A designer specified motion characteristics can be obtained using the double crank external Geneva mechanism presented in this work. This mechanism basically consists of double cranks and double curved slots that work together in generating the desired output motion. In other words, the profiles of the slots are defined based on the specified output motion. This feature opens the door for big motion improvements, such as minimizing the maximum acceleration and eliminating infinite jerk. Furthermore, it allows for stepping angles larger than 120 deg (the upper limit for simple Geneva mechanism) and even operates at smaller overall pressure angle. In this paper, the equations defining the slot profiles for some desired output motion are derived. The expression for the pressure angle as a function of the crank displacement angle is obtained. The equations are put into application by an example design of double slotted replacement Geneva mechanism, showing the applicability of the approach and the improvement gained in reducing the pressure angle.

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