Sector Plates - Any prototype Examples?

[Hobby]

I think Peter made my point better than I Keith! I was just trying to show one so BGJohn could get an idea what they look like in NG and "retro" one for his use, which it seems he's now doing, it is all about gathering ideas so something can be made which doesn't look out of place.. That German NG one in the photo would probably be old enough though not British!

[peter220950]

I think all I need is a brick lined pit, two girders supporting the rails, and wood planking between the rails to hide the framework and moving bits. Much like this, but without the concrete and the platform with the winding handle etc.

 

So, using materials and equipment that were readily available in the 1890s/early 1900s, what size girders would I need under each rail to support a 15 ton loco on a 17ft sector plate, with a pivot at one end, and supported on wheels running on a rail at the other?

 

 

It's years since I did any calcs, but I seem to recall a 'rule of thumb' was 3/4" per foot span as a rough guide (or 20 x thickness = span), this would bring you in at around 12" (I stand to be correct by any Structural Engineers), but it's also dependent upon your design. If there are a couple of intermediate rollers that run on radial beams on the ground, there's not much support needed as the load is being spread through 4 points on each beam ofthe carrying turntable, (At each end and the two intermediate positions), each beam therefore only having to support half the loco weight, through 4 positions, meaning the load at any given point where it meets the ground is less than 2 tons.

 

Standard Universal Beam sizes are here

 

http://www.elitesteel.co.uk/rsj-beams.php

 

and will give a reasonable idea of the proportions, I would go for either 254 or 305 deep, in reality probably whatever the fabricator had lying around that looked strong enough! Maybe check out Plastruct sections to see what's close to being credible. Eileens Emporium do a 7mm x 7mm 'H' section, which may be a bit too fat (but might not show), and a 5mm x 3mm 'I' beam that might work, if you were going down the metal route.

 

Peter

[BG John]

I've been having another look at this one, and it looks as if it wasn't for a loco run round. If what I can make sense of from this page is right, it was to give access to a siding, and this photo from the page seems to support that. So maybe it served the same purpose as a wagon turntable.

 

 

That doesn't mean I won't base mine on it though!