Hanhart, Type 217 Movement
(Impulsed; moving coil; mechanically
This movement is an example of a mechanically
switched moving coil balance wheel. The magnets are arranged in a circular
pattern and are fixed to the clock frame, and the coils are mounted on
the balance wheel. One coil contact is through the balance wheel, hair
spring and clock frame, and the other is through an insulated pin on the
under side of the balance wheel which touches a flat spring contact on
each swing. Mechanical switching of the current to the coils is subject
to fluctuations due to a build up of dirt and corrosion of the contacts.
Over time this can make the clock lose accuracy.
Drive to the hands is via an inverted Sully
escapement. The movement dates from the late 1960s.
|one LR14/MN1400/C size cell
Copyright Text & Pictures - Martin Ridout. Last updated