The Keyless works

 
 

 
 

The keyless works is a rather strange name for one of the basic functions of the movement. The name indicates that there are key works as well! In the old days the pocket watches were wound by a key and the same key was used for setting the time, or hands. A clever invention by Patek Philippe in 1841 enabled one button to have the double function of both winding and setting the watch.

The double function is achieved in a very clever way by letting a clutch wheel slide back and forth on the winding stem. The stem is square at the portion where the clutch wheel slides so the clutch wheel will turn when the stem is turned.

 
 
  Here the Clutch Wheel (407) is in place at the square portion of Winding Stem. The Clutch Wheel can be shifted between two detent positions, winding and setting, by the Clutch Lever (435)

 
  1) Winding
  A view where the interaction between the Clutch Wheel (407) and the Winding Pinion (410) can be seen. The place of the Clutch Wheel in this case is in the winding position i.e. the Clutch Wheel engages the Winding Pinion through their Breguet (ratchet) teeth. Top right in the picture the detent function can be seen. An arm, called Detent Spring, made out from the Set Bridge (445) has two detent notches, in this case the when the movement is set in the winding position the Set Lever (443) is kept in the upper detent notch. The Clutch Lever (435) can be seen right below the Detent Spring.

 
 
  The rotation of the Winding Stem is transferred via the Clutch Wheel to the Winding Pinion, which in turn drives the Crown Wheel, see figure top right. The Crown Wheel (420) engages the Ratchet Wheel (415) which is fixed to the Barrel Arbor (195) by a square mount. When the Stem is rotated the Mainspring will be wound through this wheel and pinion chain.

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2) Setting
  In the hand setting position, with the winding button pulled out, the Set Lever (443) gives the Clutch Lever a force, which in turn pushes the Clutch Wheel to the left. This movement disengages the Clutch Wheel from the Winding Pinion and instead engages the Set Wheel, see the center in figure above. The Set Lever is fixed in this position by the detent post being moved to the lower detent slot in the Detent Spring.

 
 
  Turning the winding button in this set position gives the Set Wheel a rotation, which is transferred to the Minute Wheel which causes the hands to move. In figure you can see how the Clutch Wheel engages the Minute Wheel.

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