The transimission-wheel and click auto-winding construction is one of the auto-mechanical watch winding constructions. There are many other ways, such as revesing wheel construction. But the transimission-wheel and click auto-winding construction is the simplest construction and it is the most accepted widing constructure. The edge of the transmission-whell is full of helical teeth. The two clicks are very sensitive to the the rotation of the rotor, even though the amplitude of the rotor is not too big, it can winding the spring as well.
Looking from the structural principle, i think its actually a kind of variation motion from circling motion to rectilinear motion. The pivot of the clicks is set under of the rachet wheel and the eccentric direction of the eccentric click is exactly in the wheel block hole of rachet wheel, that means this hole is a position mark.
But there is a problem. Because the relationship between the rotation of the rotor and the motion of the transmission-wheel is not a homogeneous linear relationship, so there is a dead angle. When the pivot of the click is on the position of the line between the transmission-wheel pivot and the rachet-wheel pivot, the widing process is noneffective, while when the angle between the click pivot and the pivots line of the transimission-wheel and the rachet-wheel is 90 degree, the winding process is most effective. So the relationship between them is mostly like a sine relationship.
In the late 1970s, Seiko was selling the 6119 automatic watch. This watch is using this winding constructure and there were no manual winding system at that time, the winding process is totally automatic. They called this auto-winding constructure "MAGIC LEVER", because they were very accepted with this constructure. But there were still some people concerning about the abrasion of the helical teeth and the clicks. But it has been proved that that worry is unnecessary, because the pressure of the clicks on the transmission-wheel is not too much and the special molybdenum disulfide lubricant can reduce the friction of the components.
So, when you install the rotor of the auto-winding watches, pay attention to the position of the the wheel block hole of the rachet wheel. You should set the rotor in the time of the the rotor center in the 3 o'clock position when the arm is naturally prolapsing and notice the position of the wheel block hole. The angle between the hole and the pivots line of the transmission-wheel and rochet wheel must be a right angle, or it will influence the auto-winding efficiency.
