The automatic pull coupler (Z-AK) is a system compatible to the classic
screw-link coupler which is designed to speed up shunting and allow 
heavier trains. The side buffers are still needed with this system. The
air hose, and optionally the electric coupler, are coupled automatically.
110 prototypes have been built by Knorr-Bremse and tested successfully in
1996 by the DB AG. From 1997 on, this system will be standardized, and
can gradually replace the old couplers. As the system is backwards-compatible,
transition problems are not expected.

<p>Drawing by DB AG