Chiltern Railways 165 at one of the Greenford Semaphore Signals.

[notentirelysure85]

These signals aren't very safe are they? If the linkage breaks wouldn't the arm fall to the "Clear" position even if it's meant to be showing "Danger"?

[GreatRailwayJourneys]

Your Quite Right, There have been a Few Fatal Train Crashes in the Uk when Semaphores show Clear instead of Danger,Usually in Cold Weather when the cables between the Signal Box and the Signal freeze,

I think the Upper quadrant signals are better as the Up position means clear and the Level position means Danger.

[paullubliner]

@GreatRailwayJourneys God's Wonderful Railway's Signal Engineers would beg to differ. That sheet steel blade weighs a great deal less than the cast iron spectacle on the opposite side of the pivot. They did serve with great distinction for say something on the order of 159 years or there abouts. (C.H. Gregory's patent of 1841.)

[LeamingtonSteve]

@GreatRailwayJourneys WRONG! They are counterbalanced by a weight at the base of the post

[roscalen]

It's been a legal requirement for many years that the arms must return to danger if the push-rod breaks. This is achieved by ensuring the weight of the spectacle casing is sufficient to more than counterbalance that of the arm.

[Yanamation]

Nowadays the semaphore signals which still operating the railways r very slow! As u see after the train passed the signal for a while, it's changed lately! But in the past, when the trains just passing the signals, they changed immediately!

[paullubliner]

@Yanamation That's entirely determined by the veracity of the signalman at the levers.