LORENZ FÖRSTER, NÜRNBERG, GERMANY, c. 1880

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 homeland.

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.

   Forster_vid_1.mpg    Forster_vid_2.mpg   Forster_vid_3.mpg   Forster_vid_4.mpg    Forster_vid_5.mpg