I have seen this intersting product on the youtube.
There are some claws/gears on top of the cocking rod. In order to keep the holding device stable,there must be a ratchet to bear those claws like Greek's gastraphetes.
But what puzzled me is that after the man release the arrow, he pull back the cocking rod a litter first, then push forward the cocking rod to catch the bow string.
If there is a ratchet mechanism, he can't simple push forward the rod without disengaging the ratchet and claws.
Anyone can explain its working mechanism, sorry I can't post any picture in this topic.