The pink gear is driving. The orange output shaft of a bevel gear oscillates. The two blue gears rotate freely on the orange shaft. The white clutch part is slidingly splined on the orange shaft.
The clutch connecting force is due to the weight on the green lever. The bevel drive on the right is for controlling the clutch. The oscillation forward and backward angles depend on transmission ratio of the said drive.
Instead of the weight action, the spring toggle mechanism can be used.
.
آی-ویدئو