Model 38: rotating Scotch Yoke mechanism


Kinematic scheme:




Points A0 and B0 are fixed pivots. In the model point B0 can manually be displaced in the direction of A0. The Scotch Yoke slides relative to the input link (the outer disk), performing a sine function with amplitude A0B0. The output body the coloured disk that is co-axial with the input link - obtains a superposition of the input rotation and the relative sliding motion. To perform the superposition a gear-and-rack could be applied, but in this model a toothed belt is used for easiness of construction. With proper amplitude, when distance A0B0 equals the radius of the output pulley, the output motion shows an infinitesimal dwell. This is demonstrated in the graph of the transfer function.

This mechanism can perform thus a continuous rotating stepping motion with a step of 360 and smooth motion. Another characteristic application is: non-uniform driving with run-time adjustable non-uniformity.









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