When the four Die Glockes were built in a secret facility, they were launched into the Space via a complex of stones called the Henge, towards the end of the War.
Each Die Glocke was linked to a gold pocket watch called The Designator.
When the Power button is pressed the watch becomes part of the Holder (which in the story is the Deputy Reichsführer-SS Scott Sutton) and uses the electrical impulses from the brain to keep the Holder in the Timeline he set.
On the reverse side of the watch there's a symbol called the Schwarze Sonne – The Black Sun.
Each ray of the Sonne is an electrode, and each electrode shoots for melting the Holder's flesh so he can become one with the Designator. By setting time and coordinates the Holder wish to travel to, the watch will link itself to the nearest Die Glocke, also known to O.S.S. As Nazi Time Machine.
It will transport the Holder to the required destination.
If the Holder is somewhat rendered unconscious, the watch will take him back to the starting location from which he leapt from.
The Designator will still display the last timedate and coordinates set, just in case the Holder needs to get back and undo any mistake in the Timeline.
The Designator Pocket Watch
Die Glocke Time Machine