:What got me wondering was that small horizontal bar down from the signal arms that should have some significance and indicate a " non-human semaphore " ( or a definitely, um, male human ) . ..
22.
Drivers of trains must know which signal arm applies to which route, and the speed limit on that route; accidents have resulted from drivers either mis-reading splitting signals or forgetting speed restrictions, and consequently approaching junctions too fast.
23.
The levers each were lockable in four different positions, that exactly corresponded to the position of signal arm : 0?( arm hanging downward parallel to the mast ), 45? 90?( perpendicular to the mast ), and 135?
24.
On changing from the'warning'aspect ( Vr 0 ) to the'clear'aspect ( Vr 101 or 102 ) both halves of the disc folded to the rear, so that, in their place, a signal arm appeared pointing up and to the right.
25.
Since by day the signal arms were clearly visible from the signal box from which they were worked, the system had no repeater in the signal box to confirm a signal was actually showing the aspect corresponding to the lever position.
26.
The advantage of the upper quadrant signal is that should the signal wire break, or the signal arm be weighed down by snow ( for instance ), gravity will tend to cause the signal to drop to the safe " danger " position.
27.
At night ( or in poor visibility in daytime ) an oil lamp displayed a white light when the signal was at'all clear'; when the signal arm moved to the horizontal danger position it brought a red lens in front of the light, so that a red light was then displayed to oncoming trains.
28.
If you have a long signal arm and a short, heavy counterweight-then much more snow / ice can accumulate on the signal arm and the longer moment would compound that problem to the point where the arm would be too heavy to lift . Then it would show " clear " when it's not clear-which would be " A Very Bad Thing ".
29.
If you have a long signal arm and a short, heavy counterweight-then much more snow / ice can accumulate on the signal arm and the longer moment would compound that problem to the point where the arm would be too heavy to lift . Then it would show " clear " when it's not clear-which would be " A Very Bad Thing ".
