Russian jigsaw puzzle
When I restored a solidly built alarm clock made in the USSR recently, it became apparent that the cut-outs in the movement plates were designed to save brass and to save time with manufacturing processes at the same time. The photograph shows that the alarm escape wheel blank was sourced from one of two cut-out circles in the front and back plates. The alarm escape wheel is shown at the left side of the photograph and one of the circular holes can be seen in the back plate beside it. Also recognisable is the source of one of the winder handles.
If we now look at the front plate, shown at the right of the photograph, we can see the hole which was the source of the other winder handle, another circular hole the same size as the one in the other plate, and in exact detail, the source of the alarm stop wheel. Shown at the far right of the photograph, the alarm stop wheel is fixed on the alarm great wheel arbor. A pivoted stop arm interrupts the rotation of the stop wheel when the alarm stop button is pressed.
What came out of the other circular hole? I tried some of the other wheels. None would fit, so I thought that perhaps the brass disc had been used in some other clock made in the same factory. The day after I took this photograph, the thought occurred to me that it could be the alarm let-off disc, behind the dial. Sure enough, when I measured the disc, fastened to the back end of the pipe for the alarm-setting hand, it had exactly the same diameter as the circular holes in the plates. The Russian jigsaw had been solved!
Alf Wilford, Australia
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