TOOTH STRAIGHTENING:
Bent teeth can be straightened if they haven’t been bent so far so as to
crack when they are driven back k into position. Check with a magnifier at the base
of the teeth that have damaged . If there is no visible start of a fracture line
then they will probably straighten without breaking. One or two teeth can be
straightened without much consequence on most spring barrels. The bigger the barrel
the more risk involved . #2 and #3 wheels are less critical, obviously because
less power is involved.
After the tooth is straightened , be sure to smooth the rough edges , taking
care to keep the original tooth shape as much as possible. Reinstall the gear in the
mechanism with the gear on the top and the gear on the bottom and carefully check
to determine if the gear train operates smoothly. This is a last resort fix: sometimes
it works; and sometimes it doesn’t . If a gear can’t be cut ans a replacement can’t
be found then the teeth must be straightened or replaced if the mechanism is to work.
GEARS:
The gears found in most clocks differ in several ways from other gears.
Usually the main wheel , 2nd wheel , and third wheels are part of a slow moving gear
train in time and strike and chime gear trains. The time train , particularly , is slow
moving all the way through the gear train. These gear trains work in an opposite
fashion from the gears; say; in an automobile. In a clock there are gears driving pinions
in a slow moving situation. In other situations there are pinions driving gears in a
speed reduction situation and gaining power as the energy is transferred through the
gears. In a clock , power is lost as the energy is transferred, Because of this , the tooth
design is cycloidal instead of involute. The gears are almost always brass and the
pinions steel because the brass is softer than the steel and will not wear out the
smaller pinions because there are many more teeth on the gear. In practice what
actually happens is exactly what should by design the pinion teeth and the brass
teeth both wear at the same rate if oil is kept out of the gear teeth. If , however , the
gear teeth are oiled they will destroy them selves , Looking at the illustrations you
will see that the involute tooth is stronger, but the cycloid is smoother and offers
less resistance to movement.