The Accutron 218

The Accutron 218 would probably be the most common type you will find. It is an excellent movement, both for its functionality and also relative ease of repair (by watch-repair standards that is). It can be found with a great variety of case styles. The many derivatives of this calibre movement are mainly seen as variations of the date and day function. 12 and 24 hour versions are also seen. A very collectible version is the "Astronaut" in which it is possible to change the hour-hand indication without disturbing the time displayed.

Click to enlarge

There are a couple of variations to the electronics and hack mechanism that I know of. This is the device which stops the watch when the crown is pulled out for time-setting. I have not seen all of the derivatives listed above, so it is possible there may be more variations still.

Std 218 Component Coil	Std. 218 Pillar Plate

The pics above shows the component coil assy for a standard 218 (ie 2180, 218D, 2181, 2182). The ground plate is indicated by an arrow, because changes were made to this in other 218's. The ground plate on these models has a permanent electrical connection to the pillar plate by a screw, which also acts as a mounting screw. When the watch crown is pulled out, a small pin attached to a lever (the Hack Lever) lifts the pawl finger off the index wheel, stopping the watch. The electronics continue to function as per normal and the fork keeps humming. When the crown is pushed back in, the pawl finger re-engages the index wheel, which begins to turn again. Simple and effective.

Model 2181F Pillar Plate

This version still has the standard component coil assy, however, the pillar plate hole which receives the ground-plate screw has been replaced by an insulated bush. Thus the screw is now isolated electrically from the pillar plate. The standard ground screw is replaced by a longer gold-plated one which has a tip that projects through the other side of the pillar plate. This forms one of a pair of contacts. The other contact is made of a gold-plated leaf spring which is attached to the pillar plate. These contacts are operated by the setting lever.

The effect of this is to form an electrical disconnect switch to stop all current flow when the crown is out. This means the watch could be stored in setting position, without draining the battery, a feature found on some other models, ie 2210.

But there is more....Bulova also replaced the hack pin with an adjustable collett, which touches and instantaneously stops the tuning fork from vibrating. I am mystified why they did this. The only reason I can think of is that they decided that lifting the pawl finger was not such a good idea, as it might change the pawl finger tension slightly and thus affect the watch accuracy. However, 25-30 years later, who can say whether this was really a problem. There are thousands of standard 218's out there humming away just fine.

Model 2181G Pillar Plate

With this model, Bulova changed the hack system again. They dropped the idea of the stop collett on the hack lever, and again used the hack pin, which as before, lifts the pawl finger off the index wheel. The component coil assembly was modified from the standard type, and the ground plate was deleted. Instead, a contact plate was fitted to the underside of the plastic molding, and this projected through a hole machined in the pillar plate. The original ground screw position was retained, but its only purpose was to serve as a mechanical mounting point.

In this new machined hole in the pillar plate, a contact spring was fitted (different to the 218F type). These two contacts were operated by the setting lever (modified yet again to suit). Again, whether this could be considered an "improvement" is doubtful in my opinion. The only advantage I can see is the ability to disconnect the battery when the watch is in setting position, same as the 218F.