Ratchet

The back-and-forth movement of the Mystery Clockís pendulum must be converted to rotary movement to turn the gears and the hands.  This is done with a ratchet and pawl mechanism.

For this mechanism to function properly, the back-and-forth movement of the driving pawl must be within a certain range of travel. Too little, and the pawl wonít pull the ratchet wheel far enough for it to jump to the next tooth on the wheel. Too much, and the pawl will jump two or more teeth.

Letís look at how the Mystery Clock deals with this problem.

The Mystery Clockís pendulum pivot employs a special design. At about 15 degrees and more of travel in one direction, the pivotís outer surface is a constant larger radius (R1). At about 15 degrees of travel and more in the opposite direction, the outer radius is smaller (R2).  In between, the radius constantly varies in a smooth curve.

A lever is located next to the pivot.  A wheel, actually a bearing, is in contact with the pivotís outer surface. The pawl is attached to the lever such that the movement of the lever at the pawl is amplified.  A weight on the end of the lever keeps the wheel in contact with the pivot.

When the pendulum swings left, the pivot pushes the lever right, and likewise the pawl (not shown) also moves to the right.

If the pendulum swings even more to the left, the wheel rides on the constant radius portion of the pivot, so the lever, and the pawl, move no farther.

Movement to the right is similar.

The result is that for any swing of the pendulum between 15 and  25 degrees, the range of movement of the lever, and therefore the driving pawl, is constant.

[Home] [Clocks] [Numechron] [Sychronicity] [Mystery] [Naked] [7 Day] [Custom] [Lake maps] [CarveWright] [Custom] [Orders] [About Us] [Contact] [Stuff]
 
dick@carveshop.com
website design software