Toy Clock

You may be familiar with toy clocks, those with no working parts. Just a couple of hands fastened to the center of a clock face, used by kids when constructing buildings from blocks and by teachers when trying to teach them to tell time.

These kind of toy clocks have a short coming that could be easily rectified and would go a long way towards helping kids learn to tell time. If the hour and minute hand were connected by gears then when one hand was moved the other would move in concert with it. This would establish the rule that these hands follow.

The gears would not need to be complex. A twelve to one ratio is all that would be needed. This could be accomplished with two pairs of gears. One pair with a three to one ratio, the other with a four to one ratio. Using one pair with 15 and 45 teeth would give you the three to one ratio, another pair with 12 and 48 teeth would give you the four to one ratio. Summed together they both give 60, which means they could all use the same pitch and the distance between centers of the two pairs would be the same.

Of course someone will complain that the kids will get their fingers caught between the hands. This could be alleviated by painting the minute hand on a disk and putting it behind the hour hand. With this arrangement there would be no opportunity for pinching fingers.