The pink shaft with a bevel gear is fixed.
The orange bush with a spur gear receives rotation from the input blue gear. The green satellite bevel gear has a pin sliding in a circular slot of the blue output cylinder.
The latter rotates and linearly reciprocates simultaneously.
If two bevel gears have the same tooth number, 1 revolution of the cylinder corresponds its 1 double stroke. This relation can be varied by using bevel gears with different tooth numbers.