Linear reciprocative pseudogears
Basically intermeshing racks with angled teeth.
Not referring to the attack angle but to the angle relative to the tacks normal vector.
But unlike racks they are used like gears to …
– get transmission leverage rations (gear-up / gear-down)
– get the functionality of a mechanical differential
… thus "reciprocative (pseudo)gears".
(wiki-TODO: Add visual examples of use as gearing transmission and as differential.)