Tag Archives: restoration rotary pendulum clock

torsion pendulum clock

A patience-related work is the restoration or repair of a rotary pendulum clock.

A rotary pendulum clock is, as the name implies, a mechanical clock that generates the clock from a pendulum rotating around its own axis. The vibration energy is transmitted here with a torsion spring (Horolovar spring), ie a very fine steel wire special alloy. IMAG1268_1 The rotary pendulum clock is also called annual clock, as due to the very slow oscillation and corresponding mechanical implementation of the escapement, a lift of the spring accumulator only once in 300-400 days is necessary.

Of course, this also requires a certain precision of the mechanical components. If something is not set correctly here, the clock will switch off after a few minutes. Even the fine adjustment of the accuracy requires some patience. And just like a clock has done to me. In an online auction house, I have a cheap ‘defective’ but purchased from the components ago complete rotary pendulum clock and immediately started to disassemble and clean the parts.

IMAG1265
Knurled screw for the pendulum diameter

 

IMAG1266
suspension spring

After this work we went back to the assembly. The Horolovar feather was replaced by a new one. Now we went to the adjustments. First, I had to find out how many pendulum oscillations, more precisely half vibrations, should make the clock in one minute. At my watch (a Kundo) these are eight beats. The easiest way is to use a stopwatch to measure the time it takes to reach the 8th half-cycle. For example, if the measured time is over one minute, the watch will run too slowly and must be adjusted with the thumbscrew (the one that changes the position of the pendulum weights in diameter). Turning the thumbscrew clockwise will make the clock slower and counterclockwise faster, of course.

Hemmung mit Ankerplatte
Escapement with anchor plate

It should be a precision of +/- 1 minute per month possible. So a deviation of 12 minutes a year. Of course this requires optimal environmental conditions. (constant temperature and humidity, as well as a firm, vibration-free state)

 

 

 

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