# semaphore



## Chewie46 (Feb 2, 2016)

what is the purpose of the 151 semaphore , where should I place it in my layout, and how should it operate. I'm kinda new to this. My train set is from 1949, and has been packed away for 40 yrs. thanks


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## Big Ed (Jun 16, 2009)

Chewie46 said:


> what is the purpose of the 151 semaphore , where should I place it in my layout, and how should it operate. I'm kinda new to this. My train set is from 1949, and has been packed away for 40 yrs. thanks


Here is an semaphore explanation for you, ( a copy and paste)



Semaphore signal

Perhaps the most classic of all railroad signals, the semaphore, came into general use in the 1860's. This type, based on an ancient form of communication that used a moveable "arm" or "blade," soon became by far the most common signal. 

Various signal indications were conveyed by setting the blade in different positions. The problem of night visibility was addressed by using lamps in conjunction with the blade. Semaphores were constructed with castings in which were set red, yellow, and green lenses, which were moved in front of a single white light (oil at first, later electric) as the blade moved. 

At first, the "lower-quadrant" semaphore design was used - the blade moved in the lower-right portion of an imaginary circle whose center was the blade's pivot point. Most lower-quadrant semaphores had two aspects: A horizontal (raised) blade meant "stop;" a blade hanging down about 60 degrees from horizontal meant proceed. Lower-quadrant blades had to be counterweighted so they would go to the horizontal position in case of failure of the controlling mechanism. Although there were three-position lower-quadrant semaphores, the two-position Union Switch & Signal "Style B" of 1898 (usually employing two arms) has come to be the best known. 

Shortly after the turn of the century, the three-position (vertical, diagonal, horizontal) upper-quadrant semaphore was introduced. It had three aspects: horizontal for stop, 45 degrees above horizontal for caution, vertical for proceed. In 1908 this type became the standard for new installations. Such signals still exist on several roads. With the advent of light signals, semaphores came to be seen as inherently inferior, since they used two different aspects - blade position by day and light color by night - to convey their message. Also, their relatively numerous and heavy moving parts made them less attractive from a maintenance standpoint. 

One place to check the status of sempahores still in use on U.S. railroads is the Web site www.semaphores.com.


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## DonR (Oct 18, 2012)

Big Ed's explanation is very complete.

What it fails to clearly say is that the purpose of
the semaphore is to convey to the approaching train crew
the situation on the track ahead of him so he won't crash
into an earlier train. That is done today by the trackside
lighted signals as well as in cab radio and satellite communications.

Don


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## bluenavigator (Aug 30, 2015)

Oh, I had not seen these semaphores in age! I didn't realize that they are disappearing... Thank to higher technology!


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## cv_acr (Oct 28, 2011)

Yeah, the semaphore is basically just an older version of a signal, with a light and corresponding physical moveable blade instead of a modern color-light signal.

They were used for interlocking, approach, and block signals, as well as for train order signals. (Most of the time, train order signals were still semaphores when regular signal systems were replaced or implemented with light signals.)

Train order signals informed train crews that they had orders to pick up when passing a station (to simplify -in the early days reliable radio communication was not available and Timetable/Train Order operation was all designed to work in the absence of direct contact between the dispatcher and train crews with orders passed up by station operators)

More discussing of how/where/why the signal might have been used requires a much fuller understanding of railroad operations and how signal systems work - except for a train order signal at an open station, signals don't exist in isolation (and technically the train order signal isn't really in isolation either).


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## Chet (Aug 15, 2014)

I managed to get my hands on a real semaphore signal and installed it outside my shop. When I'm in there working on my classic cars, I set it on green. If I have to go to the house but will be back it goes to yellow and when I'm not in the shop it goes to red. My wife wouldn't let me put in at the end of the driveway. No sense of humor.


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