permissive) 2-position automatic semaphore signals appeared in NSW in the 1900s. Later (1920s?) a 3-position variant of the absolute signal 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.
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.
The starting signal in the rear of the absolute signal protecting entry to a country station's yard was too far away to provide a CAUTION indication when the station yard was occupied. Instead an automatic distant signal was placed in the rear of the absolute signal at a distance that would allow all trains to come to a stop at the absolute signal if required.
The distant signal had the semaphore mounted below a red/green auxilliary light, whereas the absolute signal had the semaphore above the auxilliary light. The distant semaphore had 3 positions (including failed horizontal position) but the 3 spectacles showed only 2 colours (red, red, green). By day, CAUTION was indicated by the semaphore at 45 degrees, while at night the light indication was green (auxilliary light) over red (semaphore light).
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 upper 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.
No telephone is provided at a distant signal as they normally cannot show STOP. Because trains cannot stand at the distant, and there is no telephone, it is not necessary to provide a label for a distant signal.
By opening the asset Properties editor, the user can set the number of signals (max 6) in advance of the distant of which the script will test the state. The distant will only display PROCEED if the specified number of signals in advance are all in the EX_PROCEED state (State 8).
Тип: Сигнал