A discussion came up on lugnet.trians not to long ago. In order to move the wheelsets of a car further from the edge of the car, a coupler was needed that could be attached directly to the car. To allow cars to make it around the sharp corners the couplers needed to pivot while the car was being pulled, but the coupler also needed to stay straight when the car was being pushed.

Here is my solution to the self-centering extended coupler.

In pull mode the coupler is free to rotate.

In push mode the coupler is pushed backward and stays centered.

But more important than staying centered, when the car enters a turn in push mode the coupler can still pivot.

When the car exits the turn the coupler is pushed back to the centered position.

This system was tested on a very lightweight car and works in a standard curve and when a car is pushed or pulled through a switch that connects a single track to two parallel tracks. There are still two problems with the coupler, since I am not using this coupler yet I have not addressed the issues. (1) The magnet is too high, but this is easy enough to fix. (2) The slack action caused by this design is extreme! The coupler needs some room to move, and in this design the coupler can move 2 studs. One stud is not enough space; I think 1.5 studs would be enough but I have not tried to optimize the design.