Can you figure out what this does?

[John Delacour]

At 06:50 -0500 3/2/08, Farrell wrote:

>I don't understand how this device would significantly change 
>key/hammer ratio (I assume you are really referring to overall 
>action ratio)? Seems to me capstan and wippen heel are roughly in 
>the same place. Hammer knuckle and rep lever will be elevated 
>causing some change, but wouldn't that be minor? Please explain. I 
>don't get it.

Well, just from looking at the pictures it seems to me that when the 
half-blow rod pushes up the adjustable button, the red cloth at the 
bottom of the half-blow lever pivots on the capstan and the lever 
(wippen) is raised by the half-blow lever centre pin.  A _gap_ is 
thus created between the beige cloth at the top and the lever heel 
profile.  When the key is pressed, the half-blow lever pivots on the 
adjustable button and again the lever (wippen) is raised at the point 
of the centre pin, which is moving at about half the speed, or 
travelling about half the distance, of the capstan.  Ignoring other 
slight differences in leverage, it looks to me as if the lever is 
designed just as I said.  The half-blow lever is working according to 
exactly the same laws as a crow-bar or any other lever.

JD