I was recently involved in some work on a clock tower in the Cronulla Mall . My teacher was centrally involved with several decades ago. At the time of the bi-centenary, a clock was given by Caltex to the Sutherland Shire, the clock having been made in 1770, the year Captain James Cook arrived in Kurnell.
The clock was made by Ainsworth Thwaites (of Thwaites and Reed) for Julion of Brentford.
When the clock arrived, it was not in good condition and my teacher was given the task of restoring it. This involved extensive work, including completely rebuilding the wooden barrels. It’s a testament to his good work that the clock remains in good condition all these years later. And those barrels are a work of art!
At the time, my teacher also installed an automatic winding system of his own design which has worked well up until the last few years when it has become a little unreliable. When we sat down with the Shire staff, it was decided to replace the winders and add a device which can keep the clock telling the correct time very accurately (a couple of minutes a year) and automatically change the clock for Summer/Winter time changes. Both the winders and regulator are made by the Cumbria Clock Company in England.
The winders consist of an epicyclic gearbox and an electric motor with switches to keep the weights near the top of their drop. The power from the weights is transmitted through the gear box to the drums via a chain and a custom made (according to the size of the barrel) split sprocket which is assembled around the drum and clamped in place by 12 grub-screws. The entire system can be removed from the clock without any evidence that the clock has had such a device fitted. You can see the added sprockets in the picture of the clock on the previous page.
The escapement and the setting dial of the clock
The regulator consists of a control box with a small computer and display, an ‘actuator’ which gently interacts with the pendulum and an infrared beam sensor which monitors the ticking of the clock. The basic mode of operation is this:
- you set the clock going slightly slow (a couple of minutes a week)
- The regulator monitors when the ticking of the clock is just getting into exact sync with an accurate internal timebase
- When that happens, the actuator gives the pendulum a push to put the clock ahead of the internal timebase
- The clock then runs until it has slowed down enough to get back into sync with the internal timebase and the cycle repeats (approximately once every couple of minutes).
The regulator performs the Summer/Winter time changes by simply pushing the pendulum gently to one side and leaving it there for either 1 hour or 11 hours, depending whether the time is going back or forward. The best way to understand this is to watch the video in the following link.
A view of the automatic winders installed under the clock
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