Hi Ron.Let me ask you a question . Is 134' the largest length of turn table that Diamond scale makes.I would really like to see your finished model .I'm thinking about doing on a round house ( Modern ) module and I run large locos Dash 8s , DDX ,80 and 90 Macs so I will need a large TT
134' is plenty long enough for any of those...it can handle an 18" wheelbase locomotive. The DDA40X, the longest of all diesels, fits on a 90' turntable...which was a very common medium sized TT. Cheyenne, I do believe, is 120'...for the Big Boys.
In my previous post, I mentioned that Ron can fit a medium-large sized locomotive and an auxillery tender on his TT...here is what I meant by that:
NKP 765 & tender have a wheel base of 88'. An auxiliary tender would add about 44'. That requires a 132' TT. This is huge because there are water lines that need to be connected between the tenders. That, or having doubledeaded small-medium locomotives on the TT (I recall a picture of a pair of 3' 2-8-0s of the C&S on the CB&Q's Denver TT...120', IIRC). That is the principle functional benefit to a TT beyond 120'...unless you plan on running the S-1...with its 123'9" WB...the longest of any steam locomotive or diesel...don't know the length of the turbines...