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A three legged gravity design, this type of escapement
required a huge amount of weight drop since it turned at such a rapid rate. This is a shot
of the escapement as found. Again, it is difficult to associate this work with that of the
frame and movement wheel work. It is a clumsy, severely deficient design. |
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Look at this vague attempt at making an adjustable gravity
escape fly fan clutch. The rest of the fly construction was no better. |
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The original gravity arm locking pallets had white stones,
probably agate. An attempt at a better level of quality. |
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One of the three legs of the gravity escapement was broken.
Note the crude attempt at a repair. |
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The overall workmanship is rough. The design displays a poor
sense of proportion and balance - in short it's clumsy - if indeed it ever really worked. |
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A final parting shot as we bid farewell to this sorry state of
affairs. |
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Our first design was to have the overall shape of the gravity
escapement follow the upside-down heart shape originating in the going train frame. It is
already reflected in the pendulum design. Due to technical reasons, chief amongst them the
desire for a large set of anti-friction wheels to be used as our escapement impulse
pallets, we abandoned this. |
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The final design is developed incorporating the anti-friction
wheels. Other gravity escapements have used roller pinions positioned on the escape wheel
to reduce the friction point between the gravity arm and the impulse pins of the
escapement. Here we have a solid cam instead of pins or roller pins, but use large wheels
to greatly reduce friction. An additional benefit is that it is for more visually
interesting than any other design I've ever seen. I have Donald Saff to thank for this
idea as represented by the drawing he sent me (below, left). The original pendulum was
a 1 1/4 second, too long for the movement to be viewed at a comfortable height. The fact
that we altered the gravity escapement from three legs to four gave us the opportunity to
shorten the pendulum. Several design iterations were contemplated changing various wheel
and / or pinion counts. The last drawing was best, where only the escape wheel and it's
pinion needed changing. The pendulum was made to fit the wheel counts resulting in a
pendulum that beats just slightly longer than a standard 1 second. |
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Recreated gravity escape fly fan. |
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Overall shot of the escapement. |
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Locking jewels shown. The escapement is fully jeweled;
impulse, locking pallets and pivots. |
