Elgin used the Junghans movement for this watch. It’s an electro-mechanical movement, based on the principles invented by Leon Hatot (that’s why Junghans called these movements ato-chron – ato from Hatot, chron from the Greek chronos = time). The idea is to provide the moving force for a watch or clock by accelerating the pendulum or balance wheel with a coil that pulls a magnet. So no winding, and an electronic watch that is almost entirely mechanical.
The movement is completely encased in a shield made of sheet metal to protect it from outside electromagnetic influence. The gray bit at the bottom holds the coil and simple electronics. The coil consists of two coils, and the balance wheel is magnetic. When the balance swings, it excites the first coil, which switches the transistor, which opens and closes the circuit to the second coil, which pulls the balance wheel. The balance wheel is started by the hacking seconds lever when the crown is pushed in.
The electronic unit with the coil visible.
The balance wheel has a permanent magnet, which makes it a lot heavier than a normal balance wheel – one of the problems with this type of movement. There is a lot more wear on the balance pivots, and the watch is more prone to change its beat rate when moved.
If you follow the balance bottom jewel outwards, you see the Junghans star – the only indication that the movement wasn’t made by Elgin. Click on the photo to enlarge it and have a look at the pallet fork. The movement works “in reverse”. Instead of the pallet fork accelerating the balance, here, the balance moves the pallet fork, which moves the gear train. So there is almost no wear on the whole gear train. Also, check out the shape of the escape wheel. Again, it’s driven by the two pallets on the pallet fork, rather than driving it, so its shape is completely different.
The rest of the gear train is as usual. You can see the brass lever for the hacking second.
The bottom plate doesn’t give much away – apart that there is no provision to wind a mainspring.
As you can see, not a great amount of components. Off to the cleaning machine.
Time to put everything back together.
With the grey coil / electronics assembly from a donor watch and a new battery, the balance starts swinging straight away.
The dial and hands go back on.
Pretty cool watch. You’ll want one of those for your collection!