Geneva Wheel

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WM2D File

Software copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.

Info

A Geneva mechanism converts the motion of a continuous rotating crank to a intermittent motion of the Geneva wheel. For a four-slot wheel, the Geneva wheel rotates 90 degrees for a complete rotation of a crank.

The mechanism was originally invented to prevent over-winding a watch spring. The watch spring was wound by the shaft attached to the Geneva wheel and the winding handle was fixed to the other shaft. When the designers omitted one of the slots they restricted the number of turns, through which the winding handle could be turned, thus protecting the spring. The mechanism is now used  for indexing purposes. For example, indexing of a turret of an automated lathe, an automatic tool changer in a milling machine, or  to move the film on one frame at a time in film projectors. 

Source

This Working Model file is adapted from Figure 2-12(a) on p.45 in Design of Machinery, 3rd ed. by Norton, R.L., McGraw-Hill, 2004.

Credits

This Working Model file was first developed by Fan (Michael) Mo.