I love finding minor pieces of technology that I never would have thought about because they work so smoothly that they’re invisible. The picture above shows the existing non-original mechanism for the clock in a clock tower. You can see one clock face, but actually there are three, all driven by the same mechanism, with the one behind me and one off to the right.
The black cylinder on top of the middle pile of stuff is an electric motor, and the slivery cube below it is a gear box. The gearing (I assume) has two jobs: first, slowing down the motor’s shaft rotation to the very slow speed required of a clock; and second, splitting the motion from a single shaft to four, so that all of the clock faces will show the same time. Note that I say four even though there are only three faces: you can see the stub of a fourth shaft on the left side of the gear box. I’d guess that the gear box is a standard piece of equipment for installations like this, and if you only have three faces, you simply leave on side unused; if you only have two faces, you leave two sides unused.
In our current cultural moment, when just about everyone walks around with a cell phone that automatically syncs its clock, decorative clocks like this are more important as symbols and aesthetic elements than they are as timepieces. That said, it is annoying when the different faces on a clock tower display different times, and this set up, which is slightly more complicated than using a separate motors for each face, is more likely to have the faces synchronized.
One last thing: the gear box connection points are horizontal and oriented toward the walls, and the shafts for the clock hands are in theory horizontal with the same orientation. But the connections between the gear box and the shafts are universal joints, which allow for non-parallel movement. You can see that the shaft running to the right is not parallel – it looks as if the gear box is mounted a little too high for perfect alignment. But in real life, in a building, perfect alignment can be difficult, and using the joints means that there’s less risk of the hands binding in their bearings due to misalignment.
