semaphore signal

 

Railway semaphore signal is one of the earliest forms of fixed railway signals. This semaphore system involves signals that display their different indications to train drivers by changing the angle of inclination of a pivoted 'arm'.

Semaphore signals were patented in the early 1840s by Joseph James Stevens, and soon became the most widely used form of mechanical signal.

Designs have altered over the intervening years, and colour light signals have replaced semaphore signals in most countries, but in a few they remain in use.

 The first railway semaphore signal was erected by Charles Hutton Gregory on the London and Croydon Railway  at New Cross, southeast London, about 1842.

 The semaphore was afterwards rapidly adopted as fixed manual signals throughout Britain and the United States superseding all other types in most uses by 1870.

Components

The semaphore signal arm consists of wooden or metal arm  and a spectacle holding colored lenses which move in front of a lamp in order to provide indications at night.














Horizontal position of arm indicate 'stop' or danger and when arm is lowered at an angle vary from 45º to 60º, it indicate “proceed”.

 

 

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