--- In STMFC@..., "railwayman" <stevelucas3@...> wrote:
I actually agree with you. I suppose I should mention that I'm the guy responsible for the Accumate PROTO:HO coupler, which has the pivot .176" [4.47mm] from the end of the box (striker) and .205", 18 scale inches behind the striker horn of the coupler head. Those dimensions were chosen for a couple of reasons; since the pivot point is also the mounting screw, it needed to be back far enough to engage the car floor, not the edge of the end, and the Kadee 711 "Old Timer" coupler also uses a similar dimension. Frank Sergent then chose to use the same dimension for the narrow shank version of his scale working knuckle. Why Kadee didn't also adopt this dimension is a mystery to me, especially when they already make a product that uses it, but I'm hardly in a position to tell them what to do.
However, I pointed out the limitations of the prototype operating on these tight radii because those who try to do this need to understand those limitations. If one wants to switch freight cars on 90' radius curves, you need to use a short locomotive with a short end overhang, or you need a locomotive equipped with a radial drawbar, or the old hobby standby, the overly wide coupler box. If one builds the Bronx terminal, then decides to switch it with a GP-9, it's just not going to work, not if the GP-9 has scale couplers.