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#20 Turnout in HO Gauge


trisonic

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You'll have to explain a bit more about US terminology I think for most people to know what a #20 is. Im guessing its a 1:20 crossing at the moment but no idea about the switches..

Hi Craig,

 

Traditionally, US switches are straight loose-heel switches. The switch lengths are arrived at by cutting standard 33ft rail lengths in half, thirds, etc., so are 11ft-0in, 16ft-6in, 22ft, 33ft. The heel offset is always 6.1/4"

 

I imagine for a 1:20 crossing the switch would be 22ft or 33ft.

 

regards,

 

Martin.

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A couple of documents in the meantime using the Black River Railroad as an example (a local to me shortline):

 

1. Track Standards and Specs:http://www.bdrry.com/Black%20River%20Railroad%20System%20Track%20Standards%20&%20Specifications%20100101.pdf

 

2. "Request for Proposals (turnout replacement):http://www.bdrry.com/2010%20Track%20A%20Turnout%20RFP%201002.pdf

 

I think Martyn has already seen these - in any event they are useful to have to hand when discussing US Specs.

 

Best, Pete.

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In the July 2011 NMRA Magazine there's an interesting article (6 pages long) on how a # 20 turnout was made in 3.5mm/ft.

The thing ended up 3 feet long.

1:20 turnouts can be built using the same techniques as fo any other turnout, there is just more of it!

Easy enough to fill 6 pages with any turnout construction article if you include plenty of pictures.

I have an F20 in P4 that I built as a demo back in 1968, I had to remount it on a new bit of board for exhibiting at the 25th anniversary and the alignment was a bit upset by that, but it still sits around under the layout.

Its actually 27" toe to nose and of course would need as much again before the tracks separate to clearance.

Some PICs following.

post-3169-0-84168500-1309039673_thumb.jpg

post-3169-0-66831400-1309039701_thumb.jpg

post-3169-0-99061100-1309039728_thumb.jpg

post-3169-0-38473300-1309039758_thumb.jpg

When I built this it was considered a high speed switch (turnout speed 50mph) and the longest available on BR was a G28, with the higher speeds nowadays turnouts go up to a 'J' switch with 1:44.5 crossing, this has a turnout radius of 5.6 km. and turnout speed of 125mph.

Regards

Keith

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this has a turnout radius of 5.6 km. and turnout speed of 125mph.

Regards

Keith

 

That scales to 255ft radius in 00 !! Makes my Peco large radius points look very sharp, though the HST still negotiates them :D

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Most of these large radius points have multiple stretcher bars which can be actuated in sequence looks a bit odd the switch rail seems to snake. I think Chris Turnbull made one in 0 not sure if he used it on his Cromer layout.

Don

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All the ones I have ever seen have all the stretcher bars moving in synch. I don't think the P-way engineers would appreciate having their carefully crafted switchblades made into sine waves.

So would be intrigued to see an example.

Regards

Keith

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