Three train, cast iron and steel strap frame construction. Bolt and shutter maintaining
power. Eight day duration; 1 1/4 second wooden rod pendulum. There is no escapement,
rather what is termed a 'free swinger' pendulum system is employed. A count wheel is
mounted on the pendulum. At each period of swing of the pendulum the wheel is advanced one
notch. Upon this wheel is a finger which once each revolution comes into contact with a
complicated set of levers that causes the main going train to be released, thus allowing a
roller to contact an incline plane on the pendulum giving it an impulse. This same set of
levers also raises the roller before the pendulum returns on the following swing. The
going train is then locked until the next cycle. This process occurs every 40 seconds. In
between the only work the pendulum does is the very small energy needed to advance the
count wheel. The pendulum performs no locking function in the conventional sense.
26.5"w x 40"h x 21"d.
This type of escapement contains elements of a remontoire in that there is a cycling of
the going train at determinate intervals mediated by an air brake (fly fan). It also has
elements of a gravity escapement, whereby the impulse is delivered by a mass of the same
amount at identical intervals directly to the pendulum, has no sliding friction and thus
needs no oil.
This concept was invented by Joseph Mannhardt of Berlin,
Germany in the late 1870's. To the best of my knowledge it was used exclusively by German
makers. One maker of tower clocks in the United States, Mathias
Schwalbach of the Star Tower Clock Company used this same system, along with the
crutchless type of escapement with pendulum suspension spring safety feature that was
commonly used in Germany. He was, however, a German immigrant who used the ideas of his
Click on the picture to go to a page for more detail.
The lower painted structure is derived from what would be from a conventionally
designed Förster tower clock. The upper steel colored structure contains the free swinger
mechanism. Clocks equpped with this type of escapement are quite rare as they were much
more expensive to make than a conventional Graham or pinwheel deadbeat, gravity escapement
or most types of remontoire.