Pedal cocking device for Divine-Armed-Crossbow/Shen-Bi-Nu

I found some very interesting video on the youtube website.This guy reproduced a list of famous ancient crossbow items,for example,Greek gastraphete, Roman catapult,modified chinese repeating crossbow,electrical aid repeating crossbow, traditional chinese crossbow triggers and Divine-armed crossbow.

Here is the link of divine-armed-crossbow for those unknown.

www.youtube.com/watch?v=7LkIXFQU9B0‎
www.youtube.com/watch?v=_siUBX_JH_g


Some useful picture can be seen in the website.
http://www.guokr.com/post/552737/




The ancient historical description of divine-armed-crossbow:
Bow span - 98cm
Length - 140cm
String length - 77cm
Effective range - 150m
Maximum range - 370-460m


It is recorded as the most powerful crossbow for single soldier in the ancient china. It represented the highest technical level of single soldier crossbow. After it, the fire arms gradually replaced its role on the battlefield. In order to protect enemy states from its technical statistics, any further description was strictly forbidden, So the most important cocking device was lost after the coming Ming dynasty.

(Sony dynasty[invent 宋代发明]-->Mongolian dynasty[in use元朝继续使用]--->Ming dynasty[lost 明末失传])


I was confused for this guy's replica of Shen-Bi-Nu. It may not the true ancient Shen-Bi-Nu，but this method is quite impressive. I got some questions here:

1. I don't know the reset principle of pedal cocking device without the help of spring.(Up---Down---Up---Down----)

2. I can see the ratchet in the cocking device to prevent the mis-firing of the bow string. But I don't know the mechanism of cog-release.


Any genius can draw and design such a pedal cocking device ? Great appreciate.