Omega's patent winding and setting mechanism.

The Omega 1896 design with their patent setting and
winding mechanism.

From the user’s point of view, Omega watches with this system work as a normal pendant set watch, just pull out the crown, turn to set and press back in.

 

The design was intended to give (and does) a more positive and robust action to setting so as to persuade railroad companies and regulators that the watch was safe for railway use, reducing the chance of the time being accidentally changed. That failed to convince in the USA (probably not helped by the fact that Webb C. Ball, a key player, had a profitable business reselling American made railroad watches), but it was accepted in Austria, Australia and a few other places that had regulations regarding the design of pocket watches used on the railways.

 

The UK did not have any regulations for watches as the entire railway system had signalling of one sort or another so good time keeping was not a safety issue, just an annoyance for passengers when trains were late.

 

Which perhaps explains a lot.