Paul Kallus posted:The O-54 diameter criterion could prohibit Lionel from using a shorter drawbar, but am not certain. The kinematic drawbar would work well - assuming I understand its design.
From swapping drawbars on Premier steamers I know that just 5 mm makes a huge difference in how tight an engine can safely make a turn without tender and cab hitting together.
Unfortunately, I don't posses the skills to cut and re-weld the existing drawbars.
Yes, true. Also, the slightest change in grade on a curve can make all the difference as well. If the front of the locomotive is slightly raised going through the curve, the back of the cab dips down and could hit the tender (whereas that might not happen if completely level throughout the curve).
And S curves really complicate the issue as well, which basically cause a kind of diagonal-drawbar situation that is the first place to require the longest drawbar on the layout. Avoid S curves (e.g., back to back 072, etc). Even a bit of a straight between them is much better!
