Points

Points

Postby Martino » Sat Nov 22, 2014 5:40 pm

I am surprised to find that TT points do not isolate the side track (as in Hornby - without the additional spring connector). Do I have to use a piece of isolating track next to the point?
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Re: Points

Postby krokodil » Sun Nov 23, 2014 1:37 am

Martino wrote:I am surprised to find that TT points do not isolate the side track (as in Hornby - without the additional spring connector). Do I have to use a piece of isolating track next to the point?


If you remove the connection strips from the bottom of the points you will get isollated, but not switched points. This means after that you have to install a switch operated by the switchmotor to connect the power to the corresponding tracks.

(There are 2 different systems, In one system, preferred in UK the points automatically switches also the power to the corresponding tracks, while other systems prefer both tracks from the points always powered, so you have to cut the rails to get isolated areas.)
Greetings from Austria
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Re: Points

Postby railtwister » Sun Nov 30, 2014 8:57 am

Martino wrote:I am surprised to find that TT points do not isolate the side track (as in Hornby - without the additional spring connector). Do I have to use a piece of isolating track next to the point?


Typically, turnouts that route power to the diverging tracks will have both points bonded together electrically. This means that the open point will have it's polarity opposite that of the stock rail nearest to it, which can cause a "wheelback" short as a metal wheel passes through the flange way at that point, unless the flange way is exceptionally wide. With the higher amperage used with DCC (and the exceptionally fast circuit breakers usually built into most DCC systems), such momentary shorts can cause serious operational problems that might otherwise go unnoticed by someone operating on traditional DC. Also, using the contact of the point touching the closed stock rail to provide power is not very reliable, especially as the rails and points become older and more oxidized.

Bill in FtL
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