Backlight Blinders

IanSpalding
Posts: 9
Joined: Tue Feb 08, 2011 8:54 am

Backlight Blinders

Postby IanSpalding » Tue Dec 31, 2013 5:18 pm

Hi,

I understand the basic principle of the backlight blinder (or back spectacle) is that they are not required when the signalman can see the front lights (unless for the information of the station staff) [Mechanical Railway Signalling Raynar Wilson p52]. My layout is LSWR 1908. I have a signal which has two arms: a starter operated by the West Box which can see the front of the signal and a Junction Up Distant which is operated by the Main Box and can see the rear of the signal. The rear of the signal cannot be seen by station staff. So, in theory, does the starter not have a backlight blinder and the distant does? Or is this confusing to the Main Box so both would have them?

A supplementary question is that there are actually two of these signals, a short (20ft) starter/distant at the end of the platform and a 45ft starter/distant repeater on the opposite side of the track. It is unlikely that the short signal can be seen by the Main Box (there's a bridge in the way among other things) but the tall signal can be seen. So, for whatever answer is given to the first question, would you not bother with blinders on the signal which cannot be seen but have them on the tall signal which can?

Regards,

Ian Spalding

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grovenor-2685
Posts: 3109
Joined: Sun Jun 29, 2008 8:02 pm

Re: Backlight Blinders

Postby grovenor-2685 » Tue Dec 31, 2013 6:05 pm

Seems somewhat unusual to have a distant so close to the box working it that a back light would be useful, normally a distant would have an electrical arm and light repeater. But if it is that close then a backlight blinder makes sense. No need for one on the starter as the distant would be slotted with it anyway.
Second part pretty self evident really, no use providing something that can't be seen, probably adequate to assume both work if one works, if not happy with that then an electrical repeater is called for.
Keith

IanSpalding
Posts: 9
Joined: Tue Feb 08, 2011 8:54 am

Re: Backlight Blinders

Postby IanSpalding » Tue Dec 31, 2013 6:59 pm

grovenor-2685 wrote:Seems somewhat unusual to have a distant so close to the box working it that a back light would be useful, normally a distant would have an electrical arm and light repeater. But if it is that close then a backlight blinder makes sense. No need for one on the starter as the distant would be slotted with it anyway.
Second part pretty self evident really, no use providing something that can't be seen, probably adequate to assume both work if one works, if not happy with that then an electrical repeater is called for.
Keith


Keith,

Thanks for the reply. The Richmond West Box is about 200 yds from the signal and the Main Box 300 yds in the other direction. Yes I assumed it would be slotted (Annetts slot) but I'll do the slotting electrically not mechanically!

Regards,

Ian


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