action ratios

[Bill Ballard]

At 11:59 AM +0100 11/1/02, Isaac OLEG wrote:
>I wonder something about the assist springs too :
>
>As they are less strong when the whippen is at letoff height than when
>at rest, they can lighten the beginning of the key move, or make
>heavier the letoff moment, depending of the way they regulate, if the
>difference is enough.

Agreed. This is one of the nice by-products in the behavior of srping 
balancing. The spring's effect is greatest at the beginning of the 
stroke, when you need help to get the parts moving up to speed. At 
the far end of the cycle, its effect is at its minimum, right where 
you want gravity (now about to pull the hammer back down) to have as 
little opposing competition as possible.

Kind of like the angled capstan. File the hammers, they get lighter 
and shorter. Raise the hammerline to compensate for the shortened 
hammerbore, and the angled cap moves backwards on the rep heel, 
raising the action ratio and compensating for the lightened SWs.

>Do someone try to measure the difference of efficiency between these
>two positions, in grams ?

One could certainly measure the rep weight at the start and end 
positions of its movement, giving you the decrease in balance weight 
due to the motions' lightening of the spring pressure. I'd guess it 
would fall in the bag of things resulting in the friction gradient we 
all encounter measuring DW/UW.

Bill Ballard RPT
NH Chapter, P.T.G.

"When writing a mental note, first procure a mental piece of paper"
     ............mental graffitti
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